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doi: 10.16030/j.cnki.issn.1000-3665.zhenggaoqishi
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doi: 10.16030/j.cnki.issn.1000-3665.202212043
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2023, 50(6): 3-13.
doi: 10.16030/j.cnki.issn.1000-3665.202303060
Abstract:
The supra-permafrost water is a vital water source to support the ecosystem and an important link in maintaining the hydrothermal cycle in the permafrost area. Under the intensification of climate change, scientific understanding of the effect of permafrost degradation on the supra-permafrost water is of great significance to water resources and ecological protection. Focusing on the hydrological effects of permafrost degradation in the source areas of the Yellow River, this study analyzed the degradation characteristics of permafrost, and revealed the response of the depth of groundwater level and recharge process of the supra-permafrost water to the permafrost degradation, on the basis of the temperature and moisture content of frozen soil at typical monitoring points and the runoff change at the Huangheyan Hydrologic Station. The results show that the average temperature increased 0.42 °C at the 0−2.4 m profile of the monitoring point from 2010 to 2020. The depth of the upper interface of the permafrost reduced from 2.1m to 2.5 m, with an average decrease rate of 4cm/a. After 2018, the depth of supra-permafrost water level reduced from less than 0.9 m to 0.9−1.8 m. The permafros degradation led to the runoff process in the melting period of active layer (May−October) being advanced, the ratio of extreme value being reduced, and the runoff hydrograph in January being more prominent. Ground temperature is the dominant factor in controlling the changes of depth of the supra-permafrost water. Under the condition of warm and humid climate change, Permafrost degradation would change the dynamic characteristics of the water above the frozen layer and its hydraulic relationship with surface water, affecting the hydrological and ecological processes in the source area of the Yellow River.
The supra-permafrost water is a vital water source to support the ecosystem and an important link in maintaining the hydrothermal cycle in the permafrost area. Under the intensification of climate change, scientific understanding of the effect of permafrost degradation on the supra-permafrost water is of great significance to water resources and ecological protection. Focusing on the hydrological effects of permafrost degradation in the source areas of the Yellow River, this study analyzed the degradation characteristics of permafrost, and revealed the response of the depth of groundwater level and recharge process of the supra-permafrost water to the permafrost degradation, on the basis of the temperature and moisture content of frozen soil at typical monitoring points and the runoff change at the Huangheyan Hydrologic Station. The results show that the average temperature increased 0.42 °C at the 0−2.4 m profile of the monitoring point from 2010 to 2020. The depth of the upper interface of the permafrost reduced from 2.1m to 2.5 m, with an average decrease rate of 4cm/a. After 2018, the depth of supra-permafrost water level reduced from less than 0.9 m to 0.9−1.8 m. The permafros degradation led to the runoff process in the melting period of active layer (May−October) being advanced, the ratio of extreme value being reduced, and the runoff hydrograph in January being more prominent. Ground temperature is the dominant factor in controlling the changes of depth of the supra-permafrost water. Under the condition of warm and humid climate change, Permafrost degradation would change the dynamic characteristics of the water above the frozen layer and its hydraulic relationship with surface water, affecting the hydrological and ecological processes in the source area of the Yellow River.
2023, 50(6): 14-24.
doi: 10.16030/j.cnki.issn.1000-3665.202305018
Abstract:
The Loess Plateau region is seriously affected by soil erosion, water scarcity, and fragile ecosystems, which severely hinder social and economic development in the region. There is currently a lack of quantitative analysis and research on how human activities will affect the changes in water and sediment on the Loess Plateau and how to allocate the areas for reforestation and grassland restoration. This study focuses on the Beiluo River Basin in the Loess Plateau, analyzing the spatiotemporal variations of precipitation, runoff, water resources, sediment yield and normalized difference vegetation index (NDVI) over the past 20 years. The study establishes a distributed hydrological model for the basin, quantitatively evaluates the impact of returning farmland to forests and grassland on water resources and sediment transport, and explores the optimal land retirement plan under different decision-making conditions. The results show that the total water resources, runoff, groundwater resources and sediment yield in the basin are decreasing, and the annual reductions are 7×108 m3, 1×108 m3, 1.2×108 m3, and 1.6×104 tons respectively. While NDVI and precipitation is increasing, and the annual increases are 0.0064 and 65×108 m3 respectively. The continuous increase in NDVI has resulted in a reduction in runoff volume and sediment transport. Returning farmland to forests and grassland or increasing vegetation density can reduce the amount of runoff and sediment transport, with sediment transport being more sensitive. Considering both the impact on runoff and sediment transport, based on multi-objective optimization, an optimal allocation proposal for the area of returning farmland to forest and grass is proposed. The optimal land retirement area is 28.1%. This study provides decision-making support for ecological environment construction, soil and water conservation, and rational utilization of water and sediment resources in the Loess Plateau region.
The Loess Plateau region is seriously affected by soil erosion, water scarcity, and fragile ecosystems, which severely hinder social and economic development in the region. There is currently a lack of quantitative analysis and research on how human activities will affect the changes in water and sediment on the Loess Plateau and how to allocate the areas for reforestation and grassland restoration. This study focuses on the Beiluo River Basin in the Loess Plateau, analyzing the spatiotemporal variations of precipitation, runoff, water resources, sediment yield and normalized difference vegetation index (NDVI) over the past 20 years. The study establishes a distributed hydrological model for the basin, quantitatively evaluates the impact of returning farmland to forests and grassland on water resources and sediment transport, and explores the optimal land retirement plan under different decision-making conditions. The results show that the total water resources, runoff, groundwater resources and sediment yield in the basin are decreasing, and the annual reductions are 7×108 m3, 1×108 m3, 1.2×108 m3, and 1.6×104 tons respectively. While NDVI and precipitation is increasing, and the annual increases are 0.0064 and 65×108 m3 respectively. The continuous increase in NDVI has resulted in a reduction in runoff volume and sediment transport. Returning farmland to forests and grassland or increasing vegetation density can reduce the amount of runoff and sediment transport, with sediment transport being more sensitive. Considering both the impact on runoff and sediment transport, based on multi-objective optimization, an optimal allocation proposal for the area of returning farmland to forest and grass is proposed. The optimal land retirement area is 28.1%. This study provides decision-making support for ecological environment construction, soil and water conservation, and rational utilization of water and sediment resources in the Loess Plateau region.
2023, 50(6): 25-40.
doi: 10.16030/j.cnki.issn.1000-3665.202305007
Abstract:
Quantitatively identifying the effects and contributions on the water balance evolution is the premise of ecological environmental protection and scientific management of water resources. However, most of the previous studies focused on the effects of climate change and human activities on runoff attenuation; few studies paid attention to the attribution and quantitative identification of different factors in human activities. On the basis of identifying the evolution process of water balance in the study area, the effects of precipitation change and human activities on the evolution of water balance at different time periods were analyzed by using the double cumulative curve method and the quantitative separation method of runoff change. The effects of the increase of water resource exploitation and forestry water consumption on water balance evolution were analyzed in the Laiyuan Basin and Qingshuihe Basin, respectively. The results show that: (1) The annual precipitation presented a slightly decreasing trend with a decreasing rate of 0.97 mm/a in the past 65 years; since the 21st century, precipitation has increased slightly. (2) Compared with the period of 1956−1979, the natural runoff attenuation during 1980−2000 was affected by precipitation change and human activities, with corresponding contributions of 49.25% and 50.75%, respectively. Soil and water conservation and afforestation are the main factors of human activity affecting the change of water balance. the decrease in natural runoff was mainly caused by human activities, with the influence contribution of 68.2%. The increase of groundwater exploitation was the main factor of human activity, and the increase of water consumption was the second factor of human activity. (3) The increase in reservoir storage and water consumption in mountainous areas led to the actual runoff attenuation directly, which was the main reason for the intensification of water balance in the plain areas. (4) In the Qingshuihe River Basin, there was a positive correlation between the increase of forest water consumption and the decline of mountain runoff at a certain scale. The effect of runoff attenuation on the increase of forest area was not immediate, with a lag of 15−20 a. As the forest area reached 23.48%, the increase in forest water consumption had a significant negative effect on the natural runoff. An average increase of 1 km2 of forest land led to water consumption being increased by 37.25×104 m3/a, and the natural runoff being decreased by 59×104 m3/a. The increase in annual water consumption of forest land accounted for 63.22% of the natural runoff attenuation. It indicated that the increase in forest area played an important role in water conservation, resulting in a decrease in effective runoff. The results of the study are of great significance for the ecological and environmental protection, scientific management of water resources and regulation of water balance in the Beijing-Tianjin-Hebei mountain area.
Quantitatively identifying the effects and contributions on the water balance evolution is the premise of ecological environmental protection and scientific management of water resources. However, most of the previous studies focused on the effects of climate change and human activities on runoff attenuation; few studies paid attention to the attribution and quantitative identification of different factors in human activities. On the basis of identifying the evolution process of water balance in the study area, the effects of precipitation change and human activities on the evolution of water balance at different time periods were analyzed by using the double cumulative curve method and the quantitative separation method of runoff change. The effects of the increase of water resource exploitation and forestry water consumption on water balance evolution were analyzed in the Laiyuan Basin and Qingshuihe Basin, respectively. The results show that: (1) The annual precipitation presented a slightly decreasing trend with a decreasing rate of 0.97 mm/a in the past 65 years; since the 21st century, precipitation has increased slightly. (2) Compared with the period of 1956−1979, the natural runoff attenuation during 1980−2000 was affected by precipitation change and human activities, with corresponding contributions of 49.25% and 50.75%, respectively. Soil and water conservation and afforestation are the main factors of human activity affecting the change of water balance. the decrease in natural runoff was mainly caused by human activities, with the influence contribution of 68.2%. The increase of groundwater exploitation was the main factor of human activity, and the increase of water consumption was the second factor of human activity. (3) The increase in reservoir storage and water consumption in mountainous areas led to the actual runoff attenuation directly, which was the main reason for the intensification of water balance in the plain areas. (4) In the Qingshuihe River Basin, there was a positive correlation between the increase of forest water consumption and the decline of mountain runoff at a certain scale. The effect of runoff attenuation on the increase of forest area was not immediate, with a lag of 15−20 a. As the forest area reached 23.48%, the increase in forest water consumption had a significant negative effect on the natural runoff. An average increase of 1 km2 of forest land led to water consumption being increased by 37.25×104 m3/a, and the natural runoff being decreased by 59×104 m3/a. The increase in annual water consumption of forest land accounted for 63.22% of the natural runoff attenuation. It indicated that the increase in forest area played an important role in water conservation, resulting in a decrease in effective runoff. The results of the study are of great significance for the ecological and environmental protection, scientific management of water resources and regulation of water balance in the Beijing-Tianjin-Hebei mountain area.
2023, 50(6): 41-50.
doi: 10.16030/j.cnki.issn.1000-3665.202305032
Abstract:
The arid inland river basins in northwestern China have been experienced various stages of soil and water resources over-exploitation over the past 50 years, as well as ecological protection and restoration in recent years, which has significantly influenced the regional groundwater and ecological environment. However, the long-term evolution of groundwater and its ecological effects remain unclear. In this study, the Kongque River Basin is chosen as a study area, and the spatio-temporal evolution of groundwater flow field is analyzed based on the comparison of recent groundwater monitoring data and historical data. The ecological effects of long-term groundwater evolution are discussed by analyzing the influence of regional groundwater to Populus euphratica in the riparian zone. The results show that from 1971 to 2021, the groundwater flow in the Kongque River Basin has undergone drastic variation due to excessive groundwater exploitation, and the groundwater levels have shown a general downward trend. The total area where the groundwater levels have decreased by more than 40 m is 204.69 km2, as well as 1735.81 and 1018.56 km2 for 20−40 and 5−20 m, and eventually led to the formation of a regional drawdown funnel, which have seriously affected the water consumption of Populus euphratica in the middle and lower reaches. From 1971 to 2016, the regional groundwater level depth in the riparian zone of the Kongque River Basin decreased by more than 10 m, with a degradation and shrinkage of Populus euphratica. After the implementation of the ecological water transport project since 2016, the groundwater level depth has gradually increased by 2−4 m, and reached the critical groundwater level of Populus euphratica. From 2014 to 2018, the regional NDVI increased by 17%, which indicates that the coverage rate of natural vegetation has improved. This study can improve the understanding of evolution patterns in groundwater and ecological environment in arid inland river basins of the northwestern China, and provide scientific references for sustainable development and utilization of groundwater and ecological protection in similar regions.
The arid inland river basins in northwestern China have been experienced various stages of soil and water resources over-exploitation over the past 50 years, as well as ecological protection and restoration in recent years, which has significantly influenced the regional groundwater and ecological environment. However, the long-term evolution of groundwater and its ecological effects remain unclear. In this study, the Kongque River Basin is chosen as a study area, and the spatio-temporal evolution of groundwater flow field is analyzed based on the comparison of recent groundwater monitoring data and historical data. The ecological effects of long-term groundwater evolution are discussed by analyzing the influence of regional groundwater to Populus euphratica in the riparian zone. The results show that from 1971 to 2021, the groundwater flow in the Kongque River Basin has undergone drastic variation due to excessive groundwater exploitation, and the groundwater levels have shown a general downward trend. The total area where the groundwater levels have decreased by more than 40 m is 204.69 km2, as well as 1735.81 and 1018.56 km2 for 20−40 and 5−20 m, and eventually led to the formation of a regional drawdown funnel, which have seriously affected the water consumption of Populus euphratica in the middle and lower reaches. From 1971 to 2016, the regional groundwater level depth in the riparian zone of the Kongque River Basin decreased by more than 10 m, with a degradation and shrinkage of Populus euphratica. After the implementation of the ecological water transport project since 2016, the groundwater level depth has gradually increased by 2−4 m, and reached the critical groundwater level of Populus euphratica. From 2014 to 2018, the regional NDVI increased by 17%, which indicates that the coverage rate of natural vegetation has improved. This study can improve the understanding of evolution patterns in groundwater and ecological environment in arid inland river basins of the northwestern China, and provide scientific references for sustainable development and utilization of groundwater and ecological protection in similar regions.
2023, 50(6): 51-58.
doi: 10.16030/j.cnki.issn.1000-3665.202306022
Abstract:
The Sanjiang Plain is an important base of commodity grain production and contains lots of marsh wetlands in China. In the past 60 years, with the continuous increase of farmland area and the adjustment of planting structure, the decline of wetland and groundwater level has attracted great attention, whether the over-exploited groundwater is controversial. The remote sensing image data from 1956 to 2019 were selected to the analyze the evolution process characteristics of wetland and farmland using single land use dynamic degree. Based on the simultaneous measurement data in 1980 and 2019−2021 and the national groundwater monitoring project data, the influence of wetland reclamation on the groundwater level was explored. The results show that: (1) From 1956 to 2019, the marsh wetland presented a decreasing trend, while the dry land showed a trend of increasing first and then decreasing, and the paddy field had a trend of increasing first and then stabilizing. Sanjiang Plain was characterized by “wetland turning into dry land” with the area of 2.36×104 km2 from 1956 to 1996, while it presented “dry land turning into paddy field” with the area of 1.15×104 km2 from 1996 to 2019. (2) The decrease in groundwater level in the area of 36 546 km2 in the Sanjiang Plain from 1980 to 2021 was less than 5 m, and more than 10 m in the eastern area with 3 669 km2. The groundwater in the Jiansanjiang area is being over-exploited. (3) Compared with the groundwater level in the dry season in 1980, the groundwater depression cone area was 3 669 km2 in 2021 with the depth of 10 m as the standard, which was 269 km2 larger than that in 2019, and slightly expanded to the northeast direction. (4) In 2019, it was difficult to reach the natural regulation of “abundance to make up for deficiency” under the condition of heavy rainfall in the Jiansanjiang reclamation area, and the groundwater storage decreased by 5.81×108 m3. The results of this study provide a foundation for the study on regional water balance and are of great significance to the scientific understanding of the rational development and utilization of water and soil resources.
The Sanjiang Plain is an important base of commodity grain production and contains lots of marsh wetlands in China. In the past 60 years, with the continuous increase of farmland area and the adjustment of planting structure, the decline of wetland and groundwater level has attracted great attention, whether the over-exploited groundwater is controversial. The remote sensing image data from 1956 to 2019 were selected to the analyze the evolution process characteristics of wetland and farmland using single land use dynamic degree. Based on the simultaneous measurement data in 1980 and 2019−2021 and the national groundwater monitoring project data, the influence of wetland reclamation on the groundwater level was explored. The results show that: (1) From 1956 to 2019, the marsh wetland presented a decreasing trend, while the dry land showed a trend of increasing first and then decreasing, and the paddy field had a trend of increasing first and then stabilizing. Sanjiang Plain was characterized by “wetland turning into dry land” with the area of 2.36×104 km2 from 1956 to 1996, while it presented “dry land turning into paddy field” with the area of 1.15×104 km2 from 1996 to 2019. (2) The decrease in groundwater level in the area of 36 546 km2 in the Sanjiang Plain from 1980 to 2021 was less than 5 m, and more than 10 m in the eastern area with 3 669 km2. The groundwater in the Jiansanjiang area is being over-exploited. (3) Compared with the groundwater level in the dry season in 1980, the groundwater depression cone area was 3 669 km2 in 2021 with the depth of 10 m as the standard, which was 269 km2 larger than that in 2019, and slightly expanded to the northeast direction. (4) In 2019, it was difficult to reach the natural regulation of “abundance to make up for deficiency” under the condition of heavy rainfall in the Jiansanjiang reclamation area, and the groundwater storage decreased by 5.81×108 m3. The results of this study provide a foundation for the study on regional water balance and are of great significance to the scientific understanding of the rational development and utilization of water and soil resources.
2023, 50(6): 59-68.
doi: 10.16030/j.cnki.issn.1000-3665.202211006
Abstract:
Collapsible coefficient is an index to evaluate loess collapsibility, which is measured by laboratory test with collected intact samples. Collapsible coefficient varies with normal pressure loaded in test. It is better to use the real normal pressure in foundation when measuring the collapsible coefficient, but for reasons of convenience, the pressures are always designated as definite values in the codes or standards of construction in collapsible loess areas. However, the designated pressure for Q3 (Malan) loess in the standards is reasonable and applicable, while that for Q2 loess is still necessary to discuss. In this paper, the collapsible loess foundation of the Huaneng Electric Plant in Zhengning, Gansu Province is used as a case, the Q2-Q4 loess samples were collected in a 35.0 m deep shaft in 1 m intervals and the basic physical properties were measured in laboratory first. The collapsible coefficient is measured with the double oedometer method under low to high pressure for all the samples. Based on the test results, the collapsible coefficient with respect to depth determined with the present used GB 50025—2018 standard and the real pressure in foundation in the cases of various basement widths and basement pressures are compared. The results show that (1) the coefficient of collapsibility has a peak value. The initial collapse pressure and peak collapse pressure of Q3 loess are higher than those of Q2 loess. The peak coefficient of collapsibility of Q3 loess is higher than that of Q2 loess, which decreases with depth. (2) For Q3 loess, the collapsible coefficient and subsidence determined by the pressure of the present standard are close to those determined by the real pressure in foundation, while for Q2 loess, those determined by the pressure of the present standard in foundation deviates increasingly with depth to those determined by the real pressure. (3) Therefore, a modified test pressure for measuring collapsible coefficient of loess is proposed. It is demonstrated that the collapsible coefficients determined by the modified test pressure agree well with those by the real soil pressure.
Collapsible coefficient is an index to evaluate loess collapsibility, which is measured by laboratory test with collected intact samples. Collapsible coefficient varies with normal pressure loaded in test. It is better to use the real normal pressure in foundation when measuring the collapsible coefficient, but for reasons of convenience, the pressures are always designated as definite values in the codes or standards of construction in collapsible loess areas. However, the designated pressure for Q3 (Malan) loess in the standards is reasonable and applicable, while that for Q2 loess is still necessary to discuss. In this paper, the collapsible loess foundation of the Huaneng Electric Plant in Zhengning, Gansu Province is used as a case, the Q2-Q4 loess samples were collected in a 35.0 m deep shaft in 1 m intervals and the basic physical properties were measured in laboratory first. The collapsible coefficient is measured with the double oedometer method under low to high pressure for all the samples. Based on the test results, the collapsible coefficient with respect to depth determined with the present used GB 50025—2018 standard and the real pressure in foundation in the cases of various basement widths and basement pressures are compared. The results show that (1) the coefficient of collapsibility has a peak value. The initial collapse pressure and peak collapse pressure of Q3 loess are higher than those of Q2 loess. The peak coefficient of collapsibility of Q3 loess is higher than that of Q2 loess, which decreases with depth. (2) For Q3 loess, the collapsible coefficient and subsidence determined by the pressure of the present standard are close to those determined by the real pressure in foundation, while for Q2 loess, those determined by the pressure of the present standard in foundation deviates increasingly with depth to those determined by the real pressure. (3) Therefore, a modified test pressure for measuring collapsible coefficient of loess is proposed. It is demonstrated that the collapsible coefficients determined by the modified test pressure agree well with those by the real soil pressure.
2023, 50(6): 69-79.
doi: 10.16030/j.cnki.issn.1000-3665.202211026
Abstract:
The rock mass of open pit in cold regions is often affected by freezing-thawing cycles and long-term loads. In order to explore the influence of cold region environment on the stability of rock mass, the red sandstone of a project in northern Shaanxi is taken as the research object, starting with the macroscopic creep characteristics and meso-structure evolution characteristics of freezing-thawing rocks. The evolution of macro-mechanical indexes and meso-parameters during the creep process of freezing-thawing red sandstone is quantitatively analyzed through the loading and unloading creep test of freezing-thawing rock and the NMR detection. The results show that the pore size distribution fluctuates in a small range when the stress level is between 0.3σucs−0.5σucs, and when the stress level increases to 0.5σucs−0.6σucs, the proportion of small holes (T2<10 ms) decreases and the proportion of large holes (T2>10 ms) increases, and freezing-thawing aggravates the increase of porosity in the creep stage, and the effect of freezing and thawing on porosity growth is more significant at high stress levels. The fractal theory is introduced to characterize the complexity of pore structure. It is found that the large pores have obvious fractal characteristics, while the fractal characteristics of small pores are not obvious. The total pore fractal dimension DT is positively correlated with porosity. The complexity of pore structure only affects the creep mechanical properties of rock when the porosity is large. The freezing-thawing-damage creep model of freezing-thawing effect and creep damage is established. The model curve can well reflect the creep characteristics of the freezing-thawing rock, which is in good agreement with the experimental curve. This study can provide a theoretical basis for rock engineering construction in freezig-thawing environment.
The rock mass of open pit in cold regions is often affected by freezing-thawing cycles and long-term loads. In order to explore the influence of cold region environment on the stability of rock mass, the red sandstone of a project in northern Shaanxi is taken as the research object, starting with the macroscopic creep characteristics and meso-structure evolution characteristics of freezing-thawing rocks. The evolution of macro-mechanical indexes and meso-parameters during the creep process of freezing-thawing red sandstone is quantitatively analyzed through the loading and unloading creep test of freezing-thawing rock and the NMR detection. The results show that the pore size distribution fluctuates in a small range when the stress level is between 0.3σucs−0.5σucs, and when the stress level increases to 0.5σucs−0.6σucs, the proportion of small holes (T2<10 ms) decreases and the proportion of large holes (T2>10 ms) increases, and freezing-thawing aggravates the increase of porosity in the creep stage, and the effect of freezing and thawing on porosity growth is more significant at high stress levels. The fractal theory is introduced to characterize the complexity of pore structure. It is found that the large pores have obvious fractal characteristics, while the fractal characteristics of small pores are not obvious. The total pore fractal dimension DT is positively correlated with porosity. The complexity of pore structure only affects the creep mechanical properties of rock when the porosity is large. The freezing-thawing-damage creep model of freezing-thawing effect and creep damage is established. The model curve can well reflect the creep characteristics of the freezing-thawing rock, which is in good agreement with the experimental curve. This study can provide a theoretical basis for rock engineering construction in freezig-thawing environment.
2023, 50(6): 80-89.
doi: 10.16030/j.cnki.issn.1000-3665.202210019
Abstract:
To reduce the slope collapse and soil erosion under the action of rainfall erosion in desertification areas, the self-developed nano silicon-based sand-fixation material (Nano-Silicon/ Polymer Composites, NSPC) is proposed to protect the sandy slope surface of the Yarlung Zangbo River Valley in Xizang. In view of the unclear effect of NSPC sand-fixing material on strengthening sand body, based on infrared spectrum, viscosity test, contact test and simulated sandy slope rainfall erosion test, the mechanism of NSPC sand-fixation material to strengthen the sandy slope is discussed, and the anti-erosion ability of the NSPC sand-fixation material under the rainfall is studied. The results show that the NSPC sand-fixation material and sand particles cross and intertwine with each other through polymerization and cementation to form a 3D network structure, so as to achieve the purpose of strengthening the sandy body. The rheological properties of the NSPC sand-fixation material belongs to Bingham fluid in the first 1 h, and gradually changes to Newton fluid in the later period. The surface tension of the NSPC sand-fixation material is 60.31 mN/m, the contact angle with sandy body is 48.6°, and the adhesion force is 0.040 N/m, therefor it has strong infiltration ability. The reinforcement layer formed on the sandy slope surface has strong blocking effect on rainwater erosion, and the reinforcement layer also has water retention ability. This study provides test support for the application and promotion of the NSPC sand-fixation material in sand fixation and protection projects in desertification areas.
2023, 50(6): 90-98.
doi: 10.16030/j.cnki.issn.1000-3665.202211036
Abstract:
The Labroatoire Central de Ponts et Chaussées (LCPC) test is a commonly used method to test the abrasivity of soil, however, the existing LCPC tests have some shortcomings in evaluating the abrasivity of shield tunnel soil, such as the high effective breakage rate of soil particles and large changes in particle size distribution during testing. In view of this, a circular steel sheet is used to replace the original rectangular steel sheet, and a comparative test is carried out. The test results show that the improved circular steel sheet significantly reduces the effective breakage rate of soil samples compared with the rectangular steel sheet, and improves the stability of particle size distribution in the LCPC test. The wear of the circle steel sheet in the test process is mainly abrasive wear, which effectively eliminates the impact wear and is more in line with the characteristics of shield tunnel engineering. The analysis shows that the conversion relationship between the two LCPC abrasivity coefficients is LAC矩=0.93LAC圆 when abrasive wear is the main wear. The improved testing method accurately evaluates the abrasivity of the pebble layer crossed by the shield tunnel sections Youanmen-Niujie of Beijing Subway Line 19 and 3# Fengjing-Caoqiao of the Beijing Daxing International Airport Line. This study improves the accuracy of the LCPC test method in evaluating the soil abrasion of shield tunnel.
The Labroatoire Central de Ponts et Chaussées (LCPC) test is a commonly used method to test the abrasivity of soil, however, the existing LCPC tests have some shortcomings in evaluating the abrasivity of shield tunnel soil, such as the high effective breakage rate of soil particles and large changes in particle size distribution during testing. In view of this, a circular steel sheet is used to replace the original rectangular steel sheet, and a comparative test is carried out. The test results show that the improved circular steel sheet significantly reduces the effective breakage rate of soil samples compared with the rectangular steel sheet, and improves the stability of particle size distribution in the LCPC test. The wear of the circle steel sheet in the test process is mainly abrasive wear, which effectively eliminates the impact wear and is more in line with the characteristics of shield tunnel engineering. The analysis shows that the conversion relationship between the two LCPC abrasivity coefficients is LAC矩=0.93LAC圆 when abrasive wear is the main wear. The improved testing method accurately evaluates the abrasivity of the pebble layer crossed by the shield tunnel sections Youanmen-Niujie of Beijing Subway Line 19 and 3# Fengjing-Caoqiao of the Beijing Daxing International Airport Line. This study improves the accuracy of the LCPC test method in evaluating the soil abrasion of shield tunnel.
2023, 50(6): 99-111.
doi: 10.16030/j.cnki.issn.1000-3665.202210044
Abstract:
The current studies of the cylindrical cavity expansion in sand still lack a deeper analysis for the results obtained in sands with different initial states. In addition, most of previous studies have not considered the influence of the shape of yield surface of sand, which made their results difficult to be popularized in different types of sand. In order to obtain a general solution to expansion of cylindrical cavity in sand under the drained condition, a unified state parameter model - clay and sand model (CASM) with Rowe’s stress–dilatancy relation is used to describe the characteristics of elastic-plastic deformation of sand. By employing that large strain occurs in sand and introducing an auxiliary variable, several partial differential equations to calculate the effective stress and specific volume of sand in the elastoplastic zone are derived on the basis of the Lagrangian description.Under the elastic-plastic boundary conditions and the elastic solution of cylindrical cavity expansion, a semi-analytical solution for drained cylindrical cavity expansion in sand is obtained by solving the governing equations numerically. The results show that the solution of cylindrical cavity expansion established in this paper can be used in many types of sand by changing the values of stress-state parameter n and spacing ratio r* to select an appropriate shape of yield surface of sand, and the greater the values of n, r* are, the greater the initial yield deviatoric stress of loose sand and the subsequent expansion pressure, but these situations will reverse in medium dense and dense sand. The ultimate expansion pressure increases with the decreasing initial state parameter of the sand, and together with the volume variation rule of sand changes from always contraction into dilatation first and then contraction, the radius of the elastic-plastic zone decreases first and then increases, and the hardening response of sand changes from always hardening into softening first and then hardening. The ultimate expansion pressure increases with the increasing coefficient of earth pressure at rest of sand, but the volume change law of sand has little change. This study provides a reliable theoretical support for the analysis of related geotechnical engineering problem.
The current studies of the cylindrical cavity expansion in sand still lack a deeper analysis for the results obtained in sands with different initial states. In addition, most of previous studies have not considered the influence of the shape of yield surface of sand, which made their results difficult to be popularized in different types of sand. In order to obtain a general solution to expansion of cylindrical cavity in sand under the drained condition, a unified state parameter model - clay and sand model (CASM) with Rowe’s stress–dilatancy relation is used to describe the characteristics of elastic-plastic deformation of sand. By employing that large strain occurs in sand and introducing an auxiliary variable, several partial differential equations to calculate the effective stress and specific volume of sand in the elastoplastic zone are derived on the basis of the Lagrangian description.Under the elastic-plastic boundary conditions and the elastic solution of cylindrical cavity expansion, a semi-analytical solution for drained cylindrical cavity expansion in sand is obtained by solving the governing equations numerically. The results show that the solution of cylindrical cavity expansion established in this paper can be used in many types of sand by changing the values of stress-state parameter n and spacing ratio r* to select an appropriate shape of yield surface of sand, and the greater the values of n, r* are, the greater the initial yield deviatoric stress of loose sand and the subsequent expansion pressure, but these situations will reverse in medium dense and dense sand. The ultimate expansion pressure increases with the decreasing initial state parameter of the sand, and together with the volume variation rule of sand changes from always contraction into dilatation first and then contraction, the radius of the elastic-plastic zone decreases first and then increases, and the hardening response of sand changes from always hardening into softening first and then hardening. The ultimate expansion pressure increases with the increasing coefficient of earth pressure at rest of sand, but the volume change law of sand has little change. This study provides a reliable theoretical support for the analysis of related geotechnical engineering problem.
2023, 50(6): 112-119.
doi: 10.16030/j.cnki.issn.1000-3665.202210017
Abstract:
Aiming at the problem of quality control of a deep mixing pile in construction process, this paper introduces a novel digital construction cloud platform incorporated in the equipment minor-disturbance four-axial soil mixing pile, realizing the real-time tracking and feedback in construction process. After inputting the parameter related to different strata into the platform, the variation of parameter is automatically controlled in construction. After inputting the threshold of underground pressure, the minor-disturbance to subsoil is realized with a measured soil lateral displacement and upheaving in millimeter scale. With a measurement of verticality of drill rod in real time, the pile verticality can be controlled to 1/250. The management cloud platform realizes a dynamic management of quality control for all parties in the construction. This practical results are beneficial to completely improve the construction quality of the deep mixing pile and digital construction level of soft soil.
Aiming at the problem of quality control of a deep mixing pile in construction process, this paper introduces a novel digital construction cloud platform incorporated in the equipment minor-disturbance four-axial soil mixing pile, realizing the real-time tracking and feedback in construction process. After inputting the parameter related to different strata into the platform, the variation of parameter is automatically controlled in construction. After inputting the threshold of underground pressure, the minor-disturbance to subsoil is realized with a measured soil lateral displacement and upheaving in millimeter scale. With a measurement of verticality of drill rod in real time, the pile verticality can be controlled to 1/250. The management cloud platform realizes a dynamic management of quality control for all parties in the construction. This practical results are beneficial to completely improve the construction quality of the deep mixing pile and digital construction level of soft soil.
2023, 50(6): 120-128.
doi: 10.16030/j.cnki.issn.1000-3665.202210014
Abstract:
The mechanical properties of Bimrock under different cementation strength are rarely studied, and the cementation strength has an important influence on the mechanical properties and deformation and failure characteristics of Bimrock. In order to explore the influence of different cementation strength on the mechanical properties of Bimrock, the proportion test of Bimrock cementation matrix was conducted by using the orthogonal test design method, and the parameter sensitivity analysis was carried out on the strength mechanical parameters of the samples with different proportions of matrix. Based on the orthogonal test results, the Bimrock samples with different cementation strength were made, and the influence of different cementation strength on the mechanical properties of Bimrock was analyzed through the uniaxial compression test. The results show that the uniaxial compressive strength and elastic modulus of the Bimrock specimens are positively correlated with their cementation strength. From weak cementation to strong cementation, the peak uniaxial compressive strength increases from 11.02 MPa to 34.21 MPa, and the elastic modulus increases from 2.11 GPa to 5.57 GPa, respectively. With the increasing bonding strength, the number of surface cracks in each stage from deformation to failure decreases. The compression failure mode of the strongly bonded specimen is the through failure of a single main crack, with short failure time and obvious brittle failure. The overall and local shear failure occurred in the moderately cemented specimen, which is represented by a shear failure surface that obviously penetrates the whole specimen and a shear failure surface that only penetrates the lower part of the specimen. The weak cementation sample is subject to transverse tensile failure. A number of tensile cracks parallel to the vertical direction can be seen, and the failure characteristics of coexistence of tensile and shear failure can be seen locally. From deformation to failure, there are many cracks that are relatively broken, and the failure time is relatively long. The engineering problems of Bimrock are complex and difficult to deal with. The research on the mechanical properties and deformation and failure characteristics of Bimrock is of great significance for engineering construction and geological disaster prevention.
The mechanical properties of Bimrock under different cementation strength are rarely studied, and the cementation strength has an important influence on the mechanical properties and deformation and failure characteristics of Bimrock. In order to explore the influence of different cementation strength on the mechanical properties of Bimrock, the proportion test of Bimrock cementation matrix was conducted by using the orthogonal test design method, and the parameter sensitivity analysis was carried out on the strength mechanical parameters of the samples with different proportions of matrix. Based on the orthogonal test results, the Bimrock samples with different cementation strength were made, and the influence of different cementation strength on the mechanical properties of Bimrock was analyzed through the uniaxial compression test. The results show that the uniaxial compressive strength and elastic modulus of the Bimrock specimens are positively correlated with their cementation strength. From weak cementation to strong cementation, the peak uniaxial compressive strength increases from 11.02 MPa to 34.21 MPa, and the elastic modulus increases from 2.11 GPa to 5.57 GPa, respectively. With the increasing bonding strength, the number of surface cracks in each stage from deformation to failure decreases. The compression failure mode of the strongly bonded specimen is the through failure of a single main crack, with short failure time and obvious brittle failure. The overall and local shear failure occurred in the moderately cemented specimen, which is represented by a shear failure surface that obviously penetrates the whole specimen and a shear failure surface that only penetrates the lower part of the specimen. The weak cementation sample is subject to transverse tensile failure. A number of tensile cracks parallel to the vertical direction can be seen, and the failure characteristics of coexistence of tensile and shear failure can be seen locally. From deformation to failure, there are many cracks that are relatively broken, and the failure time is relatively long. The engineering problems of Bimrock are complex and difficult to deal with. The research on the mechanical properties and deformation and failure characteristics of Bimrock is of great significance for engineering construction and geological disaster prevention.
2023, 50(6): 129-136.
doi: 10.16030/j.cnki.issn.1000-3665.202210009
Abstract:
To solve the optimization problem of blasting parameters and consider the influence of interaction between blastholes on the spatial distribution of surrounding rock damage, the Riedel-Hiermaier-Thoma constitutive model parameters of marble were first calibrated from numerical trial calculation and impact test. Then, the blasting excavation of a tunnel in full section was numerically simulated, and the evolution process of blasting damage of surrounding rocks under the interaction of multiple boreholes was investigated. Finally, the blasting parameters were optimized based on the three methods of initiation sequence, radial uncoupling coefficient and segmented interval charge, and the particle vibration and surrounding rock damage were further analyzed. The results show that the obtained constitutive parameters accurately describe the dynamic stress-strain response of the marble, and the simulated results can well reveal the evolution law of blasting damage. The rock damage develops outward from the blasthole center, and then the damage is connected and coalesced along the borehole connection line. Compared with the aforementioned other two methods, when the radial uncoupling coefficient k is less than 1.33, the blast damage of surrounding rock can be effectively reduced by changing the k value on the premise of ensuring the blasting effect. The average vibration velocity in the vertical direction of tunnel is greater than that in the horizontal direction, and the apex of arch and the middle of floor in this direction are more sensitive to blasting vibration. The research results in this study can provide reference for optimum selection of blasting parameters and accurate evaluation of surrounding rock damage in practical engineering.
To solve the optimization problem of blasting parameters and consider the influence of interaction between blastholes on the spatial distribution of surrounding rock damage, the Riedel-Hiermaier-Thoma constitutive model parameters of marble were first calibrated from numerical trial calculation and impact test. Then, the blasting excavation of a tunnel in full section was numerically simulated, and the evolution process of blasting damage of surrounding rocks under the interaction of multiple boreholes was investigated. Finally, the blasting parameters were optimized based on the three methods of initiation sequence, radial uncoupling coefficient and segmented interval charge, and the particle vibration and surrounding rock damage were further analyzed. The results show that the obtained constitutive parameters accurately describe the dynamic stress-strain response of the marble, and the simulated results can well reveal the evolution law of blasting damage. The rock damage develops outward from the blasthole center, and then the damage is connected and coalesced along the borehole connection line. Compared with the aforementioned other two methods, when the radial uncoupling coefficient k is less than 1.33, the blast damage of surrounding rock can be effectively reduced by changing the k value on the premise of ensuring the blasting effect. The average vibration velocity in the vertical direction of tunnel is greater than that in the horizontal direction, and the apex of arch and the middle of floor in this direction are more sensitive to blasting vibration. The research results in this study can provide reference for optimum selection of blasting parameters and accurate evaluation of surrounding rock damage in practical engineering.
2023, 50(6): 137-146.
doi: 10.16030/j.cnki.issn.1000-3665.202210024
Abstract:
Located in the city of Xianyang in Shaanxi Province, the Hanyang Mausoleum is the first fully closed underground museum in China and in the world. The fissure disease of its outer pit is developing, which seriously endangers the safety of the pit wall and the pit bottom cultural relics, and it is urgent to protect and strengthen the pit. In the past, more was learned about the disease and prevention of the ruins in the open air and semi-closed environment, while the completely closed environment was seldom examined. This paper takes the outer pit K21 of the Hanyang Mausoleum as the research object. The number and distribution characteristics of cracks are determined through field investigation. On this basis, the causes of cracks are studied and classified. The stability of pit wall and its influencing factors are analyzed by numerical simulation methods. The research results show that there are 53 cracks in the K21 outer pit, mainly occurring on the south and north sides of the surface and the pit wall. The surface longitudinal cracks are unloading cracks, the surface transverse cracks are dry shrinkage cracks, and the pit wall cracks are mainly structural cracks. The longitudinal unloading crack is the main reason for the reduction of pit wall stability. The earthquake, artificial load or the further development of cracks will lead to the pit wall to be unstable. It is recommended to use anchor bolts to reinforce the pit wall, and reset and pre-tighten the unloading cracks by applying prestress. This study is of important guiding significance for the investigation and protection of the fissure disease in the museum sites.
Located in the city of Xianyang in Shaanxi Province, the Hanyang Mausoleum is the first fully closed underground museum in China and in the world. The fissure disease of its outer pit is developing, which seriously endangers the safety of the pit wall and the pit bottom cultural relics, and it is urgent to protect and strengthen the pit. In the past, more was learned about the disease and prevention of the ruins in the open air and semi-closed environment, while the completely closed environment was seldom examined. This paper takes the outer pit K21 of the Hanyang Mausoleum as the research object. The number and distribution characteristics of cracks are determined through field investigation. On this basis, the causes of cracks are studied and classified. The stability of pit wall and its influencing factors are analyzed by numerical simulation methods. The research results show that there are 53 cracks in the K21 outer pit, mainly occurring on the south and north sides of the surface and the pit wall. The surface longitudinal cracks are unloading cracks, the surface transverse cracks are dry shrinkage cracks, and the pit wall cracks are mainly structural cracks. The longitudinal unloading crack is the main reason for the reduction of pit wall stability. The earthquake, artificial load or the further development of cracks will lead to the pit wall to be unstable. It is recommended to use anchor bolts to reinforce the pit wall, and reset and pre-tighten the unloading cracks by applying prestress. This study is of important guiding significance for the investigation and protection of the fissure disease in the museum sites.
2023, 50(6): 147-157.
doi: 10.16030/j.cnki.issn.1000-3665.202209030
Abstract:
Compared with the landslides in the general gravity environment, the earthquake-induced landslides are significantly different in formation mechanisms and kinetic characteristics. Under the normal and rainfall conditions, the fault fracture zone, as the discontinuous structural plane of the slope, often adversely affect the stability of the slope. Under the earthquake condition, the fault fracture zone within the slope has a limited filtering effect, which could weaken the seismic response of the slope. To investigate the influence of the reverse fault’s geometry on the slope’s seismic response, we took the Niumiangou landslide, the Woqian landslide, the Xiejiadianzi landslide and the Donghekou landslide as reference objects and generalized the geological model of the fault-crossing landslide in this study. The seismic response of slopes with faults of different widths, dips and positions are simulated using the 3DEC discrete element software. The simulation results show that (1) as the fault dip angle increases, the peak value of the total displacement of the slope and the peak acceleration of the slope surface show an increasing trend, and the slope stability is worse. (2) The peak acceleration of the monitoring point at the top of the slope is generally greater than that at the bottom and waist of the slope. As the width of fault fracture zone increases, the effect on the seismic response of the slope becomes obvious.(3) The presence of faults facilitates the probability of slope instability. When the fault is located at the top of the slope, the variation of the seismic response with the dip angle and the fault width shows a more obvious regularity. This study can provide a theoretical basis for further revealing the impact of fault fracture zone on the stability of slopes under the earthquake condition.
Compared with the landslides in the general gravity environment, the earthquake-induced landslides are significantly different in formation mechanisms and kinetic characteristics. Under the normal and rainfall conditions, the fault fracture zone, as the discontinuous structural plane of the slope, often adversely affect the stability of the slope. Under the earthquake condition, the fault fracture zone within the slope has a limited filtering effect, which could weaken the seismic response of the slope. To investigate the influence of the reverse fault’s geometry on the slope’s seismic response, we took the Niumiangou landslide, the Woqian landslide, the Xiejiadianzi landslide and the Donghekou landslide as reference objects and generalized the geological model of the fault-crossing landslide in this study. The seismic response of slopes with faults of different widths, dips and positions are simulated using the 3DEC discrete element software. The simulation results show that (1) as the fault dip angle increases, the peak value of the total displacement of the slope and the peak acceleration of the slope surface show an increasing trend, and the slope stability is worse. (2) The peak acceleration of the monitoring point at the top of the slope is generally greater than that at the bottom and waist of the slope. As the width of fault fracture zone increases, the effect on the seismic response of the slope becomes obvious.(3) The presence of faults facilitates the probability of slope instability. When the fault is located at the top of the slope, the variation of the seismic response with the dip angle and the fault width shows a more obvious regularity. This study can provide a theoretical basis for further revealing the impact of fault fracture zone on the stability of slopes under the earthquake condition.
2023, 50(6): 158-167.
doi: 10.16030/j.cnki.issn.1000-3665.202209052
Abstract:
The formation mechanism of caves in fissured loess at the edge of the loess platform plateau is complex and is closely related to the occurrence of geological hazards such as landslides, which pose a serious threat to the production and life of people in this region. To address the scientific problem of how internal erosion caves are formed in the fissured loess, four sets of experiments on the formation mechanism of internal erosion caves in loess under different initial fissure opening conditions are carried out using the visualisation of the internal erosion caves formation mechanism model of the fissured loess in the South Plateau of Jingyang as a reference. The results show that the development process from the fractured loess to the internal erosion of caves under water flowing erosion can be divided into three stages, including the hydraulic erosion stage, the infiltration and erosion stage and the gravity collapse stage. The formation mechanism of the internal erosion caves in the fractured loess can be summarized as follows: Softening and sputtering, scouring and widening, erosion and cavitation, and collapsing by gravity. The development rate of seepage erosion in the fractured loess is reflected by the sediment quantity and transport characteristics, which can be divided into the rapid erosion stage, the fluctuation reduction stage and the slow and stable erosion stage. The fracture opening, the erodibility of loess and the ultimate groove depth are important factors affecting the formation of internal erosion caves in the fractured loess. The research results provide theoretical support to further reveal the disaster-causing effects of loess internal erosion.
The formation mechanism of caves in fissured loess at the edge of the loess platform plateau is complex and is closely related to the occurrence of geological hazards such as landslides, which pose a serious threat to the production and life of people in this region. To address the scientific problem of how internal erosion caves are formed in the fissured loess, four sets of experiments on the formation mechanism of internal erosion caves in loess under different initial fissure opening conditions are carried out using the visualisation of the internal erosion caves formation mechanism model of the fissured loess in the South Plateau of Jingyang as a reference. The results show that the development process from the fractured loess to the internal erosion of caves under water flowing erosion can be divided into three stages, including the hydraulic erosion stage, the infiltration and erosion stage and the gravity collapse stage. The formation mechanism of the internal erosion caves in the fractured loess can be summarized as follows: Softening and sputtering, scouring and widening, erosion and cavitation, and collapsing by gravity. The development rate of seepage erosion in the fractured loess is reflected by the sediment quantity and transport characteristics, which can be divided into the rapid erosion stage, the fluctuation reduction stage and the slow and stable erosion stage. The fracture opening, the erodibility of loess and the ultimate groove depth are important factors affecting the formation of internal erosion caves in the fractured loess. The research results provide theoretical support to further reveal the disaster-causing effects of loess internal erosion.
2023, 50(6): 168-174.
doi: 10.16030/j.cnki.issn.1000-3665.202302012
Abstract:
Since 2019, the Ministry of Natural Resources has comprehensively promoted the research and development of universal equipment and the automatic monitoring and forewarning of geological hazard. As of June 2023, it has been applied to 55 000 potential points of geological hazard in 17 key geological hazard prevention provinces, and the national geological hazard monitoring and forewarning system has entered a rapid development stage. At present, the system receives more than 10 million monitoring data every day, and has made positive progress in massive data storage management, parallel processing of time series data, intelligent analysis of big data and multi-parameter risk early warning. However, there are many challenges in data security of the system, especially in data consistency, data tamper resistance and system reliability. On the basis of systematic research on the characteristics of the blockchain technology and its typical application in related fields, this paper proposes a “trusted data flow” technology based on distributed ledger and consensus mechanism, according to which the overall framework of “blockchain + NRWSL” is formed, and a prototype system is established. The test data show that the improved system can solve the problem of data inconsistency between provinces and Ministry of Natural Resources, identify and prevent illegal data tampering, ensure the stable operation of the system under multi-node failure conditions, and the overall performance loss of the system is less than 20%. The research results provide technical methods for the application of blockchain technology to geological hazard risk early warning systems at all levels in China, and also provide top-level design ideas for improving the security of geological hazard monitoring data and the early warning system.
Since 2019, the Ministry of Natural Resources has comprehensively promoted the research and development of universal equipment and the automatic monitoring and forewarning of geological hazard. As of June 2023, it has been applied to 55 000 potential points of geological hazard in 17 key geological hazard prevention provinces, and the national geological hazard monitoring and forewarning system has entered a rapid development stage. At present, the system receives more than 10 million monitoring data every day, and has made positive progress in massive data storage management, parallel processing of time series data, intelligent analysis of big data and multi-parameter risk early warning. However, there are many challenges in data security of the system, especially in data consistency, data tamper resistance and system reliability. On the basis of systematic research on the characteristics of the blockchain technology and its typical application in related fields, this paper proposes a “trusted data flow” technology based on distributed ledger and consensus mechanism, according to which the overall framework of “blockchain + NRWSL” is formed, and a prototype system is established. The test data show that the improved system can solve the problem of data inconsistency between provinces and Ministry of Natural Resources, identify and prevent illegal data tampering, ensure the stable operation of the system under multi-node failure conditions, and the overall performance loss of the system is less than 20%. The research results provide technical methods for the application of blockchain technology to geological hazard risk early warning systems at all levels in China, and also provide top-level design ideas for improving the security of geological hazard monitoring data and the early warning system.
2023, 50(6): 175-183.
doi: 10.16030/j.cnki.issn.1000-3665.202212026
Abstract:
Oxidative dissolution of stibnite (Sb2S3) is the primary process that controls the release of antimony (Sb) from rock and ore into the soil and water environment and affects its transport and transformation. Fe(III) in acid mine wastewater is a widespread natural oxidant in the mine environment. However, the role of Fe(III) on the oxidative dissolution of Sb2S3 and Sb release is unknown. By simulating a dark anoxic and acidic mine groundwater environment, this study conducted Fe(III) concentration to Sb2S3 surface area ratio (I) controlled Sb2S3 oxidative dissolution kinetics experiments, and combined the dissolved state composition and solid phase characterization means of S-Sb-Fe redox products to reveal the mechanism of Fe(III) action on Sb release. The results show that the oxidative dissolution of Sb2S3 under the action of Fe(III) is an acid-producing process, and the larger the I value is, the more obvious the promotion effect of Fe(III) on Sb release. Under anoxic conditions, Fe(III) undergoes redox with Sb2S3, and the main products are Sb(V), S(0) and Fe(II). After the reaction, S(0) and Fe2O3 were detected on the mineral surface, which hindered the continuation of the oxidative dissolution reaction of Sb2S3. At a certain value of I, both the low concentration of Fe(III) and the increase of dissolved oxygen (DO) will reduce the attachment of S(0) on the mineral surface and promote the increase of Sb release; the Cl− in solution will promote the dissolution release of Sb2S3 through the coordination complexation effect. The interaction between Fe(III) and Sb2S3 under anoxic acidic conditions controls the release of Sb, which can provide an important theoretical basis for prevention and control of groundwater Sb contamination after mine pit closure.
Oxidative dissolution of stibnite (Sb2S3) is the primary process that controls the release of antimony (Sb) from rock and ore into the soil and water environment and affects its transport and transformation. Fe(III) in acid mine wastewater is a widespread natural oxidant in the mine environment. However, the role of Fe(III) on the oxidative dissolution of Sb2S3 and Sb release is unknown. By simulating a dark anoxic and acidic mine groundwater environment, this study conducted Fe(III) concentration to Sb2S3 surface area ratio (I) controlled Sb2S3 oxidative dissolution kinetics experiments, and combined the dissolved state composition and solid phase characterization means of S-Sb-Fe redox products to reveal the mechanism of Fe(III) action on Sb release. The results show that the oxidative dissolution of Sb2S3 under the action of Fe(III) is an acid-producing process, and the larger the I value is, the more obvious the promotion effect of Fe(III) on Sb release. Under anoxic conditions, Fe(III) undergoes redox with Sb2S3, and the main products are Sb(V), S(0) and Fe(II). After the reaction, S(0) and Fe2O3 were detected on the mineral surface, which hindered the continuation of the oxidative dissolution reaction of Sb2S3. At a certain value of I, both the low concentration of Fe(III) and the increase of dissolved oxygen (DO) will reduce the attachment of S(0) on the mineral surface and promote the increase of Sb release; the Cl− in solution will promote the dissolution release of Sb2S3 through the coordination complexation effect. The interaction between Fe(III) and Sb2S3 under anoxic acidic conditions controls the release of Sb, which can provide an important theoretical basis for prevention and control of groundwater Sb contamination after mine pit closure.
2023, 50(6): 184-192.
doi: 10.16030/j.cnki.issn.1000-3665.202212006
Abstract:
Underground oil reserves are established near the sea, which can reduce the cost of oil transportation and have strong military significance. However, the proximity to the coastline makes it easy for seawater to intrude into the reservoir area, resulting in corrosion of the metal structure in the reservoir area, thus reducing the service life of the reservoir. A simulation study on the risk of seawater intrusion was carried out with an offshore underground oil reserve project as the background. A refined three dimensional hydrogeological model with 15 geological structures such as integrated faults, jointed dense zones and water conduction channels was constructed, and the groundwater seepage field and solute transport field in the reservoir area under the natural state and during the operation period were studied. The study shows that (1) there is no seawater intrusion in the undergroundoilreserve in the natural state. (2) During the operation period, a horizontal water curtain with a distance of 10 m and a diameter of 0.11 m was only set at 25 m above the top of the cavern reservoir, exceeding the cave by 50 m around, which could not effectively prevent seawater intrusion. (3) When the cave reservoir was running for 9 a, the Cl− mole concentration on the southeast side of 3# cavern room exceeded 7 mol/m3, and seawater began to invade the cavern group; when it was running for 22 a to 23 a, the seawater invasion speed was the fastest; when it was running for 41 a, the Cl− mole concentration on the southeast side of 3# cavern room exceeded 143 mol/m3, and the seawater invasion reached the strong corrosion degree of steel; when it was running for 50 a, all the cavern rooms except 1# cavern room were invaded by seawater, 3# and 4# cavity rooms have some areas to reach strong corrosion degree, seawater invasion is the most serious. It is suggested to set up additional facilities such as vertical water curtain to enhance the prevention and control of seawater intrusion. The research results can provide reference for the suppression of seawater intrusion in underground oil reserves in offshore areas.
Underground oil reserves are established near the sea, which can reduce the cost of oil transportation and have strong military significance. However, the proximity to the coastline makes it easy for seawater to intrude into the reservoir area, resulting in corrosion of the metal structure in the reservoir area, thus reducing the service life of the reservoir. A simulation study on the risk of seawater intrusion was carried out with an offshore underground oil reserve project as the background. A refined three dimensional hydrogeological model with 15 geological structures such as integrated faults, jointed dense zones and water conduction channels was constructed, and the groundwater seepage field and solute transport field in the reservoir area under the natural state and during the operation period were studied. The study shows that (1) there is no seawater intrusion in the undergroundoilreserve in the natural state. (2) During the operation period, a horizontal water curtain with a distance of 10 m and a diameter of 0.11 m was only set at 25 m above the top of the cavern reservoir, exceeding the cave by 50 m around, which could not effectively prevent seawater intrusion. (3) When the cave reservoir was running for 9 a, the Cl− mole concentration on the southeast side of 3# cavern room exceeded 7 mol/m3, and seawater began to invade the cavern group; when it was running for 22 a to 23 a, the seawater invasion speed was the fastest; when it was running for 41 a, the Cl− mole concentration on the southeast side of 3# cavern room exceeded 143 mol/m3, and the seawater invasion reached the strong corrosion degree of steel; when it was running for 50 a, all the cavern rooms except 1# cavern room were invaded by seawater, 3# and 4# cavity rooms have some areas to reach strong corrosion degree, seawater invasion is the most serious. It is suggested to set up additional facilities such as vertical water curtain to enhance the prevention and control of seawater intrusion. The research results can provide reference for the suppression of seawater intrusion in underground oil reserves in offshore areas.
2023, 50(6): 193-203.
doi: 10.16030/j.cnki.issn.1000-3665.202211077
Abstract:
In southwest China, carbonate rocks are widely distributed. It has unique dissolution features which bring a lot of resistance to engineering constructions. In order to explore the dissolution damage regular of layered carbonate rocks in acidic water, a self-made flow dissolution system was used to conduct laboratory dissolution tests on limestone cores under four different conditions. The mass loss, the change of p-wave velocity, the mass concentration of Ca2+ and Mg2+ and the morphology of the core surface were obtained. Mass loss rate after dissolution of layered limestone was used to define the damage variation. Through multivariate statistical regression analysis, the relationship between four different arguments (bedding dip Angle, pH, velocity of flow, dissolution time) and dissolution damage variation was established. The results show that the dissolution damage of layered limestone has a good mathematical relationship between the four different arguments. The following conclusions can be drawn from the analysis: The time has a significant effect on the dissolution damage of bedded limestone, followed by the velocity and pH. Under the same acidic environment, the dissolution effect shows a rule of 90° >0° >45° >30° >75° >15° >60° for limestone with different bedding inclination angles. The bedded angle has less effect on the dissolution of limestone than other factors, but plays a decisive role in the surface dissolution morphology of rock samples. The results of this study can provide some reference for engineering practice and geological disaster control in limestone areas.
In southwest China, carbonate rocks are widely distributed. It has unique dissolution features which bring a lot of resistance to engineering constructions. In order to explore the dissolution damage regular of layered carbonate rocks in acidic water, a self-made flow dissolution system was used to conduct laboratory dissolution tests on limestone cores under four different conditions. The mass loss, the change of p-wave velocity, the mass concentration of Ca2+ and Mg2+ and the morphology of the core surface were obtained. Mass loss rate after dissolution of layered limestone was used to define the damage variation. Through multivariate statistical regression analysis, the relationship between four different arguments (bedding dip Angle, pH, velocity of flow, dissolution time) and dissolution damage variation was established. The results show that the dissolution damage of layered limestone has a good mathematical relationship between the four different arguments. The following conclusions can be drawn from the analysis: The time has a significant effect on the dissolution damage of bedded limestone, followed by the velocity and pH. Under the same acidic environment, the dissolution effect shows a rule of 90° >0° >45° >30° >75° >15° >60° for limestone with different bedding inclination angles. The bedded angle has less effect on the dissolution of limestone than other factors, but plays a decisive role in the surface dissolution morphology of rock samples. The results of this study can provide some reference for engineering practice and geological disaster control in limestone areas.
2023, 50(6): 204-212.
doi: 10.16030/j.cnki.issn.1000-3665.202211030
Abstract:
The Baiyangdian Lake is located in Xiongan New Area, which has a fragile ecological environment and a shortage of water resources. Lake evaporation is one of the main discharge of the Baiyangdian Lake, and research on lake evaporation is of important practical significance and scientific value for understanding lake water circulation and evaluating ecological water demand and for recovery of lake ecological function. However, the actual observed data on evaporation in the Baiyangdian Lake is limited, so it is usually estimated by converting the data of nearby land observation stations or empirical models, which cannot accurately estimate the lake evaporation because of large calculation error. In this work, in-situ experiments were carried out in the Baiyangdian Lake. This study established an E601 evaporation station and a 20 m2 evaporation pool to observe the lake evaporation at the center of the Baiyangdian Lake, and an automatic weather station was established simultaneously to get meteorological data. The correlation between evaporation by E601 evaporation station and meteorological factors is analyzed by methods of correlation analysis and multiple linear regression model. The evaporation of the E601 evaporation station is compared with the data of the 20 m2 evaporation pool and the simulated evaporation. The results indicate that in the Baiyangdian Lake in summer, the diurnal variation of lake evaporation is intense, ranging from 0.4 mm/d to 6.6 mm/d, and the maximum evaporation occurs in June, but decreases with the increasing rainfall from July to August. Evaporation of lake water is more affected by radiation and humidity. The evaporation of 20 m2 evaporation pool is taken as the evaporation of lake water. The observed evaporation of E601 evaporation station is higher than the actual evaporation of Baiyangdian Lake, which can be used to estimate lake evaporation more accurately by local evaporation conversion coefficient. In this experiment, the evaporation conversion coefficient between the 20 m2 evaporation pool and the E601 evaporation station is about 0.98, which is slightly greater than the previous studies. The results of this study provides a basic basis for the calculation of water surface evaporation in the Baiyangdian area.
The Baiyangdian Lake is located in Xiongan New Area, which has a fragile ecological environment and a shortage of water resources. Lake evaporation is one of the main discharge of the Baiyangdian Lake, and research on lake evaporation is of important practical significance and scientific value for understanding lake water circulation and evaluating ecological water demand and for recovery of lake ecological function. However, the actual observed data on evaporation in the Baiyangdian Lake is limited, so it is usually estimated by converting the data of nearby land observation stations or empirical models, which cannot accurately estimate the lake evaporation because of large calculation error. In this work, in-situ experiments were carried out in the Baiyangdian Lake. This study established an E601 evaporation station and a 20 m2 evaporation pool to observe the lake evaporation at the center of the Baiyangdian Lake, and an automatic weather station was established simultaneously to get meteorological data. The correlation between evaporation by E601 evaporation station and meteorological factors is analyzed by methods of correlation analysis and multiple linear regression model. The evaporation of the E601 evaporation station is compared with the data of the 20 m2 evaporation pool and the simulated evaporation. The results indicate that in the Baiyangdian Lake in summer, the diurnal variation of lake evaporation is intense, ranging from 0.4 mm/d to 6.6 mm/d, and the maximum evaporation occurs in June, but decreases with the increasing rainfall from July to August. Evaporation of lake water is more affected by radiation and humidity. The evaporation of 20 m2 evaporation pool is taken as the evaporation of lake water. The observed evaporation of E601 evaporation station is higher than the actual evaporation of Baiyangdian Lake, which can be used to estimate lake evaporation more accurately by local evaporation conversion coefficient. In this experiment, the evaporation conversion coefficient between the 20 m2 evaporation pool and the E601 evaporation station is about 0.98, which is slightly greater than the previous studies. The results of this study provides a basic basis for the calculation of water surface evaporation in the Baiyangdian area.
2023, 50(6): 213-224.
doi: 10.16030/j.cnki.issn.1000-3665.202306028
Abstract:
Aiming at the problem of low degree of exploration and research of geothermal geological conditions in the Shifugou area, which seriously restricts the development and utilization of geothermal resources, on the basis of available data, the geothermal geological conditions and the characteristics of the thermal reservoir in the Lanzhou faulted basin are summarized. Combined with the exploration results of the controlled source audio frequency magnetotelluric (CSAMT) method, the potential of geothermal resources development in the Shifogou area in the southern part of the basin is inferred. The results show that (1) the geothermal geological conditions in the Lanzhou faulted basin are obviously different. Taking the buried faults of Shengouqiao (F5) and Leitai River (F8) as the boundary, respectively, the faulted basin can be divided into the western Xigu district, central Qilihe district and eastern Chengguan-Shifogou district. (2) The geothermal temperature increases from west to east, and increases vertically from the depth of 2000 to 2500 m, inferring that this is the basic depth of geothermal exploitation in the Lanzhou faulted basin. (3) In the southern section of the eastern part may exist layered-conductive geothermal resources and fault-zone geothermal resources, it is inferred that there may exist “combined type” of layered and banded geothermal water in the Shifogou district, which is located in the F2 fracture zone or the intersection of F2 fracture zone and F8 fault zone. It is suggested that the exploration and production well depth of geothermal water in the faulted-zone thermal reservoir should be considered as 800−1100 m, and that the exploration and production well depth of the “combined” layered thermal reservoir should be considered as 1500−2000 m. The wellhead geothermal water temperature in this area is expected to reach 50−60 °C, the single well yield can reach 500−1000 m3/d, and the quality of the geothermal water can reach the standard for medical bathing. The results can provide a basis for geothermal resources exploration in Lanzhou.
Aiming at the problem of low degree of exploration and research of geothermal geological conditions in the Shifugou area, which seriously restricts the development and utilization of geothermal resources, on the basis of available data, the geothermal geological conditions and the characteristics of the thermal reservoir in the Lanzhou faulted basin are summarized. Combined with the exploration results of the controlled source audio frequency magnetotelluric (CSAMT) method, the potential of geothermal resources development in the Shifogou area in the southern part of the basin is inferred. The results show that (1) the geothermal geological conditions in the Lanzhou faulted basin are obviously different. Taking the buried faults of Shengouqiao (F5) and Leitai River (F8) as the boundary, respectively, the faulted basin can be divided into the western Xigu district, central Qilihe district and eastern Chengguan-Shifogou district. (2) The geothermal temperature increases from west to east, and increases vertically from the depth of 2000 to 2500 m, inferring that this is the basic depth of geothermal exploitation in the Lanzhou faulted basin. (3) In the southern section of the eastern part may exist layered-conductive geothermal resources and fault-zone geothermal resources, it is inferred that there may exist “combined type” of layered and banded geothermal water in the Shifogou district, which is located in the F2 fracture zone or the intersection of F2 fracture zone and F8 fault zone. It is suggested that the exploration and production well depth of geothermal water in the faulted-zone thermal reservoir should be considered as 800−1100 m, and that the exploration and production well depth of the “combined” layered thermal reservoir should be considered as 1500−2000 m. The wellhead geothermal water temperature in this area is expected to reach 50−60 °C, the single well yield can reach 500−1000 m3/d, and the quality of the geothermal water can reach the standard for medical bathing. The results can provide a basis for geothermal resources exploration in Lanzhou.
Supervisor: China Geological Survey
Sponsor: China Institute of Geo-Environment Monitoring
Chief Editor: Li WenPeng
Editor&Publication: Editorial Office of Hydrogeology & Engineering Geology
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010-60850956 (宗老师)
010-60850953 (刘老师)
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010-60850986 (王老师)
Email: swdzgcdz@vip.163.com
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