ISSN 1000-3665 CN 11-2202/P
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Experimental study on seismic performance of composite reinforced structure with shock absorption and energy dissipation of potentially collapsedrock mass
ZHU Jiewang, WANG Shengyong, LI Wenle, LV Guojing, ZHANG Aishe, ZHOU Guangqiang
 doi: 10.16030/j.cnki.issn.1000-3665.202306009
Abstract(10) HTML(9) PDF (5298KB)(0)
At present, there are two types of structures for strengthening dangerous rock mass in earthquake area construction: anchorage and retaining. The connection between the two types of reinforced structures and the dangerous rock mass is rigid with very limited deformation ability between the structure and unstable rock mass, which leads to the poor seismic performance of the structure. Under the seismic load especially when the magnitude of earthquake is strong, it is easy to fail and cause collapse disaster. This kind of damage phenomenon exists in a large number of seismic projects in southwest China. To solve the existing problems of the reinforced structure, a composite reinforced structure was designed in this study, and it allows the dangerous rock mass to be dislocated to a limited extent under the action of earthquakes, can buffer the seismic impact force of the dangerous rock mass, and has the function of shock absorption and energy dissipation. The structure is composed of anchor rod (cable), shock absorber anchor head (primary energy dissipation), connecting beam, supporting pile, and a secondary shock absorber and energy dissipation device between the connecting beam and supporting pile. To verify the effectiveness of the composite reinforced structure, besides theoretical analysis, a physical model comparison test on the common anchor reinforced structure under the same conditions is carried out by using a shaking table. Different seismic waves, amplitudes and frequencies, which are representative of the region, are selected as input seismic loadings. Theoretical analysis and experimental results show that the displacement growth rate and cumulative displacement amplitude of the composite reinforced structure decrease significantly comparing to conditon for the same collapse body without protective measures. Compared with the traditional bolt-reinforced structure, the tensile force and pressure are significantly reduced. The amplification coefficient of peak acceleration PGA also decreased significantly. It is proved that the composite reinforced structure can effectively resist the dynamic stress caused by the earthquake on the dangerous rock mass by using its own elastoplastic deformation and damping force, effectively transfer the impact kinetic energy of the dangerous rock mass, and significantly reduce the shock and energy dissipation, which greatly avoids the damage of the reinforced structure and prevents the occurrence of collapse disasters. It is proved that the composite reinforced structure can slice off the peak seismic energy generated by small, medium and large earthquakes in layers, and has a good effect on damping and energy dissipation. This technology provides a new reinforcement scheme for the collapse dangerous rock mass, and has great practical significance for improving the consolidation technology of potentially collapsed rock mass in seismic area
Estimation of conductivity fields by using a correlation-based localization scheme of iterative ensemble smoother
XIA Chuanan, WANG Hao, JIAN Wenbin
 doi: 10.16030/j.cnki.issn.1000-3665.202303033
Abstract(673) HTML(168) PDF (5281KB)(121)
In the studies of groundwater flow and solute transport, many efforts have been made to estimate hydrogeological parameters through physical-distance based localization schemes of ensemble assimilation approaches. However, these methods are unavailable when there are no physical distances between parameters and observations. To avoid this limitation, we calculate the tapering factors in terms of the correlation coefficients between parameters and observations and develop a novel correlation-based localization scheme of iterative ensemble smoother. For the purpose of comparison, a physical distance-based scheme of iterative ensemble smoother together with the new approach are used to assimilate hydraulic head information and estimate the hydraulic conductivity field of a 2D confined aquifer. Among the test cases, we consider different configurations of ensemble size, observation error and number of observations, and their impacts on the accuracy of conductivity estimation can be well explored. The results show that (1) the root mean square error of hydraulic conductivity, RMSE, obtained through the new approach for each test case of interest, is lower than its counterpart through the physical distance-based approach, with the RMSE ranges of [0.8307, 0.9590] and [0.8394, 1.0000] for all test cases through the two approaches, respectively. (2) The estimated conductivity field has discontinuities when using the physical distance-based approach, but this does not happen when using the new approach. In this study, we develop a novel correlation-based localization scheme of iterative ensemble smoother, which is free of the definitions of physical distances between parameters and observations, yields higher accuracy of parameter estimation in comparison with the physical distance-based approach, and can be a useful tool for estimating hydrogeological parameters.
Abstract(9145) HTML(3268) PDF (2927KB)(1893)
Discrete element analysis of torpedo anchor penetration into calcareous sands considering particle breakage
LIU Xin, DONG Guangyang, SHI Danda
 doi: 10.16030/j.cnki.issn.1000-3665.202212030
Abstract(0) HTML(0) PDF (0KB)(0)
As a new type of deep-sea anchorage device, the torpedo anchor is widely used in deep-sea oil and gas exploitation projects, but few attentions have been paid to the torpedo anchor penetrating into coral deposits. Based on the discrete element method, the penetration process of torpedo anchor into calcareous sands is numerically analyzed. The reliability of the numerical model is verified by comparing with the existing indoor test results. The numerical simulation focuses on the evolution of particle breakage of soils around the anchor during the penetration process, and its macro and micro effects on the anchor penetration characteristics are also discussed. The results show that in the process of torpedo anchor penetration, the soil around the anchor tip is seriously broken, while the particle breakage at the anchor side is relatively weak. The particle breakage quantity increases with the increase of penetration depth, and the distribution of particle velocity field is basically symmetrical along the central axis of the anchor body. With the increase of penetration depth, the distribution range of particle velocity field expands, and the peak particle velocity first increases and then decreases during the penetration process. The peak value in the stress concentration area first increases and then decreases, when the penetration depth increases. After the flange starts to contact the soil, the stress within the soil reaches the maximum. The research results can provide references for the design of dynamic anchor penetration in island and reef engineering.
Research on the relationship between saturated permeability and pore distribution characteristics of loess-paleosol
ZHAO Zhiyan, ZHANG Changliang, SHEN Wei, QIN Tao, LI Ping, LI Tonglu
 doi: 10.16030/j.cnki.issn.1000-3665.202301009
Abstract(2) HTML(0) PDF (7720KB)(0)
Due to differences in sedimentary environments, the paleosol is denser than the overlying loess, and its saturated permeability coefficients should be lower than that of the loess. This intuitive understanding has been challenged by the experimental results of several permeability tests which indicate that paleosol and loess have similar saturated permeability. In order to reveal the mechanism behind this phenomenon, we focused on the loess-paleosol strata of the loess tableland located in Jingyang County, Shaanxi Province. Undisturbed loess and paleosol specimens were extracted at equal intervals of 1 m from a 33 m exploratory well. Variable head permeability (VHP) tests were then conducted to determine their saturated permeability coefficients. Concurrently, mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) tests were conducted to obtain the pore distribution curves and microstructure images of typical samples, respectively. The analysis of the relationship between saturated permeability and pore distribution characteristics in loess-paleosol was analyzed based on the aforementioned experimental results. VHP test results illustrated that the saturated permeability coefficients of loess and paleosol decrease regularly with increasing burying depth, and the values of the saturated permeability coefficients of adjacent loess and paleosol samples are very close. MIP and SEM test results demonstrated a consistent pore structure in loess, whereas paleosol exhibited an irregular clump-fissure structure characterized by the presence of fissures in dense clay clumps. Saturated permeability coefficients were found to be contingent on the content of permeable pores, with loess primarily featuring large pores (pore diameter > 2 μm), and paleosol predominantly consisting of micro-cracks between clumps. Despite their similar permeability coefficients, the permeability mechanism were fundamentally different. This study establishes a theoretical foundation for studying the pore distribution characteristics of loess and paleosol, as well as addressing engineering challenges in loess areas.
Study on the method of comprehensive geophysical prospecting for detecting the thin overburden buried faults in limestone area in northern Henan
ZHU Rui, REN Yunfeng, XIONG Qi, XUE Han
 doi: 10.16030/j.cnki.issn.1000-3665.202211058
Abstract(16) HTML(10) PDF (5968KB)(2)
Accurate identification of the buried faults is crucial for the water conservancy projects construction. Geophysical exploration is an effective method for identifying buried faults quickly. However, due to the multi-solution nature of geophysical problems, a single geophysical method is also one-sided. Therefore, the selection of an optimized combination of geophysical methods to identify buried faults quickly and accurately is currently a difficult and hot issue to be addressed. Based on the comprehensive analysis of the physical characteristics of various rock and soil masses and on-site geological conditions in limestone area of Taihang Mountain in northern Henan, the comprehensive geophysical exploration methods such as electrical resistivity tomography, seismic reflection survey, refraction tomography and transient Rayleigh surface wave method were carried out for the F1 small-scale tensional torsional normal fault and F16 large-scale torsional translational normal fault respectively. It is found that the combined exploration results of refraction tomography and seismic reflection survey fully revealed the development characteristics of F1 fault from the characteristics of shear wave velocity and reflection wave events respectively. For the F16 fault, the comprehensive detection results of electrical resistivity tomography, seismic reflection survey, and transient Rayleigh surface wave method are highly consistent in the abnormal areas, and the refraction tomography has also achieved complete results. F16 fault was verified by drilling and borehole television to be massive and associated with caves, which is consistent with the physical results. The research results show that the combination of seismic reflection survey and refraction tomography for detecting similar F1 fault can reduce the multiplicity of interpretation results and save exploration costs effectively. Using electrical resistivity tomography, seismic reflection survey and transient Rayleigh surface wave method for detailed investigation, rapid and accurate identification of faults similar to F16 has been achieved. The two combined detection techniques can determine the location, depth, occurrence and nature of two types of typical thin overburden buried faults in limestone areas quickly, and could reduce blindness and one-sidedness in the detection work effectively, provide a new idea for efficient detection for similar condition. The proposed method could play a greater role in this field.
Centrifuge model test and numerical simulation on evolution characteristics of fracture surface of the anti-dipped layered slope
MU Chenglin, ZHANG Yuyang, PEI Xiangjun, MA Hao, ZHOU Xin, LI Linyan
 doi: 10.16030/j.cnki.issn.1000-3665.202210015
Abstract(11) HTML(9) PDF (6340KB)(1)
The formation and evolution characteristics of fracture surface is one of the key points in anti-inclined layered slope research, and it is also the basis of stability evaluation as well as engineering design and treatment. In this study, the stress and deformation parameters of the slope are obtained by using the indoor large-scale geotechnical centrifuge. At the same time, combined with the PFC numerical simulation results, the formation and evolution process and characteristics of the slope fracture surface are displayed: firstly, the compression shear crack is generated and extends to the middle and lower part of the slope, and the compression shear zone of the slope is divided; secondly, the developments of cracks toward to the middle and upper part of the slope, and with the initial formation of fracture surface, the deep slope body is bent; finally, the shallow cracks are completely connected to form a complete fracture surface Ⅰ from the top to the foot of the slope. The middle and upper parts of the internal potential fracture surface (Ⅱ, Ⅲ) are approximately parallel to the slope surface, and the lower parts are merged gradually at the foot of the slope. While the potential fracture surface Ⅳ at the boundary between the stable compression area and the bending area is stepped. At the same time, there are three secondary fracture surfaces in the shallow layer of the slope. The formation mechanism of the fracture surface is revealed that the deformation and failure of the slope causes the differential stress of the rock stratum due to the action of gravity. Under the action of compression shear, tension shear and bending, the crack initiates and expands from the tip of the prefabricated crack, and finally penetrates to form the fracture surface. Therefore, gravity is the internal reason, and the structural characteristics of slope are the basic conditions. The research results provide a basis for further research and practice of anti-inclined layered slope.
Comparative study on land subsidence monitoring and control in the Shandong Plain, China and the Greater Houston Area, USA
ZHANG Yongwei, WANG Guoquan, BI Yubai, ZHU Xiaowei, YU Dejie, WANG Xiaowei
 doi: 10.16030/j.cnki.issn.1000-3665.202301025
Abstract(9) HTML(9) PDF (0KB)(0)
Both the Shandong Plain in China and the Greater Houston Area in the United States have land subsidence problems that were caused by excessive groundwater pumping. More than 100 years of monitoring results and 50 years of prevention and control experience have been obtained in the Greater Houston Area, and these experiences can be used as the significant references for the monitoring and prevention of land subsidence in the plain areas of Shandong Province over the past 30 years.To further promote and strengthen land subsidence monitoring and prevention, groundwater resource management, digital empowerment, and data sharing in Shandong Province, in this article a comparative study was conducted on the causes of land subsidence, monitoring techniques, groundwater management, and land subsidence prevention and control in the Shandong Plain and the Greater Houston Area. The results indicate that excessive extraction of groundwater is the main cause of land subsidence, and land subsidence management measures based on limiting groundwater extraction have been taken. Currently, the area and rate of subsidence are decreasing in both places. The monitoring methods and techniques used in two places are basically the same, mainly using precision leveling surveying, bench mark fixed on different stratum or borehole extensometers, Global Navigation Satellite Systems (GNSS), and Interferometric Synthetic Aperture Radar (InSAR) techniques, and the density and frequency of observations are gradually increasing. Meanwhile, the management and sharing of observation data is different. The land subsidence management administration agencies in the Houston area are mainly responsible for the collection and sharing of observation data, and do not undertake data processing and research tasks. All observation data are open to the public, and scientific researches based on observation data is mainly undertaken by the U.S. Geological Survey (USGS) and universities. Research results are published on USGS reports or journal articles. Differently, land subsidence and groundwater level monitoring in Shandong Plain are undertaken by the Ministry of Natural Resources and the Ministry of Water Resources, and its affiliated institutions are responsible for field observation, data storage, data analysis and research, as well as formulating regulations for groundwater management. There are certain difficulties in data sharing and integration between departments, which limits in-depth and systematic research on land subsidence.
Model test on stability of soft rock slopes composed of nearly horizontal redbeds with cracks
DENG Wei, XIAO Shiguo
 doi: 10.16030/j.cnki.issn.1000-3665.202210050
Abstract(13) HTML(10) PDF (6421KB)(1)
Regarding to the problem that soft rock slopes composed of nearly horizontal redbeds with cracks in the eastern Sichuan area is prone to sliding failure under long-term heavy rainfall conditions, based on a typical slope example with double weak interlayers, similar materials that can characterize the softening and cracking characteristics of the soft rock in water are prepared with elastic modulus and tensile strength as the main control factors. A laboratory physical test model on a soft rock slope with fissured nearly horizontal redbeds was constructed, and the deformation, crack propagation and stability evolution of the slope under long-term rainwater infiltration was investigated. The results show that (1) the development of slope deformation can be divided into three stages - initial deformation, uniform deformation and accelerated deformation failure; (2) the crack propagation of the slope mainly includes the ‘upper-narrow and lower-wide’ cracks developed from bottom to top in the rear of the slope, and the related cracks developed from top to bottom in the front of the slope. The crack propagation area is mainly concentrated between the upper and lower weak interlayers, where excess pore water pressure is easily gathered; (3) a numerical simulation of the test model via FLAC3D presents the seepage process of the thrust landslide, and shows that the excess pore pressure increases initially and then stabilizes gradually with time. At the weak interlayers and vertical cracks, the excess pore water pressure increases cumulatively; (4) the evolution process of the sliding surface and slope instability can be divided into three stages: shallow fracture development and penetration, fracture spreading to deep weak interlayers and gradual penetrating, fracture further extension and slope failure. The weakening of rock mass caused by long-term rainwater infiltration, together with the gradual development of cracks to the deep zone of the slope and their connections with the soft interlayers to form the multi-stage stepped sliding surface are fundamental reason of slope failure for the soft rock slopes composed of nearly horizontal redbeds with cracks.
Experimental study on the impact of wide graded debris flow on check dam in high altitude area
HE Shengqing, ZHENG Da, ZHANG Wen
 doi: 10.16030/j.cnki.issn.1000-3665.202211009
Abstract(17) HTML(13) PDF (6568KB)(1)
The impact force of debris flow is the main cause of damage and destruction of check dam. In high altitude area, due to high mountains and deep valleys, serious physical weathering of surface materials, a wide range of source materials gradation, high frequency of debris flow occurence and high impact force, the damages induced by debris flow to the check dam are significant. To study the impact characteristics of the wide graded debris flow on check dam in high altitude area, the debris flow developed in Tibet is taking as a prototype. A physical test model of the impact check dam of wide graded debris flow is established. The unit weight of debris flow, the slope of flume and the maximum particle size of debris flow solid are selected as variable factors. 27 groups of flume tests were carried out to study the characteristics of impact force. The results show that: (1) Wide-graded debris flow mainly undergoes three contact evolution stages during the process of impact retaining dam, i.e. impact climbing-rolling return flow-accumulation and silting. The smaller of the debris flow volume weight could lead to a higher climbing distance, and more obvious stage performance of sourcing and sliting process. (2) The impact force in front of the dam decreases with the increase of the bulk weight of wide-graded debris flow. Under the same slope and gradation, a larger the bulk weight of debris flow materials lead to a lower velocity of the debris flow materials and less impact force, because it is more difficult to carry solid material sources. (3) The impact force in front of the dam increases with the increase of the groove gradient. The larger the groove gradient, the greater the flow velocity and flow depth of wide-graded debris flow, the greater the impact force of debris flow. The larger the particle size of solid phase of debris flow, the more obvious the effect of both. (4) The impact force in front of the sand bar increases with the increase of the maximum particle size of the solid phase of the wide graded debris flow, and the change trend is more significant than when the volume density of the debris flow and the slope conditions of the groove change. The maximum particle size has no obvious regular relationship with the velocity and depth of the debris flow. The research results could provide a basis for the prevention and research of the wide graded debris flow.
 doi: 10.16030/j.cnki.issn.1000-3665.zhenggaoqishi
Abstract(20) HTML(16) PDF (2687KB)(13)
Research progress and prospect of land subsidence
ZHU Lin, GONG Huili, LI Xiaojuan, ZHOU Chaofan, YE Miao, WANG Haigang, ZHANG Ke, HAN Miaomiao
 doi: 10.16030/j.cnki.issn.1000-3665.202212043
Abstract(23) HTML(11) PDF (3160KB)(6)
Differential land subsidence has posed the major threat to urban infrastructure, linear rail transit and underground space development and utilization, and also restricted the sustainable development of the economy and society. This paper systematically elaborates on the research progresses on land deformation acquisition, evolution mechanism and simulation of land subsidence, and focuses on the analysis of land deformation acquisition technology based on InSAR monitoring and multi-source deformation data fusion, as well as the correlation analysis, statistical analysis, machine learning and other methods to analyze the relationship between the evolution of land subsidence and various influencing factors based on geotechnical experiment and long time series observation data. On this basis, the advantages and disadvantages of land subsidence evolution simulation models such as groundwater flow field-land deformation model, mathematical statistical model and machine learning model are explored. It is found that multi-source deformation data fusion can improve the spatiotemporal resolution of land deformation. The differences in geological structure, lithology, groundwater exploitation, and dynamic and static loads are the mechanisms that cause the differential evolution of land subsidence. The difficulty in balancing the computational efficiency and interpretability of mathematical models for land subsidence is the main problem in simulation. According to the literature review, the current researches mainly focus on land subsidence caused by groundwater over-exploitation. This paper further proposes the future research directions for land subsidence, under the background of climate change, new hydrological condition and dataset, and based on the fusion of data through remote sensing and field observations, integrating the latest progress of InSAR, GeoAI, cloud platform and other technologies to reveal the evolution mechanism of land subsidence considering the climate change and anthropic activities and provide technical support for regional land subsidence prevention and urban safety.
Mechanism of rainfall-induced shallow landslide and stability prediction model
LIU Jiayi, CHEN Chunli, FU Yukai, WANG Chenxing, LI Tonglu, XIAO Ruihua, LIU Yanhui
 doi: 10.16030/j.cnki.issn.1000-3665.202306051
Abstract(21) HTML(9) PDF (5242KB)(9)
The rainfall-induced shallow landslides are primarily debris landslides, characterized by chain-mass occurrence and high hazard, and the hydrological response mechanism of water table and soil moisture content to precipitation is complicated, which makes it difficult to accurately carry out the stability prediction. To further study the influence of the rainfall-triggered internal hydrological responses on the slope-stability, on-site precipitation infiltration monitoring, correlation analysis and mechanical analysis were carried out on the example of Houshanli landslide in Qingchuan County, Sichuan Province. The relationship between precipitation and water table was proposed based on three years of climate and hydrological monitoring data. The response of rainfall infiltration, soil volumetric water content and water table were analyzed. The results indicate that: (1) groundwater exhibits periodic fluctuations throughout the year, characterized by three phases of slow decline, rapid decline, and rapid ascent. Additionally, there is a linear negative correlation between precipitation and water table, with no significant correlation observed with the water table increment; (2) Through the infinite slope model and the relationship between precipitation and water table, a prediction model for shallow landslide stability was constructed. The precipitation threshold (81.8 mm/d) and water table threshold (0.73 m) were determined which align with the actual situations. This provides an early warning method for rainfall-induced shallow landslides by monitoring these two factors.
Application of long and short pile combined support to deep soft soil foundation pit
ZHENG Jinhuo, SHEN Minglong, LIU Yanghui
 doi: 10.16030/j.cnki.issn.1000-3665.202212013
Abstract(26) HTML(10) PDF (5578KB)(11)
The retaining piles for foundation pits are usually arranged with equal pile lengths. However, in foundation pit projects in deep and soft soil areas, the retaining piles need to be embedded in good soil below the soft soil, so the pile lengths are longer. The economy is poor when the pile lengths are arranged with equal pile lengths. In order to examine the effect and performance of long and short pile combined support with partial retaining piles embedded in good soil in deep soft soil foundation pits, current design methods are used to calculate the structural internal force and deformation of retaining piles under the conditions of full length pile support and full short pile support. Therefore, it is estimated that the deformation of retaining piles under the condition of using long and short pile combined support should be between full length pile support and full short pile support. Through 3D numerical simulation, a comparative analysis is conducted on the combined support of long and short piles with different lengths to determine the appropriate length of short piles, and the analysis results are used to guide the actual project design and monitor the project. The research results show that the pile length of a short pile supported by a combination of long and short piles can be intercepted to the second reverse bending point for calculating the bending moment of the retaining pile under the condition of full length pile support, which can achieve joint stress and coordinated deformation of the short pile and the long pile. At the same time, the design and calculation method of long and short pile composite support based on current design and the calculation software is given. The monitoring data show that the application of long and short pile composite support in the project is successful, and the research results can provide references for deep soft soil foundation pit engineering.
An early prediction model of regional landslide disasters in Fujian Province based on convolutional neural network
DONG Lihao, LIU Yanhui, HUANG Junbao, LIU Haining
 doi: 10.16030/j.cnki.issn.1000-3665.202211018
Abstract(6682) HTML(2110) PDF (5679KB)(178)
Landslide disasters occur frequently in Fujian Province, and early warning of landslide disasters on a regional scale is an important means of effective disaster prevention and mitigation. Due to the complex mechanism of landslide disasters, the traditional regional landslide early warning methods have such problems as insufficient accuracy. Deep learning mainly refers to the technology of feature extraction, abstraction, representation and learning by constructing the neural network model, which is a kind of machine learning. As a classical deep learning algorithm, convolutional neural network has more powerful classification and representation ability than traditional machine learning. Taking Fujian Province as the research area, this paper introduces the convolution neural network into the field of landslide disaster early warning and constructs a regional landslide early warning model of Fujian Province. The process is as follows: ① the SMOTE optimization algorithm is used to optimize the sample database of landslide disasters in Fujian Province from 2010 to 2018, enlarging the number of positive samples and expanding the proportion of positive and negative samples from 1∶3.4 to 1∶2, and the total number of samples reaches 19151. ② Construct a convolution neural network model structure, which includes an input layer, two convolution layers, two maximum pooling layers, a full connection layer and an output layer. ③ Use the convolution neural network to train the optimized samples (80% of the samples from 2010 to 2018 as the training set), and use the Bayesian optimization algorithm to optimize the model parameters to obtain the regional landslide early warning model of Fujian Province. ④ The model is verified with 20% of the samples from 2010 to 2018 as the test set, and the confusion matrix and ROC curve are used to verify the model. The results show that the accuracy of the model ranges from 0.94 to 0.97, the AUC value is 0.975, indicating that the model accuracy and generalization ability are good. ⑤ The actual situation of the landslide disaster in the flood season of 2019 is taken as a positive sample, negative samples are collected through the method of time-space sampling, and the 2019 regional landslide sample verification set (603 samples) is constructed. The model is further verified by using the confusion matrix and ROC curve. The results show that the accuracy of the model ranges from 0.75 to 0.80, and the AUC value is 0.852. Although only the actual landslide samples in the flood season of 2019 is used for verification, good results is also achieved. In this paper, the convolution neural network algorithm is applied to the regional landslide early warning, which provides a new way to establish the regional landslide early warning model. The preliminary verification shows that the model is effective and will be further applied and verified in Fujian Province in the future.
Abstract(1375) HTML(1048) PDF (2751KB)(1558)
Characteristics of geological hazards and it’s mitigations of the Ms6.8 earthquake in Luding County, Sichuan Province
TIE Yongbo, ZHANG Xianzheng, LU Jiayan, LIANG Jingtao, WANG Donghui, MA Zhigang, LI Zongliang, LU Tuo, SHI Shengwei, LIU Minsheng, BA Renji, HE Longjiang, ZHANG Xinke, GAN Wei, CHEN Kai, GAO Yanchao, BAI Yongjian, GONG Lingfeng, ZENG Xiaowen, XU Wei
 doi: 10.16030/j.cnki.issn.1000-3665.202209029
Abstract(2690) HTML(2190) PDF (5917KB)(282)
On 5th September, 2022, the Ms 6.8 earthquake in Luding County, Sichuan Province induced large numbers of geological hazards. To deeply understands the evolution, distribution, and characteristics of geological hazards caused by the earthquake, we got the distribution of geological hazards by the field investigation and remote sensing interpretation. Then we analyzed the conditions for hazard control and the countermeasures for hazard prevention and reduction. The results show that as of 22:00 on September 14, 2022, the earthquake has induced 565 geological hazards with threat objects in Luding County and Shimian County (including 331 collapses and 234 landslides), and there were 81 existing geological hazards became more deformed. The types of geological hazards induced by the earthquake are mainly medium and small mass high-level collapses, which are mainly concentrated in the areas with Seismic intensity zone ofⅨ near the epicenter. These areas include Moxi Town, Detuo Township, both banks of Dadu River between Detuo Township and Dewei town in Luding County, Caoke Township and wanggangping Township in Shimian County. According to the experience of the Wenchuan earthquake, the debris flow will be active in the next five years, and its characteristics of high frequency and viscous debris flow should be considered in the design of debris flow prevention and control engineering. Under the rainfall condition, the landslide deposition remaining on the slopes of Dadu River banks in the section of Detuo Township Dewei town can be easily transformed into debris flow. It is suggested that the transformation forms of the two hazards’ types should be fully considered in the design of prevention and control projects. The study can provide a reference for earthquake geological hazard prevention and post hazard reconstruction planning in the earthquake area.
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2023, 50(6): 1-2.  
Abstract(80) HTML(26) PDF (2862KB)(73)
2023, 50(6): 1-2.  
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The influence of permafrost degradation on the change of suprapermafrost water : A case study in the source areaof the Yellow River
ZHU Liang, YANG Mingnan, LIU Jingtao, ZHANG Yuxi, LI Bei, ZHOU Bing, CHEN Xi
2023, 50(6): 3-13.   doi: 10.16030/j.cnki.issn.1000-3665.202303060
Abstract(101) HTML(28) PDF (4458KB)(37)
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.
Ecological environmental changes and its impact on water resources and water-sediments relationship in Beiluo River Basin
HAN Shuangbao, WANG Sai, ZHAO Minmin, WU Xi, YUAN Lei, LI Haixue, LI Fucheng, MA Tao, LI Wenpeng, ZHENG Yan
2023, 50(6): 14-24.   doi: 10.16030/j.cnki.issn.1000-3665.202305018
Abstract(50) HTML(17) PDF (5174KB)(20)
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.
Identifying the evolution of water balance and influencing factors in the mountainous area of Beijing-Tianjin-Hebei
BAI Hua, YANG Huifeng, ZHANG Yingping, MENG Ruifang, BAO Xilin, DAI Lei, LI Xiangzhi
2023, 50(6): 25-40.   doi: 10.16030/j.cnki.issn.1000-3665.202305007
Abstract(104) HTML(21) PDF (4233KB)(41)
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.
Groundwater evolution and ecological effect in the Kongque River Basin, Xinjiang
LONG Rui, ZHANG Jun, YU Kun, GU Xiaofan, LI Ying, DONG Jiaqiu, SU Xiao, ZHU Jin
2023, 50(6): 41-50.   doi: 10.16030/j.cnki.issn.1000-3665.202305032
Abstract(73) HTML(22) PDF (4549KB)(32)
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.
Effects of succession processes of marsh wetland and farmland on groundwater in the Sanjiang Plain
CUI Huqun, WU Tingwen, LIU Jiangtao, LIU Weipo, LI Zhihong, CHENG Xuxue, LIU Weipeng
2023, 50(6): 51-58.   doi: 10.16030/j.cnki.issn.1000-3665.202306022
Abstract(32) HTML(16) PDF (3985KB)(12)
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.
A discussion of the test pressure of collapsible coefficient for Q2 loess
LI Tonglu, FENG Wenqing, LIU Zhiwei, GAO Jianwei, FU Yukai, LEI Yulu, LI Ping
2023, 50(6): 59-68.   doi: 10.16030/j.cnki.issn.1000-3665.202211006
Abstract(46) HTML(22) PDF (3582KB)(14)
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.
Research on creep characteristics and pore structure evolution characteristics of freezing-thawing rocks
SONG Yongjun, MENG Fandong, BI Ran, ZHANG Kun, ZHANG Jun
2023, 50(6): 69-79.   doi: 10.16030/j.cnki.issn.1000-3665.202211026
Abstract(63) HTML(26) PDF (5491KB)(21)
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.
An experimental study of the reinforcement mechanism and erosion resistance of nano silicon-based sand-fixation material
YUAN Jinke, PEI Zuan, YANG Senlin, YU Hao, HU Xiaohong, LIU Hai
2023, 50(6): 80-89.   doi: 10.16030/j.cnki.issn.1000-3665.202210019
Abstract(35) HTML(18) PDF (5315KB)(18)
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.
An improved soil abrasion testing method for shield tunnelling based on LCPC
YANG Zhiyong, ZHU Junwei, YANG Xing, SHAO Xiaokang, JIANG Yusheng, WANG Yunlong
2023, 50(6): 90-98.   doi: 10.16030/j.cnki.issn.1000-3665.202211036
Abstract(40) HTML(17) PDF (7597KB)(13)
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=0.93LAC 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.
An analysis of cylindrical cavity expansion in sand based on a unified state parameter model
LIU Guanfei, LEI Shengyou
2023, 50(6): 99-111.   doi: 10.16030/j.cnki.issn.1000-3665.202210044
Abstract(35) HTML(15) PDF (4830KB)(3)
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.
Application of digital construction of the minor-disturbance four-axial soil mixing pile
2023, 50(6): 112-119.   doi: 10.16030/j.cnki.issn.1000-3665.202210017
Abstract(64) HTML(16) PDF (4332KB)(11)
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.
An experimental study of the mechanical properties of the Bimrock rock mass with different cementing strength based on orthogonal tests
WU Qian, WEI Jihong, LIU Gang, SHI Wei, LI Kai
2023, 50(6): 120-128.   doi: 10.16030/j.cnki.issn.1000-3665.202210014
Abstract(22) HTML(13) PDF (7784KB)(5)
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.
Numerical study of tunnel blasting parameter optimization and vibration damage based on the RHT constitutive model
WANG Dawei, WANG Zhiliang, WANG Shumin
2023, 50(6): 129-136.   doi: 10.16030/j.cnki.issn.1000-3665.202210009
Abstract(50) HTML(25) PDF (4684KB)(4)
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.
Investigation and stability analysis of cracks of the K21 external pit fissures in the Hanyang Mausoleum
QIN Like, WANG Qi, DUAN Xiaotong, GUO Bin, PANG Lei, BAI Yan
2023, 50(6): 137-146.   doi: 10.16030/j.cnki.issn.1000-3665.202210024
Abstract(190) HTML(40) PDF (5863KB)(104)
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.
A study of the influence of the crossing-slope fault geometry on the slope seismic response
WANG Zhimin, LUO Gang, WANG Yuan, HU Xiewen, CHEN Shikuo
2023, 50(6): 147-157.   doi: 10.16030/j.cnki.issn.1000-3665.202209030
Abstract(54) HTML(30) PDF (4191KB)(37)
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.
A model experimental study of the formation mechanism of internal erosion caves in fractured loess
ZHANG Buping, ZHU Xinghua, SUN Hengfei, CAI Jiale, CHENG Xi
2023, 50(6): 158-167.   doi: 10.16030/j.cnki.issn.1000-3665.202209052
Abstract(56) HTML(17) PDF (6060KB)(19)
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.
Exploration of blockchain technology application in the construction of National Risk Warning System on Landslides
ZHANG Mingzhi, YANG Fei, MA Juan, FU Zheng, HUANG Zhe, LI Junfeng
2023, 50(6): 168-174.   doi: 10.16030/j.cnki.issn.1000-3665.202302012
Abstract(75) HTML(40) PDF (3492KB)(173)
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.
Mechanism of action of Fe(III) on antimony release under anoxic acidic conditions
TANG Yaning, WANG Xinghua, WANG Yingnan, LI Xiaoqian, SONG Xiaodong
2023, 50(6): 175-183.   doi: 10.16030/j.cnki.issn.1000-3665.202212026
Abstract(33) HTML(14) PDF (4054KB)(7)
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.
Study on the risk of seawater intrusion in offshore underground oil reserve
QU Jianjun, CAO Biao, SONG Dazhao, YANG Lianzhi, HE Shengquan
2023, 50(6): 184-192.   doi: 10.16030/j.cnki.issn.1000-3665.202212006
Abstract(28) HTML(13) PDF (7102KB)(8)
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 Clmole 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 Clmole 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.
Experimental study on acid dissolution damage characteristics of bedded limestone
WU Zongqin, ZUO Shuangying, WANG Lu, LI Benyun, LIU Jing
2023, 50(6): 193-203.   doi: 10.16030/j.cnki.issn.1000-3665.202211077
Abstract(33) HTML(14) PDF (3802KB)(9)
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.
Research on in-situ test of lake evaporation in the Baiyangdian Lake
WANG Xiaoyan, YIN Dechao, WANG Yushan, WU Bin, AN Yonghui, XU Rongzhen, WANG Xi, LIU Yun
2023, 50(6): 204-212.   doi: 10.16030/j.cnki.issn.1000-3665.202211030
Abstract(33) HTML(22) PDF (4567KB)(13)
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.
Evaluation of geothermal resource potential in Shifogou based on geothermal geological conditions of the Lanzhou faulted basin
CHEN Xiuqing, WANG Tao, HUANG Xiaohui, WANG Baoyu
2023, 50(6): 213-224.   doi: 10.16030/j.cnki.issn.1000-3665.202306028
Abstract(57) HTML(27) PDF (5324KB)(18)
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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