黏土结构性对孔压静力触探结果的影响分析

加瑞; 赵栋; 雷华阳

doi:10.16030/j.cnki.issn.1000-3665.202209055

黏土结构性对孔压静力触探结果的影响分析

doi: 10.16030/j.cnki.issn.1000-3665.202209055

加瑞^{1, 2,},
赵栋^{1, 2},
雷华阳^{1, 2}

1.
天津大学建筑工程学院，天津　300350
2.
天津大学滨海土木工程结构与安全教育部重点实验室，天津　300350

基金项目: 天津市科技计划项目（21JCYBJC00380）；国家自然科学基金重大项目（51890911）

详细信息

作者简介:
加瑞（1982-），男，博士，副教授，主要从事岩土与地下工程方面的教学与科研工作。E-mail：jiarui@tju.edu.cn

中图分类号: TU442
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- 被引次数: 0
出版历程
- 收稿日期: 2022-09-25
- 修回日期: 2022-11-21
- 网络出版日期: 2023-07-24
- 刊出日期: 2023-09-19

An analysis of the influence of clay structure on piezocone penetration test results

JIA Rui^{1, 2
,},
ZHAO Dong^{1, 2},
LEI Huayang^{1, 2}

1.
School of Civil Engineering, Tianjin University, Tianjin　300350, China
2.
Key Laboratory of Coast Civil Structure Safety of Ministry of Education, Tianjin University, Tianjin　300350, China

摘要

摘要: 针对目前黏土结构性对孔压静力触探结果的影响及其机理尚不是很清楚的问题，首先在ABAQUS软件中对结构性剑桥模型进行了程序实现，然后建立了孔压静力触探贯入结构性黏土的数值模型，通过数值计算分析了黏土结构性对孔压静力触探结果的影响。数值计算结果表明：（1）黏土的结构性会导致锥尖周围土体的偏应力增大，由于锥尖附近土体的结构性损伤，最大偏应力出现在距锥尖一定距离的右下方；（2）表征结构性强度的参数——初始结构屈服应力 $ p{\text{'}}_{ {\rm{yi}}} $越大，锥尖阻力q_c越大，而表征结构性损伤速度的参数——结构性对流动法则影响参数ω越大，q_c值越小；（3） $p\text{'}_{ {\rm{yi}}} $值越大，贯入停止时的超静孔隙水压力u越大，而ω值越大，贯入停止时的u值越小；（4）经验圆锥系数N_kt随 $p\text{'}_{ {\rm{yi}}} $增大明显减小，随ω的增大略有减小。因此，黏土的结构性强度及其损伤会明显影响孔压静力触探的测量结果，基于锥尖阻力q_c估算结构性黏土的不排水抗剪强度s_u时应采用考虑结构性影响的经验圆锥系数N_kt，否则将会低估结构性黏土的s_u。研究结果可为孔压静力触探结果的分析和应用提供参考。
- 黏土结构性 /
- 孔压静力触探 /
- 结构性剑桥模型 /
- 锥尖阻力 /
- 经验圆锥系数
Abstract: The effect of clay structure on the piezocone penetration test results and its mechanism are not very clear, the structured Cam-clay model is firstly program-implemented in the ABAQUS software. Then, the numerical model of piezocone penetration into structured clay is established, and the effect of clay structure on piezocone penetration test results is analyzed through numerical simulation. The numerical calculation results show that (1) the clay structure causes the increase of deviatoric stress of the soils surrounding the cone tip, and the maximum deviatoric stress appears at the lower right at some distance from the cone tip due to the structural damage of the soils near the cone tip. (2) The larger the parameter $p\text{'}_{ {\rm{yi}}} $ representing structural strength is, the larger the cone tip resistance q_c, and the larger the parameter w representing structural damage speed, the smaller the q_c value. (3) The larger the $p\text{'}_{ {\rm{yi}}} $ value is, the larger the excess pore water pressure u when the penetration stops, and the larger the w value is, the smaller the u value when the penetration stops. (4) The value of the empirical cone factor N_kt decreases obviously with the increasing $p\text{'}_{ {\rm{yi}}} $, and decreases slightly with the increasing w . Therefore, the structural strength of clay and its damage will obviously affect the measurement results of the piezocone penetration test, and the empirical cone factor N_kt considering the structural effect should be used to estimate the undrained shear strength s_u of the structural clay based on the cone resistance q_c, otherwise, the s_u of the structural clay will be underestimated. The research results can provide reference for the analysis and application of piezocone penetration test results.
- clay structure /
- piezocone penetration test /
- structured Cam-clay model /
- cone resistance /
- empirical cone factor

HTML全文

图 1 不同单元试验的数值模拟与公式计算结果

Figure 1. Numerical simulation and formula calculation results of different element tests

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图 2 模拟CPTU贯入的数值模型简图

Figure 2. Schematic diagram of the numerical model of simulating CPTU penetration

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图 3 不同结构性参数时的q_c随深度变化图

Figure 3. Variations of q_c with depth for different structural parameters

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图 4 不同结构性参数时u的消散曲线

Figure 4. Dissipation curve of u for different structural parameters

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图 5 结构性参数对N_kt的影响

注：（a）图中${S_{\sigma}} = p\text{'} _{\rm{yi}}/ p\text{'} _0$

Figure 5. Effects of structural parameters on N_kt

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图 6 贯入到0.5 m深度时的偏应力分布

Figure 6. Deviatoric stress distribution with penetration depth of 0.5 m

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图 7 距锥尖不同距离单元的偏应力和偏应变

Figure 7. Deviator stress and deviator strain of elements with different distance from the cone tip

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图 8 离锥尖不同距离土体偏应变和剪应力

Figure 8. Shear stress and deviator strain of soils with different distance from the cone tip

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表 1 结构性剑桥模型参数

Table 1. Structured cam-clay model parameters

参数	M	λ	κ	E/kPa	e_IC	υ	b	ω	γ	$\sigma\text{'}_ {{\rm{vyi}}} $/kPa	$p\text{'}_ {{\rm{yi}}} $/kPa
侧限压缩试验	1.50	0.505	0.020 0	—	5.383	—	0.7	—	0.5	430	—
三轴固结排水试验	1.50	0.208	—	76 923	2.383	0.13	30.0	4	2.1	—	2 400.0
三轴固结不排水试验	1.28	0.355	0.047 7	—	2.910	0.25	1.0	1	0.5	—	57.5
CPTU贯入模拟	1.50	0.300	0.050 0	—	3.770	0.30	5.0	1	1.0	—	250.0
注：E为弹性模量； e_IC为重塑土正常固结曲线上p' = 1 kPa时的孔隙比； $\sigma \text{'}_ { {\rm{vyi} } }$为一维固结试验中的竖向屈服有效应力；“—”表示参数不需要设置。

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