卸荷条件下结构性软黏土三维力学特性研究

杨爱武; 黄俊枭; 李建华

doi:10.20174/j.JUSE.2024.03.11

地下空间与工程学报 >

2024 , Vol. 20 >Issue 3: 812 - 826

DOI: https://doi.org/10.20174/j.JUSE.2024.03.11

理论与试验研究

卸荷条件下结构性软黏土三维力学特性研究

杨爱武 ,
黄俊枭 ,
李建华

展开

1.东华大学环境科学与工程学院,上海 201620;
2.天津城建大学天津市软土特性与工程环境重点试验室,天津 300384

杨爱武(1971—),男,安徽桐城人,博士,教授、博士生导师,从事软黏土力学特性及土体微观结构研究。E-mail: tulilab@163.com

收稿日期: 2023-10-23

网络出版日期: 2024-07-15

基金资助

国家自然科学基金(42177119,51978440);中央高校基本科研业务费专项资金(2232021A-07)

收起

Study on the Three-Dimensional Mechanical Properties of Structural Soft Clay Soils under Unloading Conditions

Yang Aiwu ,
Huang Junxiao ,
Li Jianhua

Expand

1. College of Environmental Science and Engineering, Donghua University, Shanghai 201620, P.R. China;
2. College of Civil Engineering, Tianjin Chengjian University, Tianjin 300384, P.R. China

Received date: 2023-10-23

Online published: 2024-07-15

Fold

摘要

软黏土一般具有结构性,结构性是土体变形特性的重要影响因素。以天津滨海软黏土为原料土,通过掺入少量不同含量的水泥人工制备出土质近似均匀、结构性有所不同的结构性软黏土,采用GCTS真三轴试验仪探讨基坑开挖条件下结构性土体的三维力学特性。结果表明:侧向卸荷条件下土体应变与卸荷速率、土体本身结构性、固结围压皆有关系;当土体结构性与卸荷速率相同时,围压越小的试样应变增长的速率越快,破坏时应变量越大;在土体结构性与围压相同时,随着卸荷速率的增大,破坏应变以及破坏时的应力大小都增大;当大主应变ε₁小于破坏应变,土样的结构性未发生破坏时,ε₁－ε₃关系曲线斜率增长速率较慢,当大主应变ε₁达到破坏峰值后,小主应变ε₃方向膨胀速率加快,直至试样破坏;在同一围压下,土体初始卸荷切线模量随卸荷速率的增大而减小,土体卸荷破坏强度随卸荷速率的增大而增大。在此基础上,对应力-应变关系进行分析,建立并验证了考虑卸荷速率和土样结构强度影响的卸荷破坏强度预测公式。

关键词： 结构性土; 卸荷速率; 初始卸荷模量; 卸荷破坏强度; 真三轴试验

本文引用格式

杨爱武 , 黄俊枭 , 李建华 . 卸荷条件下结构性软黏土三维力学特性研究[J]. 地下空间与工程学报, 2024 , 20(3) : 812 -826 . DOI: 10.20174/j.JUSE.2024.03.11

Abstract

Soft clay soils are generally structural in nature, and structural properties are an important factor influencing soil deformation characteristics. The soft clay soil of Tianjin Binhai was used as the raw material, and the structural soft clay soil was artificially prepared by mixing a small amount of cement with different contents to produce a nearly homogeneous soil with different structural properties. The test results show that the strain of the soil under lateral unloading conditions is related to the unloading rate, the structure of the soil itself and the consolidation envelope pressure. When the structural properties of the soil and the unloading rate are the same, the smaller the envelope pressure, the faster the strain growth rate of the specimen and the greater the strain during damage. When the structure of the soil is the same as the surrounding pressure, the strain at failure and the stress at failure both increase as the unloading rate increases. When the large principal strain ε₁ is less than the damage strain and the structural properties of the soil sample are not damaged, the slope of the ε₁－ε₃ relationship curve grows at a slower rate, and when the large principal strain ε₁ reaches its peak damage, the expansion rate in the direction of the small principal strain ε₃ accelerates until the sample is damaged. Under the same circumferential pressure, the initial unloading tangential modulus of the soil decreases with increasing unloading rate, and the unloading damage strength of the soil increases with increasing unloading rate. On this basis, the stress-strain relationship was analysed and a prediction formula for the unloading damage strength was established and validated, taking into account the effects of unloading rate and structural strength of the soil sample.

Key words： structural soil; unloading rate; initial unloading modulus; unloading failure strength; true triaxial test

参考文献

[1]Mesri G, Godlewski P M. Time and stress compressibility interrelationship[J]. Geotechnical Engineering, ASCE, 1977, 103(5): 417-430.
[2]Mesri G, Stark T D, Ajlouni M A, et al. Secondary compression of peat with or without surcharging[J]. Geotechnical Engineering, ASCE, 1997, 123(5): 411-421.
[3]Hong Z S, Zheng L L,Cui Y J,et al. Compression behaviour of natural and reconstituted clays [J]. Geotechnique,2012,62(4) : 291－301.
[4]雷华阳, 张文振, 丁小冬, 等. 考虑软土结构强度的次固结特性试验研究 [J]. 岩土工程学报, 2013, 35(7): 1221-1227. (Lei Huayang, Zhang Wenzhen, Ding Xiaodong, et al. Experimental study on secondary consolidation considering structural strength of clay[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(7): 1221-1227. (in Chinese))
[5]雷华阳, 仇王维, 丁小冬, 等. 人工结构性土的次固结特性研究 [J]. 天津大学学报(自然科学与工程技术版), 2015, 48(11): 995-1000. (Lei Huayang, Qiu Wangwei, Ding Xiaodong, et al. Characteristics of secondary consolidation considering the structure of artificial soil [J]. Journal of Tianjin University (Science and Technology), 2015, 48(11): 995-1000. (in Chinese))
[6]杨爱武, 吴磊. 结构性海积软土强度与变形时效特性试验研究[J]. 地下空间与工程学报, 2015, 11(4): 919-925. (Yang Aiwu, Wu Lei. Experimental study on time-dependent strength and deformation of structured marine soft soil [J]. Chinese Journal of Underground Space and Engineering, 2015, 11(4): 919-925. (in Chinese))
[7]杨爱武, 闫澍旺, 杜东菊. 考虑结构性影响的吹填软土流变历时特性研究[J]. 工业建筑, 2012, 42(6): 106-111, 137 .(Yang Aiwu, Yan Shuwang, Du Dongju. Study onrheological diachronic property considering structural characteristics of soft dredger fill [J]. Industrial Construction, 2012, 42(6): 106-1111, 137. (in Chinese))
[8]朱楠, 刘春原, 赵献辉, 等. 排水剪切下湿地湖泊相黏土结构性宏微观试验研究[J]. 长江科学院院报, 2020, 37(9): 128-134. (Zhu Nan,Liu Chunyuan,Zhao Xianhui, et al. Macroscopic and microscopic experimental study on structural characteristics of marshy and lacustrine clays under drained shearing [J]. Journal of Yangtze River Scientific Research Institute, 2020, 37(9): 128-134. (in Chinese))
[9]熊赟. 人工制备结构性土率敏性试验及其流变本构模型研究[D]. 湘潭:湘潭大学, 2017. (Xiong Yun. Rate sensitivity test of artificial preparation sample of structural clay and its rheological constitutive model [D]. Xiangtan: Xiangtan University, 2017. (in Chinese))
[10]扈萍, 黄茂松, 马少坤,等. 粉细砂的真三轴试验与强度特性 [J]. 岩土力学, 2011, 32(2): 465-470. (Hu Ping, Huang Maosong, Ma Shaokun, et al. True triaxial tests and strength characteristics of silty sand [J]. Rock and Soil Mechanics, 2011, 32(2): 465-470. (in Chinese))
[11]邓国华, 邵生俊. 基于真三轴试验的黄土结构性变化规律研究[J]. 岩土力学, 2013, 34(3): 679-684. (Deng Guohua, Shao Shengjun. Research on change structural characteristics of loess based on true triaxial tests [J]. Rock and Soil Mechanics, 2013, 34(3): 679-684. (in Chinese))
[12]徐志伟. 土体各向异性变形特性真三轴试验研究[D]. 南京:河海大学, 2003. (Xu Zhiwei. Study on the characteristic of soil anisotropic deformation by true triaxial test [D]. Nanjing: HoHai University, 2003. (in Chinese))
[13]燕全会. 饱和粗砂的真三轴试验研究 [D]. 广州:广东工业大学, 2012. (Yan Quanhui. The True Triaxial tests of Saturated Gri[D]. Guangzhou: Guangdong University of Technology, 2012. (in Chinese))
[14]陈昌禄, 邵生俊, 罗爱忠, 等. 结构性对原状黄土强度影响规律的真三轴试验研究[J]. 岩土工程学报, 2013, 35(12): 2322-2327. (Chen Changlu, Shao Shengjun, Luo Aizhong, et al. True triaxial tests on structural effects on strength of intact loess [J]. Chinese Journal of Geotechnical Engineering, 2013, 35(12): 2322-2327. (in Chinese))
[15]刘国彬, 侯学渊. 软土的卸荷模量[J]. 岩土工程学报, 1996, 18(6): 22-27. (Liu Guobin, Hou Xue-yuan. Unloading modulus of soft soil [J]. Chinese Journal of Geotechnical Engineering, 1996, 18(6): 22-27. (in Chinese))
[16]何世秀, 韩高升, 庄心善, 等. 基坑开挖卸荷土体变形的试验研究 [J]. 岩土力学, 2003, 24(1): 17-20. (He Shixiu, Han Gaosheng, Zhuang Xinshan, et al. Experimental researches on unloading deformation of clay in excavation of foundation pit [J]. Rock and Soil Mechanics, 2003, 24(1): 17-20. (in Chinese))
[17]郑刚, 颜志雄, 雷华阳, 等. 天津市区第一海相层粉质黏土卸荷路径下强度特性的试验研究 [J]. 岩土力学, 2009, 30(5): 1201-1208. (Zheng Gang, Yan Zhixiong, Lei Huayang,et al. Experimental studies of unloading mechanical properties of silty clay of first marine layer in Tianjin city [J]. Rock and Soil Mechanics, 2009, 30(5): 1201-1208. (in Chinese))
[18]侯晓亮, 谭晓慧, 冀春杰. 合肥膨胀土侧向卸荷力学特性试验研究 [J]. 建筑结构, 2019, 49(增2): 878-883. (Hou Xiaoliang, Tan Xiaohui, Ji Chunjie. Study on the lateral unloading mechanical character of expansive soil in Hefei area [J]. Building Structure, 2019, 49(Supp.2): 878-883. (in Chinese))
[19]魏少伟, 郑刚, 刘畅. 滨海新区浅层软土卸荷变形性状试验研究 [J]. 水文地质工程地质, 2010, 37(5): 77-82. (Wei Shaowei, Zhen Gang, Liu Chang. Experimental study on unloading deformation behavior of shallow soft soil in Binhai New Area [J]. Hydrogeology ＆ Engineering Geology, 2010, 37(5): 77-82. (in Chinese))
[20]陈筠, 高彬,白文胜, 等. 红黏土在卸荷状态下的力学特性试验研究 [J]. 地下空间与工程学报, 2019, 15(5): 1393-1401.(Chen Jun, Gao Bin, Bai Wen-sheng, et al. Experimental study on the relationship between unloading ratio and deformation of red clay under excavation unloading [J]. Chinese Journal of Underground Space and Engineering. 2019, 15(5): 1393-1401. (in Chinese))
[21]闫芙蓉, 岳小丹, 胡雪源, 等. 考虑土体卸荷力学特性的基坑变形分析 [J]. 地下空间与工程学报, 2022, 18(2): 554-561.(Yan Furong, Yue Xiaodan, Hu Xueyuan, et al. Analysis on foundation pit deformation considering soil unloading mechanical preperties [J]. Chinese Journal of Underground Space and Engineering, 2022, 18(2): 554-561. (in Chinese))
[22]王国欣, 肖树芳,周旺高. 原状结构性土先期固结压力及结构强度的确定 [J]. 岩土工程学报, 2003, 25(2): 249-251. (Wang Guoxin, Xiao Shufang, Zhou Wanggao, Determination of preconsolidation pressure and structural strength of undisturbed structural soils [J]. Chinese Journal of Geotechnical Engineering, 2003, 25(2): 249-251. (in Chinese))

Options

文章导航

模态框（Modal）标题

摘要

本文引用格式

Abstract

参考文献