不同饱和度下膨胀土原位孔内剪切试验及强度响应特征  

In-situ borehole shear test and shear strength response characteristics of expansive soil under different saturations

作　　者：罗晓倩 孔令伟[1,2] 鄢俊彪 高志傲 田升奎 LUO Xiao-qian;KONG Ling-wei;YAN Jun-biao;GAO Zhi-ao;TIAN Sheng-kui(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Guangxi Key Laboratory of Geotechnical Mechanics and Engineering,Guilin University of Technology,Guilin,Guangxi 541004,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049 [3]桂林理工大学广西岩土力学与工程重点实验室,广西桂林541004

出　　处：《岩土力学》2024年第1期153-163,共11页Rock and Soil Mechanics

基　　金：国家重点研发计划(No.2019YFC1509901)。

摘　　要：膨胀土强度随饱和度变化显著,非饱和膨胀土的抗剪强度一直是研究膨胀土工程问题的关键。选取南阳市某高速路沿线边坡膨胀土为研究对象,进行了天然条件下处于不同饱和度状态的膨胀土原位孔内剪切试验,获得了自然条件下膨胀土的抗剪强度随饱和度的变化特征。膨胀土的抗剪强度、黏聚力、内摩擦角随着膨胀土饱和度的增大而逐渐减小。结合现场试验数据和土-水特征曲线,提出了以法向应力、饱和度为变量和以法向应力、基质吸力为变量的两种非饱和膨胀土的抗剪强度计算模型,并结合试验数据对计算模型的适用性进行了验证。与之前常用的非饱和土抗剪强度计算模型相比较,提出的两种计算模型所需的拟合参数少,适用于更宽吸力范围、不同法向应力条件下非饱和膨胀土抗剪强度的计算,且结果更为准确。The strength of expansive soil undergoes significant changes with saturation,and understanding the shear strength of unsaturated expansive soil is crucial for studying engineering problems related to this type of soil.This paper focuses on the expansive soil found along a highway in Nanyang City.In-situ borehole shear tests are conducted on the expansive soil under different saturation levels in its natural state,providing insights into the shear strength characteristics of expansive soil under natural conditions.The results show that as the saturation of expansive soil increases,the shear strength,cohesion,and internal friction angle gradually decrease.To calculate the shear strength of unsaturated expansive soil,two models are proposed in this study.The first model considers normal stress and saturation as variables,while the second model incorporates normal stress and matrix suction as variables.These models are developed based on field test data and the soil-water characteristic curve.The accuracy and applicability of the models are verified using the test data.Compared to commonly used shear strength calculation models for unsaturated soils,the two new models require fewer fitting parameters.They are applicable to calculating the shear strength of unsaturated expansive soils with a wider range of suctions and different normal stresses.Additionally,the results obtained using these models are more accurate.

关 键 词：非饱和膨胀土 饱和度 孔内剪切试验 抗剪强度 基质吸力 计算模型 

分 类 号：TU411[建筑科学—岩土工程]