重塑黄土的钻孔剪切变形与强度特性研究  

Study on deformation and strength characteristics of remolded loess by borehole shear test

作　　者：于永堂 张龙[1] 郑建国 黄晓维 YU Yongtang;ZHANG Long;ZHENG Jianguo;HUANG Xiaowei(Shaanxi Key Laboratory of Behavior and Treatment for Special Rock and Soil,China Jikan Research Institute of Engineering Investigations and Design Co.,Lid.,Xi'an,Shaanxi 710043,China;College of Civil Engineering,Xi an University of Architecture and Technology,Xi'an,Shaanxi 710055,China;China United Northwest Institute for Engineering Design and Research Co.,Ltd.,Xi'an,Shaanxi 710077,China)

机构地区：[1]机械工业勘察设计研究院有限公司陕西省特殊岩土性质与处理重点实验室,陕西西安710043 [2]西安建筑科技大学土木工程学院,陕西西安710055 [3]中联西北工程设计研究院有限公司,陕西西安710077

出　　处：《岩石力学与工程学报》2021年第S02期3367-3378,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：陕西省青年科技新星计划项目(2018KJXX-001);国机集团重点研发项目(SINOMACH 2017-科-249)。

摘　　要：钻孔剪切试验是一种土体抗剪强度参数的原位测试新方法,近年来在国内被逐步推广应用。为揭示重塑黄土的钻孔剪切变形与强度特性,对传统钻孔剪切仪进行改进,增加法向位移和剪切位移观测系统,设计钻孔剪切室内模型试验装置,通过模型试验探讨首级法向压力、分级法向压力增量、固结时间和加载剪切方式等对抗剪强度参数测试结果的影响规律,并总结钻孔剪切试验参数的控制方法,用于指导采用垫层法和挤密法处理黄土地基的钻孔剪切试验,试验结果表明,法向位移曲线包括初始变形段、似弹性变形段和塑性变形段:剪切位移曲线包括似弹性增大段、塑性变形段和剪切破坏段;施加的法向压力应控制在法向位移曲线的似弹性变形段范围内:分级加载剪切法与分别加载剪切法测得的抗剪强度参数差异不显著,前者较于后者的黏聚力偏小2.3~3.5 kPa,内摩擦角偏大0.8°~2.4°。The Borehole Shear Test(BST)provides direct determination of friction angle and cohesion of soils in-situ.In recent years,BST has been gradually used to in-situ shear test for soil investigations in China.In order to reveal the deformation and strength characteristics of remolded loess by BST,the normal displacement and shear displacement observation system are added to modify the traditional BST apparatus,the model test device for BST is designed,and the influence law of shear strength parameters test results caused by the initial normal stress,normal stress increments,consolidation time and testing procedures are discussed.On this basis,the method of adjusting the test control parameters according to the shear characteristics of the tested soil layer is proposed,which can be used to guide the in-situ BSTs of loess foundation treated by cushion method and compaction method.The test results show that the normal displacement curve includes initial deformation section,quasi elastic deformation section and plastic deformation section;The shear displacement curve includes quasi elastic increasing section,plastic deformation section and shear failure section;The normal pressure applied should be controlled in the range of quasi elastic deformation section;There is no significant difference of the shear strength parameters which measured by the multi-stage testing(MT)and single-stage testing(ST),and the measured cohesion by MT is 2.3-3.5 kPa smaller than ST,and the measured internal friction angle by MT is 0.8°-2.4°larger than ST.

关 键 词：土力学 重塑黄土 钻孔剪切试验 剪切变形 剪切强度 

分 类 号：TU43[建筑科学—岩土工程]