反压诱导有效应力增生模式与土体强度关联机制研究  

Correlation mechanism between effective stress variation mode induced by back pressure and soil strength

作　　者：李永强 许言 陈波[1] 熊健辉 卢玢宇 LI Yong-qiang;XU Yan;CHEN Bo;XIONG Jian-hui;LU Bin-yu(School of Civil and Architecture Engineering,East China University of Technology,Nanchang,Jiangxi 330013,China;Nanchang Emergency Management Bureau,Nanchang,Jiangxi 330038,China;School of Water Resources and Environmental Engineering,East China University of Technology,Nanchang,Jiangxi 330013,China;Engineering Research Center for Geological Environment and Underground Space of Jiangxi Province,East China University of Technology,Nanchang,Jiangxi 330013,China)

机构地区：[1]东华理工大学土木与建筑工程学院,江西南昌330013 [2]南昌市应急管理局,江西南昌330038 [3]东华理工大学水资源与环境工程学院,江西南昌330013 [4]东华理工大学江西省地质环境与地下空间工程研究中心,江西南昌330013

出　　处：《岩土力学》2024年第8期2338-2350,共13页Rock and Soil Mechanics

基　　金：江西省自然科学基金(No.20202BABL204064);国家自然科学基金(No.52068002);江西省“双千计划”(No.DHSQT32022006,JXSQ2020101041);江西省地质环境与地下空间工程研究中心开放基金(No.JXDHJJ2022-008)。

摘　　要：反压施加是提高土体饱和度的常用有效方法,但易引起土体强度参数表观偏离。采用标准球形玻璃珠砂,开展基准固结不排水(consolidated undrain,CU),固结排水(consolidated drained,CD)及干样试验,对偏应力与孔压(或体积应变)数据进行实时精准测记与对比分析,借助p′-q应力路径图,显著呈现并定量分析了反压施加对土体力学特性的影响规律,初步厘清了反压施加对土体强度的影响机制。反压设置对CU试验结果影响显著,孔压发展形态控制着偏应力发展的形态,最终影响强度参数的确定,但应力路径始终约束在修正类剑桥模型的框架范围内。孔压发展模式和速率主要受限于反压设置大小及试样相对密实度,反压越大,孔压潜在变化幅度越大,进而导致偏应力变化区间增大;相对密实度越大,孔压发展速率越大,偏应力增速渐大。初始状态相同时,CU试验孔压发展与CD试验体积应变发展趋势高度一致,展示了试样体积应变势在不同边界条件下的共同本质。初步给出了临界状态时CU残余强度定量预测公式,根据相对密实度及反压值可初步定量评定残余孔压值,进而可确定CU残余强度。The back pressure saturation method,a widely adopted and efficient technique for enhancing soil saturation,can nonetheless introduce notable deviations in soil strength parameters.Standard spherical glass bead sand was utilized for conducting benchmark consolidated undrained(CU),consolidated drained(CD),and dry sample tests.Real-time accurate measurements and comparative analyses of deviatoric stress and pore pressure(or volumetric deformation)data were performed.Utilizing the p′-q stress path diagram,the influence of back pressure application on soil mechanical properties was significantly demonstrated and quantitatively analyzed,thereby preliminarily elucidating the mechanism of back pressure influence.The setting of back pressure significantly impacts the results of CU tests,where the shape of pore pressure development governs the shape of deviatoric stress development,ultimately influencing the determination of strength parameters.However,the stress path remains constrained within the framework of the revised Cam-Clay model.The mode and rate of pore pressure development are primarily constrained by the magnitude of the back pressure setting and the relative density of the sample.As back pressure increases,the potential change in pore pressure also increases,resulting in a greater amplitude of deviatoric stress change.Similarly,a higher relative density leads to a faster development rate of pore pressure and an increased rate of deviatoric stress.Under identical initial conditions,the development of pore pressure in CU tests exhibits high consistency with the development of volume deformation in CD tests,revealing the common essence of the sample’s volumetric deformation potential across different boundary conditions.A quantitative prediction formula for the residual strength of CU tests at the critical state is presented.The residual pore pressure value can be initially quantified based on the relative density and back pressure measurements,subsequently leading to the determination of the residual strengt

关 键 词：反压 偏应力 固结不排水(consolidated undrain CU)强度 有效应力路径 球形玻璃砂 

分 类 号：TU411[建筑科学—岩土工程]