控制吸力下低应力条件的合肥膨胀土抗剪强度试验  

Shear Strength Test of Hefei Expansive Soil under Low Stress Conditions with Controlled Suction

作　　者：侯超群 张荣健 李永鑫 HOU Chaoqun;ZHANG Rongjian;LI Yongxin(School of Automotive and Transportation Engineering,Hefei University of Technology,Hefei,Anhui 230009,China)

机构地区：[1]合肥工业大学汽车与交通工程学院,安徽合肥230009

出　　处：《中外公路》2024年第1期48-54,65,共8页Journal of China & Foreign Highway

基　　金：国家自然科学基金青年基金资助项目(编号:5210081105);安徽省自然科学基金青年基金资助项目(编号:2108085QE250)。

摘　　要：膨胀土边坡在变饱和条件下可能发生浅层滑塌失稳。为了研究非饱和膨胀土在低应力条件下的强度特性,采用非饱和三轴仪设置多组不同基质吸力和应力条件,进行合肥膨胀土的三轴剪切试验,对试验数据进行分析。试验结果表明:当膨胀土所受净围压应力不断降低时,其应力-应变曲线会由应变硬化向应变软化过渡;非饱和膨胀土强度随基质吸力增大而增大;浅层膨胀土的抗剪强度会呈现明显降低,具有非线性特点;非饱和膨胀土的黏聚力对抗剪强度影响显著,低应力条件下黏聚力会显著降低,内摩擦角明显增大;净围压应力对低应力段土体强度影响明显,而基质吸力对低应力段土体强度影响较弱。Topsoil slide and instability of expansive soil slopes may occur under variable saturation conditions.In order to study the strength characteristics of unsaturated expansive soil under low stress conditions,several different matrix suction and stress conditions were set by unsaturated triaxial apparatus.The triaxial shear test of Hefei expansive soil was carried out,and the test data were analyzed.The test results show that when the net confining stress on the expansive soil continues to weaken,the stress-strain curve transitions from strain hardening to strain softening.The strength of unsaturated expansive soil increases with increasing matrix suction.The shear strength of shallow expansive soil shows a significant reduction with non-linear characteristics.The cohesion of unsaturated expansive soils has a significant effect on the shear strength.The cohesion decreases significantly under low stress conditions,and the internal friction angle increases significantly.The net confining stress significantly affects the strength of the soil at the low stress level,but matrix suction has a weak effect on the strength of the soil at the low stress level.

关 键 词：合肥膨胀土 抗剪强度 非饱和三轴试验 低应力条件 基质吸力 非线性 

分 类 号：U414[交通运输工程—道路与铁道工程]