高分解度泥炭土直剪抗剪强度特性及机理  

Shear strength properties and mechanisms of peaty soil with high degree of decomposition in direct shear tests

作　　者：桂跃[1,2,3] 付坚[1] 侯英杰[1] 曹净[1] 周云东[2,3] GUI Yue FU Jian HOU Yingjie CAO Jing ZHOU Yundong(Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology, Kunming 650051, China Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China Jiangsu Research Center for Geotechnical Engineering Technology, Hohai University, Nanjing 210098, China)

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650051 [2]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210098 [3]江苏省岩土工程技术工程研究中心(河海大学),江苏南京210098

出　　处：《河海大学学报（自然科学版）》2016年第5期418-426,共9页Journal of Hohai University(Natural Sciences)

基　　金：国家自然科学基金(51568030);岩土力学与堤坝工程教育部重点实验室开放基金(GH201401);云南省人才培养基金(KKSY201306106)

摘　　要：基于大量室内压缩-直剪联合试验结果,系统分析了取自昆明市和大理市3个不同场地典型高分解度泥炭土的直剪抗剪强度特性及机理。试验结果表明：固结快剪、快剪和慢剪所得泥炭土的剪应力～剪切位移关系曲线表现出不同的形态;固结快剪和慢剪时,随着法向应力的增大,剪切变形从塑性变形转变为弹塑性变形为主;不同法向应力下,快剪的剪切变形均以塑性变形为主。高分解度泥炭土抗剪强度包线近似为相交的2段不同斜率的直线;固结快剪和慢剪抗剪强度包线转折点对应的法向应力σs约为200 k Pa,快剪时σs约为100 k Pa。通过分析泥炭土固结压缩变形特性并建立压缩-剪切微结构模型,分析了其抗剪强度来源及演化机理。机理分析表明：随着法向应力增大,高分解度泥炭土经历了从多孔隙状态至相对密实状态的转变,导致其抗剪强度及抗剪强度参数发生相应改变。Based on the results of a large number of laboratory compression-direct shear combined tests,the shear strength properties and mechanisms of typical peaty soil with a high degree of decomposition,sampled from three different sites in Kunming and Dali cities,were analyzed. The test results demonstrate the following： the shear stress-shear displacement curves of peaty soil showed different shapes in the consolidated quick shear test,quick shear test,and slow shear test; with the increase of the normal stress,the shear deformation changed from plastic deformation to elastic-plastic deformation in the consolidated quick shear and slow shear tests; the shear deformation in the quick shear test showed mainly the plastic deformation under different normal stresses; the shear strength envelopes of peaty soil with a high degree of decompression were,basically,two intersecting polygonal lines with different slopes; the normal stress（ σs） corresponding to the break point of shear strength envelopes was about200 k Pa in the consolidated quick shear test and slow shear test,and the value was about 100 k Pa in the quick shear test. Based on analysis of the compression deformation of peaty soil,the evolution mechanisms of the shear strength were further analyzed by means of establishing compression-shear microstructural models for peaty soil. Weconclude that the increasing normal stress causes peaty soil to change from a porous state to a relatively densified state,leading to changes in the shear strength and the shear strength parameters.

关 键 词：高分解度泥炭土 直剪试验 抗剪强度包线 抗剪强度 抗剪强度参数 

分 类 号：TU47[建筑科学—结构工程]