不同地区Q_2黄土的结构性对比分析

Comparation for structural behavior of Q_2 loess in different regions

对延安和西安Q2黄土进行了单轴压缩和CU剪切试验,研究了含水量和围压对其结构性的影响。结果表明,单轴压缩条件下两地Q2黄土的结构屈服应变均较小,且随含水量变化不明显,而结构屈服强度均随含水量增加呈指数减少。CU剪切条件下含水量和围压都对其结构性有明显的影响,围压增大时两地Q2黄土的结构屈服应力和结构屈服应变均增大,含水量增大时结构屈服应力减低,较大围压和较高含水率时,结构屈服段的应力应变曲线由强软化型向较强软化型甚至弱软化型转变。由于西安Q2黄土和延安Q2黄土的沉积环境不同,使其低含水量时结构屈服强度高于延安Q2黄土,而高含水量时结构屈服强度低于延安Q2黄土。

Q2 loess in Xian area and Yanan area are studied by the uniaxial compression test and the CU shear test,results show that the structural yield strains are all smaller,and do not change significantly with the water content,structural yield stresses are decreasing exponentially with water contents increasing in the former test.Structural behavior is influenced obviously by water content and confining pressure in the latter test,structural yield strains and yield pressures of loess in two regions all increase with the confining pressure increasing,but the structural yeild pressures decrease with water contents increasing.Stress-strain curves in structural yield phase change from strong strain-soften type to weaker and even weak strain-soften type with higher confining pressure and higher water content.Because of different sedimentary environments,structural yeild pressure of Q2Loess in Xian is higher when the water content is lower,but lower when the water content is higher.