高应力水平下深部黏土力学特性微观分析  

Micro analysis of mechanical characteristics of deep clay under high stress level

作　　者：商翔宇[1,2] 余海岁[1,3] 周国庆[1] 王飞[2] 陆勇[2] 

机构地区：[1]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221008 [2]中国矿业大学力学与建筑工程学院,江苏徐州221116 [3]英国诺丁汉大学土木工程学院岩土力学中心

出　　处：《岩土工程学报》2012年第2期363-368,共6页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51009136);中国矿业大学深部岩土力学与地下工程国家重点实验室开放基金项目(SKLGDUE08006X);江苏自然科学基金项目(BK2011212)

摘　　要：深部黏土在不同应力水平作用下会表现出不同的力学特性,已有试验结果表明高应力水平下正常固结饱和深部黏土的压缩指数和内摩擦角均小于中常压下相应值。为揭示深部黏土力学性质发生上述变化的内在机理,首先利用现有基于双电层理论推算高压黏土压缩曲线的计算方法对试验结果进行验证计算,发现其低估了深部黏土在高压下的压缩性,分析表明原有的两黏土薄片中点无量纲势函数与黏土薄片无量纲距离参数的对数假设关系存在不合理之处,利用新提出的假设以及相应的计算方法获得的预测计算结果能够很好地与试验结果相吻合。然后利用弹性黏着摩擦理论对内摩擦角随应力水平变化进行了计算分析,结果表明在0.2 MPa作用下土的摩擦系数是1.6 MPa相应值的2倍,与实测结果基本一致。The deep clay exhibits different mechanical properties under different stress levels. The available test results show that the compression index and internal friction angle of normally consolidated saturated deep clay at high pressure are lower than those at medium and low pressures. In order to reveal the intrinsic mechanism of the clay for the above mechanical change, the e - p curve of the clay at high pressure is firstly compared with that calculated by the existing method which can predict the e -p relationship at large pressure by use of the parameters obtained from experimental e -p data at low pressure based on the diffuse double-layer theory. It is seen that the calculated results underestimates the compression of the deep clay at high pressure. Unreasonable hypothesis that there is a logarithm relationship between the dimensionless potential function at the midpoint of two clay platelets and dimensionless distance function is discovered. The improved hypothesis and the relevant procedure are proposed. There is quite good agreement between the calculated and experimental e-p relationships at large pressure. And then, based on the elastic adhesive friction theory, the calculated results show that the friction coefficient of the clay at 0.2 MPa is 2 times the one at 1.6 MPa, which is almost consistent to the measured one.

关 键 词：深部黏土 高应力水平 力学特性 微观分析 

分 类 号：TU47[建筑科学—结构工程]