饱和黏土不排水抗剪强度特性研究

Research on undrained shear strength properties of saturated clay

饱和黏土的不排水抗剪强度(su)是海洋工程地基稳定性验算必备的参数,该参数的准确性对工程安全至关重要。室内等向固结三轴压缩试验(CIUC)是工程中获得su最普遍的方法。随着对海洋土工程特性认识的加深及国际设计方法的引入,su的室内测试方法种类增加,但不同方法测得的su存在差异。针对天津滨海黏土开展不同固结方式、剪切方式以及不同超固结比(OCR)条件下的三轴压缩、三轴拉伸和静单剪(DSS)试验,分析比较了不同试验方法得到的su,并揭示了导致同一种土体su产生差异的原因,建立起不同试验方法测得的su之间的定量关系。在此基础上结合修正剑桥模型提出了可以预测不同试验方法su的计算公式。

The undrained shear strength(s.)of saturated clay is an essential parameter for checking the stability of ocean ground,and the accuracy of s.is crucial to engineering safety.The isotropically consolidated triaxial compression test(CIUC)in laboratory is the most common method for obtaining su.With the improvement on the understanding of the engineering properties of marine soil and the introduction of international design methods,the types of laboratory test methods for s.are increased,but there are dfferences in su measured by different methods.Triaxial compression,triaxial extension and static direct simple shear(DSS)tests were carried out for kaolin under different consolidation methods,different shear methods and different over-consolidation ratio(OCR),and su obtained by different test methods were analyzed.Furthermore,the causes for the difference in Su of the same soil were revealed,and the quantitative relationship for those su measured by different test methods was established.On this basis,in combination with the modified Cam clay model,a calculation formula of predicting su of different test methods is proposed.