海相软黏土修正剑桥模型参数试验研究

Experimental study on parameters of modified Cambridge model of marine clay

修正剑桥模型是正常固结或超固结的饱和黏土广泛应用的弹塑性模型,由于沉积环境不同,各地区土体得到的修正剑桥模型参数不尽相同,因此准确地确定地区土体模型参数对于研究土体本构关系、进行数值模拟及指导工程实践具有重要意义。青岛环胶州湾地区广泛分布有海相淤泥与淤泥质粉质黏土,本文通过原状土的固结不排水三轴剪切试验、各向等压试验和标准固结试验确定了修正剑桥模型的三个参数,得到临界状态有效应力比M为1.657;各向等压固结试验得到的压缩参数λ平均值为0.132,回弹参数κ平均值为0.0480;标准固结试验得到的压缩参数λ平均值为0.178,回弹参数κ平均值为0.0407。标准固结试验得出的压缩参数λ值和回弹参数κ值分别为各向等压固结试验结果的1.35倍和0.85倍。

The modified Cambridge model is an elastic-plastic model widely used for saturated normal consolidated or overconsolidated clay.Due to the different sedimentary environment,the parameters of the modified Cambridge model for the soil in each area are different.Therefore,accurately determine the parameters of the model for regional soil is of great significance to the study of soil constitutive relationship,numerical modeling and engineering practice.The marine muck and mucky silty clay are widely distributed rounding Jiaozhou bay area of Qingdao.In this paper,three parameters of the modified Cambridge model are determined through the consolidated undrained triaxial shear tests,isotropic consolidation tests and standard consolidation tests of undisturbed soil,and the effective stress ratio M in the critical state is1.657;the average values of compression parameterλand the rebound parameterκin the isotropic consolidation tests are 0.132 and 0.0480 respectively.The average value of compression parameterλis0.178 and the average value of rebound parameterκis 0.0407 from the standard consolidation tests.The compression parameterλandκvalues obtained from the standard consolidation tests are about 1.35 times and 0.85 times of the results from the isotropic consolidation tests.