软黏土静力剪切破坏过程中小应变剪切模量变化研究

Study on the Change of Small Strain Shear Modulus During Static Shear Failure of Soft Clay

在软土地基上兴建大型建筑工程,软黏土在长期静荷载作用下土体结构的演变破坏是工程结构设计和地基稳定性分析必须考虑的问题.本文以温州软黏土为试验材料,利用动三轴联合弯曲元系统对饱和软黏土在静力剪切状态下小应变剪切模量的变化进行了研究.对比分析了弯曲元测得的数据与共振柱数据间的异同、软黏土试样的抗剪切强度、应力-应变关系及有效应力路径的变化等.结果表明,小应变剪切模量与有效应力存在一定关系,当有效应力降低到一定程度后小应变剪切模量会出现突降,且有一个明显的拐点,此时土体结构完全破坏,说明小应变剪切模量可以用来表征土体结构变化,该拐点可作为判断土体结构破坏的标准.

Building large construction engineering on soft soil foundation,the evolution and failure of soft clay under long-term static load is a problem that must be considered in the design of engineering structure and the analysis of foundation stability.Taking Wenzhou soft clay as a test material,the change of small strain shear modulus of saturated soft clay under static shear condition is studied by the dynamic three axis joint bending element system.The similarities and differences between the measured data of the bending element and the data of the resonant column,the shear strength,the stress-strain relationship and the effective stress path of the soft clay specimen are compared and analyzed.The results show that the small strain shear modulus has some relation with the effective stress,and when the effect force is reduced to a certain degree,the small strain shear modulus will appear sudden drop,and there is an obvious inflection point when the soil structure is completely destroyed,so the small strain shear modulus can be used to characterize the structure change of soil,and the inflection point can be used as a criterion to judge the destruction of soil structure.