上海典型黏土小应变剪切模量现场和室内试验研究

土体小应变剪切模量在基坑、隧道等地下工程的计算分析中有着重要作用，越来越受到人们的关注。虽然上海地区地下工程项目的建设规模不断扩大，但关于上海典型黏土层的小应变剪切模量的研究相对较少。分别采用现场波速测试和室内弯曲元试验对上海典型黏土层的初始剪切模量进行了研究。试验结果表明：在减小土样扰动、保持土样应力状态与原位土体等效的基础上，弯曲元试验得到的初始剪切模量与现场波速测试相一致；考虑了土体应力状态和孔隙比的经验公式能够合理地描述上海典型黏土层初始剪切模量的变化规律，并给出了各土层的经验参数。试验结果可为上海地区地下工程计算分析中小应变剪切模量的估算提供参考。

Field and laboratory measurements on shear modulus of typical Shanghai clay at small strain

Small-strain shear modulus plays a crucial role in numerical analyses of underground geotechnical Engineering issues such as excavations and tunnels. The research on small strain shear modulus of typical clay layers has rarely been reported, despite the fact that many large-scale underground construction projects have been ongoing in Shanghai. In this study, the initial shear moduli of typical clay layers at small strains in Shanghai have been investigated on spot by the field acoustic wave measurement and indoor bending element test. The experimental results show that the initial shear modulus obtained from the bending element test is consistent with that obtained from the in-situ wave velocity test if the soil disturbance is minimized and the soil stress state adopted in the indoor experiment is equivalent to the in-situ soil. It is shown that the proposed empirical formulation with considering the stress state and the void ratio of the soil can reasonably describe the variation of the initial shear modulus of the typical clay layer in Shanghai, and the empirical parameters of each soil layer are given. The experimental results can provide reference for calculating and analyzing the shear modulus of soft clay at small to medium strain.