K_0应力路径试验在上海地区工程勘察中的应用

Application of K_0 stress path test in engineering investigation in Shanghai

上海地区在进行软粘性土的变形特性试验时,勘察过程中极少进行对原状土在不同应力路径下的变形及强度试验研究,这使得报告中提供的参数不能很好地和基坑开挖卸荷过程中土体地层的实际相吻合。本文以上海市徐家汇某深大基坑项目为例,在勘察阶段进行K_0应力路径三轴试验,试验内容为对选取的代表性土样进行加荷、卸荷及再加荷,并记录各阶段的应力应变及变形模量。对试验结果的分析表明,应力路径对软粘性土的影响较明显,K_0应力路径可以较为真实地反映土体在天然状态下进行基坑开挖过程中的变形特性。建议以后在对变形敏感的深大基坑工程中加强推广应用。

In the test of deformation characteristics of soft clay soil in Shanghai,the test of deformation and strength of undisturbed soil under different stress paths is rarely carried out in engineering investigation,which makes the parameters provided in the investigation report not well consistent with the actual soil stratum in the excavation and unloading process of foundation pit.In this paper,taking a deep foundation pit project in Xujiahui,Shanghai for example,K0 stress path triaxial test was performed in the investigation stage.The test included loading,unloading and then re-loading of the selected representative soil samples,and recording the stress and strain as well as modulus of deformation at every stage.The analysis of the test results shows that the stress path had an obvious effect on the soft clay soil,and the K0 stress path can reflect the deformation characteristics of the soil in the process of foundation pit excavation in the natural state.It is suggested to strengthen the promotion and application of the K0 stress path in the deep and large foundation pit projects which are sensitive to deformation.