上海深层黏性土的土样扰动评价方法  

Methods for evaluating sample disturbance of deep clayey soil in Shanghai

作　　者：时振昊 屠梓真 钱建固[1,2] 黄茂松[1,2] SHI Zhenhao;TU Zizhen;QIAN Jiangu;HUANG Maosong(Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《岩土工程学报》2024年第9期1880-1888,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(52178345);中央高校基本科研业务费专项资金项目(20232ZD08)。

摘　　要：通过室内试验准确获取土样原位力学性质,需借助土样扰动评价方法进行扰动评估。现有的土样扰动评价方法大多针对浅层土,缺乏深层黏性土的相关研究。基于上海深层黏性土一维固结试验及剪切波速试验,结合结构性黏土本构模拟,对比文献中其他黏土试验数据,分析了既有土样扰动评价方法对深层黏性土的适用性,提出了基于剪切波速且排除应力和密实状态影响的土样扰动评价指标,利用本文及文献数据验证了上述评价指标的合理性。结果表明:(1)深层黏性土block样与钻孔样存在显著的扰动差异;(2)对于扰动程度相同的土样,现有评价指标?e/e_0随取样深度增大而增大,可能造成对深层黏性土土样扰动的高估,且无法区分不同取样方法引起扰动差异;(3)以室内与原位剪切波速比V_(s,lab)/V_(s,in situ)为扰动评价指标,无法反映取样方法对上海深层黏性土的扰动差异,对其他黏土给出的评估结果沿深度离散性较大;(4)提出的评价指标可以克服取样深度的影响,对同一地区黏性土,可以较好统一量化取样方法引起的土样扰动程度。To accurately understand the in situ mechanical properties of soils,it is necessary to evaluate the degree of sample disturbance.The existing sample disturbance evaluation methods mostly focus on shallow soils,while the counterpart for deep clayey soil is needed.This work investigates the applicability of the existing methods for evaluating sample disturbance of deep clayey soil,via conducting laboratory one-dimensional consolidation and shear wave velocity tests on Shanghai deep clayey soil,performing constitutive modeling of structured clay,and comparing test data in the literatures.A new sample disturbance index is proposed,which is based on the shear wave velocity and excludes the influences of stress state and void ratio.The performance of the disturbance index is assessed against the test results from this study and the literatures.The results show:(1)There is a significant difference in sampling disturbance between the block samples and borehole samples of Shanghai deep clayey soil.(2)For the soil samples with the same disturbance,the existing index∆e/e0 increases with the increase of the sampling depth,which may overestimate the sampling disturbance of deep clayey soil,and cannot reflect the above-mentioned difference in the disturbance degree.(3)The disturbance index Vs,lab/Vs,in situ(i.e.,the ratio of shear wave velocity measured in the laboratory to that in situ),cannot reflect the difference in the disturbance degree of Shanghai deep clayey soil caused by different sampling methods,and its application to other clays gives a relatively large dispersion along depth.(4)The proposed disturbance index can overcome the influences of sampling depth,and for the clayey soil in the same region,it can uniformly quantify the disturbance degree caused by sampling.

关 键 词：深层黏性土 土样扰动评价 取样方法 剪切波速 

分 类 号：TU43[建筑科学—岩土工程]