上海交通大学 土木工程系， 上海 200240
出版日期:2020-03-28发布日期:2020-04-09通讯作者:叶冠林，男，教授，博士生导师，电话(Tel.): 13611934473; E-mail: ygl@sjtu.edu.cn.作者简介:刘丽斌(1993-)，男，硕士生，江西省南昌市人，研究方向为上海深部土体沉积历史以及力学特性.基金资助:国家自然科学基金(41630633，41727802)资助项目Depositional Environment and Over-Consolidation of the 8th Layer Clay in Shanghai
LIU Libin,LAN Lixin,LI Mingguang,YE GuanlinDepartment of Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Online:2020-03-28Published:2020-04-09摘要/Abstract
摘要： 随着地下空间设施的日益拥挤，地下结构的建设深度不断增大，对深层土体的研究显得越发重要.通过研究末次冰期以来中国东海海平面和大气温度的变化，分析上海深层土(⑥～⑨层)的沉积环境，发现⑥～⑨层土沉积环境依次为：湖泊、河流-滨海、湖泊和河流-滨海、河流.通过运用Becker能量法分析高压固结试验结果得出⑧层土超固结比在3.0左右；通过全自动控制静力三轴仪三轴固结不排水试验发现土样破坏时的孔压力系数为负值，且呈现出强超固结土的性状.分别从应力和非应力的角度分析⑧层土产生超固结的原因：应力原因包括地下水位下降、土体孔隙水消散，导致土体中的有效应力有所增加；非应力原因包括长时间的次固结作用和土体的胶结作用.
关键词: 深层土, 沉积环境, 超固结, 高压固结
Abstract: With the increasing congestion of underground space facilities, the depths of underground structures are increasing. And the study of deep soils is becoming more and more important. The sedimentary environment of deep soil (the 6th—9th layer clays) in Shanghai was analyzed by studying the sea level and atmospheric temperature changes in the East China Sea since the late Pleistocene. The sedimentary environments of the 6th to the 9th layer clays were found to be lakes, rivers-marinas, lakes and rivers-marinas, rivers. By using the Becker energy method to analyze the results of the high-pressure consolidation test, the over-consolidation ratio of the 8th layer clay was about 3.0. Through the triaxial consolidated undrain test, it was found that the pore pressure coefficient while soil sample failure was negative, showing the characteristics of strong over-consolidated soil. From the perspective of stress and non-stress, the causes of over-consolidation of the 8th layer clay were analyzed. With the groundwater level decreasing, the pore water in the soil dissipated. And the increase of effective stress in the soil was the cause of stress. The long-term secondary consolidation and cementation were the reasons of non-stress.
Key words: deep soil, depositional environment, over-consolidation, high-pressure consolidation
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