崇明东滩吹填区黏性土层抗剪强度随时间变化特征及机理

doi:10.13278/j.cnki.jjuese.20220011

吉林大学学报(地球科学版) ›› 2023, Vol. 53 ›› Issue (4): 1163-1163.doi: 10.13278/j.cnki.jjuese.20220011

崇明东滩吹填区黏性土层抗剪强度随时间变化特征及机理

王清1, 吕作俊1, 姚萌1, 董佳祺1, 夏玮彤1, 杨天亮2, 牛岑岑1

1.吉林大学建设工程学院，长春 130026
2.上海市地质调查研究院/自然资源部地面沉降监测与防治重点实验室，上海 200072

收稿日期:2022-01-08 出版日期:2023-07-26 发布日期:2023-08-10
通讯作者: 牛岑岑(1986—)，女，高级工程师，博士，主要从事岩土工程方面的研究，E-mail：niucencen@jlu.edu.cn
作者简介:王清（1959—），女，教授，博士生导师，主要从事土体工程地质方面的研究，E-mail: wangqing@jlu.edu.cn
基金资助:
国家自然科学基金项目(41820104001)；自然资源部地面沉降监测与防治重点实验室委托项目(2020(D)-011(F)-03，2021(D)-004(F)-01)；国际地球科学计划项目(IGCP663)

Characteristics and Mechanism of Shear Strength Variation with Time of Cohesive Soil Layers in Chongming Dongtan Reclamation Area

Wang Qing1, Lü Zuojun1, Yao Meng1, Dong Jiaqi1, Xia Weitong1, Yang Tianliang2, Niu Cencen1

1. College of Construction Engineering, Jilin University, Changchun 130026, China
2. Shanghai Institute of Geological Survey/Key Laboratory of Land Subsidence Monitoring and Prevention, Ministry of Natural
Resources, Shanghai 200072, China

Received:2022-01-08 Online:2023-07-26 Published:2023-08-10
Supported by:
the National Natural Science Foundation of China (41820104001), the Entrusted Project of Key Laboratory of Land Subsidence Monitoring and Prevention of the Ministry of Natural Resources (2020(D)-011(F)-03，2021(D)-004(F)-01) and the International Geoscience Program (IGCP663)

摘要/Abstract

摘要： 为了对上海市崇明东滩等吹填造陆区域进行工程地质评价，针对崇明东滩吹填区下伏黏性土抗剪强度的变化特点，考虑不同吹填时间，选取由西向东的5个不同吹填区（1949围堰内、1949—1964、1964—1976、1976—1990、1990—1998）内钻孔的黏性土进行剪切试验，分析了不同时期及不同层位黏性土抗剪强度的变化，并对土样进行扫描电镜试验，观察土样的微观结构，从微观结构的角度定性及定量地分析了抗剪强度的变化规律。结果表明：1）黏土在1949—1964吹填区内的抗剪强度最高，在50、100、200、300 kPa竖向压力下的峰值剪应力分别为33.31、46.68、102.10、147.15 kPa，粉质黏土在各级竖向压力的作用下，各吹填区内的抗剪强度差距不大；自西向东，黏土层的抗剪强度指标与粉质黏土层呈现相反的变化趋势，与天然含水率的变化趋势有关。2）自西向东，各吹填区内土样的微观结构有显著变化，黏土层的微观结构从絮凝-团聚状结构向基质状结构变化，粉质黏土层的微观结构呈现骨架-团聚状—基质状—絮凝-团聚状结构的变化趋势。3）结构单元体的平均直径与土样的黏聚力负相关，与内摩擦角正相关,结构单元体的平均形状系数与土样的黏聚力正相关，与内摩擦角负相关。说明结构单元体的平均直径、平均形状系数与土体的抗剪强度指标直接相关。

关键词: 崇明东滩, 吹填区, 黏性土, 抗剪强度, 机理分析

Abstract: Abstract： To carry out engineering geological evaluation of hydraulic reclamation areas such as Chongming Dongtan, this paper aims at the change in shear strength of the underlying clayey soil layers in Chongming Dongtan. Considering different reclamation times, soil samples from boreholes in five different reclamation areas (within the 1949 cofferdam, 1949-1964, 1964-1976, 1976-1990, and 1990-1998) were selected for direct shear tests, and the variation of shear strength of soils in different periods and layers were analyzed. Moreover, the microstructure of the soil samples was observed by scanning electron microscopy, and the change in shear strength was analyzed qualitatively and quantitatively from a microscopic perspective. The results revealed that: 1) The shear strength of the clayey layer varied as， the clay layer in the 1949-1964 reclamation zone had the largestshear strength, and the peak shear stress at 50, 100, 200, and 300 kPa is 33.31, 46.68, 102.10 and 147.15 kPa, respectively. Little difference in shear strength between boreholes in silty clay layer was observed under various levels of vertical pressure. From west to east, the shear strength indexes of the clay layer showed an opposite trend to that of the silty clay layer, in relation to the trend in natural water content. 2) From west to east, significant changes in the microstructure of the soil samples were observed. The soil microstructure in clay layer changed from a flocculent/aggregate to a matrix structure， and the soil microstructure in silty clay layer gradually transitioned from a skeletal/aggregate structure to a matrix structure and to a flocculent/aggregate structure. 3) The average pore diameter of the particle was negatively related to the cohesion and positively related to internal friction angle. In addition, the average shape coefficient of the particle was positively related to the cohesion and negatively related to internal friction angle. This indicated that average pore diameter and the average shape coefficient of the particles were directly related to the shear strength indexes of the soil.

Key words: Chongming Dongtan, reclamation area, cohesive soil, shear strength, mechanism analysis

中图分类号:

P642.13

王清, 吕作俊, 姚萌, 董佳祺, 夏玮彤, 杨天亮, 牛岑岑. 崇明东滩吹填区黏性土层抗剪强度随时间变化特征及机理[J]. 吉林大学学报(地球科学版), 2023, 53(4): 1163-1163.

Wang Qing, Lü Zuojun, Yao Meng, Dong Jiaqi, Xia Weitong, Yang Tianliang, Niu Cencen. Characteristics and Mechanism of Shear Strength Variation with Time of Cohesive Soil Layers in Chongming Dongtan Reclamation Area[J]. Journal of Jilin University(Earth Science Edition), 2023, 53(4): 1163-1163.

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崇明东滩吹填区黏性土层抗剪强度随时间变化特征及机理

Characteristics and Mechanism of Shear Strength Variation with Time of Cohesive Soil Layers in Chongming Dongtan Reclamation Area

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