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《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]

卷:

第44卷

期数:

2022年第06期

页码:

959-970

栏目:

纪念刘国昌先生诞辰110周年专辑

出版日期:

2022-11-15

文章信息/Info

Title:

Effect of Drying-wetting Cycles on Matric Suction and Shear Strength of Slip Zone Soil

文章编号:

1672-6561(2022)06-0959-12

作者:

江强强¹; 2; 徐杨青^1*; 王 浩²; 杨龙伟¹

(1. 中煤科工集团武汉设计研究院有限公司,湖北 武汉 430064; 2. 中国科学院武汉岩土力学研究所,湖北 武汉 430071)

Author(s):

JIANG Qiang-qiang¹; 2;  XU Yang-qing^1*;  WANG Hao²;  YANG Long-wei¹

(1. CCTEG Wuhan Engineering Company, Wuhan 430064, Hubei, China; 2. Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, Hubei, China)

关键词:

滑带土;  干湿循环;  核磁共振;  滤纸接触法;  基质吸力;  孔隙结构;  非饱和特性;  三峡库区

Keywords:

slip zone soil;  drying-wetting cycle;  nuclear magnetic resonance;  filter paper method;  matric suction;  pore structure;  unsaturated mechanical property;  Three Gorges reservoir area

分类号:

P642

DOI:

10.19814/j.jese.2022.09069

文献标志码:

A

摘要:

滑带作为滑坡结构中的软弱带,是控制滑坡稳定的关键部位。研究干湿循环过程中滑带土非饱和力学特性的变化,对理解库水位周期性波动下滑带土抗剪强度变化以及由此导致的滑坡变形乃至失稳过程具有重要意义。以三峡库区某堆积层滑坡滑带土为研究对象,通过进行0～5次干湿循环过程模拟,对滑带土重塑样进行直剪试验和核磁共振试验,结合滤纸接触法测定剪切完成后试样的基质吸力,重点分析干湿循环过程中非饱和滑带土孔隙结构、基质吸力、土-水特征曲线及抗剪强度的变化特征,并基于试验结果建立了干湿循环下非饱和抗剪强度的预测模型。结果表明:干湿循环在土-水体系的物理化学效应作用下使土中颗粒间的联结不断遭受损伤、破坏,引起试样内部小孔隙不断发育、扩展并向大孔隙演变,土体孔隙数量增多,整体孔隙率增大; 随着干湿循环次数的增加,土体进气值与残余含水量逐渐减小,水分更易渗入与溢出土体孔隙,土体持水能力逐渐下降; 干湿循环作用下,滑带土抗剪强度的劣化特性十分明显,黏聚力和内摩擦角均随着干湿循环次数增加而逐渐减小,且干湿循环对土体黏聚力的削弱程度大于对内摩擦角。基于直剪试验联合滤纸接触法测定基质吸力,提出了滑带土非饱和抗剪强度预测方法,为干湿循环作用下非饱和滑带土抗剪强度预测提供参考。

Abstract:

As the slip zone is the weak zone in the landslide, it is the key part to control the stability of the landslide. The study on the change of unsaturated mechanical properties of the sliding zone soil during the drying-wetting cycle is of great significance to understand the change of shear strength of the sliding zone soil with periodic fluctuation of reservoir water and the resulting landslide deformation and even instability process. The sliding zone soil of a talus landslide in Three Gorges reservoir area was used as the research target. Through the simulation of 0-5 drying-wetting cycles, the direct shear and nuclear magnetic resonance(NMR)tests were carried out on the remolded samples of the sliding zone soil, and the matric suction of the samples after shear was measured by filter paper method. Further, the variation characteristics of pore structure, matric suction, soil water characteristic curve(SWCC)and shear strength of unsaturated sliding zone soil during drying-wetting cycle were analyzed, and the prediction model of unsaturated shear strength under drying-wetting cycle was established based on the test results. The results show that the connection between particles in the soil is constantly damaged and destroyed by the drying-wetting cycle, causing the continuous development and expansion of small pores in the sample to evolve into large pores, and the overall porosity increases because the number of pores in the soil increases; meanwhile, the air intake value and the residual water content of soil gradually decreases with the increase of drying-wetting cycles, which means that the water is easier to penetrate and overflow into the soil pores, and the water holding capacity of soil gradually decreases; besides, the degradation of shear strength of slip zone soil is very obvious under drying-wetting cycle; the cohesion and internal friction angle of slip zone soil decrease gradually with the number of drying-wetting cycles, and the degree of weakening of the cohesion by drying-wetting cycle is greater than that of internal friction angle. Finally, the prediction model of unsaturated shear strength of slip zone soil based on direct shear test and matric suction measurement by filter paper method provides a useful reference for the prediction of shear strength of slip zone soil under drying-wetting cycle.

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相似文献/References:

[1]王雷,赵法锁,程晓辉,等.黄土基岩接触面滑坡滑带土物理力学特性及微观结构[J].地球科学与环境学报,2017,39(03):450.
　WANG Lei,ZHAO Fa-suo,CHENG Xiao-hui,et al.Physical and Mechanical Properties and Microstructures of Slip Soil of Loess Bedrock Contact Landslide[J].Journal of Earth Sciences and Environment,2017,39(06):450.

备注/Memo

备注/Memo:

收稿日期:2022-09-29
基金项目:国家自然科学基金项目(42007279); 中煤科工集团有限公司科技创新创业项目(2020-NQ006)
作者简介:江强强(1992-),男,江西九江人,中煤科工集团武汉设计研究院有限公司工程师,工学博士,E-mail:m18162619885@163.com。
*通讯作者:徐杨青(1965-),男,安徽安庆人,教授级高级工程师,工学博士,E-mail:xyq@zh-geo.com。

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更新日期/Last Update: 2022-11-25