含水率对重塑红黏土反复抗剪强度影响试验研究

doi:10.11872/j.issn.1005-2518.2021.05.210

摘要/Abstract

摘要：

红黏土性质的稳定与安全生产息息相关，抗剪强度作为红黏土强度特性之一，与红黏土的稳定性密切相关。为探究含水率对红黏土反复抗剪强度的影响，以山西长治地区的重塑红黏土为研究对象进行反复直剪试验。试验结果表明：无竖向压力时，随着剪切次数的增加，抗剪强度减小并趋于稳定值，第2次剪切达到抗剪强度时对应的剪切位移小于第1次剪切时的位移，稳定剪切时对应的剪切位移大于第1次剪切时的位移；抗剪强度与含水率呈负线性关系，且抗剪强度为土体的真黏聚力，随着含水率的增加先增大后减小。当施加竖向压力后，抗剪强度随着含水率的增加而减小；利用抗剪强度表达式拟合得到内摩擦角和黏聚力，其中黏聚力随着含水率的增加先减小后增大；通过真黏聚力计算得出新的内摩擦角，2种分析方法得出的内摩擦角基本接近且均随着含水率的增加而减小，减小幅度逐渐增大。定义黏聚力差异指数比来研究真黏聚力与黏聚力之间的差异，分析得到黏聚力与真黏聚力的差异指数比在0.75~9.96之间，当含水率为19.5%时黏聚力差异指数比达到最小。利用所建立的相关经验公式，能够为红黏土地区矿山岩土勘察、设计和开挖过程中土性参数的合理选取提供一定参考。

关键词: 重塑红黏土, 含水率, 反复直剪试验, 抗剪强度, 真黏聚力, 黏聚力差异指数比

Abstract:

As a special soil，red clay is widely distributed in some areas of China.Due to the engineering problems such as slope cracking，subgrade subsidence and insufficient foundation bearing capacity，the strength characteristics of red clay is one of the main problems concerned by engineers，and the stability of red clay is closely related to safety production.In order to explore the influence of water content on the repeated shear strength of red clay，the repeated direct shear test was carried out on remolded red clay in Changzhi area of Shanxi Province.Because the water content of undisturbed soil in this area is between 17.0% and 23.7%，and the plastic limit water content is 20.34%，considering the law of test results and the influence of plastic limit，soil samples with five water contents of 15.0%，18.0%，19.5%，21.0% and 24.0% were prepared for test.The test results show that when no vertical pressure is applied， repeated direct shear is conducted on the sample，and the test is stopped when the sample’s strength gradually stabilizes.When there is no vertical pressure，the shear strength decreases and tends to be stable with the increase of shear times.The displacement of secondary shear to shear strength is less than that of the first shear，and the stable shear displacement is greater than that of the first shear.In the process of shearing，the shear strength has a negative linear relationship with the water content.When there is no vertical pressure，the shear strength is equal to the cohesion，and the shear strength is defined as the true cohesion.The vertical pressure of 50，100，150 and 200 kPa was applied to carry out the direct shear test.When there is vertical pressure，the shear strength decreases with the increase of water content.The internal friction angle and cohesion of shear strength index were obtained by physical expression fitting，and compared with the internal friction angle obtained by true cohesion and no vertical pressure.The internal friction angle obtained by the two kinds of analysis is basically close，and decreases with the increase of water content，and the decreasing range gradually increases.Due to the dilatancy effect in the test process，the true cohesion first increases and then decreases with the increase of water content，and the cohesion first decreases and then increases with the increase of water content.The contrast analysis shows that the difference of cohesion is obvious，so the difference index ratio of cohesion and true cohesion with vertical pressure is 0.75~9.96，and the change rule of the difference index ratio of cohesion is the same as the fitting cohesion，and the difference index ratio reaches the minimum when the water content is 19.5%.The empirical formula can provide some reference for the reasonable selection of soil parameters in the process of geotechnical investigation，design and excavation of mines in red clay area.

Key words: remolded red clay, water content, repeated shear test, shear strength, true cohesion, difference index ratio of cohesion

中图分类号:

TU411.7

林斌,田竹华,陈雨漫. 含水率对重塑红黏土反复抗剪强度影响试验研究[J]. 黄金科学技术, 2021, 29(5): 680-689.

Bin LIN,Zhuhua TIAN,Yuman CHEN. Experimental Study on Effect of Water Content on Repeated Shear Strength of Remolded Red Clay[J]. Gold Science and Technology, 2021, 29(5): 680-689.

图/表 12

图1

表1

图2

图3

图4

表2

不同剪切次数时剪应力与含水率关系拟合参数值"

剪切次数/次	$a$	$b$	$R 2$
1	-10.5783	270.1575	0.9704
2	-5.5840	137.6000	0.9729
3	-2.9095	73.6614	0.9972
4	-2.9095	73.6614	0.9972

表2

图5

表3

图6

表4

黏聚力（c）和摩擦角（φ）参数拟合值"

含水率/%	$c$ /kPa	$φ$ /（°）	$R 2$
15.0	45.35	41.14	0.999
18.0	34.71	40.48	0.974
19.5	29.15	37.80	0.958
21.0	31.91	24.20	0.998
24.0	40.54	10.40	0.911

表4

表5

摩擦力计算值和内摩擦角拟合参数值"

含水率/%	真黏聚力（ $c'$ ）/kPa	不同竖向压力下的摩擦力（ $τ f - c'$ ）/kPa				内摩擦角（ $φ'$ ）/（°）	$R 2$
含水率/%	真黏聚力（ $c'$ ）/kPa	50 kPa	100 kPa	150 kPa	200 kPa	内摩擦角（ $φ'$ ）/（°）	$R 2$
15.0	4.63	82.37	130.49	173.07	213.79	48.87	0.9887
18.0	10.18	65.71	105.51	165.67	187.88	45.48	0.9917
19.5	16.66	42.57	98.10	138.82	158.26	40.66	0.9923
21.0	12.96	40.72	65.66	85.14	109.21	29.95	0.9903
24.0	3.70	42.58	59.23	66.64	70.71	23.23	0.9359

表5

表6

Δc和kc计算值"

含水率/%	$? c$	$k c$
15.0	40.72	8.79
18.0	24.53	2.41
19.5	12.49	0.75
21.0	18.95	1.46
24.0	36.87	9.96

表6

参考文献 0

	Chen Hongbin，Chen Xuejun，Qi Yunlai，al et，2019.Influence of dry density and moisture content on shear strength parameters of remolded red clay soil［J］.Journal of Engineering Geology，27（5）：1035-1040.
	Chen Jiayu，Liu Zhikui，2019.Strength change mechanism of undisturbed red clay and remolded red clay［J］.Journal of Henan University of Science and Technology（Natural Science），40（3）：53-59.
	Chen Zhenghan，Qin Bing，2012.On stress state variables of unsaturated soils［J］.Rock and Soil Mechanics，33 （1）：1-11.
	Cheng Yun，Wei Changfu，Niu Geng，2017.The effect of dry-wet cycle on the shear strength of red clay in karst area［J］.Rock and Soil Mechanics，38（Supp.2）：191-196.
	Hu Xin，Hong Baoning，Du Qiang，al et，2009.Influence of water contents on shear strength of coal-bearing soil ［J］.Rock and Soil Mechanics，30（8）：2292-2294.
	Huang Kun，Wan Junwei，Chen Gang，al et，2012.Testing study of relationship between water content and shear strength of unsaturated soil［J］.Rock and Soil Mechanics，33（9）：2600-2604.
	Li Chunhong，Kong Gangqiang，Liu Hanlong，2019.Study of temperature-controlled pile-red clay interface tests and stress-strain relationship［J］.China Civil Engineering Journal，52（Supp.2）：89-94，101.
	Li Guangxin，2004.Advanced Soil Mechanics［M］.Beijing：Tsinghua University Press.
	Li Huaixin，Lin Bin，Chen Shiwei，al et，2020.Study on softening model and strength of red clay at different water content［J］.Gold Science and Technology，28（3）：442-449.
	Li Xiaoli，Zhai Tao，Zhang Qiang，2015.Experiment on mechanical properties of Pisha-sandstone at recurrent shear［J］.Transactions of the Chinese Society Agricultrual Engineering，31（21）：154-159.
	Haibo Lü，Zeng Zhaotian，Yin Guoqiang，al et，2012.Analysis of mineral composition of red clay in Guangxi ［J］.Journal of Engineering Geology，20（5）：651-656.
	Ly H B，Pham B T，2020.Prediction of shear strength of soil using direct shear test and support vector machine model［J］.The Open Construction and Building Technology Journal，14（1）：41-50.
	Mu Rui，Guo Jianqiang，Huang Zhihong，al et，2018.Effect of uneven moisture content on shear strength of red clay［J］.People’s Pearl River，39（6）：63-66.
	Nanjing Water Conservancy Research Institute，1999.Standard of soil test methods：［S］.Beijing：China Planning Press.
	Uyeturk C E，Huvaj N，2021.Constant water content direct shear testing of compacted residual soils［J］. Bulletin of Engineering Geology and the Environment，80：691-703.
	Wang Haixiang，2018.Research on engineering properties of lateritic clay in Hezhou［J］.Highway，63（1）：13-19.
	Xia Caichu，Song Yinglong，Tang Zhicheng，al et，2012.Shear strength and morphology characteristic evolution of joint surface under cyclic loads［J］.Journal of Central South University（Science and Technology），43（9）：3589-3594.
	Xue Ke，Wen Zhi，Ma Xiaohan，al et，2019. Effect of freezing on microstructure of Qinghai Tibet red clay and Lanzhou silt［J］.Glacial Frozen Soil，41（5）：1122-1129.
	Zhang Kunyong，Xu Na，Chen Shu，al et，2020.Experimental study on fully softened shear strength of expansive soli［J］.Chinese Journal of Geotechnical Engineering，42（11）：1988-1995.
	Zhang Wenshu，Zhang Xifa，1991.Theoretical basis and method of soil shear strength index statistics ［J］.Hydrogeology ang Engineering Geology，（2）：53-55.
	Zhang Zelin，Wu Shuren，Tang Huiming，al et，2017.Dynamic characteristics and microcosmic damage effect of loess and mudstone［J］.Chinese Journal of Rock Mechanics and Engineering，36（5）：1256-1268.
	陈鸿宾，陈学军，齐运来，等，2019.干密度与含水率对重塑红黏土抗剪强度参数影响研究［J］.工程地质学报，27（5）：1035-1040.
	陈佳雨，刘之葵，2019.原状与重塑红黏土强度变化机理［J］.河南科技大学学报（自然科学版），40（3）：53-59.
	陈正汉，秦冰，2012.非饱和土的应力状态变量研究［J］.岩土力学，33（1）：1-11.
	程允，韦昌富，牛庚，2017.干湿循环作用对岩溶区红黏土剪切强度的影响［J］.岩土力学，38（增2）：191-196.
	胡昕，洪宝宁，杜强，等，2009.含水率对煤系土抗剪强度的影响［J］.岩土力学，30（8）：2292-2294.
	黄琨，万军伟，陈刚，等，2012.非饱和土的抗剪强度与含水率关系的试验研究［J］.岩土力学，33（9）：2600-2604.
	李春红，孔纲强，刘汉龙，等，2019.桩—红黏土接触面温控测试及应力—应变关系研究［J］.土木工程学报，52（增2）：89-94，101.
	李广信，2004.高等土力学［M］.北京：清华大学出版社.
	李怀鑫，林斌，陈士威，等，2020.不同含水率下红黏土软化模型及强度试验研究［J］.黄金科学技术，28（3）：442-449.
	李晓丽，翟涛，张强，2015.反复剪切作用下砒砂岩土壤力学性能试验［J］.农业工程学报，31（21）：154-159.
	吕海波，曾召田，尹国强，等，2012.广西红黏土矿物成分分析［J］.工程地质学报，20（5）：651-656.
	穆锐，郭建强，黄质宏，等，2018.不均匀含水率对红黏土抗剪强度的影响研究［J］.人民珠江，39（6）：63-66：
	南京水利科学研究院，1999.土工试验方法标准：［S］.北京：中国计划出版社.
	王海湘，2018.广西贺州红黏土的工程性质研究［J］.公路，63（1）：13-19.
	夏才初，宋英龙，唐志成，等，2012.反复直剪试验节理强度与粗糙度变化的研究［J］.中南大学学报（自然科学版），43（9）：3589-3594.
	薛珂，温智，马小涵，等，2019.冻结作用对青藏红黏土及兰州粉土微观结构的影响分析［J］.冰川冻土，41（5）：1122-1129.
	张坤勇，徐娜，陈恕，等，2020.膨胀土完全软化强度指标试验研究［J］.岩土工程学报，42（11）：1988-1995.
	张文殊，张喜发，1991.土的抗剪强度指标统计的理论基础及方法［J］.水文地质工程地质，（2）：53-55.
	张泽林，吴树仁，唐辉明，等，2017.黄土和泥岩的动力学特性及微观损伤效应［J］.岩石力学与工程学报，36（5）：1256-1268.

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含水率/%	平行试样反复直剪次数/次
含水率/%	试样1	试样2	试样3	试样4	试样5	试样6	试样7	试样8
15.0	5	4	5	7	3	4	5	4
18.0	4	4	4	4	6	4	4	5
19.5	4	5	4	4	5	5	4	3
21.0	4	4	4	5	3	5	4	4
24.0	4	3	3	6	4	4	4	4

竖向压力/kPa	不同含水率下的抗剪强度/kPa
竖向压力/kPa	15.0%	18.0%	19.5%	21.0%	24.0%
50	87.00	75.89	59.23	53.68	46.28
100	135.12	115.69	114.76	78.62	62.93
150	177.70	175.85	155.48	98.10	70.34
200	218.42	198.06	174.92	122.17	74.41

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