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中南大学学报(自然科学版)

Journal of Central South University

第50卷    第1期    总第293期    2019年1月

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文章编号:1672-7207(2019)01-0206-08
酸雨入渗对膨胀土抗剪强度的影响及微观试验研究
常锦1,杨和平1,肖杰1, 2,毛瑞1,童超3

(1. 长沙理工大学 交通运输工程学院,湖南 长沙,410114;
2. 长沙理工大学 道路灾变防治及交通安全教育部工程研究中心,湖南 长沙,410114;
3. 中铁科研院有限公司,四川 成都,611731
)

摘 要: 为探究酸雨入渗对膨胀土抗剪强度的影响,以广西酸雨重灾区的百色原状膨胀土为研究对象,根据干湿循环影响区土体的实际状态及边界条件,模拟不同酸雨入渗情况(pH为3,5和7)进行抗剪强度试验研究,探究膨胀土抗剪强度变化规律;结合微观试验,研究其微观结构和矿物成分变化特性,揭示酸雨入渗对膨胀土的微观作用机理。研究结果表明:随酸液pH减小,试样抗剪强度不断衰减,黏聚力降幅明显,内摩擦角出现小幅度下降,且在2次干湿循环作用后,黏聚力出现最大降幅;上覆压力越小,抗剪强度衰减越明显;酸雨入渗作用下土体中游离的胶结物呈不同程度溶蚀和淋滤,微孔隙体积和数目均增大,入渗酸液pH越小,该变化趋势愈明显,微结构单元更松散,致使土体结构性减弱,抗剪强度下降。

 

关键字: 酸雨入渗;膨胀土;抗剪强度;胶结物;溶蚀;淋滤

Effect of acid rain infiltration on shear strength of expansive soil and its microscopic test
CHANG Jin1, YANG Heping1, XIAO Jie1, 2, MAO Rui1, TONG Chao3

1. School of Traffic and Transportation Engineering, Changsha University of Science & Technology, Changsha 410114, China;
2. Engineering Research Center of Catastrophic Prophylaxis and Treatment of Road & Traffic Safety of Ministry of Education, Changsha University of Science & Technology, Changsha 410114, China;
3. China Railway Research Institute Co. Ltd., Chengdu 611731, China

Abstract:In order to explore the effect of acid rain infiltration on the shear strength of expansive soils, the original expansive soil of Baise in the acid rain-affected areas in Guangxi was studied. According to the actual state and boundary conditions of soils in the dry-wet cycle affected area, the different conditions of acid rains infiltration were simulated pH=3, 5, 7) to investigate the evolution law of shear strength of expansive soils. The shear strength tests were conducted under different acid rain infiltration conditions to explore the changing law of shear strength of expansive soils. Microscopic tests were also carried out to clarify the changes in microstructure and mineral composition, and to reveal the mechanism of microscopic action of acid rain infiltration on expansive soils. The results show that with the decrease of pH of acid solution, the shear strength of the sample decreases continuously, and the cohesion force decreases sharply; the internal friction angle decreases slightly, and the maximum drop occurs after 2 times of dry-wet cycles. The reduction of the overburden load makes the attenuation of the shear strength more obvious. The free colloidal minerals in the soil exhibits different degrees of dissolution and leaching under the action of acid rain infiltration, the size and number of micropores increase, and the micro-structure units are looser, which leads to the weakening of soil structure and the decrease of shear strength.

 

Key words: acid rain infiltration; expansive soil; shear strength; cement; dissolution; leaching

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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