水压力作用下三峡库区侏罗系软岩裂纹扩展规律及力学机制  

Crack propagation law and mechanical mechanism of Jurassic soft rock in the Three Gorges Reservoir area under water pressure

作　　者：简文星[1] 潘永亮 李林均 李豪 徐长江 Jian Wenxing;Pan Yongliang;Li Linjun;Li Hao;Xu Changjiang(Faculity of Engineeing,China University of Geosciences(Wuhan),Wuhan 430074,China;Central&Southen China Municipal Engineering Design and Research Institute Co.,Ltd.,Wuhan 430015,China;Chongqing Survey Institute,Chongqing 401121,China)

机构地区：[1]中国地质大学(武汉)工程学院,武汉430074 [2]中国市政工程中南设计研究总院有限公司,武汉430015 [3]重庆市勘测院,重庆401121

出　　处：《地质科技通报》2023年第3期1-8,共8页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金项目“三峡库区典型顺向岸坡库水与降雨联合作用失稳观测与理论解析”(41272306)。

摘　　要：三峡库区侏罗系地层滑坡发育广泛,研究该地层软岩夹层在不同水压力作用下的强度及变形破坏特性对库区岸坡的长期稳定性评价具有重要理论指导意义。以三峡库区侏罗系典型软岩——沙溪庙组泥质粉砂岩为例,对其进行了不同水压力下的力学试验系统(MTS)三轴压缩试验,并基于断裂力学与有效应力原理对水-力耦合效应下岩石的起裂及裂纹扩展机制进行了分析。研究结果表明:水压力的存在可降低岩石的峰值抗压强度,水压力越大岩石破坏后控制性裂纹的长度及倾角也总体随之增大,次生裂纹的数目也呈现出随之增多的趋势;原生裂纹的起裂及次生裂纹的扩展分别受控于K_(Ⅱ)、K_(Ⅰ)型应力强度因子,原生裂纹的起裂角最大为70.5°;次生裂纹的临界扩展长度随原生裂纹长度的增加而增大,当原生裂纹倾角约为45°时,在相同条件下次生裂纹的扩展长度最大;说明水压力的存在加剧了岩石裂纹的扩展,且使岩石的张拉破坏趋势更为明显,而原生裂纹形态特征对裂纹的扩展规律亦具有较大的影响。Jurassic landslides are widely developed in the Three Gorges Reservoir area.The study of the strength and deformation failure characteristics of the soft rock interlayer under different water pressures is of great theoretical significance to the long-term stability evaluation of the reservoir bank slope.MTS triaxial compression tests were carried out on the argillaceous siltstone of Shaximiao Formation,a typical soft rock of Jurassic in the Three Gorges Reservoir area,to study the strength and deformation damage characteristics of the rock under different water pressures.Based on fracture mechanics and effective stress principle,the mechanism of crack initiation and crack propagation under hydro-mechanical coupling effect was analyzed.It was found that water pressure can reduce the peak compressive strength of rock.With the increase of water pressure,the length and dip angle of dominant cracks increase,and the number of secondary cracks also shows a trend of increasing.The primary crack initiation and secondary crack propagation were controlled by K_(Ⅱ)and K_(Ⅰ)stress intensity factors,respectively.The maximum initiation angle of the primary crack was 70.5°.The critical propagation length of the secondary crack increases with the increase of the primary crack length.When the dip angle of the primary crack is about 45°,the propagation length of the secondary crack reaches the maximum under the same conditions.The results show that the existence of water pressure is conducive to the crack propagation,and the geometric characteristics of primary cracks also have a great influence on the crack propagation law.This study provides some theoretical guidance for the long-term stability evaluation of the reservoir bank rock mass.

关 键 词：三峡库区 侏罗系软岩 水压力 裂纹扩展 力学机制 

分 类 号：TU41[建筑科学—岩土工程]