承压片理化岩石各向同性转换的临界围压条件  

Critical confining pressure condition for isotropic transformation of foliated rocks under compressive loads

作　　者：尹晓萌 晏鄂川[2] 李凌 马超 YIN Xiaomeng;YAN Echuan;LI Ling;MA Chao(College of Intelligent Construction,Wuchang University of Technology,Wuhan,Hubei 430223,China;Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China;Xiangyang Institute of Geological Engineering Investigation,Xiangyang,Hubei 441003,China;School of Automotive and Transportation Engineering,Hubei University of Arts and Sciences,Xiangyang,Hubei 441053,China)

机构地区：[1]武昌理工学院智能建造学院,湖北武汉430223 [2]中国地质大学(武汉)工程学院,湖北武汉430074 [3]襄阳地质工程勘察院,湖北襄阳441003 [4]湖北文理学院汽车与交通工程学院,湖北襄阳441053

出　　处：《岩石力学与工程学报》2023年第2期403-412,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41972289);国家自然科学基金青年基金资助项目(41807240)。

摘　　要：岩石的各向异性随着围压增加逐渐弱化甚至消失,对岩石向各向同性转换的临界条件尚缺乏深入研究。以片理化岩石为对象,总结这类典型各向异性岩石的组构特征,构建沿弱面剪切滑移破坏的经验准则,结合建立在临界状态概念与莫尔-库仑准则基础上的岩石破坏判据,理论预测了片理化岩石的各向同性转换围压,并通过对前人试验数据的统计分析予以验证。结果表明:具代表性的层状硅酸盐矿物构成片理化岩石内的定向软弱层,并与粒状矿物构成的坚硬层呈似互层状分布;在一定加载方向下,片理化岩石可产生沿弱面剪切滑移破坏,此破坏模式下岩石的经验摩擦因数分别为0.40(中、低围压)、0.25(高围压);各向同性转换围压与垂直片理面加载时的岩石单轴抗压强度σ_(c(90))和内摩擦角Ф_((90))有关,片理化岩石的转换围压常大于1.5 σ_(c(90)),并随着Ф_((90))和σ_(c(90))的增加而增大;当层状硅酸盐矿物含量较高时,片理化岩石的各向同性转换围压系数往往在1.9~3.6范围。The anisotropy of rock gradually weakens or even disappears with increasing the confining pressure.However,the critical condition for the transformation from anisotropic to isotropy is still lack of in-depth research.Taking foliated rocks as the object,the fabric characteristics of this kind of typical anisotropic rock were summarized and the empirical criterion for shear-slip failure along the weak plane of rock was constructed.Combined with the previous failure criterion created based on the concept of critical state and Mohr-Coulomb criterion,the critical confining pressure at the point where the anisotropy of foliated rock is transformed into isotropy was predicted theoretically.Then,the prediction result was verified by statistical analysis on previous experimental data.The results are as follows.Foliated rocks contain representative phyllosilicates,which constitute directional weak layers and are distributed in a quasi interbedded manner with the hard layers composed of granular minerals.Under a certain loading direction,foliated rocks suffer shear-slip failure along the weak plane.The empirical friction coefficients of rocks in this failure mode are 0.40 and 0.25 under the conditions of medium-low and high confining pressure respectively.The transformation confining pressure is dependent on the uniaxial compressive strength σ_(c(90))and internal friction angleФ_((90))of foliated rocks subjected to compressive loading perpendicular to weak planes.The transformation confining pressure of foliated rocks is generally greater than 1.5 σ_(c(90))and increases with the increase ofФ_((90))and σ_(c(90)).For the foliated rocks with a high content of phyllosilicates,the transformation confining pressure coefficient is often between 1.9 and 3.6.

关 键 词：岩石力学 片理化岩石 层状硅酸盐矿物 各向异性 转换围压 

分 类 号：TU45[建筑科学—岩土工程]