含裂隙充填节理岩体的压剪断裂机制研究  

Study on the compression-shear fracture mechanism of infilled jointed rock mass with pre-crack

作　　者：钟志彬[1,2] HU Xiaozhi 邓荣贵 付小敏[3] 吕蕾[2,4] ZHONG Zhibin;HU Xiaozhi;DENG Ronggui;FU Xiaomin;LV Lei(School of Civil Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China;School of Mechanical and Chemical Engineering, University of Western A us tralia, Perth, WA 6009, Australia;State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, Sichuan 610059, China;Sichuan Jiaoda Engineering Inspection and Consulting Co., Ltd., Chengdu, Siehuan 610031, China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]西澳大学机械与化工学院,澳大利亚西澳大利亚洲珀斯6009 [3]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059 [4]四川交大工程检测咨询有限公司,四川成都610031

出　　处：《岩石力学与工程学报》2018年第A01期3320-3331,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41272321); 西南交通大学博士生创新基金(13017001); 国家留学基金委资助(201507000052)

摘　　要：节理弱面是造成岩体力学性能弱化的主要因素,而充填物质的非均质性将显著影响节理岩体的剪切力学特性。考虑压剪应力作用下贯通性节理充填物中沿节理方向裂隙对节理岩体断裂特性的影响,制取含不同长度初始裂隙的充填砂浆节理岩体试样,在单轴压缩作用下研究含裂隙充填节理岩体的压剪断裂机制及初始裂隙尺寸对节理岩体破裂模式和断裂能的影响规律。试验结果表明:(1)单轴压缩作用下,充填节理岩体的失稳过程分为断裂和摩擦两阶段,前者为节理内裂隙的起裂、扩展到贯通过程,峰值强度后承载力迅速降低,之后因宏观破裂面的压剪摩擦作用而出现强化现象,直至剪应力达到其抗剪强度而失稳破坏;(2)随着充填体内初始裂隙长度增大,试样峰值荷载线性减小,峰值脆性断裂特征更加明显;(3)无初始裂隙节理试样破裂过程中裂隙在节理内分布均匀,而含初始裂隙试样断裂从裂隙尖端开始,向充填体和花岗岩块体黏接面扩展贯通,充填体内裂隙集中而密度较低;(4)采用节理韧带体积Vjc改进断裂能计算公式,计算充填节理岩体压剪断裂能Gf-V;基于充填节理的断裂机制,提出局部断裂能gf-V沿韧带双线性分布的前边界效应模型,解释了平均断裂能Gf-V随初始裂隙长度增大而减小的原因,试验结果验证了模型的正确性。Joints and weak layers are the key factors for possible rock mass failure or sliding,within which the heterogeneous infilled materials in joints strongly influence the shear mechanical behavior of rock mass and then its shear failure. Considering the effect of crack in infilled materials on the fracture characteristic of pre-existing jointed rock mass under compression-shear stress state,mortar infilled jointed rock mass specimens including various artificial lengths were prepared,and uniaxial compressive tests were carried out to investigate their compression-shear fracture mechanisms and the effect of pre-cracks sizes on fracture modes and fracture energy of jointed rock mass. The experimental results show that：（1） under uniaxial compression,the failure process of infilled jointed rock mass can be divided into two stages：fracture stage and friction stage. The former was the process of initiation,propagation and coalescence of cracks. The load bearing capacity was rapidly reduced after the peak load,and then gradually increased due to the increasing friction force. Finally,it failed when the shear stress reached its shear strength.（2） With the increasing pre-existing crack length in infilled jointed rock mass,the peak load of specimens was decreased linearly,while the fracture process was more brittle.（3） For the infilled jointed specimens without pre-crack,multiple micro-cracks were generated throughout the infilled joint during the fracture. However,for the pre-cracked specimens,they cracked from the tips and propagated to the adhesive surface of infilled mortar and joint. The stress-induced cracks concentrated with relatively low density in the infilled joint.（4） The volume of ligament in joint Vjc was used to modify the formula of fracture energy Gf-V. Based on the fracture mechanism of the infilled joint,the front boundary effect model,whose local fracture energy gf-Vwas bilinear distribution along the ligament,was proposed. It explained the reason why the average fracture energy Gf-V de

关 键 词：岩石力学 充填节理 初始裂隙 压剪断裂机制 断裂能 前边界效应 双线性模型 

分 类 号：TU45[建筑科学—岩土工程]