碳酸盐岩应力-应变关系与微结构分析  

MICROSTRUCTURE AND STRESS-STRAIN RELATIONSHIP OF CARBONATE ROCK

作　　者：罗强[1] 

机构地区：[1]中南大学

出　　处：《岩石力学与工程学报》2008年第S1期2656-2660,共5页Chinese Journal of Rock Mechanics and Engineering

基　　金：交通部西部交通建设科技项目(200231800018)

摘　　要：碳酸盐岩微裂隙的存在、产生和发展对宏观力学性质有显著的影响,通过碳酸盐岩扫描电镜图像分析和进行三轴剪切试验,发现碳酸盐岩中白云岩、灰岩、白云质灰岩的应力–应变关系均可分为压密阶段、线弹性变形阶段、微裂隙的产生和稳态扩展阶段以及断裂破坏阶段,与之对应的微裂隙表现为:原始微裂隙发生闭合,稳定持续存在形成线弹性变形,新的微裂隙在应力集中处产生、扩展并稳定发展以及微裂隙扩展强烈、发展成宏观裂隙最终导致岩块整体破裂。试验表明,受压状态下岩石裂隙是从孔隙的外围开始发育,逐渐扩展到孔隙,最后导致孔隙及岩体失稳。裂隙发育以张性的微裂隙起始,逐渐形成剪裂隙,并出现追踪剪裂隙的张裂隙,直至裂隙贯通。碳酸盐岩的初始微观裂隙主要的表现为张裂隙和剪裂隙,岩石破裂从先存的裂隙端部开始,原有裂隙的端部是加载后应力集中的地方,在岩石介质的晶粒边界的接触点或断层附近,应力高度集中导致裂纹密度增加,当压力达到或接近峰值压力时,由于裂纹的汇交与集中迅速失稳形成宏观断裂,随后就出现开裂和应变软化。Generation and development of micro-crack in carbonate rock will affect its mechanical characteristic obviously. Based on triaxial test and stereoscan photograph of carbonate rock consisting of dolomitic rock,limestone,dolomitic limestone,the relationships between stress and strain are divided into tightening phase,linear elastic deforming phase,generation and development of micro-crack phase and fracture phase. Corresponding to these four phases,the change of micro-crack shows the close of original micro-crack,stably sustained linear elastic deforming,new micro-crack generation,expanding and stably developing,and integral breaking. The experiment shows that the micro-crack begins from off-lying to circum of the pore in compression,and then to the pore and rock collapse. The development of micro-crack begins from separation fracture to shear fracture,then to occurrence of separation fracture tracking shear fracture,until fractures are penetrated. The separation fracture and shear fracture are included in initial micro-crack of carbonate rock. The rock fracture begins at the end of micro-crack,which is the stress concentration position after loading. Right round fault,contact point of grain boundary and the micro-crack density increase because of stress concentrating highly. The fracture generates when the stress reaches or approaches to the peak value,and then,crack and strain softening occur successively.

关 键 词：岩石力学 碳酸盐岩 三轴试验 应力–应变关系 微裂隙 

分 类 号：TU452[建筑科学—岩土工程]