“丁”字形交叉裂隙类岩体的力学特性研究

岩体的力学性能受赋存在其中的裂隙的影响较大。本文以实际岩体工程中的节理岩体为背景,通过按一定比例配制而成的石膏砂浆材料来制作类岩石试件,采用在类岩石试件中预埋金属条抽出的方法来模拟不同倾角的“丁”字形交叉裂隙,研究室内单轴压缩条件下,“丁”字形交叉裂隙试件的力学特性。研究发现:(1)主裂隙倾角对试件的峰值应力有决定性作用,次裂隙则在一定程度上影响试件的峰值应力;(2)相对于仅有主裂隙的情况,次裂隙的存在,增大试件的弹性模量,但却减小试件的峰值应变和起裂应力;(3)次裂隙对裂隙试件裂纹起裂位置及其扩展方向的影响可归为三类:次裂隙对裂隙试件的裂纹起裂位置及其扩展方向的影响较小;次裂隙使裂隙试件的翼裂纹沿着主(次)裂隙的一端及其次(主)裂隙的两端开始起裂及扩展;次裂隙的存在引起了主裂隙两端次生裂纹的产生。

Experimental study on mechanical properties of rock mass samples with T-shaped cross crack subjected to uniaxial compression

Mechanical properties of rock mass are greatly influenced by the fissures occurrence in it. Taking the jointed rock mass in actual rock mass engineering as background, rock-like specimens were made up by gypsum mortar material prepared in certain proportion. T-shaped cross fissures with different dip angles were simulated by pre-berrried metal strips in the rock-like specimen. The mechanical properties of specimens with T-shaped cross fissures were studied through indoor uniaxial compression experiment. Results indicate that (1) the main fissure dip angle determine specimen's cross fissures stress peak valure, the secondary fissure dip angle has influence on specimen's peak stress to a certain degree.(2) Relative to the occurrence of only main fractures, the existence of secondary fissures increase the elastic modulus of specimen, but decreases the peak strain and crack initiation stress of the specimen.(3) The influence of secondary multi-fissures on crack initiation location and propagation direction of fractured specimens can be classified into three categories: the influence of secondary fissures on crack initiation position and propagation direction of specimen is small;To cause the wing crack of a fractured specimen to begin to crack and spread along one end of the main (secondary) fissure and the two ends of the secondary (primary) fissure;the existence of secondary fissures causes secondary cracks at both ends of main fractures.