单轴压缩作用下孔隙砂岩破坏过程试验

Experimental on failure process of porous sandstone under uniaxial compression

孔隙砂岩在单轴压缩作用下的破坏过程及模式对能源开采和地下空间工程建设具有重要意义。以陕西渭南细粒砂岩和咸阳粗粒砂岩为研究对象,进行了不同粒径的砂岩在单轴压缩荷载作用下的高速摄影实时观测试验,获得了两种粒度岩样在各个破坏阶段的图像,揭示出两种不同粒度岩样单轴压缩过程中宏观裂纹萌生、扩展、贯通直至岩样破坏的全过程。探讨了孔隙砂岩粒度对其宏观变形破坏过程和模式的影响规律。研究表明,粒径是影响孔隙砂岩单轴压缩破坏模式的一个重要因素,细粒砂岩在破坏瞬间产生强烈的动力效应,而粗粒砂岩在破坏瞬间则没有。粗粒砂岩破坏模式表现为拉伸劈裂,而细粒砂岩破坏模式表现为剪切滑移。从岩样宏观裂纹产生到裂纹贯通过程中,粗粒砂岩裂纹扩展持续时间较长,而细粒砂岩持续时间较短。在残余试件完整性方面,粗粒砂岩完整性较好,细粒砂岩较差。

The failure process and mode of porous sandstone under uniaxial compression have importanct influenceon energy exploitation and underground space engineering construction.Taking the Weinan finely-grained sandstone and Xianyang coarsely-grained sandstone in Shanxi as the research object,the high-speed photographic real-time observation experiment of sandstones with different grain sizes under uniaxial loading were carried out,and the images of the two granularity rock samples in each failure process stage were obtained.The whole process of initiation,propagation and penetration of macroscopic cracks in the uniaxial compression process of rock samples with different particle sizes is carried out.The influence of particle size of sandstone on its macroscopic deformation and failure process and mode is discussed.It is found that particle size is an important factor to affect the uniaxial compression failure mode of pore sandstone.Finely-grained sandstone produces strong dynamic effects at the moment of failure,while coarsely-grained sandstone does not have.The coarse sandstone failure mode is tensile splitting,while the fine sandstone failure mode is shear slip.During the crack propagation from the macroscopic crack of the rock sample,the crack propagation of the coarsely-grained sandstone lasts longer than the finely-grained sandstone.In terms of the integrity of the residual test piece,the coarsely-grained sandstone has better integrity than the finely-grained sandstone.