弱胶结砂岩的物理力学特征及定义

李回贵; 李化敏; 汪华君; 陈善乐

弱胶结砂岩的物理力学特征及定义

Physical and mechanical characteristics and definition of weakly cemented sandstone

LI Huigui LI Huamin WANG Huajun CHEN Shanle,

摘要

摘要: 为给弱胶结砂岩明确的定义,以布尔台煤矿覆岩中弱胶结砂岩为研究对象,采用地面钻孔取心的方法,采集了3种砂岩试样,首先对其成分以及微观结构进行了分析,然后分别对这3组试样进行了单轴压缩、三轴压缩、巴西劈裂试验,分析了弱胶结砂岩的密度、波速、抗拉强度、抗压强度、弹性模量、黏聚力及内摩擦角等参数。试验结果表明:弱胶结砂岩是以石英和长石为骨架颗粒的岩石,胶结物含量小于总含量的30%;弱胶结砂岩颗粒之间的孔隙非常大,主要集中在40~100μm;胶结物非常少,颗粒边界非常清晰;弱胶结砂岩破裂时主要沿颗粒的边界破裂,宏观破裂类型以“I”形为主;弱胶结砂岩的波速(<1 200 m/s)和密度(<2 200 kg/m3)非常小;抗拉强度(<2 MPa)、抗压强度(<20MPa)、弹性模量(<2 GPa)以及黏聚力(<10 MPa)也非常的小。研究成果有助于进一步揭示弱胶结岩层巷道变形大、巷道支护困难、矿压显现剧烈以及地表台阶下沉等现象的内在原因。

Abstract: In order to give clear definition of weakly cemented sandstone, taking weakly cemented sandstone in Buertai Mine overburden as the research object, th ree kinds of sandstone samples were collected by using the core drilling method. Firstly, the composition and microstructure were analyzed.Secondly, the three kinds of specimens were carried out with uniaxial compression, triaxial compression and Brazil split experiment.Finally, the parameters such as density, wave velocity, tensile str ength, compressive strength, elastic modulus, cohesion and internal friction angle were analyzed. Experimental results show that weakly cemented sandstone is a rock with quartz and feldspar as the skeleton particles.And the cement content is less than 30% of the total content.The pores between the grains of weakly consolidated sa ndstone are very large, mainly concentrated in the 40 ~ 100 um.The cement is very small and the grain boundaries are very clear.The weakly cemented sandstone is m ainly along the boundary of the particle.The macroscopic fracture type is dominated by the' I"type.The wave velocity (

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