神东矿区含天然弱面砂岩的力学特征研究

Study on mechanical characteristics of sandstone with natural weak plane in Shendong coal field

为了研究神东矿区含天然弱面砂岩力学特征,以补连塔煤矿2-2煤层基本顶中粒砂岩为研究对象,采用CMT5000大门式微机控制电子万能试验机、RDS-200XL全自动伺服控制岩石直剪/残剪仪和RMT-150C力学试验机对完整砂岩和含天然弱面砂岩进行直接拉伸、直接剪切和单轴压缩试验,运用X射线衍射仪和扫描电镜分析弱面的成分、微观结构及元素特征。结果表明:天然弱面对纵波波速、抗压强度、残余剪切强度基本没有影响,纵波波速、单轴抗压强度和残余剪切强度分别降低了0.4%,1.4%和3.2%;天然弱面对直接拉伸强度、拉伸峰值应变、峰值剪切强度和弹性模量有显著的影响,峰值拉伸强度降低了83.1%,拉伸峰值应变降低了82.7%,峰值剪切强度降低了12.6%,弹性模量降低了7.3%。研究结果有助于进一步了解这种含天然弱面砂岩顶板的运动、破断以及力学传递规律。

In order to study the influence of natural weak face on the physical and mechanical characteristics of sandstone in Shendong coal field,the basic top medium-grained sandstone of No.2-2 coal in Bulianta coal mine was taken as the research object.Direct tension,direct shear and uniaxial compression tests of intact sandstone and sandstone with weak surface were carried out by using CMT5000 gate computer controlled electronic universal testing machine,RDS-200XL automatic servo controlled rock direct shear/residual shear tester and RMT-150C mechanical testing machine.X-ray diffraction and scanning electron microscopy were used to analyze the composition,microstructure and element characteristics.Results showed that:The natural weak plane had no effect on the longitudinal wave velocity,compressive strength and residual shear strength.P-wave velocity,uniaxial compressive strength and residual shear strength decreased by 0.4%,1.4%and 3.2%,respectively.Natural weak surfaces had significant effects on direct tensile strength,peak strain,peak shear strength and modulus of elasticity.The peak tensile strength decreased by 83.1%,the peak tensile strain decreased by 82.7%,the peak shear strength decreased by 12.6%,and the elastic modulus decreased by 7.3%.The results of this study were helpful to further understand the law of movement,breaking and force transmission of this kind of roof with natural weak plane.