含孔洞层状砂岩动态压缩力学特性试验研究  

Dynamic compressive mechanical properties of bedding sandstone with pre-existing hole

作　　者：李地元[1] 刘濛 韩震宇 周子龙[1] LI Diyuan;LIU Meng;HAN Zhenyu;ZHOU Zilong(School of Resources and Safety Engineering,Central South University,Changsha410083,China)

机构地区：[1]中南大学资源与安全工程学院

出　　处：《煤炭学报》2019年第5期1349-1358,共10页Journal of China Coal Society

基　　金：国家重点研发计划资助项目(2016YFC0600706);国家自然科学基金资助项目(51474250);国家重点基础研究发展计划(973)资助项目(2015CB060200)

摘　　要：隧道、矿山巷道和硐室等地下岩石工程中揭露的层状岩体往往具有不同的产状,层理弱面的方向与主要动荷载作用方向存在多种组合,相应的动态各向异性力学特性和变形破坏特征对地下岩石工程安全稳定具有至关重要的影响。针对冲击载荷下倾斜层状岩体中巷道围岩稳定性问题,选取一种层理构造显著的黄砂岩,其中层理倾角φ为层理面与加载方向之间的夹角,加工制备倾角分别为0°,15°,30°,45°,60°,75°和90°的7组预制中央圆形孔洞板状试样(尺寸为宽度60mm×高度60mm×厚度15mm),在75mm杆径分离式霍普金森压杆(SHPB)试验平台上进行冲击压缩试验,并使用高速摄影仪实时记录试样动态裂纹扩展演化过程,研究不同层理倾角条件下预制中心孔洞层状岩石的动态力学参数、裂纹扩展演化过程及最终破坏模式等动态压缩力学特性变化规律。结果表明,峰值应力处试样破坏的峰值应变在0.0081~0.01237变化,随着层理倾角的增加,试样动态抗压强度、弹性模量及峰值应变整体均呈先增大后减小的变化规律;初始起裂裂纹总是从孔洞周边压应力集中处萌生,随后逐渐形成宏观裂纹,宏观裂纹为剪切裂纹或拉剪复合裂纹;倾角0°试样发生局部沿层理和局部穿越层理的复合张剪破坏,倾角15°~45°试样发生局部沿层理和局部穿越层理的剪切破坏,倾角60°~90°试样最终发生穿越层理的类X型剪切破坏;利用正交各向异性板理论计算孔洞周边应力分布,发现随着层理倾角的增加,孔洞周边应力集中系数的峰值也逐渐增大,且层理倾角为0°,15°,30°,45°的试样孔洞周边最大压应力出现在θ(θ为孔洞周边任意一点的极角)为74°,81°,86°,90°及关于原点中心对称的254°,261°,266°,270°处,同时试验中观测到相应的层理倾角试样分别在88°,85°,79°,70°及关于原点对称的271°,264°,262°,252°处萌生剪切裂纹,与理论分The exposed layered rock masses with different attitudes can be found in many underground openings such as tunnel,mine roadway and chamber.With various combinations of orientation of layers and loading direction,the dynamic anisotropic mechanical and deformation properties of rock masses affect crucially the engineering stability and safety.The paper aimed to research the surrounding rock stability of roadway in inclined stratified rock mass.To investigate the variation of the dynamic mechanical parameters,fracture propagation and failure modes of flawed bedding sandstone under different layer dip angles,the plate-shape bedding sandstone specimens were manufactured with a single circular hole in the specimen center.A series of dynamic impact tests were carried out using a ? 75 mm split Hopkinson pressure bar (SHPB) system on seven groups of bedding sand-stone specimens (size of 60 mm×60 mm × 15 mm ) which contain different layer dip angles φ(including 0°,15°,30°,45°,60°,75° and 90°),where the dip angle φ is the angle between the orientation of layers and the loading direction.The dynamic fracture evolution processes of specimens were recorded with a high-speed camera.The experimental results indicate that the strain corresponding to stress peak value ranges from 0.008 1 to 0.012 37.With the increase of dip angle,the dynamic compressive strength,the strain corresponding to the stress peak value and elastic modulus of specimens increase firstly and then decrease in general.Shear cracks or tensile-shear mixed cracks always initiate from the compressive stress concentration areas around the holes,and then develop to macroscopic fractures.The low-dip specimens (φ=0°) exhibit combined tensile-shear failure across and along the bedding plane.The medium-dip specimens (φ=15°,30° and 45°) exhibit shear failure across and along the bedding plane.The highly dipping specimens (φ=60°,75° and 90°) exhibit X-type shear failure.Orthogonal anisotropic plate theory was applied to calculate the stress distributi

关 键 词：岩石动力学 分离式霍普金森压杆 层状砂岩 层理倾角 动态强度 裂纹扩展 破坏模式 

分 类 号：TU45[建筑科学—岩土工程] TD313[建筑科学—土工工程]