弱胶结砂岩在冲击荷载下的动力学性能研究

Experimental Study on Dynamic Performance of Weakly Cemented Sandstone under Impact Load

为研究粉砂岩在冲击荷载下的动力学性能,选取内蒙古东胜煤田红庆河煤矿副井-680 m处的弱胶结粉砂岩,运用Hopkinson杆测试技术进行不同冲击能量下的冲击荷载实验。通过实验数据分析,得出结论如下:选取的弱胶结砂岩为侏罗系延安组粉砂岩,强度较低,均值为39.08 MPa。遇水易崩解,且极易风化,内部颗粒较细、多为泥质胶结。弱胶结砂岩冲击荷载条件下的峰值强度均较单轴抗压强度下的峰值强度有大幅度提高,提高值为单轴抗压强度的1.14倍。但相比于中部地区砂岩,其动、静强度较低,动载强度提高值有限,达不到中部砂岩静载强度。冲击荷载越大,应变率越高,峰值强度越大。应变率与峰值强度间存在良好的指数增长或线性增长关系。其应力—应变曲线按照应力的增速大致分为3个阶段:应力骤升阶段、应力—应变平缓上升阶段、应力陡然下降阶段。

In order to study the dynamic performance of sandstone under impact load,the weakly consolidated sandstone is researched in the auxiliary shaft at-680 m of Hongqinghe coal mine of Inner Mongolia Dongsheng coal powder.Using the Hopkinson bar test technique,the samples were studied by different impact load test.Through the experimental data analysis,the conclusions are as follows:The weakly cemented sandstone of Jurassic Yan’an Formation siltstone is selected,whose strength is lower and the mean strength is 39.08 MPa.It is easy to collapse in water,and extremely easy to weathering.The peak strength of weak cemented sandstone under impact load conditions has greatly improved compared with peak strength under uniaxial compressive strength,and the improved value is 1.14 times the uniaxial compressive strength.Compared to the sandstone in middle district,its dynamic and static strength is lower.The increase of dynamic load strength is limited,and can not reach the middle sandstone static load strength.The greater impact load,the higher strain rate,and the greater the peak strength.There is a good exponential or linear relationship between growth rate and peak strength the strain.According to the growth rate of stress,the stress-strain curve can be roughly divided into three stages:stress swell stage,stress-strain gently rising stage and stress suddenly decline phase.