在煤矿巷道掘进过程中，巷道围岩在动载作用下变形将会增大，为研究煤系砂岩在冲击荷载作用下的力学特性及能量耗散，以河南陈四楼煤矿巷道围岩中的砂岩为研究对象，利用直径为50 mm的分离式霍普金森压杆试验装置对煤矿砂岩开展单轴单次冲击压缩试验和循环冲击压缩试验，对冲击荷载作用下煤矿砂岩的应变率效应、能量耗散特征和破坏模式等进行分析。研究结果表明:在单轴单次冲击荷载作用下，随着平均应变率的增加，砂岩试样的峰值应力和峰值应变均增大，割线模量逐渐降低，砂岩试样的塑性增加，强度提高;且峰值应变与平均应变率呈线性递增关系，峰值应力近似与平均应变率的1/3次幂呈递增关系;随着平均应变率的增加，砂岩试样的单位体积吸收能呈线性增加趋势，且试样破碎程度不断增大，在压应力持续作用下砂岩试样内部裂纹不断交叉扩展，沿轴向发生劈裂破坏。在循环冲击荷载作用下，随冲击荷载作用次数的增加，砂岩试样的平均应变率和峰值应变均逐渐增大，峰值应力、割线模量和第2类割线模量均随着冲击次数的增加而逐渐降低;在固定冲击气压下进行循环冲击时，随着冲击次数的增加，入射能基本保持不变，反射能和吸收能均逐渐增大，透射能逐渐减小，砂岩试样的单位体积吸收能随冲击次数增加呈先缓慢增加后突然增加的趋势;在循环冲击荷载作用下，砂岩试样吸收能量的能力增强，随着冲击次数的不断增加，试样内部微裂纹分布增多且扩展速度加快，主要发生受拉破坏，沿轴向加载方向产生贯穿于砂岩试样的环状破坏面。

The deformation of surrounding rock will increase under dynamic load during the excavation of coal mine roadway.In order to study the mechanical properties and energy dissipation of sandstone in coal measures under impact loading,the sandstone in the surrounding rock of Chensilou coal mine roadway was collected as the research sample,and a split Hopkinson pressure bar test device,with a diameter of 50 mm,was used in uniaxial single impact compression test and cyclic impact compression test.The strain rate effect,energy dissipation characteristics and failure modes of the sandstone were analyzed.Under the uniaxial single impact loading,with the increase of average strain rate,peak stress and peak strain,the plasticity and strength of the sandstone samples increase,while the secant modulus decreases gradually.Moreover,the peak strain has a linear increase relationship with the average strain rate,and the peak stress approximately increases with the 1/3 power of the average strain rate.With the increase of the average strain rate,the absorption energy per unit volume of the sandstone samples shows a linear increase tendency,and the degree of fragmentation of the samples continues to increase.Under the impact of constant compressive stress,the internal cracks of the sandstone samples keep crossing and expanding,and the splitting failure occurs along the axial direction.Under the cyclic impact loading,the average strain rate and peak strain of sandstone samples gradually develop with the increase of the cyclic loading times,while the peak stress,secant modulus and second type secant modulus gradually decreases.During the cyclic impact under the fixed pressure,with the increase of the impact times,the incident energy basically remains unchanged,and the reflection energy and absorption energy gradually increase,whereas the transmission energy gradually decreases.The absorption energy per unit volume of the sandstone samples increases slowly firstly and then suddenly in-creases with the impact times.Under the cyclic impact loading,the energy absorption capacity of the sandstone samples is enhanced.With the increase of impact times,the distribution of microcracks inside the samples enlarges and the expansion speed accelerates.As a result,the tensile failure mainly occurs,and the annular failure plane running through the sandstone samples generates along the axial loading direction.

1 砂岩SHPB试验

   1.1 试样制备

   1.2 试验装置及原理

   1.3 冲击气压确定

   1.4 试验方法

2 SHPB冲击试验结果分析

   2.1 冲击荷载作用下砂岩试样的破坏形态

   2.2 砂岩试样应力、应变和应变率分析

   2.3 冲击荷载作用下能量耗散特征分析

3 结论