动静复合加载下红砂岩破碎规律研究

Study on the fragmentation law of red sandstone under combined dynamic and static loading conditions

振动碎岩具有能量消耗量低、所需轴向压力小等特点。为提高碎岩效率同时降低成本,进行了振动-加压相结合的碎岩模式研究。本文以红砂岩为研究对象,围绕动静复合加载条件下球齿侵入导致的红砂岩内部裂纹扩展规律开展研究。结果表明,球齿下岩石的破碎程度随着动、静载荷的增大而变大,并且只有当组合载荷峰值达到100 kN时,岩石才会发生明显的体积破碎。在破岩初期,当载荷较小时,岩石倾向于发展为侧向裂纹,岩石损伤成“宽而浅”特点。随着载荷的增大,岩石更倾向于发展中间的深部裂纹,而后才倾向于发展侧向裂纹,即呈“窄而深”的特点。岩石破碎的各项指标受各载荷参数的影响程度存在差异:即在相同的幅值增量条件下,增加动载幅度导致的破碎程度要大于增加相同静载荷时的破碎程度。以上结论可为提高动静载复合破碎硬岩效率、攻克硬岩钻进技术难题提供重要支撑。

Vibratory rock fragmentation has the characteristics of low energy consumption and low required axial pressure.In order to improve the efficiency of rock fragmentation while controlling costs,a study was conducted on the rock fragmentation mode combining vibration and pressure.This article takes red sandstone as the research object and conducts research on the crack propagation law inside the rock when spherical teeth invade red sandstone under dynamic and static composite loading.The results indicate that the degree of rock fragmentation under the spherical tooth increases with the increase of dynamic and static loads,and only when the combined load peak reaches 100kN,will the rock undergo significant volumetric fragmentation.In the early stage of rock breaking,when the load is small,the rock tends to develop lateral cracks,and the rock damage becomes“wide and shallow”.As the load increases,the rock tends to develop deep cracks in the middle,followed by lateral cracks,which exhibit a"narrow and deep"characteristic.The various indicators of rock fragmentation are affected by different load parameters to varying degrees:that is,under the same amplitude increment conditions,the degree of fragmentation caused by increasing the dynamic load amplitude is greater than that caused by increasing the same static load.The above conclusions can provide important support for improving the efficiency of dynamic and static load composite crushing of hard rock and overcoming the technical difficulties of hard rock drilling.