高压水射流冲击速度对砂岩破坏模式的影响研究

 高压水射流冲击岩石会导致其发生结构破坏，不同的射流速度下，岩石呈现出各异的破坏形式。基于理论研究，分析水射流冲击岩石的应力波效应。选取速度分别为157，316，447，547，632，707和774 m/s的高压水射流开展冲击砂岩试验，分析不同射流速度下，砂岩内裂纹的数量、尺寸与形态。采用有限元法数值模拟了水射流破碎砂岩的过程，分析岩石内应力波的传播规律与裂纹的产生过程。研究表明：(1) 当射流速度大于72 m/s时，砂岩表面出现破碎坑和环形裂纹，前者由水锤压力的剪切作用导致，后者由瑞利表面波的拉伸作用导致；(2)当射流速度为300～700 m/s时，砂岩内部产生大量的横向裂纹并出现体积破碎，裂纹的产生主要由应力波产生的径向拉伸应力导致；(3) 当速度大于700 m/s时，砂岩产生的横向裂纹减少，主要以劈裂剪切方式破坏。

Influence of velocity of high-pressure water jet on failure patterns of sandstone

The impingement of rocks by the high-velocity water jet causes the erosion of structures. The failure patterns of rocks subjected to water jet with different velocities vary greatly. The stress wave effect of water jet impacting on rock was analyzed based on the previous studies. A number of impacting experiments were conducted with the water jet velocities of 157，316，447，547，632，707 and 774 m/s respectively. According to the failure phenomenon of sandstone，the number，size and patterns of cracks inside the rock subjected to the water jet with different velocities were analyzed. Finite element models of water jet impacting on the cylindrical sandstone were established. The propagation of stress wave and the generation of cracks in rock were studied. The broken pit and the circumferential cracks on the surface of sandstone occurred when the velocity of water jet was above about 72 m/s，and the former was produced by the shear stress of water hammer pressure and the later was induced by the tensile component of Rayleigh wave. Many transverse cracks were produced by the radial tensile stress waves when the velocity was between 300 and 700 m/s. The major failure pattern of sandstone is the split cracks when the velocity is above 700 m/s.