三维动静组合加载下岩石力学特性试验初探  

PRELIMINARY EXPERIMENTAL STUDY OF CHARACTERISTICS OF ROCK SUBJECTED TO 3D COUPLED STATIC AND DYNAMIC LOADS

作　　者：宫凤强[1,2] 李夕兵[1,2] 刘希灵[1,2] 

机构地区：[1]中南大学资源与安全工程学院,湖南长沙410083 [2]中南大学深部金属矿产资源开发与灾害控制湖南省重点实验室,湖南长沙410083

出　　处：《岩石力学与工程学报》2011年第6期1179-1190,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点基础研究发展计划(973)项目(2010CB732004);国家自然科学基金资助项目(50934006);中南大学前沿研究计划资助项目(2010QZZD001)

摘　　要：基于对深部岩石承受高地应力并在动力开挖扰动下发生破坏这一问题的科学认识,利用改造的三维霍普金森动静组合加载试验装置,开展三维动静组合加载下砂岩力学特性试验的初步研究。选取3个围压水平(0,5,和10 MPa)和3个典型轴压水平(60,80和100 MPa),开展不同应变率下的三维组合加载试验。研究结果表明,当围压一定,轴压比在0.52～0.87范围内变化时,砂岩的抗压强度都会随着轴压的增大而逐步减小。当轴压一定,围压为5 MPa时砂岩的抗压强度跟无围压情况下差别不大。但是当围压增大到10 MPa,砂岩的抗压强度会有较大提高。本文的研究结果也证明了冲击过程中轴压对砂岩内部的裂纹起催生作用,弱化微元体的承载能力,导致割线模量降低;围压则可以抑制裂纹的萌生和扩展,强化了微元体的承载能力,使得割线模量会增加。研究结果还表明,在本文轴压比范围内,当围压一定时,砂岩单位体积释放能会随着轴压的增大而降低,当常规静载轴压比为0.6～0.7时,转化为吸能状态。在三维动静组合加载下,砂岩会呈现出"单锥"压剪破裂形式。Based on the scientific understanding of deep rock under high crustal stress and dynamic excavating perturbation,the dynamic failure characteristics of sandstone subjected to three-dimensional（3D） coupled static and dynamic loads are experimentally studied preliminarily with a modified 3D split Hopkinson pressure bar（SHPB） apparatus.Three levels of confining pressures（0,5 and 10 MPa） and three typical levels of axial compressions（60,80 and 100 MPa）,are designed;and the 3D coupled loads tests are carried out under different strain rates.The results show that,when the confining pressure is constant,the impact compressive strength will decrease when the ratio of axial compressive stress to axial compressive ultimate capacity increases from 0.52 to 0.87.Compared with the influence of confining pressure 10 MPa,the impact compressive strength changes a little under confining pressure 5 MPa.The results also show that the axial pressure will induce the internal cracks in rock,weaken the carrying capacity of microelement and reduce the secant modulus of rock;While the confining pressure will inhibit the initiation and propagation of cracks,consolidate the carrying capacity of microelement and enhance the secant modulus of rock.When the confining pressure is constant,the results also show that the release energy per unit volume will decrease when the ratio of axial compressive stress to axial compressive ultimate capacity increases and change into absorbing energy state at the ratio of axial compressive stress to axial compressive ultimate capacity of 0.6-0.7.The rock will show a single-cone compression-shear failure model under 3D coupled static and dynamic loads.

关 键 词：岩石力学 深部岩石 三维动静组合加载 霍普金森压杆 抗压强度 动态强度 

分 类 号：TU458[建筑科学—岩土工程]