初始应力下岩石爆破过程模拟研究

发布时间：2018-08-07 08:24

【摘要】：由于浅部资源的减少及某些工程的需要,资源开采和隧道开挖都进入了深部地下。深部岩体往往处于高初始地应力环境中,爆破时,岩石在初始应力和爆炸载荷的共同作用下而破裂,这个过程非常复杂,已经不能用浅部岩体的爆破理论来分析了。因此有必要对初始应力下岩石的爆破过程进行分析。本文利用有限元软件LS-DYNA和ABAQUS对初始应力下的岩石爆破过程进行了数值模拟研究,完成了如下的工作：(1)从理论上分析了岩石爆破的过程,结合岩石爆破过程,分析了岩石在爆炸动载荷下的应变率效应、岩石爆破的动力学进程以及爆炸载荷和初始应力的叠加。(2)利用LS-DYNA对初始应力下球状装药的岩石爆破过程进行了数值模拟,对比了不同抵抗线下的爆破漏斗大小,结果表明：不同抵抗线下形成的爆破漏斗差别很大,本文计算的模型中,抵抗线W=20mm时爆破漏斗最大,初始应力不影响球状装药应力波的传播,但会抑制垂直于初始应力方向的爆破漏斗的形成；对初始应力下柱状装药岩石爆破过程进行了数值模拟,结果表明：初始应力不影响柱状装药爆炸应力波的传播和衰减,也不影响爆破粉碎区的形成,但会抑制垂直于初始应力方向的裂纹的形成；对卸载初始应力下的岩石爆破过程进行了数值模拟,结果表明：卸载应力波可以改善岩石中应力场的分布,并促进爆破裂纹的形成。(3)利用LS-DYNA对初始应力下排孔爆破过程和预裂爆破过程进行了数值模拟,结果表明：各炮孔距离合适时,不同炮孔之间形成贯通裂纹,当排孔与初始应力平行时,排孔爆破效果最好,排孔与初始应力垂直时,排孔爆破效果最差,预裂爆破中,排状的预裂孔、炮孔和初始应力平行时,预裂孔能诱导两炮孔间裂纹的形成；对初始应力下含节理的岩石爆破过程进行了数值模拟,结果表明：节理对爆炸应力波有透射和反射作用,并使岩石产生反射拉伸裂纹,但贯通节理阻碍了裂纹的进一步扩展,当局部节理尖端、炮孔连线与局部节理之间夹角较小时,局部节理尖端可以诱导裂纹扩展；对初始应力下含空区的岩石爆破过程进行了数值模拟,结果表明：空区给爆破提供了自由面,改善了岩石中应力分布和爆破效果。(4)利用ABAQUS对爆生气体驱动裂纹扩展过程进行了数值模拟,结果表明：随着裂纹的扩展,爆生气体压力减小,裂纹扩展速度降低,当爆生气体压力达到临界压力时,裂纹停止扩展；对初始应力下爆生气体驱动裂纹扩展过程进行了数值模拟,结果表明：初始应力会抑制垂直于初始应力方向的裂纹的扩展,当初始裂纹方向与初始应力方向或初始应力合力方向一致时,裂纹沿着原来的方向扩展,否则,裂纹偏向初始应力大的方向扩展。
[Abstract]:Due to the decrease of shallow resources and the need of some projects, resource mining and tunnel excavation have entered deep underground. The deep rock mass is often in the environment of high initial in-situ stress. When blasting, the rock ruptures under the joint action of initial stress and explosion load. This process is very complicated and can not be analyzed by the blasting theory of shallow rock mass. Therefore, it is necessary to analyze the rock blasting process under initial stress. In this paper, the numerical simulation of rock blasting process under initial stress has been carried out by using finite element software LS-DYNA and ABAQUS. The following works have been accomplished: (1) the rock blasting process is analyzed theoretically, combined with the rock blasting process. The strain rate effect of rock under explosive dynamic load, the dynamic process of rock blasting and the superposition of explosion load and initial stress are analyzed. (2) the rock blasting process of spherical charge under initial stress is numerically simulated by LS-DYNA. The blasting funnel size under different resistance lines is compared. The results show that the blasting funnel formed under different resistance lines is very different. In the model calculated in this paper, the blasting funnel is the largest when the resistance line is W=20mm. The initial stress does not affect the propagation of the stress wave of the spherical charge, but it will inhibit the formation of the blasting funnel perpendicular to the direction of the initial stress, and the blasting process of the columnar charge rock under the initial stress is numerically simulated. The results show that the initial stress does not affect the propagation and attenuation of the explosive stress wave of the cylindrical charge, nor does it affect the formation of the blasting comminuted zone, but it inhibits the formation of cracks perpendicular to the initial stress direction. The blasting process of rock under initial unloading stress is numerically simulated. The results show that unloading stress wave can improve the distribution of stress field in rock. (3) numerical simulation of the blasting process under initial stress and pre-splitting blasting process is carried out by using LS-DYNA. The results show that when the distance between the holes is appropriate, the through-through cracks are formed between different holes. When the row hole is parallel to the initial stress, the effect of the row hole blasting is the best. When the row hole is perpendicular to the initial stress, the row hole blasting effect is the worst. Pre-cracking holes can induce the formation of cracks between two holes, and the blasting process of rock with joints under initial stress is numerically simulated. The results show that the joints can transmit and reflect the explosion stress waves, and make the rocks produce reflective tensile cracks. However, through joint hinders further crack propagation. When the angle between the local joint tip and the hole line and the local joint is small, the crack growth can be induced by the local joint tip. Numerical simulation of rock blasting process in hollow zone under initial stress is carried out. The results show that the empty zone provides free surface for blasting. The stress distribution and blasting effect in rock are improved. (4) numerical simulation of crack propagation process driven by explosion gas is carried out by using ABAQUS. The results show that with the crack propagation, the gas pressure decreases and the crack growth speed decreases. When the explosion gas pressure reaches the critical pressure, the crack growth stops, and the crack propagation process driven by the explosion gas under the initial stress is numerically simulated. The results show that the initial stress can suppress the crack propagation perpendicular to the initial stress direction. When the initial crack direction is the same as the initial stress direction or the initial stress resultant direction, the crack propagates along the original direction, otherwise, the crack tends to propagate in the direction of large initial stress.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU45

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