高应力下硬岩巷帮钻孔爆破卸压动态模拟

钻孔爆破卸压是转移或释放高地压的有效措施。采用显式非线性动力分析有限元程序ANSYS/LS-DYNA与快速拉格朗日有限差分程序FLAC3D相结合的方法,动态模拟了硬岩巷帮钻孔爆破卸压过程,分析了不同施工条件对卸压效果的影响。结果表明:合理的钻孔深度处于支承压力峰值与支承压力区边界之间的中部位置;装药量越大,支承压力峰值降低越明显,装药量上限应确保爆炸产生的损伤区与巷道已有损伤区不贯通;钻孔间距越小,支承压力峰值降低越明显,钻孔间距下限应满足在确保不扩大巷道已有损伤区范围的前提下,钻孔之间能够形成基本贯通的塑性带。

Dynamic modeling simulation for the destress blasting in the hard rock tunnel wall under the high geostress

This paper intends to describe the situaiton for and present the results of a dynamic numerical simulation model for ways to destress the blasting risks in the hard rock tunnel walls with high geostress via a nonlinear hybrid dynamic explicit finiteelement program (ANSYS/LS-DYNA) and the fast Lagrangian explicit finite-difference program (FLAC30) scheme.As is often the case,rockburst are prone to take place due to the interaction of the internal forces of the high geostress.Since the blasting destress or reduction serves as one of the most effective measures for transforming,reducing and relieving or releasing high geostress,it has become a major challenge for the safe and successful coalmining in the deep mine running practice.Based on the up-to-date research practice,it is believed that the control of rockburst can,first of all,be achieved by calibrating a numerical model with a single blast hole to test and determine the blast pressure and damping coefficient of the rockmass.And,secondly,it is necessary to build up a numerical model in a tunnel of a national known gold mine,and in turn conduct a simulation of tunneling with a series of static analyses before the rockburst conditions were prepared.At that point,we have managed to finish a series of dynamic analyses for the destress blasting in the different construction conditions by exerting the calibrated blast pressures to the wall of the zone to be crushed.The results we have gained from the aforementioned analyses indicate that the peak abutment pressure in the test tends to get reduced significantly when the depth of the blast hole is in the middle range between the position of the peak abutment pressure and the boundary of the abutment pressure zone.And,when the peak abutment pressure tends to get decreased with the increase of the explosive charge,the upper limit of the explosive charge ought to prevent the blasting-induced plastic zone from being transfixed with the already existing plastic zone in the nearby tunnel.What is more,the peak abutment pressure also tends to decrease with the distance going on increasing between the blast holes.However,it is necessary to satisfy the precondition to keep the range of the already lowered-down limit of the distance between the blast holes to the existing plastic zone in the nearby tunnel from being extended,whereas the space between the blast holes ought to have resulted in forming the plastic bands.Thus,it can be seen that the above mentioned method for preventing from the rock bursts we have developed above can be successfully adopted to other hard rock tunnel walls under high geostress conditions.