作　　者： (郭东明）; (刘康）; (罗浪）; (杨俊）; (王豪）; (肖正星）;

机构地区： 中国矿业大学(北京)力学与建筑工程学院

出　　处： 《矿业科学学报》 2017年第4期348-356,共9页

摘　　要： 为探究爆炸载荷下邻近硐室迎爆侧围岩中原先裂纹的扩展机理,采用动态焦散线方法进行了试验研究。研究发现:爆炸载荷作用下,裂纹动态断裂韧度与硐室自由面和裂纹倾角无关,但硐室自由面的存在使预制裂纹的起始扩展时间提前;迎爆侧围岩中预制裂纹的扩展方向与硐室自由面、炮孔处诱发主裂纹扩展方向以及硐室围岩应力分布特征有很大关联。预制裂纹扩展初期,由于自由面反射拉伸波的作用,裂纹近似竖向扩展;裂纹扩展中期,炮孔诱发主裂纹对应力波能释放的导向性改变了预制裂纹周边应力场,使裂纹扩展方向与主裂纹扩展方向基本平行;裂纹扩展后期,受邻近硐室自由面应力分布特征影响,裂纹扩展方向偏向于拱形部位,并最终与拱形部位贯穿。结合LS-DYNA软件,分析了爆炸载荷下邻近硐室围岩应力分布特征,从迎爆侧底角到起拱点再到拱顶,有效应力表现为先减小后增大再减小的规律。其中,极大值点位于底角、起拱点和拱顶之间位置,极小值点位于直墙位置,最终导致预制裂纹往往止裂于拱顶与起拱点之间的某一位置。 The method of dynamic caustics is adopted to investigate the mechanism of original crack existing in the surrounding rock of adjacent tunnel under the action of blasting load. Conclusions are drawn as follows. Under the action of blasting load,dynamic fraction toughness of pre-crack is not related to the dip angle of pre-crack and the free surface of tunnel. However,the existence of free surface makes pre-crack initiation in advance. In general,the propagation path of pre-crack facing the blasting side of adjacent tunnel under the action of blasting load is related to the propagation path of principal crack from the blast-hole,the free surface of tunnel as well as its section form. Initial propagation path presents approximate vertical upward because of the action of tension wave reflected by the free surfaceof tunnel. The middle and later periods of pre-crack propagation,the propagation path of principal crack and the stress distribution characteristics of free surface have great effect on the propagation path of pre-crack. The stress distribution characteristics of surrounding rock facing the blasting side are analyzed through the LS-DYNA. From the base angle of side wall to vault facing the blasting side of tunnel,effective stress presents the variation rule of decreasing-increasing-decreasing,of which the maximum points lie to the base angle and the location between sprung arch and vault,the minimum point lie to the side wall. As a result,the pre-crack propagation path is partial to the arch parts and arrest at certain location between the sprung arch and vault.

关 键 词： 爆炸载荷 邻近硐室 迎爆侧 预制裂纹 动态焦散线