节理岩体爆生裂纹扩展动态焦散线模型实验研究

Dynamic caustics model experiment of blasting crack developing on sandwich rock

应用动态焦散线测试系统,模拟含节理岩体断裂爆破过程,进行了PMMA模型透射式动态焦散线实验,着重研究了爆炸初始裂纹与节理面夹角不同的情况下,裂纹尖端动态强度因子的变化规律、裂纹穿过节理面的扩展规律、以及炮孔与节理距离不同时裂纹穿过节理扩展的规律。实验结果分析表明,爆生裂纹穿过节理面时,裂纹尖端的动态强度因子和裂纹扩展速度显著下降,穿过节理面后,强度因子又增强;裂纹穿过节理面时,裂纹会沿节理面偏离一段距离后沿原方向继续扩展。实验结果还表明,炮孔与节理间距适宜的情况下,裂纹才会穿过节理继续扩展,间距太小和过大都不利于裂纹的扩展。

Using the dynamic caustic-test system, the PMMA model transmission-type experiment of dynamic caustics was carried out to simulate the blasting process of rock with joints. Varieties of dynamic intensity factors in the crack-tip field, extensions of cracks going through the joint planes for different distances between hole and joint were analyzed especially under the condition that the initial cracks and joint planes had different separation angles. Experimental results show that the dynamic intensity factor of the crack-tip and the extension speed decrease dramatically while the cracks go through joint planes but afterwards the intensity factor increases, that when the crack goes through the joint plane, it can deviate a short distance along the joint, and then continues to develop in its initial direction with respect to the appropriate distance between hole and joint.