Development of VSP Probe for Inspection of Blast Damaged Zone

本文对爆炸损伤区的评价进行了一系列的实验和理论研究。获得的结果如下。(1)开发了一套用于评价开挖爆破松动圈的VSP系统。采用超弹性合金板作为弹簧的材料，将振动传感器以恒定的力压在井壁上。实验结果表明，该系统可以方便、快速地测量隧道周围的爆炸损伤区。(2)采用有限元法分析了光面爆破中考虑裂纹扩展的岩石破碎过程，阐明了延时精度对表面平整度和残余岩石损伤的影响。特别指出，相邻炮孔爆破引起的动、准静态应力场的干涉对控制爆破裂纹扩展起着重要作用。(3)采用应力解除技术，对光面爆破开挖隧道周边损伤区的诱导应力进行了测试。结果表明，采用电子雷管光面爆破，可有效地减小残余岩体的破坏面积。

A series of experimental and theoretical investigation for the evaluation ofblast damaged zone has been carried out. Results obtained are as follows.(1) A compact VSP system to evaluate the loosened zone caused by excavation blasting has been developed. A super-elastic alloy plate has been adopted as material for the spring which presses a vibration sensor to the borehole wall with constant force. It is confirmed that the blast-damaged zone around a tunnel can be measured easily and quickly by using the developed system.(2) The fragmentation process of rock in the smooth blasting was analyzed by FEM with taking into account the crack propagation and the effect of delay time accuracy on surface smoothness and remaining rock damage has been clarified. Especially, it is pointed out that the interference of dynamic and/or quasi-static stress fields induced by blasts of adjacent holes plays an important role to control the crack propagation in SB.(3) Induced stress in damaged zone around a tunnel excavated by smooth blasting has been measured by the stress relieving technique. It is confirmed that the smooth blasting using electronic detonators decreases the damaged area in remaining rock.