坑道出口现场爆破模型试验

针对某坑道出口爆破工程，研究决定采用“预裂爆破成型，平面药包分层剥离、定向抛掷”的爆破方案来解决坑道出口的可控爆破破碎和抛掷问题，采用“预留缷碴坑，抵抗层双向抛松，一次成型”的爆破方案来解决坑道出口两侧临空岩壁单向抛掷问题。为验证方案的可行性与时效性，根据工程环境地质条件及坑道几何参数，由爆破相似律确定试验爆破模型主要设计参数与试验爆破参数，进行现场爆破模型试验。试验结果得知爆后坑道出口全部贯通，洞口成型较好，岩石抛掷距离达到了设计要求。表明该爆破方案试验设计合理可行，爆破设计参数选择正确，得出了该爆破方案能实现坑道出口爆破的快速疏通，试验为坑道出口爆破提供了设计参数和理论依据。

Model test of site blasting at tunnel exit

For the blasting project at tunnel exit，and dealing with the controllable fragmentation by blasting and throwing，this study will apply the blast plan of “shape by presplit blasting，layered splitting by flat charge and throwing in fixed direction”.Through “reserving unloading dump，losing the resistance layerbi-directionally，and shaping in one blasting”，this study can address the throwing of exposed rock on either side of the tunnel exit.In order to verify the feasibility and effectiveness of the plan，according to the engineering geological conditions and tunnel geometric parameters，site blasting is carried out based on the fact that the main design parameter of the blasting test model and blasting test parameters are determined by blasting similarity law.Test results show that tunnel exit is dredged well，the cave’s entrance has a good shape，and rock throwing distance meets design requirements.Thus this blasting project can be considered reasonable and its blasting design parameters are adequate.This blasting project also provides design parameters and a theoretical basis for prototype blasting at the tunnel exit，given that it can dredge the exit quickly after blasting.