采石场爆破振动对附近沙峁沟铁路隧道影响有限元研究

摘要

针对采石场临近既有沙峁沟铁路隧道,爆破点与隧道中线距离逐渐缩短,且装药量大的实际工程背景,采用静力学和动力学数值分析方法,对沙峁沟铁路隧道混凝土衬砌的质点振动速度及应力分布情况进行计算.结果表明:静力开挖及爆破采石对隧道衬砌结构均有影响,且爆破振动效应影响较大;爆破点与隧道中线距离逐渐缩短时,迎爆侧拱腰处为最危险区且产生水平方向的拉伸破坏,动拉应力及质点振速峰值逐渐增大,表现为非线性关系;以安全爆破开挖边界范围为基准,确定最大开挖边界范围应使2级开挖边坡坡脚与隧道中线的距离大于等于40 m;进行爆破开挖时,如考虑3倍的安全系数,当隧道衬砌振速小于4.96 cm/s时,衬砌内产生的动拉应力小于衬砌极限抗拉强度,可按此控制指标进行现场监测.%Based on practical engineering background, numerical analysis of statics and dynamics have been used to research the particle vibration and stress distribution at the existing adjacent tunnel concrete lining.The calculation result shows that both physical and blasting excavation have influence on tunnel lining structure, and the effect of blasting vibration is larger.When the distance between blasting point and the center line of the tunnel shortens gradually, the hance of facing the blasting side is the most dangerous zone and generates horizontal tensile failure.The dynamic tensile stress and the peak particle vibration velocities increase gradually, the relationship between them is nonlinear.Based on the safety blasting excavation boundaries, while the distance between the base of second slope and tunnel center line is larger than 40m, the inner force of tunnel lining will increase but the structure is still in safety.If we consider a triple safety factor, and while the vibration velocity is smaller than 4.96cm/s, the dynamic tension stress of the tunnel lining is smaller than its ultimate value, and therefore we can undertake field monitoring by the reference control vibration velocity.