隧道钻爆法水封装药结构爆破引起振动计算分析

装药结构是影响爆破振动效应的一个主要因素,针对隧道钻爆法施工中常见的水封爆破装药结构以Heelan短柱状药包激发引起远场质点运动理论解为基础,将该种装药结构分为炸药段和水介质段,并假定爆源远场质点最大振速主要由两段孔壁压力叠加作用引起,求得远场位置处振动速度解析解,并通过现场实测数据进行了验证,同时针对爆破振动影响因素进行了分析。研究结果表明:理论计算值与实测数据存在一定误差,但能满足工程要求,可用于指导施工;水介质段对围岩的作用主要由水介质段的长度和对孔壁的径向压力决定,水介质段长度与炸药段长度的比例直接影响水介质段作用产生的爆破振动数值及在爆破振动总效应中的比例;由于水介质段本身作用强度较小,在远场作用不明显,适于预测和评价爆破近场爆破振动速度。

Calculation and analysis for water-sealed charge structure blasting vibration in tunnel drilling and blasting construction

Charge structure is one of main factors affecting blasting vibration effect. Aiming at a common water-sealed charge structure in tunnel drilling and blasting construction, theoretical solution to far-field mass point motion excited by Heelan short column charge was taken as the foundation, this charge structure was divided into explosive section and water medium one, it was assumed that blast source far-field mass point’s maximum vibration velocity is caused by superposition of hole wall pressures of the two sections, then the analytical solution to vibration velocity at far-field position was solved and verified with the actual field measured data. Meanwhile, factors affecting blast vibration were analyzed. The results showed that there is a certain error between theoretical calculation values and the actual measured data, but the former can meet engineering requirements, and be used to guide the construction; the action of water medium section on surrounding rock mainly depends on length of this section and radial pressure on hole wall; the ratio of water medium section length to explosive section one directly affects blasting vibration value caused by water medium section action and its proportion in the total effect of blasting vibration; as the action intensity of water medium section is smaller, this action is not obvious in far-field, so it is suitable to predict and evaluate blasting vibration velocity in near-field.