城市地铁隧道基岩、大块孤石控制爆破技术

Controlled blasting technology of bedrock and large solitary stone in urban subway tunnel

为解决城市地铁隧道施工过程中遇到坚硬基岩、大块孤石致使盾构无法正常掘进的难题,结合福州地铁4、5号线隧道基岩、大块孤石爆破处理成功的实例,对地下基岩、大块孤石控制爆破技术展开研究。在参数设计上,采取直径为90 mm的炮孔,装药直径为50 mm,不耦合系数为1.8,单耗为3.23 kg/m^(3),孔距为0.7~0.8 m,排距为0.7 m时,花岗岩(普氏硬度系数为12~16)爆破效果良好;在施工过程中,钻孔要严格按设计要求控制炮孔位置、深度误差,并用带保护帽的PVC管护孔;装药根据隧道断面,精准确定孔内装药的药量、装药结构,可解决地下孤石爆破难点;在安全防护上,根据最大单段药量控制孔网参数,采用合理分段、不耦合装药结构等减振措施,可有效降低爆破振动对周边建(构)筑物影响,供类似工程参考借鉴。

In order to solve the problem that the shield cannot be normally excavated due to the hard bedrock and large solitary stone in the construction of urban subway tunnels,combined with the successful example of bedrock and large boulder blasting in Fuzhou Metro Lines 4 and 5,the control blasting technology of bedrock and large solitary stone underground is studied.In terms of parameter design,when the blast hole diameter is 90 mm,the charge diameter is 50 mm,the uncoupling coefficient is 1.8,the unit consumption is 3.23 kg/m^(3),the hole spacing is 0.7-0.8 m,and the row spacing is 0.7 m,the blasting effect on granite(the Protodyakonov hardness coefficient is 12-16)is good.During the construction,the position and depth error of borehole should be strictly controlled according to the design requirements,and the PVC pipe with protective cap should be used to protect the borehole.According to the tunnel section,the charge quantity and charge structure in the hole can be accurately determined,which can solve the underground boulder blasting difficulty.In terms of safety protection,the hole net parameters are controlled according to the maximum single-stage charge,and the vibration reduction measures are adopted such as reasonable segmentation,non-coupling charge structure are so on.They can effectively reduce the influence of blasting vibration on surrounding buildings(structures),and can be referred for similar projects.