地铁隧道钻爆法施工中敏感区间及安全药量确定

Determination Method of Sensitive Interval and Safety Dose for the Construction of Subway Tunnel Drilling and Blasting

为了加强隧道钻爆开挖过程中对周边建筑结构的保护,基于统计学的原理,建立了t分布药量优化式,同时,建立了敏感区间计算模型.基于贵阳地铁2号线钻爆开挖工程实践,以比例药量为变量,研究了t分布优化药量随比例药量的变化规律,并且对爆源向前移动过程中的药量控制进行了研究.结果表明:传统的安全药量预测式的置信概率只有50%,基于t分布药量优化式的置信概率可以达到99%.t分布药量优化式可以增加对周边建筑结构的保护程度.当比例药量0<λ≤0.053时,临界药量的渐近线趋近于0,无法指导爆破施工.当比例药量λ>0.053时,垂直向振动速度最大,可用优化药量指导爆破施工.在隧道开挖方向线上,安全控制药量是一个逐渐减小-达到最小值-加快增大的过程,当爆源开挖至敏感区间范围时,要及时调整爆破施工方案,加强对周边建筑的保护.

In order to strengthen the protection of the surrounding building during the tunnel drilling and excavation process,a t-distribution charge optimization formula and a sensitive interval calculation model were established based on the principle of statistics in this paper.Meanwhile,based on the practice of drilling and blasting excavation in Guiyang Metro Line 2,taking the proportional charge as a variable,the variation tendency of the optimized charge in the t-distribution with the proportional dose and the charge control of the explosion source in the forward movement process were studied.The study results present following conclusions.Firstly,the confidence probability with the traditional safety charge prediction formula is only 50%,the confidence probability based on the t-distribution formula can reach 99%.It is known that the t-distribution charge optimization formula can increase the protection degree to the surrounding building.Secondly,when the proportional charge is between 0 and 0.053,the asymptote of the critical charge approaches 0,therefore,this proportional dose interval cannot be used to guide the blasting construction.When the proportional charge is more than 0.053,the vertical vibration velocity is the largest,so the optimization charge formula can be used to guide the blasting construction.Finally,in the tunnel excavation direction line,the safety control charge is a process of gradually decreasing-reaching the minimum-rapidly increasing.When the working face is in the sensitive area,it is necessary to adjust the blasting design project in time to strengthen the protection to the surrounding buildings.