一次爆破成型技术在大断面洞室开挖中的应用

Application of One-time Blasting Technology in Excavation of Large Section Cavern

目前,部分大断面洞室开挖工程进度较慢,安全性较差,造成施工成本高、效益低等问题。因此,笔者提出了一种基于一次性爆破成型技术的大断面洞室开挖技术。本文以陕西省东庄水利枢纽工程导流洞I标段为工程案例,分析开挖爆破过程及成果,确定了预裂爆破的设计方案,包括爆破参数、爆破布孔图、爆破联网图及装药结构等。试验结果表明,设计的施工爆破方案有效地提升了大断面隧道的开挖质量,开挖爆破后,半孔率超过90%,两个循环之间的台阶小于5 cm,平整度控制在±10 cm之内,混凝土的浇筑用量大幅度降低,投资成本也因此减少。该技术应用于大断面洞室开挖,不仅提高了经济效益,而且可以实现在安全施工的前提下加快施工进度,为现场爆破施工提供技术依据。

At present,some large-section cavern excavation projects are progressing slowly and the safety is poor,causing problems such as high construction costs and low benefits.Therefore,the author proposed a large-section cavern excavation technology based on one-time blasting forming technology.This paper took the I bid section of the diversion tunnel of Dongzhuang Water Conservancy Project in Shaanxi Province as an engineering case,analyzed the excavation and blasting process and results,and determined the design plan of pre-split blasting,including blasting parameters,blasting hole layout diagram,blasting network diagram and charge structure,etc.The test results show that the designed construction blasting scheme has effectively improved the excavation quality of large-section tun⁃nels,after excavation and blasting,the half-hole rate exceeds 90%,the step between the two cycles is less than 5 cm,and the flatness is controlled within±10 cm,the amount of concrete pouring is greatly reduced,thus the investment cost is reduced.The application of this technology to large-section cavern excavation not only improves economic benefits,but also accelerates the construction progress under the premise of safe construction,providing a technical basis for on-site blasting construction.