Study on Partition Optimization Design of Large Section Tunnel Excavation Blasting
The engineering geology,hydrogeology and other conditions of a tunnel are complicated.The original blasting design and construction scheme(conventional"two-step"step method)is often used,and the tunnel section is often over-ex-cavated and roof falling,which seriously restricts the construction of the tunnel project and cannot meet the construction objec-tives of the tunnel project.It is necessary to optimize and adjust the parameters of the original design scheme.According to the tunnel section specifications,engineering lithology and other conditions,in order to control the exposed area of the tunnel roof,prevent the roof from falling and reduce the support cost,the operation methods such as"CRD method","three-step bench"and"two-step bench"were selected to carry out the experimental study on the excavation of the tunnel blasting zone,and the spacing of the surrounding holes of the tunnel roof was strictly controlled(400～450 mm).In order to reduce the use of digital electronic detonators in tunnel blasting,the surrounding holes at the top of the tunnel are tied with 32 mm emulsified explosive(tape winding)by detonating cord,and the detonation is transmitted between each blast hole through the detonating cord,re-placing the traditional smooth blasting parameters.The field construction results show that the grad V surrounding rock tunnel is constructed by"CRD method",and the amount of over-excavation and under-excavation at the top meets the technical speci-fications;the grade Ⅳ surrounding rock tunnel is constructed by"three steps",and the residual rate of blast hole is 60％～72％.The grade Ⅲ surrounding rock tunnel is constructed by"two steps",and the residual rate of blast hole is 84％～94％.By optimizing the layout of traditional smooth blasting parameters and using the detonating cord to realize the detonation between the holes around the top and the initiation in the hole,the use of digital electronic detonators can be reduced in general,and the blasting cost can be reduced by about 18.5％.This technology can provide reference for similar tunnel engineering and under-ground mine roadway excavation blasting.
CRD methodbench construction methodsmooth-faced blastingdetonating corddigital electronic detonator
万方数据
维普
