Study on Database Establishment and Parameter Optimization of Rock Tunnel Cutting Blasting
Blasting parameters of trenching are the key parameters of the construction of rock tunnel drilling and blasting method,and optimization of blasting parameters is one of the important ways to ensure the efficient construction of drilling and blasting method.Based on 200 representative blasting cases,this paper analyzes the change characteristics of blasting parame-ters in two dimensions of rock tunnel characteristic parameters,namely Pratt's coefficient and cross-sectional area,by using sta-tistical methods to study the objective law of rock tunnel trenching by constructing a database of blasting cases.The results show that:with the increase of Pratt's coefficient,the ultimate compressive strength of the rock is greater,and the length of the blast hole and the unit consumption of explosives will be increased appropriately to ensure the blasting effect,and the single cy-cle feed will also be slightly increased,but the high stress of the rock itself causes the clamping process to reduce the utilization rate of the blast hole.Usually the empty hole is set to provide a new free surface for the trenching blasting,and the reflected stretching of the stress wave makes the rock body near the free surface.The damage area is larger,and hard rock passages are more suitable for straight-hole trenching.In the process of trenching and blasting in larger section rock tunnel,the rock itself is less entrapped,and good blasting effect can be achieved with less explosive consumption,thus promoting the improvement of single-cycle feed and utilization rate of shell holes.Because the limiting effect of large section area on rock blasting is reduced,it is not necessary to increase the number of shell holes and charge excessively,instead,the growth rate of the number of shell holes can be slowed down appropriately to achieve good blasting effect.The effect of blasting can be achieved by slowing down the growth rate of the number of holes.This study provides theoretical guidance for optimizing blasting parameters and efficient construction of rock tunnel.
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