Blasting Method for Dome of Large Section of Tunnel

Abstract

The invention discloses a blasting method for forming a dome through a tunnel large section. The method comprises the following steps that firstly, an excavating face of a tunnel is measured, a blasting central point is determined, and a blasting central hole is drilled in the blasting central point; secondly, positions and distribution manners of a cuthole set, a first auxiliary hole set, a second auxiliary hole set and a peripheral hole set are determined sequentially; thirdly, an air drill is used at the determined positions of all cutholes, first auxiliary holes, second auxiliary holes and peripheral holes for drilling, the cutholes, the first auxiliary holes, the second auxiliary holes and the peripheral holes are formed, and the bottoms of the cutholes, the first auxiliary holes, the second auxiliary holes and the peripheral holes are provided with blasting caps and filled with explosives, and segmental-jumping blasting is carried out; and fourthly, the first step, the second step and the third step are repeatedly executed, and the next cycle is carried out. The excavating face capable of forming a dome structure through blasting has the beneficial effects of being high in safety and reliability and high in practicability, the problems of roof carving and block falling are solved, and the safety coefficient of tunnel excavation is greatly improved.

Description

technical field [0001] The invention relates to a tunnel excavation method, in particular to a blasting method for forming a dome with a large section of the tunnel. Background technique [0002] The current excavation method for large and extra-large sections is smooth blasting by jumping sections, mainly using oblique eye cutting, the fundus of the auxiliary eye all falls on the same section, and the length of the cutting eye is slightly longer than that of the auxiliary eye. The length of the peripheral eye is the same as that of the auxiliary eye. After smooth blasting, the face of the tunnel is almost on the same plane. The main problem is that such a cross-section is prone to roof fall and block falling, and the degree of freedom is less when excavating, and the applicable surrounding rock grades are less, and it is more dangerous and consumes more explosives. [0003] Tunnel deformation is mainly due to the deformation and elongation of the surrounding rock on the t...

AI Technical Summary

Problems solved by technology

[0009] The technical problem to be solved by the present invention is: after the blasting of the surrounding rock in the existing blasting excavation, the flat surrounding rock that is blasted out has no temporary stable support, resulting in excessive deformation of the surrounding rock and the stability of the surrounding rock. Problems with poor performance, such as roof fall, block drop, etc.

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