Two-time detonation method for sub-section of large-section tunnel

Abstract

The invention discloses a two-time detonation method for a sub-section of a large-section tunnel, and relates to the technical field of underground engineering blasting. The method comprises the following steps that a tunneling section is divided into an upper section and a lower section, and peripheral holes are formed along a section excavation contour; a plurality of hole vertical lines are arranged on the lower section in the vertical direction, a plurality of hole horizontal lines are arranged in the mode of being parallel to a bottom plate, and intersection points of the hole vertical lines and the hole horizontal lines are taken as hole base points; empty holes are formed in the hole base points of the lower section, the groove expanding holes are evenly formed around the empty holes, and middle division holes formed along middle division lines; a plurality of rows of auxiliary holes are formed in the upper section in the mode of being parallel to a tunnel bottom plate, and all blast holes in the lower section are detonated for the first time; and the charging holes of the lower section are detonated according to the distance from the charging holes to the empty holes from near to far, and then all the blast holes of the upper section are detonated for the second time. According to the method, the problems that the cutting part of the positive step method is high, and blasting flying rocks seriously damage equipment are solved; and under the condition that the number of sections of detonators is limited, full-section blasting of the large-section tunnel can be completed through two times of detonation.

Description

technical field [0001] The invention relates to the technical field of coal mining and blasting engineering, in particular to a method for twice detonating a subsection of a large-section tunnel, especially a method for detonating twice a subsection of a large-section tunnel based on the detonation of a coal mine permissible electric detonator. Background technique [0002] The allowable electric detonators in coal mines have only 5 delay periods, which are 0ms, 25ms, 50ms, 75ms and 100ms. Therefore, in large-section tunnels, multiple detonations are required to complete the blasting of a section, which greatly reduces the time required for excavation. Blasting construction efficiency. In order to improve the blasting efficiency, it is generally achieved by increasing the amount of charge at the cutting part to achieve a good blasting effect. After increasing the amount of charge, the flying stones generated by the blasting method can be thrown to an area 20-30m away from th...

AI Technical Summary

Problems solved by technology

This problem is especially serious when the number of available detonator segments is insufficient, especially when there are only 5 detonator segments for coal mine blasting

In addition, due to the large amount of primary explosives in the blasting of large-section tunnels, the amount of primary explosives in a single section is large, and the charge is concentrated, making it difficult to control the blasting vibration

[0005] The existing technology has the advantages of large cycle footage and convenient blasting vibration control, but it also has the following disadvantages: (1) Because the cavity needs to be blasted and expanded layer by layer from the hollow hole with a small diameter, compared with the oblique cut, More detonator segments need to be detonated

(2) For coal mine blasting, there are only 5 detonator sections available, and the blasting efficiency is lower

(3) The distance between the hollow hole and the expansion hole should not be controlled. If the distance is too large, it will not be blasted, resulting in the failure of the cut; if the distance is too small, explosives will be wasted and flying stones will easily appear, which will damage the equipment near the excavation face.

(4) When multiple hollow holes are used to create a free surface, the blasting will expand outward layer by layer with multiple hollow holes as the center, and it is very easy to produce rock pillars that have not been blasted at the junction of adjacent hollow holes, seriously affecting the blasting effect, and even cause blasting failure

(5) For large-section tunnels, there are problems in the prior art that single-stage detonation has a large amount of explosive charge, concentrated charge, and difficult control of blasting vibration

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