Small cross-section tunnel long and short straight eye combined slotting blasting method

By employing a combination of long and short straight-hole excavation methods and setting electronic detonator delays in small-section tunnels, the problem of insufficient blasting advance in small-section tunnels was solved, resulting in higher blasting advance and borehole utilization, and improved construction efficiency.

CN118258277BActive Publication Date: 2026-07-21CHINA RAILWAY NO 3 GRP CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
CHINA RAILWAY NO 3 GRP CO LTD
Filing Date
2024-04-12
Publication Date
2026-07-21

AI Technical Summary

Technical Problem

When blasting small-section tunnels, insufficient blasting advance results in long residual holes, affecting construction efficiency and reducing the utilization rate of blast holes, which is difficult to meet the needs of modern infrastructure construction.

Method used

The method of combining long and short straight holes is adopted. By arranging straight holes and enlarged holes in the tunnel and combining them with the delay setting of electronic detonators, the effective blasting sequence and charge of each blast hole are ensured, forming a continuous blasting funnel and improving the utilization rate of the blast holes.

Benefits of technology

It significantly increased the blasting advance from 1.8-2.0m to over 2.5m, reduced the problem of residual holes, and improved construction efficiency and hole utilization.

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Abstract

The application discloses a kind of small section tunnel long short straight eye combination cut blasting method, by cut hole one deep one shallow cooperation, the part of upper portion of deep hole without charge when shallow hole blasting provides free surface and fragmental expansion space for shallow hole;Shallow hole length is close to optimum depth, and rock is in broken impact state when blasting: the rock near free surface will be damaged, and the volume of blast crater formed in rock is maximum.Shallow hole blasting provides new free surface and compensation space for deep hole blasting, and the new free surface generated can reduce the anti-blast capacity of rock and minimum resistance line.In this way, the problem that deep hole straight cut blasting after residual hole is too long and the rock at the bottom of deep hole is not thrown out is avoided, and the blasting footage is increased from 1.8‑‑2.0m to more than 2.5m.
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