Method for determining safe distance of secondary lining construction of first hole in small-spacing tunnel blasting excavation

By using on-site vibration monitoring and Sadovsky's formula calculations, the safe distance for the secondary lining of the pilot tunnel during blasting excavation of tunnels with small clearance was determined. This solved the problem of the impact of blasting vibration of the subsequent tunnel on the secondary lining of the pilot tunnel, ensuring the safety and service life of the tunnel structure.

CN117703516BActive Publication Date: 2026-06-12CHINA ENENG GRP THIRD ENG BUREAU CO LTD
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Patent Information

Application Number
CN202311737491.3
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2023-12-18
Publication Date
2026-06-12
Estimated Expiration
2043-12-18

AI Technical Summary

Technical Problem

During the blasting excavation of tunnels with small clearance, the impact of blasting vibrations from the subsequent tunnel on the secondary lining of the preceding tunnel has not been fully considered, which may lead to cracking and spalling of the secondary lining, affecting its service life and safety.

Method used

By conducting orthogonal tests to monitor vibration velocity on-site, the safe allowable distance was determined. The conservative safe allowable distance was then calculated using the Sadovsky formula to ensure the safe distance for the secondary lining of the tunnel and reduce the vibration impact caused by blasting excavation of the subsequent tunnel.

Benefits of technology

The safe distance for the construction of the secondary lining of the pilot tunnel was precisely determined, which reduced the vibration impact of the subsequent blasting excavation on the secondary lining of the pilot tunnel, ensuring structural safety and service life.

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Abstract

This invention discloses a method for determining the safe distance for secondary lining construction of the pilot tunnel in small-clearance tunnel blasting excavation, which involves judging the stability of the surrounding rock deformation and deformation rate, and determining the safe allowable distance R. i Given the range of values, design an orthogonal test scheme for on-site vibration velocity monitoring, and calculate the safe distance R for each scheme. i First, based on the safe allowable distance Ri, monitoring points for blasting vibration velocity are set up, and on-site vibration monitoring is conducted. A unique K value and α value are obtained by fitting parameters such as the measured vibration velocity and explosive charge, and the calculated safe allowable distance R is then calculated. j Determine the conservative safety allowable distance R b Does it meet the requirements? If it does, then it is the final safe allowable distance R. z This scheme can determine the safe distance between the blasting source of the subsequent tunnel and the secondary lining of the preceding tunnel, thereby reducing the impact of vibrations generated by the blasting excavation of the subsequent tunnel on the secondary lining of the preceding tunnel.
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