HOME

Science and Technology of Energetic Materials

Vol.62, No.3 (2001)

Research paper

Effects of rock pressure on crack generation during tunnel blasting
Woo-Jin Jung, Manabu Utagawa, Yuji Ogata, Masahiro Seto,
Kunihisa Katsuyama, Atsumi Miyake, and Terushige Ogawa
p.138-146

Abstract

We performed a stress analysis in the area around a smooth blasting borehole on the expected fracture line of a tunnel in order to clarify the effect of rock pressure on crack generation during tunnel blasting. We also carried out test blasts on PMMA plates, marble plates and sandstone blocks those were assumed the borehole on the expected fracture line in the tunnel was under initial rock pressure. In addition, we made a numerical simulation of a blast and compared with the results of the test blasts.
Our results showed that tensile stress was generated around the borehole by the effect of initial rock pressure. Moreover, around the borehole in the side wall and in the shoulder part of the tunnel, i.e. the intermediate point between the roof and the side wall, tensile stress was always generated vertically with respect to the expected fracture line. However, around the borehole in the roof of the tunnel, the position where the tensile stress was generated varied depending on the state of the rock pressure. Moreover, the results of the test blasts using plates and blocks clearly indicated that cracks were generated and spread in the same direction as the applied pressure, and that blasting in the area around the borehole in the initial stress state had the effect of creating and lengthening cracks. The results of blast simulation showed a good agreement with the experimental results.

> Full text (Open access*)

© Copyright 1999-2017 Japan Explosives Society. All right reserved.