关键词: 松动圈, 声波测试, 松弛深度, 爆破参数, 爆破开挖

Abstract:

In the underground cavern's excavation, blasting will bring about unloading on the surrounding rock and form a loose circle in annular distribution along the excavation border. Based on sonic wave testing, the loose circle of a typical cross section in an underground powerhouse was tested. By counting and observing the quantitative changes and distribution law of the acoustic velocity of rock mass, we discussed the advantages and disadvantages of sound wave test in single-hole and cross-hole respectively. It demonstrates that the wave test in cross-hole test could better reflect the rock wave velocity than that in single-hole test, as the influence of micro fissures of rock is smaller. Also we analyzed the impact of blasting excavation on relaxation depth of rock mass in the test areas, and successfully controlled the relaxation depth less than 0.6m by optimizing the blasting parameters, thus providing basis for stability analysis of rock mass, optimization of blasting parameter and safety strengthening in rock excavation construction.

Key words: loose circle, sound wave testing, relaxation depth, blasting parameter, blasting excavation