不同开挖方式下深埋大理岩岩爆发生范围预测

Range prediction on the rock burst of deep-buried marble under different excavation methods

针对锦屏二级深埋大理岩在钻爆法和TBM开挖下围岩中能量变化进行了数值模拟,讨论了岩爆潜在发生范围与围岩力学特性的联系,并研究了岩体脆性、岩体强度特征对岩爆发生范围的影响。同时,结合锦屏二级引水隧洞岩爆实测数据加以验证。研究发现:TBM开挖对围岩的扰动较小,开挖面附近用于诱发岩爆的储能较高,但由于脆性特征的岩层厚度较薄,岩爆发生等级一般较小,岩爆爆坑度深度在0～1.0 m,且小于0.5 m的低等级岩爆居多;钻爆法开挖下,围岩中应变能瞬态释放,降低了岩爆潜在发生的能量源,而脆性特征的岩层厚度却较大,岩爆爆坑一般为2.0 m,高等级岩爆较多。

According to the energy change of deep-buried marble in Jin-ping Ⅱ Hydropower Station under drilling blasting method and TBM excavation, a numerical model was proposed to discuss the relationship between the potential occurring range of rock burst and the mechanical characteristics of surrounding rock. The effects of the brittleness and strength of rock mass were studied. Besides, the results of numerical simulation were analysed and verified through the rock burst monitoring data of the diversion tunnel in Jin-ping Ⅱ Hydropower Station. The research shows that the disturbance of surrounding rock is small during TBM excavation and the stored energy near the excavation face is higher. As the thickness of the brittle rock is small, the rock burst grade may be rather lower. The burst depth is generally in the range of 0-1.0 m,and mostly less than 0.5 m. For blasting excavation, the strain energy of surrounding rock releases in a transient state, which reduces the energy source of rock burst, but owing that the thickness of the brittle rock is small, the burst depth is generally 2.0 m, and high-level rock bursts may more happen.