探讨优化工程岩体分级标准BQ方法,使其更好地应用于岩爆隧道中。(1)综合RSR法、RMR法和HC法对结构面产状、洞轴线方向和掘进方向对围岩稳定性影响的考虑,对主要软弱结构面产状影响修正系数(K2)进行了优化。当结构面走向与洞轴线垂直并且结构面陡倾,倾向与掘进方向同向时,围岩稳定性最好,K2取小值;当结构面走向与洞轴线平行时,围岩稳定性最差,K2取大值。(2)结合岩爆烈度分级体系,针对硬岩高地应力隧道,对初始应力状态影响修正系数(K3)进行了优化。轻微岩爆对围岩基本质量指标BQ值较高的围岩影响较小,K3取小值;岩爆级别越高,对围岩的稳定越不利,K3取大值。对四川泥巴山隧道的部分掌子面围岩应用优化后的BQ方法重新计算[BQ]值并确定级别,分级结果与实际情况更吻合,能更好地用于确定围岩支护措施。
This paper discusses the BQ method that optimize the standard for engineering classification of rock masses so that it can be applied in the rockburst tunnel more effectively. The orientation of the rock mass structural plane, the direction of the tunnel axis and the tunneling direction have influences on the rock mass stability, which RSR, RMR and HC methods are considered. Integrating these considerations, the correction coefficient (K2) influencing the main weak structural plane orientation is been optimized. When the strike of the structural plane is perpendicular to the tunnel axis and the structural plane is inclined to the same direction with the tunneling, the stability of the surrounding rock mass is good, so K2 gets a large value. When the strike of the structural plane parallel to the tunnel axis, the stability of the surrounding rock mass is poor, so K2 gets a small value. Combined with the intensity of rock burst, the correction coefficient (K3) influencing the initial stress state is optimized based on the high initial stress of hard rock mass. A slight rock burst has little effect on thesurrounding rock with a high value of the rock mass basic quality index (BQ), so Ks gets a small value. The higher class of the rock burst, the poorer stability of the surrounding rock mass, so Ka gets a large value. The paper uses the optimized BQ method to recalculate the ~_BQ~ value of some surrounding rock of the working face in the Niba mountain tunnel. It is found that the classification results are more coincide with the actual conditions. So the supporting methods of the surrounding rock can be more accurately selected by this optimized method.