基于声波的洞室围岩岩体质量分区优化方法

开挖会对围岩岩体产生扰动,影响围岩的质量,常用钻孔声波法来观测确定开挖对岩体质量的扰动影响。常规方法确定岩体质量分区时,波速变化率曲线和阀值直线往往有多个交点,很难判定质量分区边界,利用波速变化率曲线的细部特征对常规方法进行了优化,重新定义岩体质量分区的判定准则,使岩体质量分区具有唯一性。将优化方法应用到白鹤滩水电站4^#导流洞工程中,4^#导流洞开挖后的岩体质量可以分为3个区,即扰动一区、扰动二区及未扰动区,随着距开挖面深度的增加,围岩受到开挖的扰动影响逐渐减小,围岩质量逐渐变好,后续开挖步会使岩体的质量变差,扰动区范围进一步增加。

Method of Optimizing Surrounding Rock Quality Partition Based on Acoustic Wave Technology

Drilling and acoustic wave observation is often used to determine the disturbance of excavation on rock quality. However, it is difficult to determine the boundary of rock quality partition by using conventional methods because there are more than one intersection between the curve of acoustic velocity changing rate and the threshold line. In this research, we optimize the conventional method by considering the detail features of acoustic velocity changing rate curve, and redefine the criteria of rock quality partition, which is made unique. Furthermore we apply the optimized method to the 4^# diversion tunnel project of Baihetan hydropower station, and divide the rock quality of 4^# diversion tunnel into 3 zones: the first disturbed zone, the second disturbed zone, and non-disturbed zone. Along with the increase of the depth from the excavation face, the disturbance of excavation on surrounding rock gets weaker and the rock quality becomes better. Subsequent excavation steps could worsen the rock quality, and the disturbed area will increase.