深部地下实验室扩挖岩爆监测与动态防控技术研究

ROCKBURST MONITORING AND DYNAMIC PREVENTION OF ENLARGING EXCAVATION IN DEEP UNDERGROUND LABORATORY

中国锦屏地下实验室二期(CJPL-Ⅱ)扩挖工程建设潜在高等级岩爆风险。为此,建立了深部地下实验室相邻同向短洞室固定式和单侧相向扩挖移动式微震传感器阵列优化布置方法,构建了基于岩爆风险程度的岩爆预警频次优化原则,提出了针对性的CJPL-Ⅱ扩挖岩爆防控措施,实现了CJPL-Ⅱ扩挖过程岩爆实时监测、动态预警与防控,岩爆预警与实际情况吻合良好,保障了CJPL-Ⅱ扩挖顺利完成。分析了CJPL-Ⅱ扩挖各洞段开挖过程微破裂时空演化规律及其差,研究结果表明新增通道微震活动较扩挖段更为活跃,岩爆风险亦更高,扩挖微震活动活跃程度与空间集聚特征受扩挖断面尺寸,扩挖深度以及结构面影响。研究成果可为类似深埋工程安全建设提供借鉴。

There was intensive rockburst risk during the excavation of China Jinping Underground Laboratory(CJPL-Ⅱ)expansion project.Therefore,we established an optimization layout method of fixed microsesmic(MS)sensor array for adjacent short tunnels with same excavation direction,as well as dynamic MS sensor array for opposite expansion excavation at one-side.Meanwhile,we proposed an optimization principle of rockburst warning frequency based on the degree of rockburst risk.The rockburst control measures corresponding to CJPL-II enlarging excavation is given too.The real-time monitoring,dynamic warning and prevention on rockbursts during CJPL-II anisotropic excavation is realized based on these proposed methods.The rockburst warning is in good agreement with the actual situation and the CJPL-II enlarging excavation project is successfully completed.We analyzed the difference of temporal and spatial evolution laws of MS activity between each CJPL-II enlarging excavation segments.The results show that the MS activity of the new tunnel is more active than that of the expansion excavation section,and the rockburst risk is also higher.The size of excavation section,depth of excavation and structural plane affect the degree and spatial characteristics of MS activity during enlarging excavation.This study can provide reference for the safety construction of similar deep projects.