Study on the Characteristics of Vibration Induced by Tunnel Excavation under Middle to High In-situ Stress

摘要

The characteristics of vibration induced by the excavation of tunnel under middle to high in-situ stress is studied in the paper with combined method of theoretical analysis, numerical simulation by Dynamic FEM and verification with monitored field vibration data. It is found that the vibration induced by the excavation of tunnel under high in-silu stress is the result of superposition of blasting-induced vibration (BIV) and the transient unloading of in-situ stress induced vibration (DUIV).The study reveals that, under low in-situ stress condition, the vibration in surrounding rock mass is mostly induced by blasting load. Under high in-situ stress condition, for example higher than 20 MPa, the DUIV becomes absolutely the main factor of total seismic wave induced by the excavation of tunnel with method of drilling and blasting.In the end part of the paper, monitored vibrations induced by the excavation of tail-water and inlet water tunnel in Pubugou Hy-dropower Station, Shichuan Province, P. R. China are presented as a verification, which are corresponded to in-situ stresses of 10 MPa and 20MPa respectively.