Analysis of Water Inrush for Tunnel Boring Machine Passing through Fault

It may be encountered with the water and mud inrush when a TBM (tunnel boring machine) passes through the fault fracture zone. In this study, the Xianglushan tunnel of Central Yunnan Water Diversion Project was taken as an example, the variation characteristics of surrounding rock seepage field during TBM tunneling through the Qingcaitang fracture zone without advanced grouting support and different advanced support (grouting) schemes are compared. Meanwhile, prevention and control measures are given accordingly. The results show that: 1) When the TBM cutterhead begins to enter the fault fracture zone, the seepage channel firstly occurs between the fault fracture zone and the tunnel, and the maximum local water inflow of the tunnel occurs near the interface between the fault fracture zone and the intact rock zone. 2) When TBM completely enters the fault fracture zone, the low pore pressure area around the tunnel further expands, forming a pumping well effect, and the seepage flow of surrounding rock increases significantly when compared with the intact rock zone. 3) Without considering the advanced support, the total water inflow of TBM cutterhead area in the fault fracture zone reaches 562.85 m
³
/h, which is about 11 times of that in the intact rock zone. After considering different advanced support (grouting) schemes, the maximum water inflow of TBM cutterhead area is 324.27 m
³
/h and 262.11 m
³
/h, respectively reducing by 42.4% and 53.4% when compared with that in the intact rock zone.