Advance Grouting Test Using Seismic Prospecting Method in TBM Tunneling: A Case Study in the Water Supply Project from Songhua River, Jilin, China

Advance grouting is an important approach to reinforce the rock mass ahead of the tunnel face in TBM tunneling. To estimate the grouting result in TBM tunneling, a test method based on seismic ahead prospecting method was proposed. To check the grouting result, the seismic ahead prospecting was applied firstly to obtain the distribution and location of adverse geologies for grouting; Then, the geological conditions was estimated again after grouting; By studying the characteristics of reflections and velocity distributions, the grouting result could be checked. Numerical simulations prove the availability: Wave field snapshots indicate the energy of reflected waves reduces after grouting; Migration results indicate that the reflections reduce or disappear after advance grouting, as well as the estimated velocity increases. Moreover, the method was successfully applied in the diversion tunnel of the water supply project from Songhua River, which reveals the grouting result well and provides important geological guidance for construction.