COMPREHENSIVE ADVANCED GEOLOGICAL PREDICTION METHODS FOR TUNNEL CONSTRUCTION WITH DOUBLE SHEILD TBM

Some geological prediction methods e.g. geological sketch, explosive seismic method and electromagnetic method cannot be used in tunnel construction by double shield TBM, because of the impact of shield, segment and electromagnetic interference. According to the characteristics of double shield TBM, we put forward comprehensive advanced geological prediction methods including geological analysis, geophysical prospecting and advance drilling, based on CCS Hydropower Station Diversion Tunnel. The guide lines of comprehensive advanced geological prediction are from rough to fine and combine points and areas. The geological analysis includes geological analysis along the tunnel, observation of rock mucks and tunneling parameters. It does not occupy the tunneling time and its cost is low. So it can be used along whole tunnel. ISIS seismic method and BEAM electric method are used as geophysical prospecting. Geophysical prospecting and advanced drilling method need some tunneling time and their cost is higher. The advanced prediction methods should be determined after considering accuracy, cost and time occupation integratedly. The corresponding measurements to deal with the adverse geological conditions are given based on the results of comprehensive advanced geological predictions. The research results show that comprehensive advanced geological methods can meet the characteristics of double shield TBM, and identify the adverse geological conditions effectively. Additionally, it can supply basic references for treatments, and then reduce and even avoid the influence of the adverse geological conditions.