Study On The Advanced Geological Forecast Technology For Soft Rock Tunnel Construction

Tunnels are always in rock and soil with complex engineering geology and hydrological geology,"safe, high-quality, fast, and no future trouble" to build tunnel is the precondition of understanding and predicting the hydrogeological and engineering geological conditions in front of the surrounding rock, geological work and advance geological forecast in tunnel construction become the essential working procedure in tunnel construction. Because of its low strength in geotechnical engineering, soft rock tunnel construction process may be accompanied by soft rock large deformation, the occurrence of landslides, sudden mud gushing water and other geological disasters. In this case, a study on advance geological forecast in tunnel construction, detect geological conditions of the front surrounding rock is particularly necessary.The Dongsong hydropower station diversion tunnel engineering in this paper as engineering background, with the soft rock tunnel construction advanced geological forecast technology as the research object, combined with the nowadays at home and abroad research achievements on construction advance geological forecast, in contrast the current commonly used tunnel advance geological forecast method, and concluded on the basis of the geological method, by means of Group Penetrating Radar comprehensive advanced geological prediction method is suitable for this project, and based on the results of advance geological forecast, put forward in view of the soft rock large deformation and collapse geological hazards, such as, sudden mud water engineering measures, choosing the appropriate construction methods, in order to eliminate or reduce the construction process of geological hazard, safety, high quality and quickly complete the preliminary support, tunnel excavation supporting etc.On the basis of the geological method, by means of Group Penetrating Radar in the comprehensive advanced geological prediction technology in the engineering of forecast accuracy and precision meet the construction requirements, especially the fault fracture zone of the forecast results are accurate; by finite difference software FLAC3D simulation analysis shows that in addition to the inverted arch of the full face pregrouting can very good control of surrounding rock displacement and plastic zone development, fault fracture zone of easy cause landslide should be on the basis of the grouting construction, construction methods change method of excavation steps instead of full face excavation method, to control the deformation of surrounding rock, prevent landslide effect is obvious, sudden mud water period in the preliminary check of the whole section water grouting and drainage, on the basis of strengthening can avoid the increase of water inflow, while protecting the ecological environment of Tibetan area.