Study on Water Diversion Characteristics of Tunnel Based on Hydrogeological Comprehensive Investigation

Deep-buried long tunnel is a key control project in highway construction. Identifying hydrogeological conditions and accurately predicting water inflow are important prerequisites for ensuring construction safety. This paper takes the Tiantoushan tunnel of the third phase project of Shenzhen outer ring expressway as an example, and uses the hydrogeological comprehensive survey method combining hydrogeological surveying and mapping, geophysical prospecting, drilling, hydrogeological test and indoor test to analyze and study the segmentation and classification of tunnel surrounding rock, the division of water-rich sections, and the prediction of water inflow. The tunnel passes through the synclinal axis section, which is a good water storage structure. Geophysical exploration also shows that the water-rich section is concentrated in K84 + 680 ~ K84 + 840. It is predicted that large water gushing will occur during construction. The tunnel section in this range is divided into Ⅴ-level surrounding rock, which is determined as the main water-conducting rock mass. At the same time, the tunnel is affected by the fracture structure, and the fault zone and wide tensile cracks in the water-rich section will become important water-conducting channels. Furthermore, after obtaining the permeability coefficient of the rock mass in the typical depth section of the tunnel site, the tunnel water inflow is predicted by using the precipitation infiltration coefficient method, the Dupuit theoretical formula and the Goodman empirical formula respectively, indicating that the hydrogeological comprehensive survey method can well evaluate the tunnel water conductivity characteristics and estimate the water inflow.