Study On Water Inrush Mechanism And Construction Safety Control Technology For Tunnels Adjacent To High Water Pressure Cavity

With the deepening of the western development strategy in China,there are more and more karst water rich layers passing through the tunnel,among which the high water pressure solution cavity has the most significant influence on the tunnel.Under the continuous influence of high water pressure in the cavity,it is very easy to encounter sudden water gushing during tunnel construction,which seriously threatens the safety of tunnel structure.In view of this situation,this paper,relying on the Huaying Mountain tunnel project,adopts the means of theoretical derivation,orthogonal test,numerical simulation and field monitoring,and related research on the mechanism of water inrush in tunnel near high water pressure solution cavity and the construction safety control technology.The main research contents and results are as follows:1、The mechanical mechanism of water gushing in tunnel under the action of high water pressure solution cavity is analyzed from two aspects of microcosmic and macroscopic,and the triggering factors of water inrush in high water pressure dissolving cavity are studied.2、Based on the theory of water gushing in tunnel,the criterion of the critical safety distance between the high water pressure solution cavity and the tunnel is put forward by the failure of the rock stratum and the passage of the water gushing channel.3、Based on the strength theory,shear failure theory and compression shear crack propagation theory,three simplified mechanical models are established,and the analytic formula of the safety distance between the high water pressure solution cavity and the tunnel is derived respectively.4、Based on the orthogonal experimental design method,the influence degree and influence law of the surrounding rock grade,the pressure coefficient of the surrounding rock side,the diameter of the cavity,the water pressure inside the cavity and the depth of the tunnel depth on the safety distance are studied,and the safety distance between the high water pressure dissolving cavity and the tunnel is established based on the multiple linear regression method.The prediction model is used to guide the construction of Huaying Mountain tunnel.5、On the basis of practical engineering,the optimal control scheme and construction measures for the water gushing area of high water pressure dissolving cavity are put forward.Combining with the field monitoring data,the mechanical characteristics of tunnel construction in high water pressure dissolving cavity area are studied,the mechanism of water gushing treatment is revealed,and the rationality of the treatment scheme is verified,which provides the theoretical basis and practical guidance for the construction of similar tunnel engineering.