Study On The Effect Of Grouting On Seepage Field In Water-rich Fractured Rock Mass Of Tunnel

In this paper, the numerical analysis method is adopted, analysis of seepage field of cross fractured rock mass in high pressure and rich water area, and analyzes the influence of grouting circle parameters of seepage field characteristics. According to the characteristics of tunnel construction, the model is built with the three-dimensional discrete element software 3DEC, then analysis and calculation.The existence of 3 vertical direction in the model(10 m pitch) perpendicular to the tunnel axis and 10(spacing 10 m) parallel to the tunnel axis cross fracture, through the analysis of the initial state, without grouting excavation, grouting after excavation, for shotcrete, secondary lining and drainage system of the five main construction process of the model, the numerical simulation and the distribution of seepage field of water pressure behind each step after the construction of the tunnel is obtained, and then select 4 slit in-depth analysis(perpendicular to the tunnel axis fracture, tunnel excavation face fracture, fracture of the grouting circle, grouting circle joints), Through the analysis of the changing characteristics, we obtained the influence of each construction step of a construction process in high pressure and rich water cross fractured rock in tunnel construction.By using the high pressure water rich cross fractured rock mass tunnel model, the influence of the thickness of the grouting circle and its equivalent permeability coefficient(filling ratio) on the characteristics of the seepage field is analyzed, and give a reasonable range of values(grouting circle thickness 2~8m; grouting circle equivalent permeability coefficient 2×10-8~1×10-7 m/s). The analysis shows that with the increase of the thickness of the grouting circle, the water pressure is gradually decreased and the amount of water in the tunnel decreases gradually, grouting circle thickness in the range of 0~10 m, the water pressure behind the shotcrete and tunnel seepage water has a significant impact; Grouting circle equivalent permeability coefficient decreases, sprayed concrete behind the water pressure is small, the equivalent permeability coefficient of grouting circle in 0~1×10-7 m/s range, the shotcrete behind the water pressure and tunnel water seepage effect.Selecting appropriate parameters of grouting circle, numerical simulation was carried out on two different conditions(vertical cross fractured rock mass tunnel and vertical horizontal direction cross fractured rock mass tunnel), The influence of water pressure on the lining of the tunnel under two conditions and the change of water pressure in the crack are obtained.