Research On Grouting Parameters And Water Inflow Forecast Of Urban Tunnels In Water-Enriched Region

The design philosophy that blockage is dominant and drainage is limited is put forward for the construction of urban tunnel in water-enriched region to control undergroundwater emissions and reduce external water pressure on the lining,so as to achieve the purposes that considerations are given to both the tunnel structure security and the environmental effects.Injection grout is considered as an important measure of tunnel water blocking,The selection of its parameters should consider the aspects of technology,environmental influence and economic rationality.The rationality of the grouting parameters can be verified by the water pressure distribution rule inside and outside the tunnel grouting circle,and its influence on surrounding rock-supporting system.The reduction of external water pressure on the lining depends on the tunnel drainage rate,that is the ratio of tunnel allowable water discharge and water inflow.Tunnel allowable water discharge can be comfirmed by specific engineering geology and environmental conditions and using function.Tunnel water inflow can be predicted by hydrogeological conditions,conditions of surrounding rock and grouting parameters.The researches are based on the eastern highway connection tunnel project in the downstream of Shenzhen reservoir.The rationality of the grouting parameters can be studied through the grouting test,numerical simulation and laboratory model test.According to the research results,selecting the suitable grouting parameters and establishing a large-scale three-dimensional seepage field model of Shenzhen reservoir downstream urban tunnels to forecast the tunnel water inflow of each section before and after grouting,forming a perfect tunnel water inflow prediction system in grouting state.The main contents and results are listed as follows:(1)According to the geological exploration data,choosing typical section to carry out grouting test,the results show that surrounding rock in tunnel site area can be grouted and grouting can reduce the permeability up to two orders of magnitude.(2)According to the geological exploration data and design data,choosing representative sections,researching the water pressure distribution rule inside and outside the tunnel grouting circle and lining stress and displacement through the numerical simulation and laboratory model test,then analyzing the impact of different grouting parameters,so as to confirm the suitable range of grouting parameters.(3)Simulating grouting state for each section of the eastern highway connection tunnel project in the downstream of Shenzhen reservoir,and getting the suitable grouting parameters scope for each sections,selecting the suitable grouting parameters and establishing a large-scale three-dimensional seepage field model of Shenzhen reservoir downstream urban tunnels to forecast the tunnel water inflow of each section before and after grouting,forming a perfect tunnel water inflow prediction system in grouting state.