Study On Portal Section Flood Discharge Of Large Longitudinal Slope Road Tunnel Under Rainstorm Condition

Large longitudinal slope road tunnel in this thesis is the road tunnel with relatively large longitudinal slope road on which the rainwater will flow into the tunnel in a short period of time under rainstorm condition.Under the rainstorm condition of new features,the rainwater easily gathers at the large longitudinal slope road tunnel entrance and inflows in the tunnel,while the surface water cannot be drained away in time by the drainage system,the tunnel suffers flood and waterlogging as a result.In order to avoid this situation,a portal section flood discharge system of large longitudinal slope road tunnel can be designed to discharge the flood when it flows along the tunnel portal section,so as to ensure the normal traffic of the tunnel.This thesis has done some research on the flood discharging of the tunnel portal section,and mainly includes the following aspects:?The reason of the large longitudinal slope road tunnel suffering from flood disasters under the rainstorm condition are summarized and analyzed,and some countermeasures are proposed theoretically.?To take the rainstorm condition of urban area in Chongqing as the background,rainstorm intensity formula applicable to the research of this thesis is chosen by referring to some meteorological data and investigation documents.And the amount of designed flood water is calculated on the basis of the designed rainstorm intensity.?A new portal section flood discharge structure of large longitudinal slope road tunnel is proposed.The structure discharges flood by the plum-shaped arrangement of drainage holes in the road.Two different fluid dynamics formulas are used to do the simple theoretical calculations.The discharging effects of the structure under the influence of several controlling factors are summarized and the necessary theoretical length of the discharging road of the portal section is obtained by the comparative analysis of the calculation results.? FLOW-3 D fluid simulation software is used to build numerical model and calculate.The numerical calculating section length of the discharging structure under the influence of several controlling factors is summarized.?The "test model of portal section flood discharge of large longitudinal slope road tunnel under rainstorm condition" is built by self-developing to form a model test system to simulate the portal section flood discharge situation of large longitudinal slope road tunnel under the influence of various combinations of several factors including different rainfalls,different longitudinal slopes,different drainage hole sizes and different drainage hole spacing.?The flood discharging rule is analyzed and the recommended values of the parameters of the flood discharge structure are obtained based on the model test data.A more reliable discharge scheme of portal section flood discharge of large longitudinal slope road tunnel is proposed according to the comparative analysis results of the theoretical calculation,numerical calculation and model tests.