Study On Portal Section Flood Discharge Of Urban Road Tunnel Under Rainstorm Condition

In recent years,urban road tunnels floods caused by heavy rains occur frequently in our country,therefore urban road tunnels' drainage is facing enormous challenges.Under the situation of the heavy rains,the water is prone to become pooling.The tunnel drainage system can not drain off the rain,which leads to the flood damage.In order to avoid this kind of situation,establishing a set of urban road tunnel entrance spillway system,which can drain off the water when it flows through the tunnel entrance and thus can guarantee the normal traffic of roads.In this paper,do some research about tunnel entrance flood discharge,the main research contents and results are as follows:?Form the acquaintance of domestic and foreign researches,summarize the reasons of urban road tunnel occuring flood disaster under the condition of heavy rains,analyze the urban road tunnel drainage systems and their shortages in our country,?The background is heavy rain conditions in Chongqing,the selection of rainstorm intensity formula is suitable with the research contents in this paper.For urban road tunnels in Chongqing,the return period is up to 50 a,according to the different regional rainstorm intensity formula calculate the 50 a rainfalls,and choose the larger single-seat tunnel results in Shapingba district to do the model test.And carrying on engineering instantiation research,the background is Epping mountain tunnel flood disaster on August 17,2015,estimating the water volume of single-seat tunnel and making the results as the parameter of the model test.Finally,the two input flows of the model test are determined by this.?Within the scope of spillway length in requirement(3,4 and 5 m),adjusting the diameter of holes,distance between holes and longitudinal slope,carrying out the experiment of urban road tunnel entrance section water drainage under the condition of heavy rain,analyzing the experiment data,the graph of.flow changing in different processes is given and each working conditions which satisfy the requirement of spillway section length are analyzed in detail.?Using FLOW-3D simulation software to establish the numerical model,and doing numerical simulation analysis for each working conditions which satisfy the requirement of spillway section length,and concluding the numerical calculation length of such type of the spillway.?Comparing and analyzing the model test and numerical calculation results,and finally giving the selection suggestions of flood discharge structure that could satisfy the requirement of spillway length.It can provide reference for pavement discharge type and basis for the regulation and standard of flood control and drainage.