Numerical Simulation Research On Surface Drainage Model Of Turtleback Terrain

With the rapid changes in the global climate,floods occur frequently.The problem of urban flooding has become a very prominent problem.my country’s existing underground pipe network has problems such as low design standards,random connections and destruction.The existing underground pipe network drainage system is not enough to deal with the large return period of rainfall.The surface drainage system can effectively deal with the flood problem caused by rainfall during the recurrence period through the surface drainage method.Turtle-back terrain is widely used in ancient urban architecture as a terrain with good drainage effect,but there are very few related studies in recent years.Therefore,the research on the turtle-back terrain surface drainage model is of great significance to solve the problem of urban flood disasters.In this paper,the GAST model(GPU Accelerated Surface Water Flow and Transport Model)is used to simulate the surface drainage process of the turtle-back terrain under the ideal terrain and the combined turtle-back terrain.By comparing the turtle-back terrain with the bilateral slope terrain,the different slopes of the turtle-back terrain,and the surface drainage process under the combined turtle-back terrain,the law of the surface drainage pattern of the turtle-back terrain is explored.Through the simulation study of the influence of the layout of urban road gutters on the discharge capacity,the rule of gutter layout is explored to supplement the surface drainage mentioned above.The conclusions are as follows:1.The surface water and its accompanying transport process model(GAST model)accelerated by the graphics card developed by Xi’an University of Technology are used to simulate the surface drainage process of the turtle-back terrain.Existing experiments and analytical solutions of existing research results have proved that the model has high accuracy in the simulation of the flood evolution process.The model accelerates the calculation through the graphics card and improves the calculation efficiency.2.Simulating rainfall in ideal terrain once in 1 year,once in 5 years,and once in 50 years,compared with bilateral slope terrain,the drainage of the turtle-back terrain increases by 0.41%-9.02%;the peak flow rate increases by 1.06%-9.14%.Compared with the 0.5%slope tortoise terrain,the 0.8%slope terrain increases the drainage volume by 3.61%-28.78%,the peak flow increases by 7.91%-15.66%;the 1%slope terrain increases the displacement by 4.3%-37.61%,and the peak flow increases by 9.67%-26.54%.It can be concluded that:(1)Under the same rainfall conditions,the surface drainage effect of the turtleback terrain is better than that of the bilateral slope terrain;and the impact on adjacent areas is less.(2)Under the same rainfall conditions,as the slope of the turtle-back terrain increases,the better its drainage effect;(3)With the increase of the rainfall return period,the turtle-back terrain and the bilateral slope terrain drainage The difference in the process and the impact on adjacent areas is reduced;and the difference in the drainage process of the turtle-back terrain under different slopes becomes smaller3.Simulating the surface drainage process of the combined turtle-back terrain plot under the condition of 2h rainfall,the ratio of drainage to rainfall is 94.8%under a one-year rainfall,95.5%under a five-year rainfall,and 95.8%under a 50-year rainfall.There is less water accumulation in the area under the conditions of one-year and five-year rainfall.The deepest water-accumulating area is concentrated on the road under the 50-year rainfall,and there is no obvious water accumulation on the road at 3.5h.4.By simulating the impact of urban road gully layout scheme on discharge capacity,it can be concluded that:(1)The greater the road longitudinal slope,the worse the drainage effect of gully.When the gradient changes from 0.3%to 8%,the gully discharges.The variation range of the water rate is 11.89%-55.64%,and the discharge rate is reduced by 3.18%-34.87%;(2)The more the number of gutters,the greater the drainage effect of gutters.When the number of gutters is arranged from 2-5,the rainwater The variation range of the outlet water discharge rate is 11.89%-55.64%,and the water release rate is increased by 5.07%-30.14%;(3)With the increase of the flow rate from small,medium and large,the variation range of the rainwater outlet rate is 19.24%-55.64%,The water discharge rate has been reduced by 0.36%-18.36%.