Analysis Of Pavement Structure Stability With Subgrade Cavity Under Traffic Load

In recent years,urban pavement collapse accidents have occurred frequently,mostly caused by the leakage of underground pipelines,which has caused great safety risks to people's daily lives.Scientifically analyzing the causes of pavement collapse,clarifying the mechanism of soil failure,the cause of the formation of underground cavity,the development process and the limit state of collapse are of great engineering significance for preventing the hidden dangers of pavement collapse accidents,quickly dealing with the accident site,and restoring traffic.The soil characteristics of tianjin binhai area,the author of this paper,by means of FLAC3 D finite difference software for calculating for subgrade of pipeline leakage problems underlying hole instability destruction of road structure mechanics comprehensive analysis,explores the underground empty space position and size and traffic load effect on the stability of road structure,summarizes the judge the stability of road structure method,provides the technical guidance for the engineering practice.The main research contents are as follows:1.Analyze the existing accidents and find the main reason for the collapse of urban roads.Based on the theory of limit equilibrium,derive the limit span formula for the cavity to maintain a stable state.2.Using FLAC3 D finite difference software,simulating practical engineering problems,establish a simulation model of soil and choose according to the research content and the constitutive model of pavement structure,material parameters,the initial conditions,boundary conditions and contact conditions to analyze pavement underlying cavity effect on the stability of road structure,it is concluded that the bigger the hole depth,the smaller the radius of the horizontal,road structure more stable;The evaluation parameters of the loss of the stability of the cavity and the failure of the ground structure are given.3.By simplifying the traffic load into static uniformly distributed load and semisinusoidal fluctuating load,and applying them to the pavement above the cavity for calculation,comparative analysis shows that the cavity is more likely to collapse under the action of traffic load.4.The influence of the spatial structure of the void and the change of its geometric size on the stability of the road structure was analyzed by using the method of control variables.With the increase of the thickness of overlying soil,the radius of the cavity's stable limit span gradually decreases.With the increase of its own height,the radius of the cavity's stable limit span gradually decreases.With the increase of the overburden thickness,the radius of the limit span to ensure the safety of the top of the subgrade gradually increases.With the increase of its own height,the radius of the failure limit span also shows a trend of increasing gradually.