| Highly embankment culverts are widely seen in mountainous roads,causes largescale roadbed diseases,which affects the service quality and the life of mountainous highways in China seriously.The current theory of earth pressure calculation in the "General Design Code for Highway Bridges and Culverts"(JTG D60-2015)reflects the change law of the vertical earth pressure at the top of the culvert inaccurately,making the earth pressure,calculated by the engineering design,differ from the actual stress conditions of the culvert.If reasonable and effective measures are taken to reduce the vertical earth pressure which on the top of the culvert,the smaller size of the culvert can be used and the bearing capacity of the culvert to the foundation be reduced,thereby saving project cost,ensuring the safety of the culvert and reducing the incidence of high embankment culverts.This paper starts from solving practical engineering problems,establishes a 1:1 numerical calculation model and analyzes the stress characteristics of high embankment culverts,hoping that the research results can scientifically guide the design and construct high embankment culverts in mountainous roads to prevent corresponding diseases.The main research contents and conclusions are as follows:(1)According to the disease types of high filled subgrade and high embankment culverts,the influences and the mechanism of action are analyzed based on the characteristics of the diseases.It is determined that laying cinder on the top of the culvert,and filling the foamed lightweight soil on both sides of the culvert to solve the problem of the top pressure concentration of the culvert,reduce the lateral earth pressure of the culvert,and solve various problems caused by inadequate compaction;(2)Midas GTS NX software was selected as the carrier for the finite element numerical simulating study to analyze the influence of various parameters on the settlement difference between the soil inside and outside the culvert and the concentration coefficient of the earth pressure.Through orthogonal test establishing and using range analysis method,the influences on the settlement difference between the soil inside and outside the top culvert were as follow: the elastic modulus of the fill Poisson's ratio> the elastic modulus of the foundation> the internal friction angle;(3)The variance analysis method has proved that the elastic modulus and Poisson's ratio of the soil have a significant influence on the settlement difference,while the elastic modulus of the foundation and the internal friction angle have less effect.It shows that the larger values of the elastic modulus and Poisson's ratio of the soil are,the greater the settlement difference.However,the change of each parameter cannot solve the problem of vertical earth pressure concentration at the top of the culvert;(4)Through finite element numerical simulation,when foamed lightweight soil is used as the unique reducing material,numerical simulating calculations and results analysis are made for the formulated relief program,and the optimal relief program is compared to achieve foamed lightweight soil.Optimal design of load reduction measures.The results show that the load-reducing scheme of the culvert side with a backfilling width of 10 m and a backfilling height of 4m(with culvert height)is smaller,more uniform,and has the best relief effect;(5)It has been proved that the method which 1m thick cinder is placed on the top of the culvert as the load-reducing material(flexible filler),the backfill width of the culvert side lightweight soil is 10 m and the backfill height is 2m(1/2 culvert height),is the best solution.The vertical earth pressure at the top of the culvert is reduced by about 50%,and the comprehensive decompression effect is the best.It is the best solution for finite element numerical simulation. |
PDF Full Text Request