Dynamic Response Analysis Of Buried Pipe Asphalt Pavement Structure Under Traffic Load

With the rapid development of China’s cities and the improvement of transportation infrastructure,the number of municipal pipelines has also increased year by year.However,the existence of underground pipelines makes a rigid and flexible transition layer under the asphalt concrete pavement,which is prone to produce diseases,which not only adversely affects the safety of vehicle driving and normal traffic operation,but also brings great inconvenience to the maintenance work.Therefore,it has important theoretical and practical significance to analyze the bearing characteristics and structural design of buried asphalt concrete pavement structure.In this paper,ABAQUS finite element software is used to simulate the asphalt pavement structure embedded with reinforced concrete pipes under moving harmonic loads,and analyze the change rules of stress and surface deflection of each structural layer under different pipe burial depths and backfill modulus.And analyze the stress and displacement changes of the road structure after laying the geogrid.Based on the laying of geogrids,the orthogonal test method is used to study the bearing characteristics of buried pipe roads under the coupling of multiple factors,obtain the primary and secondary order of influencing factors,and determine the key influencing factors.Based on the principles of mechanical stability and economy,an optimal design idea for buried pipe asphalt pavement structure is proposed.The main conclusions are as follows:(1)The burying of the pipeline makes the vertical stress of the pavement structure increase to a certain extent,while the transverse stress and surface deflection decrease.The greater the buried depth of the pipeline,the smaller the vertical stress,so increasing the buried depth of the pipeline can reduce the vertical stress.With the increase of the buried depth of the pipeline,the transverse stress at the bottom of each structural layer and the deflection of the road surface will increase,but these two indicators are smaller than those without pipes.When the buried depth of the pipeline reaches 2m,the impact on the road structure can be ignored.(2)Increasing the modulus of elasticity of backfill plays a positive role in buried asphalt roads.Compared with the modulus of backfill of 20 MPa,the vertical stress of the base course bottom under the modulus of backfill of 140 MPa is the best,with a decrease of 2.96%;The transverse stress at the bottom of the lower layer changes the most,with a decrease of 10.37%;The maximum reduction of road surface deflection is 8.93%.(3)After laying geogrids in the road structural layer,the corresponding stress is reduced compared to the road without geogrids,and the overall effect is relatively ideal,with the most obvious effect on the base and subbase.After laying the geogrid,the deflection of the road surface has been effectively reduced,with the maximum deflection of the road surface decreasing from 0.8229 mm to 0.7829 mm,with a decrease of 4.86%.(4)On the basis of laying geogrids,an orthogonal test with four factors and three levels is established.The influencing factors are sorted according to the degree of influence: base layer thickness,subbase layer thickness,upper layer thickness,and lower layer thickness.By establishing the correlation between the thickness of the base layer and the mechanical stability and economy of the road structure,an optimal design scheme for the asphalt pavement structure containing underground pipes is proposed: laying geogrids,4cm thick AC-13 fine grained asphalt concrete upper layer,6cm thick AC-20 medium grained asphalt concrete lower surface layer,18 cm thick cement stabilized crushed stone subbase,and the thickness of the cement concrete base layer ranging from 21 cm to 25 cm.According to the research results of this paper,it is recommended to strengthen the compaction of backfill around the pipeline and increase the buried depth of the pipeline as much as possible.The recommended buried depth of the pipeline is more than 2m;The bearing capacity of the road is effectively improved after the geogrid is laid,which can be used as a good optimization measure;When the base course thickness is between 21 cm and25cm,the road bearing capacity and cost are moderate,and the level of economic and mechanical stability are excellent.The design unit can select the appropriate base course thickness within this interval.It is hoped that the research results of this paper can provide some reference for other buried asphalt roads.Figure [71] table [17] reference [66]...