Influences Of Rainfall Infiltration On Subgrade Properties And Drainage Measures In Highway Reconstruction And Extension Project

Highway in China has developed rapidly in recent years.At the same time,the reconstruction and expansion of the road also reflect some problems about the imperfect drainage facilities.There are several means for rainwater to enter the road,such as infiltration in the central partition zone,infiltration under the road surface and lateral infiltration.If the water entering the pavement is not discharged in time,the strength of the wetted roadbed and structural materials will be reduced and the deformation will be caused.Therefore,in the reconstruction and extension project of expressway,the drainage design of road is the key to ensure traffic safety and the function of roadbed and pavement.In order to further understand the impact of rainfall infiltration on road widening,this paper analyzed the impact of rainfall infiltration on different roadbed,based on the research progress at home and abroad,and provided reference theory for actual road design.The main contents are as follows:(1)Some basic concepts related to unsaturated soils,including saturation,matrix suction,soil-water characteristic curve and hydraulic conductivity,are systematically expounded.Then the constitutive model of soils and the seepage theory of saturated-unsaturated soils,the finite element theory and software are introduced,and the widening model of commonly used fill and foam lightweight soil roadbed is established,and the modeling method is verified.(2)The influence of rainfall infiltration on Widening Roadbed is analyzed.The change of moisture content of widened subgrade under capillary action is simulated and analyzed.The change of deformation,pore water pressure,saturation and plastic deformation under different embankment filling,different rainfall intensity and different rainfall duration are discussed.Law.Thus,the deformation characteristics and influencing factors of widening subgrade differential settlement are more deeply understood,and the mechanical properties of roadbed widened by different soil are compared.(3)Based on the removal of moisture from roadbed and pavement,different drainage measures were analyzed.The drainage measures are mainly from two aspects of zonaldrainage and pavement internal drainage.The measures of setting gravel drainage wall,zonal internal drainage and pavement internal drainage are put forward,and the drainage effect is analyzed,which provides some theoretical guidance for widening the road drainage scheme.