Effect Of Capillary Effect On Widening Subgrade Deformation And Disposal Strategy

With the development of society and economy,the demand for road transportation is getting higher and higher.Many important traffic roads can not meet the current needs,so the road widening project has become a hot topic nowadays.As to the road widening project,the most important problem is the differential settlement of the old and new roadbed.In order to solve the adverse effects of differential settlement on the road,researchers at home and abroad have carried out a lot of theoretical research and engineering practice.Although some valuable experiences have been obtained from practical engineering,the research on the influencing factors of differential settlement is relatively simple,which is limited to the study of deformation under road weight and vehicle load,and does not form a complete theoretical system.In some high-water areas,the damage to the road caused by capillary action is very seriously.It is very meaningful to introduce capillary phenomena in unsaturated soils into practical widening of road works.To further understand the effect of capillary action on the widening road,This paper on the basis of research progress at home and abroad,that analyzed the rising height of capillary water and the characteristics of differential settlement under the capillary action by finite element software,which can provide reference for practical road design.Firstly,the rising process of capillary water and the trend of subgrade height with water content were simulated by numerical simulation.The rising height of capillary water in different soils was calculated by the formula,which provided a theoretical basis for the subsequent research and analysis.Then,in order to analyze the law of widening subgrade settlement under capillary action,this paper analyzed the settlement characteristics and water content of subgrade under capillary action by software simulation.Secondly,aiming at the widening of the subgrade model in the high groundwater level,the effects of different factors such as the difference of the embankment soil,the widening width of the roadbed,the difference between the new and old roadbed compression modulus and the foundation compression modulus on the deformation of the subgrade were discussed respectively.Thus,the understanding on the generation and influence factors of differential settement had moredeeply.Finally,this paper discussed the technical measures of widening the differential settlement control of the road from two aspects: the inhibition of capillary water rise and the improvement of road rigidity.The measures to suppress the increase of capillary water are mainly from the two aspects of cutting and absorption,and mainly discussed the analysis of the gravel laying,coarse sand laying,soil improvement and other measures;the improvement of road rigidity is mainly from the point of view of increasing soil contact and raising its own strength,and mainly discussed the steps of excavation,the old road cutting slope and the light filling material and other measures,which provided theoretical guidance for controlling the widening of road settlement by controlling the above measures.