Study On The Disease Of Highway Frost Heaving And Frost Boiling In The Northeast Seasonal Freezing Region

Soil moisture-heat change and the stress redistribution caused by it are the main factorscausing the heaving and boiling. Based on the road of Beian-Heihe, Yincun-Suihua andLinkou-Daluomi of Ji-Ne in Heilongjiang province, this paper adopted the method of fieldinvestigation and finite difference numerical calculation and studied anti frost boil roadstructure in the seasonal freezing region：1) Based on the former research results, combined with the real time monitoring oftemperature and moisture of the typical sections, we analyzed frost heaving and pumpingmechanism from the points of view of hydrothermal changes of subgrade, what is more, theeffect factors of road frost heaving mechanism were carried on the detailed analysis. By themethod of site investigation and data collection, we investigated the natural environmentalcharacteristics and roadbed diseases of the typical sections of the existing road inHeilongjiang areas. The roadbed disease were classified considering the naturalenvironment characteristics and the characteristics of frozen soil on asphalt road frostheaving pumping.2) I summarized the typical road structure of seasonal frozen soil area at home andabroad, and analyzed the advantages and disadvantages of them. Based on the road frostheave and frost boil mechanism, I put forward a new road structure from the subgradefilling subgrade cross-section form, and drainage design and so on.3) Based on the control equation of temperature field with phase change in the frozensubgrade, taking into account the moisture migration control equation of permafrostsubgrade, I put forward the permafrost subgrade deformation model calculation method bybuilding the models of coupled thermo-hydro-mechanical (THM) using the finite differencemethod FLAC3D.4) By building the numerical model which considered the influences on temperaturefield and deformation field groundwater brought for the road setting up waterproof pad, Ianalyzed the influence of moisture on the change characteristics of temperature field anddeformation field. The results showed that setting waterproof cushion could weaken the effect of groundwater on the freezing–thawing deformation of road.5) This paper established the numerical model of insulation board of differentembedding position to the deformation and temperature field and field on the road andanalyzed the influence on pavement temperature field and deformation field changecharacteristics with and without thermal insulation board and insulation board buried indifferent depth. The results showed that the presence of road construction insulation boardhad a significant impact on improving freeze-thaw and weakling frost heaving and boiling.6) Established the numerical model of different berm width of the road to thedeformation and temperature field and field on the road, this paper analyzed the changeprocess of pavement temperature field and deformation field in different berm width. Theresults showed the berm width of3m insulation works best and freezing-thawing processin minimum degree.7) This paper established the numerical model of presence of clay layer road structureor not to the deformation and temperature field and field on the road and analyzed theinfluence on pavement temperature field and deformation field change characteristics withand without clay layer road structure. The study showed that the clay layer structure reducedthe saturation of road embankment and weakened the degree of frost heaving and boiling.