Application Research Of Foamed Concrete Inroads In Seasonal Frozen Zone

The area of frozen soil in China is widely distributed,and seasonal frozen soil accounts for 53% of the total area of frozen soil.Seasonal frozen soil is relatively cold in winter,and the soil freezing,which easily caused the frost heaving of highway subgrade in the region.The frozen soil melted after the cold season.At this time,the roadbed often suffered from uneven settlement and tumbling.Based on this,this paper briefly analyzes the frost heave mechanism and influence factor of the roadbed,and proposes the use of foam concrete insulation board to heat and freeze the roadbed in the seasonal frozen soil area.This paper relies on the reconstruction and expansion project of the Provincial Highway 434 to the Kangding North Gate Gymnasium.Considering the influence of the route and altitude,the variation of the temperature field in the project area and the seasonality of the foam concrete insulation board in the area are studied.The optimization plan for the laying of frozen soil areas.According to the requirements of the test pressure of the indoor pressure and freeze-thaw cycle test,the preparation of the laboratory foam concrete test block was carried out.The pressure test was carried out in the laboratory,and the compressive strength of the test block of the foam concrete under different weight conditions was obtained at different times.Afterwards,the freeze-thaw cycle test was carried out in the laboratory.It was found that the larger the bulk density,the smaller the porosity of the foam concrete,the thicker the pore wall,the stronger the frost resistance and the more stable the performance.By comparing the pressure,flexural strength,thermal conductivity and frost resistance of ordinary concrete and foam concrete,it is found that foam concrete can not only meet the basic road performance,but also has better thermal insulation than ordinary concrete in cold and frozen soil areas..The project team then carried out soil sampling and laboratory tests to obtain the optimum moisture content and maximum dry density of the soil,and obtained the thermal conductivity and specific heat of the soil under different water content conditions,which was the subgrade temperature.The establishment of the field model provides soil parameters.By collecting the measured geothermal data of the area,the temperature field distribution,variation law and influence factor of the natural surface,the subgrade centerline,the left and right shoulders of the subgrade,and the ground temperature ofthe subgrade slope are analyzed.Taking the typical section of C(K30+660)as the research object,the finite element calculation model of ABAQUS is established,and the simulation results are verified with the field measurements to ensure the practicability and reliability of the model.By changing the length and thickness of foam concrete insulation board laying,the model under different working conditions was built for numerical simulation,and finally the optimal laying foam concrete insulation board scheme suitable for the seasonal frozen soil roadbed in this area was explored.According to the simulation results,the laying of foam concrete insulation board can greatly increase the maximum freezing depth of the roadbed,and has obvious effect on the thermal insulation of the roadbed;the thickness of the foam concrete insulation board is 80 mm,and the slopes on both sides extend 1.3m(When 1/3 of the slopes on both sides),the insulation of the subgrade is increased to the greatest extent and the effect is optimal.The research results in this paper can provide a certain reference for further research on the prevention of roadbed frost heaving.The research results in this paper also provide a design idea for the design institute to design for seasonal frozen soil roadbed in Sichuan and Tibet.