Temperature Control Effect And Stability Analysis Of The Particle Size Improved Roadbed In The Permafrost Regions Of Qinghai Province

The analysis based on the previous research and theoretical analysis, this paper puts forward a new type of structural form of the frozen soil sub-grade, which is a new type of structure, which has the following important conclusions through a large number of indoor and outdoor experimental research and analysis:1.Detailed analysis of the size of the roadbed in the freezing and thawing cycle of the ground temperature change and the change of the law of heat, and with other roadbed structure and natural site for a comparative analysis. It was found that the particle size improved the thermal diode effect of the cooling capacity and heat shield compared with the other sub-grade structure;2.In the cooling effect, all kinds of roadbed structure on the upper limit of permafrost are different degrees of uplift. In the comparison of the sub-grade structure, uplift is the largest of the particle improved roadbed, followed by common ventilated embankment, the smallest is the common sub-grade; common ventilated embankment in the freezing period, compared with the particle improved roadbed freezing strength, freezing speed characteristics;3.To ground temperature and deformation curve based on Fill Sub-grade structure parameters in the freeze-thaw cycle between cold and warm season show as a guide, from the soil particle geometry or structure, soil and water combination between attribute change and water film interface characteristics, granular skeleton of coarse grained soil and contact between particles in water film formed non particulate contact the fine grained soil skeleton, reveals the intrinsic mechanism of the particle improved roadbed temperature control mechanism from the micro;4.Based on the roadbed temperature and thermal state analysis as the foundation, with the deformation analysis as the control condition, the stability of the roadbed stability was evaluated. Shows that no matter from the upper limit of permafrost or from a single subgrade deformation(including frost heave and thaw settlement) to consider, particle size improved roadbed is a stable roadbed structure form;5.The study analysis the therms physical parameters of the improved soil, obtained the thermal conductivity of soil is mainly affected by the soil composition and physical properties(such as dry density, porosity, water content and soil particle size distribution, etc.), the mineral crystal particles to the direction of arrangement of the and the influence of freezing and thawing changes in the state of multiple factors. Through the reasonable control of different particle size distribution, dry density and moisture content, the thermal conductivity of the soil can be changed under different freezing and thawing conditions.