Study On The Frost Heaving Simulation Model Of Pile-Plank Structure In High-Speed Railway In Seasonally Frozen Region

With the development of the high-speed railway in seasonally frozen region, the study on the stability of subgrade in frozen region gets more and more attention in the engineering. Owing to the high-speed traffic density, speed and other characteristics, the frost-heaving and thawing-settlement of frozen soil will seriously affect the comfort, stability and security of subgrade. As a new type of structure form under the railway, the pile-plank structure has obvious advantages to control the settlement and deformation of subgrade. However, there is few example about the application of the pile-plank structure in seasonal frozen soil area foundation subgrade treatment. Given the research on the pile-plank structure is not mature, study on the load and deformation characteristics of pile-plank structure under the affect the frost-heaving and thawing-settlement in the seasonally frozen region systematically will helpful to recognize and develop the methods on the foundation and subgrade treatments. By means of numerical simulation and theoretical analysis in this paper, we have studied the load and deformation of pile-plank structure under the action of frost heave force in seasonal frozen region. Through the analysis and study, we get the following main conclusions:(1) The moisture transfer is the main mechanism on the formation of the frost heaving. The moisture transfer will form the frozen ice lens with water freeze constantly, which can result in volume expansion. In all factors, the amount of frost heaving of soil is mainly affected by the water level and water content.(2) Combined with the analysis of fasteners and the specifications of high-speed railway design, clarifying the railway subgrade frost heave quantity limit is 4mm. When the amount of frost heave is more than 4mm, it is harmful to non-ballasted track.(3) In the process of soil freezing, without considering phase change would increase the depth of frozen and the quantity of frost heave accordingly, and lead to distortion of numerical simulation to can't get the actual data.(4) According to the change of displacement and stress of bearing sheet and pile foundation over time, the process of soil frost heave can be divided into three stages:the phase of initial fluctuations, the phase of frost heave rapid development and stable development.(5) In the process of frost heaving, on the top of the pile foundation will endure the normal frost heave force and the pile body will endure tangential force at certain depth...