Study On Subgrade Construction Technology Of Saturated Sand In The High Salt Content And Sand Control Measures

The local railway, which refers to the railway managed by People’s Government,represents the economic benefits of this region. The stability and safety of its operation isparticularly important for the region’s development and economy. However as an integral partof railway, the riding comfort and stability of the subgrade is also necessary in safe operation.The subgrade is the basis of the track and the trains operation, especially in the railway fortransporting salt requiring high strength, stiffness, good shape retention，strong stability anddurability. Taking consideration for larger axle load in local railway, especially in railway fortransporting salt, the stiffness of the vertical railway line needs to be changed slowly andevenly. To meet these requirements, the design of the subgrade should be taken a series oftargeted measures combined with the real local condition.Based on the real engineering---the Qinghai region Xitie Mountain to North Huobuxunline test section, the article conducts numerical simulation on subgrade settlement respectivelyby using two construction filling method with recent observed subgrade settlementdeformation data on different positions from test section to obtain mechanical parameters ofsoil from laboratory test and using finite element software combined with the actual situation.Original method was to eradicate0.4m salt crust surface and then replace permeablesoil.Because of salt crust surface is too hard to eradicate during construction,original methodis replaced with now the method.now the method is to fill subgrade on the salt crust withoutdisturbing it. Comparing two engineering methods by using numerical simulation in thesedimentation in each layer of subgrade changes over time, the article determines thereasonable laying time in two construction method and analyses the subgrade settlementunder the road plates and rail loading after construction. Saturated sand, used in the finiteelement model, applies the Drucker-Prager criterion. In order to determine the relationshipbetween foundation settlement and time, and set a reasonable track-laying time, consideredthe rheological mechanical properties of the soil, the article also proposes simulatedcalculation (3D model) to the foundation settlement after the foundation work.Because of the region being in the seasonal frozen soil area, the soil frost heave is one ofthe factors that must be considered. In this paper, through the indoor experiment of frostheave, we make a research of the frost heave amount of fine sand under the same high saltcontent and different water content. Experiments show that the soil with different watercontent have a certain amount of frost heaving, and the amount of frost heaving with theincreasing of initial moisture content increases linearly. In the simulation of this paper, basedon the experimental results to frost heave, investigate the vertical displacement of thesubgrade under different engineering methods. Taking the real environment of the test section into consideration, the sandstorm disastersare not neglected.So based on wind data, numerical simulation from Xitie Mountain to theNorth Huobuxun line, the article analyses the sandstorm disasters regulation and identify thedistribution and pattern of sandstorm disasters. By on-site investigation and numericalsimulation, the article also studies the way of setting the railing sand barrier. Combined withthe actual situation of the Xitie Mountain to the North Huobuxun line, and the articleultimately determine the reasonable setting space.