Field Test And Numerical Simulation Of Soaking Loading In Saline Soil

Saline soils have different properties from other soils.with high-speed railway and other infrastructure construction in the saline soil area,due to the lack of relevant norms,encountered a lot of practical problems,the urgent need to propose a solution.Based on the field immersion load test in saline soil area,this paper mainly studies the following problems:(1)According to the different saline soils(coarse,fine particles,containing gypsum layer)has different collapsibility properties,in order to study the influence of different particle gradation and gypsum layer on the collapsibility of saline soil,we were carried out field immersion load test on saline soil in different particle size,the following conclusions were obtained: For coarse granular saline soil,it is possible to have a common character of collapsibility under certain particle gradation.The soluble salt content is an important factor to affect the deformation of the fine grained saline soil.When the content of soluble salt reaches a certain extent,the fine granular saline soil has the property of collapsibility,and on the contrary,it has no collapsibility.Because of the collapse of the gypsum layer in the gypsum layer saline soil,it is characterized by collapsibility.Generally speaking,the particle size of saline soil has an important influence on its collapsibility.It is found that the amount of collapsibility of saline soil containing gypsum layer is greater than that of fine granular saline soil,and the change of fine grain saline soil is greater than that of coarse granular saline soil.(2)We carried out field tests on the bearing capacity of different types of saline soils.The following conclusions are drawn: The characteristic values of the bearing capacity show the tendency of the coarse particles → the gypsum layer → the fine particles to decrease in turn.It can be seen that the soil particle size and salt content have the influence on the bearing capacity.Based on the ABAQUS finite element software,the calculation of the settlement,the salt expansion and the seepage of the saline soil is simulated.Mainly on the following research:(1)For the collapsibility of saline soil,a typical field test site is selected,which is modeled according to the actual size.The results show that the settlement deformation under load is mainly in the area below the load plate,and the change of the settlement on both sides of the load plate is very small.(2)Study on salt expansion of saline soil according to laboratory test measured,with local meteorological data records as the boundary condition of salt expansion of foundation of the temperature field and stress field calculation of the coupling,influence of the formation of salt expansion and the foundation of the salt expansion.The results show that the soil salt expansion areas are mainly concentrated in the surface,the formation of salt expansion effect on Subgrade the limited scope of the annual salt heaving is cumulative,but the increment decreased,with the increase of time tends to be stable in the late.(3)According to the range of field test,the permeability coefficient of different types of saline soil was calculated by inversion.On the basis of this,the infiltration extent of different types of saline soil was calculated under different water conditions.Results show the infiltration width of different types of saline soil is very different.The width of the coarse saline soil is larger than that of the fine granular saline soil.With the increase of the seepage time,the increment of the infiltration in the width direction decreases,the more slowly the direction of penetration.