Research On Infiltration And Salt Resolving Slump Characteristics Of Saline-alkaline Soil In Lake Area Of Western Jilin Province

In the river-lake connectivity project carried out in the western part of Jilin Province,it has large number of unlined channels of saline-alkali soil connected by“lake-lake”,water infiltration leads to the collapse of the foundation soil of the canal building,accompanied by fluid-type damage,which makes the project's benefits difficult to fully exert,and the safety of the channel needs to be solved urgently.This paper takes the saline-alkali soil belt of typical lakes in Qian'an County of western Jilin Province as the research object,and studies the water infiltration and sedimentation characteristics of saline-alkali soil in this area,which provides reference for the prevention and treatment of the dissolution of saline-alkali soil-based channels.The physical,mechanical and chemical properties of saline-alkali soil were obtained by field investigation combined with laboratory test method.The surface characteristics and the permeability characteristics of the saline-alkaline soil were analyzed by cluster analysis method.The uniaxial compression test-double line method was used to explore the permeability characteristics.The variation of the coefficient of salt resolving slump of saline-alkali soil with the overlying load.Research indicates:?1?The content of sand in the saline-alkaline soil in the lake area of Qian'an County is higher than 50%,belonging to sandy loam,the liquid limit is less than 30%,the plasticity index is less than 17.4,and the name is sand-containing low liquid limit silt,the optimal moisture content is 16.8%,the maximum dry density 1.798 g/cm³,soil particle size is concentrated,loose and unstable,poor engineering properties,and heterogeneous in depth profile.0³0cm soil layer is a salt accumulation layer,the salt content is between0.798⁰.948%,and the main salt depth is about 30cm,the Na⁺?SO₄^2-?HCO₃^-?Cl^-that dominate the soil salinization increased by 237.43%,220.59%,122.74%and 925.00%,the salt content of 30¹50cm soil layer is between 0.687%and 0.353%,the void ratio is increased from 0.739 to 0.925,the plasticity index is reduced from 17.4 to 8.2,the physical and mechanical properties of soil are strongly changed,and the salt content decreases with depth.The phenomenon of salt accumulation is obvious.?2?The permeability of the saline-alkali land section in Qian'an County is“Lower Part Is Larger Than Upper Part”.The infiltration rate of 0⁵0cm soil layer is between 10^-7-10^-8cm/s,and the permeability is the lowest at 30-40cm.The infiltration rate of 50-80cm soil layer changes with the depth of the open parabola,reaching the apex at about 70cm,and the infiltration rate reaches 10^-6cm/s.From 80cm down,the infiltration rate increases,greater than 5x10^-6cm/s.The clustering method is used to cluster the 0¹50cm soil through physical and chemical properties.The 0¹50cm soil is divided into three consecutive layers,which are 0⁵0cm,50¹10cm and 110¹50cm,according to the clustering results,the infiltration rate-depth relationship curve can be divided into uniform stratification rules,indicating that the soil above the 150cm depth is essentially composed of three different soil layers.The permeability of the 50¹10cm soil layer changed greatly,and the infiltration rate at the first end was nearly 100 times different.Due to the fluctuation of lake water level and other factors,the infiltration rate fluctuated strongly.?3?After soaking in soda saline-alkali soil at different depths in the lake area of Qian'an County,the coefficient of salt resolving slump is the largest under the pressure of 200 kPa.With the increase of pressure,the coefficient of dissolution decreases.The coefficient of salt resolving slump of soils with different depths are different.The coefficient of salt resolving slump of 20¹30cm saline-alkali soil is between 0.010⁰.031,and the coefficient of salt resolving slump of 0²0cm and 130¹50cm soil layers is less than0.010,in the soil layer of 20¹30cm,the physical and chemical properties of the upper and lower layers are unstable,which is one of the reasons for causing the dissolution of saline-alkaline soil.The part of the saline-alkaline soil-based channel at a depth of 0 to130 cm is the main area for preventing and controlling the subsidence.