Experimental Research On Engineering Characteristics Of Saline Soil In Baicheng Area

In recent years,affected by climate and topographic conditions,the area of saline soil in Baicheng area,located in Western Jilin Province,has a tendency to further increase and the degree of salinization is becoming more and more serious.Due to the poor engineering geological properties of saline soil itself,the engineering activities in Baicheng area have been greatly hindered.In view of the national policy of vigorously revitalizing Northeast China and the basic situation of backward economic development and infrastructure construction in Baicheng area,experts and scholars will play a vital role in the development of relevant regions.Therefore,the typical distribution points of saline soil in Baicheng area are selected for sampling,and the undisturbed saline soil with different depths is selected as the research object.The engineering characteristics of saline soil are studied experimentally.Based on the perturbation state model theory,the mechanical models of each sampling point are established,and the following research results are obtained:?1?The material composition and basic properties of saline soil at each sampling point were obtained.The main compounds in the three sampling sites are SiO₂,Al₂O₃and CaO;NaCl is the main component of soluble salt in Tongyu saline soil,and the curve of water content decreasing with depth shows a downward trend on the whole,and the vertical movement law of salt is similar to that of water;NaHCO₃ is the main component of soluble salt in Deshun saline soil,and the maximum value of water content and total soluble salt in the study area appears.At 20 cm to 30 cm below the surface,the vertical migration of water and salt caused by the absorption of water by plant roots was considered;NaHCO₃ was the main component of soluble salt in saline soil in Sheli area,and the change rule of water content and total soluble salt was similar to that in Deshun saline soil.?2?The mineral compositions and microstructures of the samples were obtained.The mineral composition of the three sampling points shows that primary minerals account for the main component,of which quartz or calcite is the most abundant;the primary minerals of Tongyu saline soil account for about 80%,and the difference between deep and shallow layers is small.The main component of clay minerals is illite/smectite mixed layers,and the shallow layer is more abundant than the deep layer,while the other secondary minerals?illite,kaolinite,chlorite?are deep.The proportion of shallow layer is higher than that of deep layer,illite,kaolinite and chlorite distribute more in deep layer;the shallow layer of primary minerals is 74%and the deep layer is 80%in Deshun area,and the main component of clay minerals is the mixed layer of illite and montmorillonite,and the distribution of minerals is similar to that in Yulin area;the primary minerals of saline soil in Sheli area account for about 85%,the difference between deep and shallow layer is not significant,and the clay minerals are similar.The mineral distribution of the mixed layer is contrary to that of the other two study areas,but the variation of clay minerals is less than that of the other two sampling points.The microstructures of the sampling points are generally characterized by large porosity,large number of pores,small shape,poor connectivity between large pores,and disorderly distribution of clay minerals.Pore and structural unit bodies differ greatly in depth and shallowness within the same sampling point,and there is no obvious change rule between different sampling points.?3?The mechanical properties of saline soil at each sampling point were obtained and the mechanical model was constructed according to the test results.Through the high-pressure consolidation test results,the soil can be defined as compressive soil;Tongyu saline soil shows little difference in compressive strength in different depths;Deshun and Sheli saline soil show the longitudinal law of compressive strength in space,which is that the compressive strength of shallow soil is greater than that of deep soil.The results of triaxial tests show that the strength of saline soil in Deshun area is the highest,Sheli area is the second,and Tongyu area is the lowest.For the same sampling point,the shear strength in the shallow layer is less than that in the deep layer.Based on the disturbed state model theory,the shear disturbed state model and the volume change disturbed state model are established by defining different disturbed factors.After comparing the model simulation curve with the triaxial test result curve,the model curve can basically show the constitutive law and characteristics of saline soil in Baicheng area.