Research on the influence of water and salt migration and deformation characteristics of saline soil in cold and arid regions by water and breathable separation layer
In recent years,under the "Belt and Road" initiative and the "transportation power" strategy actively promoted by China,the transportation infrastructure in the cold and arid regions of northwest China has been strengthened. As these constructions progress,it was inevitable to cross sections of saline soil,which created a series of challenges and problems for the construction and maintenance of the area. Problems caused by saline soils can not only be problematic during construction,but also have an impact on the long-term maintenance and operation of the facility.In the cold and arid regions of northwest China,the distribution of saline soils poses con-siderable challenges to infrastructure construction. In these areas,sulfate saline soil,as the most representative saline soil,exhibits a particularly obvious salt frost heave phenomenon when the temperature changes. The fluc-tuation of temperature,humidity and salt concentration in sulfated saline soil will cause salt heave and frost heave in the subgrade of sulfate saline soil,resulting in uneven uplift,structural relaxation and cracks on the pavement. These diseases not only affect the structural strength and stability of the roadbed,but also may cause hidden dangers to traffic safety and increase the risk of traffic accidents. In view of this,researchers and engi-neers have been exploring effective treatment technologies and methods to mitigate or eradicate the negative ef-fects of saline soil. Among the many solutions,geopartition technology has been widely recognized and adopted for its economy and practicality. On this basis,this study proposes an innovative water-permeable membrane partition treatment technology,which aims to effectively control the movement of water and salt in saline soil by means of physical isolation and reduce the structural deformation and damage caused by salt frost heave. Based on the theory of porous medium and continuum media,and considering the effects of temperature change and wa-ter-salt recharge conditions on the water-salt phase transition in soil pores,a comprehensive water-heat-salt-force multi-field multiphase coupling mathematical model was established. The model covers a variety of transport mechanisms such as the movement of liquid water and water vapor,the diffusion and convection of solutes,the heat conduction,and the mechanical response of soil,which can accurately describe the complex interactions in unsaturated saline soil systems and predict the dynamic behavior of water and salt under actual conditions. In or-der to verify the effectiveness of the model,numerical simulation technology and laboratory model tests were used to study the water-salt migration law and salt heave deformation characteristics of unsaturated sulfate saline soil under the condition of simulating natural water and salt recharge under the condition of simulating natural water and salt recharge. By comparing the numerical simulation results with the laboratory test data,the accura-cy and practicability of the model are confirmed,which provides a solid theoretical foundation for engineering application. In this study,the effects of the water-insulated and breathable membrane on the thermal migration and deformation behavior of unsaturated sulfate saline soil were analyzed. The experimental and numerical simu-lation results show that the water-permeable layer can significantly inhibit the vertical migration of liquid water and dissolved salts,and effectively prevent secondary salinization and structural damage of soil. In addition,the air permeability of the waterproof air permeable layer solves the problem of gas accumulation under the tradition-al geomembrane,and avoids the additional engineering problems caused by gas accumulation. In short,the re-sults of this study not only provide a new technical scheme for the treatment of saline soil subgrade in cold and ar-id areas and other similar areas,but also provide a set of theoretical basis for engineering designers to refer to. The implementation of this new waterproof and breathable membrane treatment technology will significantly im-prove road stability,prolong the service life of roadbed,and reduce maintenance costs,which has important en-gineering practice value and wide application prospects.
sulfate saline soilwaterproof and breathable partition filmwater salt migrationnumerical simulationindoor testing
万方数据
维普
