Study On Anti-freezing Mechanism And Numerical Simulation For U-shaped Canal Lining

For seasonally frost-heaving regions, canal frozen disaster is a major problem to affect the operation of lining project of anti-seepage of channels. The influence rule of frost-heaving mechanism of canal lining and relevant parameters on anti-frost heaving performance of lining structure is one of the key technical problems to be solved urgently in canal lining. As for the typical features of U-shaped canal lining in Ningxia, experiments and numerical simulation method are adopted to analyze and study the frost-heaving mechanism of U-shaped canal lining and the relevant parameters affecting the anti-frost heaving of U-shaped lining according to the basic theories of Physics of Frozen Soils, Finite Element,Elastic-plastic Mechanics, and Structural Mechanics. This thesis presents a frost heaving sensibility prediction model of U-shaped canal lining under the typical soil texture, amends and verifies the numerical model of U-shaped canal lining, and analyzes the influence rule of different parameters on frost resistance of U-shaped concrete lining. The main research conclusions and achievements include:(1) Established a continuous observation method to test the frost heaving characteristics of U-shaped concrete-lined channel. Established a frost heaving observing system in different canal foundation and soil moisture observing system in different canal bases. Confirmed the features of plane layout and cross section layout that affect frost heaving force observational system of lining in different positions.Developed the continuous observation equipment and method observational steps and observational method of the frost heaving characteristics of U-shaped concrete-lined channel.(2) Discussed the elementary physical property of seasonal frozen thawed soil of canal bases, soil heat flow, the influence factors of water migration equation and hydro-thermal coupling equation.Ascertained the changing rules of the soil freezing temperature of U-shaped canal in canal base and the changing rules and distribution characteristics of temperature and unfrozen water of soil in canal base in different position and different depths. Established the relation equation between the content and temperature of soil unfrozen water under the typical soil texture.(3 ) Revealed the relevancy and changing rules of the temperature, moisture and frost heaving rate of U-shaped canal in different depths of canal base under the typical soil texture and the relevancy between the frost heaving force of U-shaped concrete lining and the frost heaving rate of soil in canal base as well as their changing rules. Established a prediction model of frost heaving sensibility of soil in canal base and frost heaving force of canal lining under the typical soil texture.(4) Corrected the basic parameters of numerical model of the commonly used concrete lining in Ningxia through material characteristic test of concrete. Established smeared crack analytical model of U-shaped concrete lining through ADINA, which is large finite element analytic software. Verified the feasibility of smeared crack analysis, and put forward numerical modeling nonlinear analysis mode of U-shaped lining under the function of frost heaving force.(5) Integrated the related criterion of China's current canal lining design and employed smeared crack model to reveal mechanical response rules of concrete lining with different parameters under the effect of frost heaving force as well as the influence rules of parameters on anti-frost heaving of lining according to the material strength grade of U-shaped concrete lining, the side angle of U-shaped lining structure and the thickness of lining. Presented the method of judging the anti-frost heaving of the U-shaped lining through lining anti-frost heaving coefficient.