| The shortage of water resources is a global problem. China is a country with severe shortage of waterresources. China’s per capita water resource is far below the world average level, which is only a quarter ofthe world average level and ranked110in the world. China is a big agricultural country. The shortage ofwater resources and the waste caused by unreasonable use of water resources restrict the development ofthe agriculture in China. The waste of water resources of agriculture mainly reflected in irrigation. China’sirrigation water reaches ninety percent of agricultural water. Channel water loss in the process oftransporting due to leakage accounting for nearly half of agricultural water, which reaches one-third ofChina’s total water consumption. To effectively reduce the water loss in the process of transporting and todevelop water-saving agriculture, seepage canal lining project has been widely used. In our cold northernpermafrost region, however, the phenomenon of frost heave is widespread exist. In recent years, thecomposite lining form of flexible film combining with rigid concrete is widely used, which is able to adaptto the deformation, seepage frost, while lack of specific mathematical calculations for anti-freezing. Thispaper has done the following work based on analyzing and summarizing the extensive literature:(1)Discussed the mechanism and influencing factors of frost heave of the soil. Analyzed thedestruction characteristics of various forms of channels and summarized the basic measures of canalseepage anti-frost.(2)For composite lining channels of films combined with concrete of trapezoidal, arc bottomtrapezoidal and U-shape cross-section, build the mechanical model of frost heave of compositeimpermeable lining channel from the practical engineering and according to the basic laws of frost heave.Gave the formula of internal forces and cracking checking, and checked the thickness. Calculation showsthat the composite lining form of geomembrane combined with the concrete, compared with the plainconcrete lining form, the effective frost heave force of three canals of different cross-section were reducedby4.9%,2.6%,7.7%;the effective tangential binding were reduced by11.3%,7%,19.2%;the channel slopeplate tensile stress decreased by16.7%,3.9%,8%;the bottom tensile stress decreased by6.1%,4%,7.5%.Itproved that the composite lining is beneficial to anti-seepage channels heave from the mechanical point.(3)Using the ANSYS finite element analysis software, simulated the heaving of composite liningchannels of trapezoidal, arc-bottom trapezoidal and U-shape cross-section and analyzed the temperaturefield, stress field and deformation field. Temperature field contours parallel with the lining board. Thedisplacement maximum value is in the top of the slope plate. For trapezoidal, The stress value is larger atthe junction of slope plate and bottom plate; for arc bottom trapezoidal, the stress value is larger at curvebottom; and for U-shape, the stress value is larger at curve bottom. The stress, deformation values of shadywere greater than sunny. The simulation results consistent with the actual heaving situation. It verified themechanical analysis and revealed the mechanism of frost heave. By comparing and analyzing the software simulation results and mechanical model results, thedistribution of frost heaving force and the law of the frost heave are consistent. The heaving damage ofchannel occurred under water, temperature, soil and other factors working together. Simplified mechanicalmodel and finite element simulation method presented in this paper is feasible. It has practical significancefor the further applications of the composite lining channel. |
PDF Full Text Request