Studies On Channel Damage Mechanism And Its Prevention Measures In Tarim Irrigation

This article takes the existing canals in Tarim irrigation as the research object, selecting typical and representative canals first, fielding monitor changes in temperatures during the test process, ground temperature, frost depth and soil moisture changes, determining changes of the items with time and space, analyzing the reasons and main factors causing canal damage, eventually proving the basic law of frost damage. On this basis, with special temperature, moisture and soil conditions in irrigation, this article presents reasonable assumption and simplification, and the mechanical analysis and load calculation were done. Finally, integrating the results of field monitoring and the results of mechanical analysis, and referencing the successful engineering design at home and abroad, proposing some anti-freezing bilge measures which are suitable for popularizing and applying in the irrigation. The results of the study show that:(1)In Tarim irrigation, the winter is long, temperature decreased slowly and negative temperature has long duration. Generally, its temperature characteristics showed large temperature difference between day and night, temperatures at night is low but the change is stable, with the sunrise or sunset during the day and the start of increase or decrease rapidly.(2)As scarce precipitation in Tarim irrigation and most of the channels not used in winter, soil moisture content before freezing maintained at between 15%～25%, most of the drainage channels in the freezing process-based soil moisture migration is mainly the strength of the frost level play a decisive role.(3)Channel base soil surface temperature in one day to see a maximum value and a minimum value, and generally, soil temperature gradually increased with depth, but the magnitude of diurnal variation of soil temperature decreased with the increase in depth.(4)According to temperature, moisture and soil conditions in Trim irrigation, improved and revised assumptions and formulas. For example, as the distance between channel base layer and groundwater become the main factor influencing the intensity of frost heave, in the calculation of channel slope constraint forces and internal forces of moment, this article doesn't neglect the bending moment caused by slope plate tangential force. Accordingly, the value of bending moment in the junction between channel slope plate and channel floor is zero, also proved that the channel bottom slope board and simplify the complex interactions hinge end of the treatment is reasonable.(6)For the integrity of the small size trapezoidal channel better than of the big size one, this article presents a method to determine the point of the frost heaving forces on slope plate. As a example, the mechanical analysis and load calculation for the main channel named qiagelake were done. The results show that the maximum bending moment away from the channel bottom slope sheet about 1/3 of the slope plate strength, the normal freezing point of force plate channel slope away from the top 1/3 of the slope plate strength.