季冻区渠道湿干冻融离心模拟试验设备的研制

Development of centrifuge model test equipment for canals in seasonal frozen areas under cyclic action of wetting-drying and freeze-thaw

季节冻土占中国国土面积的一半以上,位于季冻区的渠道随着季节变换和通停水的周期变化,会经历湿润—干燥—冻结—融化(简写为湿干冻融或者WDFT)的循环过程,从而造成渠道结构的破坏。研制了一套可以在超重力场下模拟渠道湿干冻融反复作用的离心模型试验设备,该设备主要由干湿系统、热交换系统、模型箱、地面冷水装置和数据采集控制系统等组成。干湿系统主要包括水位升降装置、风干装置等,热交换系统包括半导体热交换装置、空气内循环装置等,模型箱采用内外双层隔热结构,地面冷水装置可以实现将30℃的常温水快速冷却至3℃~5℃以供热交换系统使用,数据采集控制系统包括干湿控制、热交换控制、数据采集分析等。该套设备可以实现在50g离心力场下渠道模型温度在-40℃~30℃之间,渠基土体湿度在干燥—饱和状态的准确控制,为季冻区渠道的渐进劣化破坏过程和机理研究提供了新的重要手段,并可推广应用到寒旱区的水利、交通等领域的工程科研当中。

Seasonal frozen soil accounts for more than half of China’s land area. The canals located in the seasonal frozen areas undergo a wetting-drying and freeze-thaw cycle with seasonal change and periodic change of water supply and suspension, thus causing damage to the canal structures. A centrifugal model test system which can simulate the cyclic action of wetting-drying and freeze-thaw under high gravity field is developed. The system consists of wetting-drying system, heat exchange system, sample model box, aboveground water cooler, data acquisition and control system. The wetting-drying system mainly includes the devices of rising and falling of water level and air drying. The heat exchange system includes the devices of semiconductor heat exchange and air internal circulation. The sample model box adopts double-layer heat insulation structure. The aboveground cooling water device can transfer the normal water of 30℃ to that of 3℃~5℃ for subsequent heat exchange system. The data acquisition and control system includes wetting-drying control, heat exchange control, data acquisition and analysis. The system can accurately control the model temperature between-40℃~30℃ and the moisture of soil in the drying-saturated state under a centrifugal force of 50 g. It may provide a new important means for investigating the progressive deterioration process and mechanism of canals in seasonal frozen areas, and it can be applied to engineering researches in the fields of water conservancy and transportation in cold and arid areas.