季节性冻土区管道浅埋换填防冻模式研究

输水管道是节水灌溉工程建设的重要组成部分,管道铺设模式不仅直接影响到节水灌溉工程的投资和施工进度,同时还影响工程的直接效益和使用寿命。本文中通过在低温实验室进行PE管浅埋模型试验,获得了不同管道埋深、保温措施、回填措施和换填措施等条件下管道内温度和管道变形的动态变化过程。试验结果表明:不同换填措施、保温措施对管道内温度影响不大,而管道埋深和回填措施对管道内温度影响显著,适当增加管道埋深,管内温度升高,EPS轻质土回填的保温效果好于珍珠岩散料轻质土回填措施。在管道变形方面,炉渣换填措施略优于砂土换填措施,适当增加管道埋深,管道变形明显减小。与设置换填措施、回填措施和保温层的复杂工况处理相比,采用炉渣换填和回填措施的裸管,可以达到较好的防冻效果。综合考虑冻土区机械耕作等需要和防冻措施的经济可行性,推荐80 cm埋深的炉渣换填回填模式作为季节性冻土区(冻深2.3 m)PE管道的浅埋模式。

Research on anti-freezing pattern of shallow buried pipe by replacement filling of pipe trench in seasonal frozen area

Pipeline is an important part of water-saving engineering in well irrigation area. The laying mode of pipelines will directly affect investment and construction progress of water-saving engineering, and have significant influence on its efficiency and service life directly. A series of shallow buried pipeline ex-periments was conducted in a low temperature laboratory in the paper, temperature in pipelines and pipe deformations were obtained dynamically in a cycle of freezing and thawing condition. The influences of dif-ferent pipeline buried depth, heat preservation measures, replacement filling on pipe working condition were analyzed through comparative study. As for temperatures in pipe, deep replacement mode and heat preservation facilities had little effect on the temperatures within pipelines, while buried depth and backfill-ing measures temperature had significant influence on the internal temperatures of pipelines. The internal temperatures were increased when pipelines are buried deeper. The heat preservation function of EPS light-weight soil was better than that of pearlite powder mixed soil. In terms of pipeline deformation, the perfor-mance of deep replacement via slag was superior to that of similar measurement by sand. Pipe deformation decreased obviously after increasing pipeline buried depth. Compared with working condition of complex pro-cessing, replacement measures of pipe trench by slag could be achieved similar anti-freezing effect. In view of machinery needs and the operability of anti-freezing measures,the paper recommended 80 cm pipe buried depth and slag replacement in pipes where the frozen depth is less than 2.3m.