多年冻土路堤水平排水板的作用机理与试验研究

为了解决青藏高原的冻土浅层雨季雨水下渗和蒸发所产生的冻土冻胀与融沉问题,在青藏高原开展水平排水板结构性路基和普通通风路基的原位模型对比试验,并从理论上探讨水平排水板在多年冻土路基中浅层重力排水和结构加劲的作用机理,确定水平排水板的铺设参数;运用光纤监测技术对水平排水板在多年冻土路基中的变形进行监测,对比分析水平排水板铺设与否这2种条件下冻土路基变形监测结果.研究结果表明:铺设水平排水板缩短了冻胀变形的冻结期,延长了相对稳定的稳定冻结阶段,减小了冻胀变形范围和冻胀变形;在铺设水平排水板的路基段,最大融沉变形为3.7 mm,累计最大冻胀变形为5.7 mm,而在未铺设水平排水板的试验路基段,最大融沉变形为3.1 mm,累计最大冻胀变形为9.2 mm.水平排水板在冻土路基工程中,可以有效控制雨水量在路堤下的下渗,减小雨水下渗量所带来的多年冻土路基的冻胀变形.

Test and mechanism of horizontal plastic drain in permafrost regions embankment

In order to solve the frost heave and thaw settlement, the model tests were made in Tibetan Plateau. Two kinds of model were designed to horizontal drain structure embankment and the ventilation embankment in suit. The effect of horizontal plastic drain was analyzed in contrast with the ventilation embankment. The mechanisms of horizontal plastic drain were studied in permafrost, such as gravity draining in the superficial layer and structure stiffing in the embankment in the theory. According to the design theory, the parameters of horizontal plastic drain were confirmed in the embankment. The values of deformation were inspected by fiber monitor system in the permafrost embankment. The results show that the time of the frost heave is shortened, the time of relatively steady freeze is prolonged. From the deformation, the range and value of the frost heave are decreased. In the embankment of the horizontal plastic drain, the max value of thaw settlement is up to 3.7 mm, and the cumulative value of the frost heave is up to 5.7 mm. To the contrast embankment, the values are 3.1 and 9.2 mm respectively. It is indicated that the rainfall seepage is controlled to the embankment in superficial layer, the influence of precipitation and evaporation are weaken, the deformation values of the frost heave are decreased in the horizontal plastic drain embankment.