Abstract Subsurface drains, when installed in non-cohesive soil, are typically covered with an envelope to tackle problems of clogging and siltation. Selecting a suitable envelope material, however, is complicated and depends primarily on soil characteristics in the area where the drains are to be installed. A new promising drainpipe-envelope concept, Hydroluis, has been developed which the designers claim works in a wide range of soils. The Hydroluis drainpipe consists of a corrugated inner pipe with three rows of perforations at the top and an unperforated outer pipe that covers the top two thirds of the inner pipe. We analysed the hydraulic and filter functions of this new drainpipe in a soil tank laboratory model with a saline-sodic problem soil from south-western Iran and compared Hydroluis performance with that of a locally-manufactured synthetic envelope material (PP450). The silty clay soil used in this study was 40 % clay, with a plasticity index (IP) of 16.9 and an exchangeable sodium percentage (ESP) of 60.4 %. The Hydroluis drainpipe clogged during the first two weeks of the test due to invasion of the test soil into the space between the inner and outer pipes. Of the substantial volume of sediment that entered the Hydroluis inner pipe, 38 % removed from the pipe in the first day. In contrast, the PP450 drainpipe showed good hydraulic and filter functions, entering very little sediment to drainpipe during the entire test period and stabilizing at drainage rate of 28 mm/day and entrance resistance of 55 days/m, at around day 50. Our analyses suggest that the clogging and poor drainage function of the Hydroluis drainpipe was caused by the higher flow velocity (21.5 times higher) at the soil-envelope interface of the drainpipe, in addition to the lower Hydroluis drainpipe’s soil retention capacity (18 times lower) compared to the PP450 drainpipe. Assuming Stokes’ Law governs filter function, the results of Hydroluis design evaluation also suggest that in stable soils, very fine sand or coarser soil particles (D > 0.05 mm) place no serious limitations for Hydroluis drainpipe application, whereas the current design is unsuitable for filtering fine silt particles (0.002

中文翻译：

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Hydroluis排水管-信封系统在盐碱土中的性能评价

摘要 当安装在非粘性土壤中时，地下排水管通常覆盖有一个信封，以解决堵塞和淤积的问题。然而，选择合适的围护材料很复杂，主要取决于要安装排水管的区域的土壤特性。一种新的有前途的排水管信封概念 Hydroluis 已经开发出来，设计师声称它适用于各种土壤。Hydroluis 排水管由顶部有三排穿孔的波纹内管和覆盖内管顶部三分之二的无孔外管组成。我们在土壤罐实验室模型中分析了这种新型排水管的液压和过滤功能，该模型具有来自伊朗西南部的盐碱问题土壤，并将 Hydroluis 的性能与当地制造的合成外壳材料 (PP450) 的性能进行了比较。本研究中使用的粉质粘土为 40% 粘土，可塑性指数 (IP) 为 16.9，可交换钠百分比 (ESP) 为 60.4%。由于测试土壤侵入内外管道之间的空间，Hydroluis 排水管在测试的前两周堵塞。在进入 Hydroluis 内管的大量沉积物中，第一天就从管道中去除了 38%。相比之下，PP450排水管表现出良好的液压和过滤功能，在整个试验期间进入排水管的沉积物很少，在第 50 天左右稳定在 28 毫米/天的排水速率和 55 天/米的入口阻力。我们的分析表明 Hydroluis 排水管的堵塞和排水功能差是由排水管的土壤-包络界面处更高的流速（高 21.5 倍）引起，此外与 PP450 排水管相比，Hydroluis 排水管的土壤保持能力较低（低 18 倍）。假设斯托克斯定律支配过滤器功能，Hydroluis 设计评估的结果还表明，在稳定的土壤中，非常细的沙子或较粗的土壤颗粒 (D > 0.05 mm) 对 Hydroluis 排水管的应用没有严重限制，而当前的设计不适合过滤细泥沙颗粒 (0.002 我们的分析表明，除了 Hydroluis 排水管的土壤保持能力较低（低 18 倍）之外，Hydroluis 排水管的堵塞和排水功能差是由于排水管的土壤-包络界面处的流速较高（高 21.5 倍）造成的。 ) 与 PP450 排水管相比。假设斯托克斯定律支配过滤器功能，Hydroluis 设计评估的结果还表明，在稳定的土壤中，非常细的沙子或较粗的土壤颗粒 (D > 0.05 mm) 对 Hydroluis 排水管的应用没有严重限制，而当前的设计不适合过滤细泥沙颗粒 (0.002 我们的分析表明，除了 Hydroluis 排水管的土壤保持能力较低（低 18 倍）之外，Hydroluis 排水管的堵塞和排水功能差是由于排水管的土壤-包络界面处的流速较高（高 21.5 倍）造成的。 ) 与 PP450 排水管相比。假设斯托克斯定律支配过滤器功能，Hydroluis 设计评估的结果还表明，在稳定的土壤中，非常细的沙子或较粗的土壤颗粒 (D > 0.05 mm) 对 Hydroluis 排水管的应用没有严重限制，而当前的设计不适合过滤细泥沙颗粒 (0.002 此外，与 PP450 排水管相比，Hydroluis 排水管的土壤保持能力较低（低 18 倍）。假设斯托克斯定律支配过滤器功能，Hydroluis 设计评估的结果还表明，在稳定的土壤中，非常细的沙子或较粗的土壤颗粒 (D > 0.05 mm) 对 Hydroluis 排水管的应用没有严重限制，而当前的设计不适合过滤细泥沙颗粒 (0.002 此外，与 PP450 排水管相比，Hydroluis 排水管的土壤保持能力较低（低 18 倍）。假设斯托克斯定律支配过滤器功能，Hydroluis 设计评估的结果还表明，在稳定的土壤中，非常细的沙子或较粗的土壤颗粒 (D > 0.05 mm) 对 Hydroluis 排水管的应用没有严重限制，而当前的设计不适合过滤细泥沙颗粒 (0.002