Abstract The suction drain is a novel concept for low-carbon temporary ground stabilisation in clayey soils alternative to jet grouting and ground freezing. Boreholes are drilled into the ground and air is injected to the borehole end through a delivery pipe. The air flowing through the gap between the pipe and the borehole surface backward towards the borehole entry removes water by evaporation and, hence, increases the undrained shear strength of the soil surrounding the drain. There are no studies that allow quantifying soil water evaporation generated by tangential airflow for the case of ‘wind tunnel’ only a few centimetres high over an evaporating surface a few meters long. This paper first presents an experimental investigation on water evaporation induced by air flow. A 3 m long wet surface was subjected to tangential air flow into a 40 mm gap. Tests were carried out by considering different air velocities and inlet air relative humidities. A model was then formulated to quantify the water evaporation rate for any length of the wet surface. The model parameters were calibrated against one experimental dataset and the model was then validated against an independent dataset. Finally, an empirical equation is proposed to estimate model parameters without the need of carrying out experimental tests. This is based on the vapour transfer coefficient established empirically for evaporation from open water (external air flow), which was found to remain valid for confined evaporation (internal air flow). The paper therefore provides a tool to estimate airflow-induced evaporation to successfully design the suction drains.

中文翻译：

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蒸发引起的土壤水通量设计用于低碳地面稳定的吸水排水管：实验研究和建模

摘要 抽吸排水管是一种替代喷射灌浆和地面冻结的黏性土壤中低碳临时地面稳定的新概念。钻孔进入地下，空气通过输送管注入钻孔端。通过管道和钻孔表面之间的间隙向后流向钻孔入口的空气通过蒸发去除水，因此增加了排水管周围土壤的不排水剪切强度。对于在几米长的蒸发表面上只有几厘米高的“风洞”，没有研究可以量化切向气流产生的土壤水分蒸发。本文首先对空气流动引起的水分蒸发进行了实验研究。3 m 长的湿表面受到切向气流进入 40 mm 的间隙。通过考虑不同的空气速度和入口空气相对湿度来进行测试。然后制定一个模型来量化任何长度的湿表面的水蒸发率。针对一个实验数据集校准模型参数，然后针对独立数据集验证模型。最后，提出了一个经验方程来估计模型参数，而无需进行实验测试。这是基于经验为从开放水域（外部空气流）蒸发而建立的蒸汽传递系数，发现该系数对受限蒸发（内部空气流）仍然有效。