Abstract The most common soil reinforcement methods used in tunnelling, such as jet grouting, fiberglass reinforcement and ground freezing, leave spoils into the ground and have high costs of implementation. On the other hand, preloading methods for soils improvement require long construction periods and limit the enhancement of the undrained shear strength to the applied surcharge load or vacuum load. This paper presents the concept of suction drain as an innovative technique for temporary stabilisation of geostructures in soft clayey soils, which overcomes the inconvenience of current soil reinforcement techniques and the limitation of the preloading. Based on suction generated in the ground by the evaporation from pre-drilled holes, the suction drain enables the enhancement of the undrained shear strength in soft clayey soils. The concept and its validation at mock-up scale level are presented in this study. The experimental investigation assessed the capacity of the suction drain to reduce the soil water content via soil water evaporation induced by forced ventilation. The mock-up scale test was then validated numerically via FEM modelling. Finally, the suction drain modelling was extended to an ideal case of tunnelling for assessing the potential impact of the suction drain on undrained shear strength and, hence, on tunnel face stability.

中文翻译：

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吸排水作为一种低碳地面改良技术：实验室规模的概念验证

摘要 隧道掘进中最常用的土壤加固方法，如喷射灌浆、玻璃纤维加固和地面冻结，将弃土留在地下，实施成本高。另一方面，用于土壤改良的预压方法需要较长的施工周期，并且将不排水抗剪强度的增强限制为施加的超载载荷或真空载荷。本文提出了吸水排水的概念，它是一种在软粘土中临时稳定地质结构的创新技术，它克服了当前土壤加固技术的不便和预加载的局限性。基于预钻孔蒸发在地下产生的吸力，吸水排水管可以增强软粘土的不排水抗剪强度。本研究介绍了该概念及其在模型规模级别的验证。实验研究评估了抽吸排水管通过强制通风引起的土壤水分蒸发减少土壤含水量的能力。然后通过 FEM 建模对模型规模测试进行数值验证。最后，吸水口模型扩展到隧道开挖的理想情况，以评估吸水口对不排水剪切强度的潜在影响，从而对隧道掌子面稳定性产生影响。