Retaining structures above groundwater level support soils that are usually in a state of partial saturation and subject to the actions of atmospheric agents. The current design approach considers the possible extremes of soil conditions – either totally dry or totally saturated – but it neglects matric suction’s contribution to soil shear strength. This work aims to describe how unsaturated-soil mechanics of can positively influence the sustainability of retaining structures through a holistic, multidisciplinary, geotechnical, and environmental analysis. The geotechnical analysis allows to estimate the lateral earth pressure of a geostructure in both unsaturated and extreme soil conditions (dry or saturated), which will directly influence the geometrical dimensions of the geostructure. Next, the environmental analysis is performed with the standardized and globally applied Life Cycle Assessment (LCA) tool, in order to quantify the potential environmental impacts of the retaining structure according to both a life cycle and a multi-criteria perspective. First, an LCA model is built for a cantilever retaining wall according to two design approaches: (a) an unsaturated design approach (UDA), i.e. when unsaturated soils’ principles are considered in the design procedure, and (b) a conventional design approach (CDA), i.e. if soil is considered dry or saturated. Three different types of retained soil (i.e. fine-grained soil, volcanic ash, and coarse-grained soil) are considered. Then, the associated environmental impacts on climate change, human health, ecosystems and resources are calculated for the two design approaches. Their comparison allows to quantify the potential reductions in environmental damages provided by the adoption of unsaturated-soil mechanics. The presented case study shows a high potential reduction in environmental impacts for retaining walls interacting with fine-grained soils (silt), lower potential environmental benefits with volcanic ash (clayey–silty sand), but no environmental gain for interaction with a coarse-grained soil (sand) compared to a conventional design approach considering extreme soil conditions.

地下水位以上的挡土结构支撑着通常处于部分饱和状态并受到大气因素作用的土壤。目前的设计方法考虑了土壤条件的可能极端情况——完全干燥或完全饱和——但它忽略了基质吸力对土壤剪切强度的贡献。这项工作旨在描述非饱和土力学如何通过整体、多学科、岩土工程和环境分析对挡土结构的可持续性产生积极影响。岩土工程分析允许估计非饱和和极端土壤条件（干燥或饱和）下地质结构的侧向土压力，这将直接影响地质结构的几何尺寸。下一个，环境分析使用标准化和全球应用的生命周期评估 (LCA) 工具进行，以便根据生命周期和多标准视角量化挡土结构的潜在环境影响。首先，根据两种设计方法为悬臂式挡土墙建立 LCA 模型：(a) 非饱和设计方法 (UDA)，即在设计过程中考虑非饱和土的原则，以及 (b) 常规设计方法(CDA)，即如果土壤被认为是干燥的或饱和的。考虑了三种不同类型的滞留土（即细粒土、火山灰和粗粒土）。然后，计算两种设计方法对气候变化、人类健康、生态系统和资源的相关环境影响。他们的比较可以量化采用非饱和土力学对环境损害的潜在减少。所提出的案例研究表明，挡土墙与细粒土壤（淤泥）相互作用可以大大降低环境影响，火山灰（粘土-粉砂）的潜在环境效益较低，但与粗粒土壤相互作用没有环境收益与考虑极端土壤条件的传统设计方法相比。