Effects of embedded walls on tunnelling-induced sandy ground displacements: a numerical investigation

Urban tunnelling projects pose significant risks to the integrity of nearby structures due to ground movements induced by the excavation process. Embedded walls are commonly employed as a protective measure to mitigate these adverse effects. This paper presents a comprehensive numerical investigation into the effects of embedded walls on tunnelling-induced ground displacements, aiming to provide insights and recommendations for optimal embedded wall design. The study assesses the impact of varying embedded wall length and horizontal distance from the tunnel on soil settlement and horizontal displacements. Results demonstrate the complex interplay between embedded wall length, horizontal distance and ground movement patterns, and the highly non-linear influence of key parameters on embedded wall efficiency (i.e. its ability to reduce settlements). A preliminary design chart is proposed to guide engineers in determining the appropriate horizontal location and depth of embedded walls to effectively reduce tunnelling-induced ground displacements. The findings contribute to a better understanding of embedded wall performance in the context of tunnelling and provide valuable guidance for the practical design and implementation of protective measures in urban areas.