<p>The study examines the collapse incidence that occurred with the steel sheet pile and the subsequent displacement of the Lahoun Regulator retaining wall. The primary objective is to numerically analyze the cantilever secant-pile wall's behavior in supporting the soil behind the Larsen type III retaining wall at the failure site. Accurate forecasting and controlling ground displacement during excavation, especially in soils lacking cohesion, is essential to avert overall instability and catastrophic collapses. The main factors that primarily affect the lateral earth pressure and ground movement characteristics are the soil qualities, excavation depth, excavation plan geometry, supporting wall stiffness, and inter-pile bonding within the secant wall structure. A PLAXIS finite element model was created to predict the behavior of the soil and wall geometry accurately. This study evaluates the effects of different soil layers with constant thickness, varying pile lengths, and different spacing from an existing retaining wall. The findings provide insights into optimization strategies and performance characteristics relevant to structural stability. The secant-pile wall efficiently reduces both horizontal and vertical movements of the new curtain wall, guaranteeing a satisfactory safety level for the nearby road infrastructure after it is installed.</p>