This study focuses on an “X”-shaped irregular excavation in Shanghai, presenting a detailed numerical analysis of the impact of the excavation on the surrounding area and the deflection of the retaining wall. By comparing computational outcomes with onsite observations, the research delves into the interaction between the excavation process and pre-existing underground structures within soft clay environments. The present findings reveal that proximate subsurface structures can mitigate retaining wall deflection and ground settlement by up to 30% within a distance ranging from 0.65 He to 1.0 He (He denotes the excavation depth). Furthermore, the intersection angle between the excavation site and the existing underground infrastructure significantly affects the excavation’s dynamics. Within areas influenced by these underground structures, the observed retaining wall deflection and ground subsidence were approximately 15-20% less compared to regions without such constraints.