English：

With the continuous increase in urban road traffic, pedestrian underpasses play an importantrole in ensuring pedestrian crossing safety and alleviating surface traffic pressure. Based on the EastPedestrian Underpass of the Huanghe Bridge in Chengguan District, Lanzhou, a three⁃dimensionalnumerical model was established using the FLAC3D finite difference software to investigate the surfacesettlement characteristics, stress state of the support structures, and deformation response of a loop⁃shaped pedestrian underpass during construction. The results indicate that based on the CRD constructionmethod, surface settlement generally exhibits a distribution pattern centered on the tunnel axis andgradually decreasing toward both sides. Continuous settlement influence zones are formed above eachmain passage, with the influence range mainly concentrated between 16 and 18m. The tunnel intersectionareas are the regions where the stress and deformation responses of the support structures are mostconcentrated. Stress concentration mainly occurs at the upper corner positions where the crown intersectsthe sidewalls, with a maximum compressive stress of 40.1kPa and a maximum tensile stress of 134kPa.Meanwhile, structural deformation is most pronounced at the intersections of the main passages, with amaximum deformation of 19.1mm. Under shallow⁃buried conditions, when the CRD method is adoptedfor the construction of loop⁃shaped pedestrian underpasses, the tunnel intersection areas should beregarded as key zones for deformation control. The overall structural stability can be improved byreasonably controlling the excavation step length and strengthening temporary supports.