In foundation pit engineering supported by “diaphragm walls with internal supports”, joint leakage frequently occurs. Existing studies often attribute leakage causes to joint quality defects while neglecting the impact of joint dislocation induced by support axial forces. Large-scale field tests and numerical simulations were performed to investigate the formation mechanism and development process of joint dislocation at the Yijing Road Station project of Tianjin Metro Line 11. On-site monitoring was conducted, and displacement patterns were analyzed. Results reveal that significant dislocation exists at joints, with maximum vertical displacement reaching 15 mm along diaphragm wall depth. This phenomenon primarily stems from differential deformations between adjacent diaphragm wall panels caused by asynchronous installation of corresponding supports. The deformation in panels with delayed support installation increases by 25%~50% compared to those with simultaneous support installation. Furthermore, the sequencing of support loading demonstrates measurable effects on joint dislocation characteristics. Based on these findings, an optimal erection scheme is proposed regarding the quantity and positioning of locally delayed supports for dislocation mitigation. Two process control measures are recommended: adjusting pre-applied axial forces on adjacent supports and timely installation of lower-level supports. These countermeasures effectively reduce joint dislocation through coordinated deformation control during construction phases.