Calculation Method of Horizontal Displacement of Diaphragm Wall in Deep Foundation Pit during Internal Support Removal

The maximum horizontal displacement of underground diaphragm wall of deep foundation pit usually occurs in the internal support removal stage. Based on the superposition principle of elastic deformation, the horizontal displacement increment of the diaphragm wall is considered as the superposition of free deformation and compensation deformation. The contact point between the bottom plate and the diaphragm wall is considered as the fixed end. Then the variation rule of the horizontal displacement of the diaphragm wall is obtained by the limit equilibrium method. Finally, the horizontal displacement increments of the underground diaphragm wall at different stages of dismantling the bracing are calculated and analyzed against the background of two examples of deep foundation pit projects——the deep foundation pit engineering of "underground continuous wall + steel bracing" in Sanyuan Bridge station of Beijing Metro Line 12 and "underground continuous wall + reinforced concrete internal bracing" in Xiaguangli, Chaoyang District, Beijing. The results show that: The horizontal displacement curve of the diaphragm wall obtained by the established method is in good agreement with the measured curve. The horizontal displacement increment of the diaphragm wall is 2~5 times larger than that of the bottom. The maximum horizontal displacement of the diaphragm wall moves up in the process of bracing removal, with an upward displacement of about 0.15H ~ 0.2H. The results can provide important theoretical reference for similar projects.