Abstract: To achieve precise control of horizontal soil displacement in beam string structures, the influences of factors such as waling thickness, strut width and spacing, and excavation depth on active displacement control are comprehensively considered. The Heaviside function is introduced to characterize the concentrated load response of the struts, thereby circumventing the difficulties of excessive segmentation and complex boundary conditions in model development. Subsequently, the Laplace transform is employed to solve the higher-order governing differential equations, and a coupled mechanical model integrating the beam string structure and Timoshenko beam theory is established. An analytical solution model for active displacement control, applicable to various soil parameters and beam string structural configurations, is derived, and unified explicit expressions for the shear-force, bending-moment, and displacement equations are formulated. Validation against an engineering case shows that the discrepancy between the measured data and the model predictions is 8.74%. Parametric analysis reveals that altering the strut width reduces the maximum horizontal displacement by 47.5%, and for a 16 m-span beam string structure, a strut spacing of 4~6 m yields optimal displacement control performance.