密贴大断面顶管施工对既有车站及反顶装置安全影响OA

With the rapid development of the urban economy and the continuous expansion of rail transit networks,the demand for transfer passage construction has surged,while challenges such as significant ground disturbance and high costs are increasingly prominent.Based on the No.1 Underground Transfer Passage Project at Wangjing West Station in Beijing,a refined three-dimensional finite element model was established to systematically analyze the deformation behavior of the existing station under different jacking forces and the stress response of the reaction frame under the maximum jacking force.Targeted construction control measures were then proposed,and a comprehensive monitoring scheme covering the diaphragm wall,intermediate slab,and reaction frame was developed.Using field monitoring data,the deformation and stress evolution of the existing station and the reaction-jacking devices were revealed.The results show that,owing to its high structural stiffness and benefiting from the isolation effect of the back wall on the new construction,the existing station exhibits small overall horizontal deformation,characterized by a"bulging"pattern.Under a relatively small jacking force,the horizontal deformation increases significantly,whereas the growth slows down as the jacking force increases further.A safety analysis of the reaction-jacking system indicates that the structural stress,weld shear strength,and bolt shear strength all meetcode requirements;however,an obvious tensile stress concentration zone exists at the bolts located at the intersection of the diagonal and horizontal members of the reaction frame,constituting a structurally weak point.Therefore,a scheme of adding connecting bolts is proposed to enhance system reliability.Increasing the number of reaction frames can effectively reduce horizontal displacement,but the reduction becomes marginal when three or more frames are employed.