Dynamic Simulation And Safety Performance Evaluation Of The Construction Process Of The Anchorage Caisson Foundation

With the development of China's economy,large and extra large-scale suspension bridges appear more and more in the urban transportation infrastructure.As the basic component and bearing unit of the suspension bridge,the mechanical properties and the safety monitoring of the construction process are the focus and hotspot of the research at home and abroad.Since the caisson will cause disturbance and settlement of the surrounding soil,it is necessary to analyze not only the mechanical characteristics and stress-strain distribution of the caisson during the caisson construction,but also the influence of its subsidence on the surrounding buildings,The dynamic process and safety performance of the construction need to be further evaluated.In this paper,based on the construction of anchorage caisson foundation of Jiangjin Zhongdu Yangtze River Bridge in Chongqing,the construction process of caisson foundation is simulated by using finite difference method.(1)during the sinking of the sinking of the basement of the excavation of the soil and the sinking of the self-weight sinking,the foundation soil is unloading-the constant cycle of loading.In the initial stage,the maximum vertical stress and the maximum horizontal stress are 0.999 MPa and 0.252 MPa respectively.The stress ratio is close to the soil Poisson's ratio.The stress increases with the increase of gravity.There is no obvious stress concentration region(band)in the whole calculation process,which indicates that the calculation model and calculation process are reasonable.(2)The stress distribution of the sidewall of the open caisson has regular regularity in the whole subsidence process.The initial lateral friction is small and the vertical stress is controlled by the gravitational field,which gradually increases from the top to the bottom.But with the subsidence continuing,The maximum vertical stress area on the sidewall of the open caisson is transferred from the lower part to the middle part,which indicates that the gravity transfer to the subsoil is weakened in the lower part of the caisson structure,and the relatively high stress area in the middle part is the sink The horizontal stress contours of the caisson structure show a uniform distribution from the beginning to the end,which indicates that there is no obvious inclination of the sunk well in the process of self-weight subsidence,which is beneficial to the engineering development.(3)During the subsidence of the caisson construction,the deformation of the foundation soil around the sidewall of the caisson is the most affected by the caisson.When using the high-pressure jet grouting pile program,the maximum settlement near the sidewall of the caisson is 132.62mm;when using the bored pile program,the maximum settlement of the foundation soil is 95.16mm;The maximum settlement of the foundation soil of the side wall exceeds 200.00 mm.From the point of view of construction safety,it is suggested to use the drilling and pouring isolation pile program.