Abstract
The caisson foundation of the No.29 main pier of Shanghai-Nantong Yangtze River Bridge has a large range of sand gushing, not only the foundation of the caisson is inclined, but also the sand layer of the base of the caisson and the side wall of the caisson has been greatly disturbed. The bearing capacity of basement soil is reduced, and the compressive modulus of soil is reduced obviously. How to determine the extent of the disturbance, the degree of disturbance and the mechanical parameters of the disturbed soil layer is the key to how to control the subsequent construction deformation. The relationship between the compression modulus and the compression modulus is established by numerical simulation of the lateral loading test process, and the mechanical parameters of the disturbed sand layer are determined. It provides reasonable and reliable calculation parameters for analyzing the attitude change of the No.29 main pier under the construction load in the later stage.
The No.29 main pier of Shanghai-Nantong Combined Highway and Railway Bridge is a rectangular caisson foundation, the caisson plane size is 86.9 meters in length and 58.7 meters in width, the height of the caisson is 105 meters, and the top of the caisson elevation is positive 8 meters, the cutting edge of the caisson elevation is negative 107 meters. When the cutting edge of the caisson sank to negative 102.5 meters, the bottom of the caisson has a large range of sand gushing. Not only the foundation of the caisson is inclined, but also the sand layer of the base of the caisson and the side wall of the caisson has been greatly disturbed. The bearing capacity of basement soil is reduced, and the compressive modulus of soil is reduced obviously. It will directly lead to the larger uneven settlement of the No.29 main pier under the later construction load, which will cause great influence on the subsequent construction of the main pier. Therefore, it is necessary to find out the extent of the disturbance and the degree of disturbance in the base layer of the caisson, and to determine the mechanical parameters of the disturbed soil layer.
