Model Test Study Of Bonding Forces Between Double-Wall Steel Cofferdam Base Sealing Concrete And Steel Pipe Pile

Since the construction of the Jiujiang Yangtze River Bridge in 1985,the construction of the double-wall steel cofferdam as an important means of deepwater foundation construction has been widely used.The Double-wall steel cofferdam as a retaining structure,because of its double-wall structure and the back cover concrete together to withstand the great water pressure,and the circular cofferdam without support for the pile foundation construction can provide a broad operating space,plus On its own structure is simple,making and assembling are very convenient,so it has a high safety and applicability,which is widely used.This paper relies on the research and preparation of the "Double Wall Steel Cofferdam Design and Construction Safety Technology Guide" and the Chongqing Local Standard "Double Wall Steel Cofferdam Design and Construction Safety Technical Regulations",in order to obtain double wall steel Cohesive backfill concrete and steel casing between the reasonable value of the cohesive force range,especially for double-wall steel cofferdam back cover concrete and steel casing cohesive force model test study.The main work done and the results achieved are as follows:(1)The double-wall steel cofferdam and its advantages are summarized,and its development and research status are analyzed.(2)The whole process of double wall steel cofferdam structural design and construction is introduced.The design steps,the structure of the cofferdam and the important problems in the design are explained,and the design and calculation of the double-wall steel cofferdam of a bridge are analyzed as examples.The general method of cofferdam construction is described in detail.(3)The relationship between the composition of the adhesive force and the distribution of the bond force in the whole process of the bond slip is analyzed theoretically,Slip constitutive model and bond strength of the theoretical formula,and the factors affecting the bond strength were analyzed in detail.And to derive a reduction factor suitable for the adhesion between the back cover concrete and the steel tube.(4)The test model of the cohesive force of double-wall steel cofferdam and back cover concrete is designed.The influence factors of the test model and the influencing factors in the test are analyzed in detail to ensure the accuracy and feasibility of the test.And then carry out the test work.(5)The reasonable range of the bond force,the bond-slip curve and the bond strength along the height direction of the double-wall steel cofferdam and the back cover concrete are obtained by the experimental data analysis and the FEA simulation.And then the influence factors of the influencing factors were analyzed.So as to make suggestions on the value of cohesive force in practical engineering.The research results are the reference of Chongqing municipal standard "double wall steel cofferdam design and construction safety technical regulations",which can be used for reference of similar projects.