Study on coaction of subsealing concrete and steel pipe pile for large steel suspension-box cofferdam

The coaction of subsealing concrete and steel pipe pile is the key technology for design and construction of a large steel suspension-box cofferdam. The strain of steel pipe and subsealing concrete was converted into the bond strength of their contact surface in this test. By monitoring of the relative displacement of subsealing concrete and steel pipe, the calculation parameters of contact surface were back analyzed and then used for 3D numerical analysis of the coaction of subsealing concrete and steel pipe, so that the average ultimate frictional strength of the contact surface was educed. According to the monitoring results, the maximum bond strength of subsealing concrete was 0.07?MPa before placement of bearing subsealing concrete. The numerical analysis indicated that the average unit friction was 0.28?MPa at the elastic stage and the local contact surface came to yield when the average unit friction was 0.37?MPa.