Analysis on vertical bearing behavior of convex concrete-cored DCM piles and pile shape optimization

To accurately simulate interaction between concrete-cored DCM piles and soil mass and solve the problem of insufficient calculation accuracy of existing simulation analysis methods due to the influence of contact interface thickness, a three-dimensional thickness-free cohesive interface element was developed based on Python language, and the pile-soil interface was embedded in the ABAQUS platform.At the same time, the reliability of this simulation method was verified by combining the in-situ pile foundation test data.Based on the foundation reinforcement project of the soft soil layer of the Zhuhai-Zhaoqing High-speed Railway, the bearing capacities of the convex-shaped concrete-cored DCM piles with different design parameters were analyzed to determine the optimal design scheme.The results show that:(1) The calculation results of the pile-soil model embedded with the thickness-free cohesive force elements are in good agreement with the test results;(2) The optimal shape of the convex-shaped concrete-cored DCM pile is diameter ratio of 1:1.2 and the length ratio of 0.722;(3) The unconfined compressive strength of the cement soil of the outer pile of the convex-shaped concrete-cored DCM pile should not be less than 1.5MPa;(4) It is appropriate to use C20 concrete for core piles.The relevant conclusions can provide a reference for the soft soil treatment problems encountered in the construction of hydraulic structures.