Horizontal Bearing Capacity of Closely-spaced Row-piles Based on Microscopic Microstructure of Soft Soil
The frame-fixed soldier pile structure (FSPS) is a new cofferdam structure of artificial island, with a notable feature of closely-spaced row-piles. Microstructure of soft soil has a significant effect on macroscopic physical quantities. The relationship between microstructure deformation characteristics of soft clay and shear strength index of soil was established by scanning electron microscope (SEM) test. Based on the subgrade reaction approach, a plane pole system finite element model (PPSFEM) was established to study displacement and internal force distribution along pile of FSPS under lateral load. The “load migrating” process was considered in the model that partial lateral load would transfer from rear pile to front pile via interior soil as interior soil reached the ultimate state. Study on how these factors affect the distribution of horizontal displacement and internal forces along pile has been performed through PPSFEM, including constraint form between frame structure and pile, m-values of subsoil and backfilling materials. The shear strength index of soil is significant affected by the microstructure. Parameter analysis indicates that the frame structure improves internal force distribution of pile foundation, that the feature of separated piles decreases the horizontal soil resistance of front pile, and that the articulated constraint form between pile and underpart of framework benefits to reduce the maximum bending moment of pile.