Research On Horizontal Pile-Soil Interaction Of Passive Piles Under Soft Soil Movement Action

Pile-soil interaction has been an important problem in geotechnical engineering. The majority of piles are designed to support "active" loadings, that is to say, loads from upper structure are directly transferred to the pile foundation by the cap. However, there are many cases in which the piles have to withstand so called "passive" loading, which are created by the deformation and movement of soil surrounding the piles due to the weight of soil and the supercharge. In this paper, the pile-soil horizontal interaction of "passive" piles is researched with the condition of soft soil movement and based on the practical engineering. By using the Finite Element Method (FEM), the nonlinear behaviors of soil's plasticity, high strain and pile-soil contact are considered. In order to deeply understand the distribution of soil pressure acting on the pile-soil interface, transversal plane strain analysis of pile-soil interaction of "passive" piles is firstly performed in the paper, and then a great deal of parameter computations are carried out to investigate the influences of such factors as the pile group effect, the plastic region of soil surrounding piles, the movement regularities of soil between piles, the radius of piles, the number of piles and the distances between piles so on. The distribution of soil pressure surrounding "passive" piles is obtained, and the curves describing this distribution and a simplified formula is also obtained, which can be easily used in engineering design. After that, 3D FE analyses of pile-soil interaction of "passive" piles are performed, including the plasticity and large deformation of soil, the pile-soil contact and varied soil parameters. The profiles of average lateral pressure along the pile length are obtained. The good accordance between the results in this paper and ones obtained by other researchers shows that the analysis in this paper are valid and the results can be used for reference to engineering designs. The numerical results concluded that the lateral pressure acting on piles due to soft soil movement is considerable, so the designers should pay attention to it. Finally, the paper proposes a approximate formula to calculate the lateral pressure acting on the piles in the soft region. This formula is used for the analysis of a bridge abutment–piled, in which the cracking of concrete and the yielding of reinforcing steel bar are taken into account, and the results can explain the damage phenomenon of the abutment...