The Behavior Of Passive Pile Against Soil Lateral Movement And Its Applications

Based on the systematic summary of existing theories, tests and analytical approaches, the behavior of passive pile against soil lateral movement has been studied thoroughly. The main contents of this paper as following:Firstly, displacement mode of unstable soil and the deformation mechanism of passive pile are analyzed in this paper, then a elastic perfectly plastic model and a hyperbolic curve model about the behavior of passive pile against soil lateral movement are developed by the author.Secondly, the elastic perfectly plastic model is extended to the pressure-based analysis method through using the mobilization factor of lateral force a m) and two new pressure-based analytical methods are proposed in this paper, the first considers the effect of the beam of multi-row structure passive piles, and the second accounts the parameters of layered soil, the arbitrary lateral force into consideration. Then two examples, a pile-supported pier and bridge piles constructed in soft clay foundation, are analyzed by above-mentioned methods. In which the admissible mobilization factor of lateral force [ a m] of piles is determined according to the admissible displacement of pier or the admissible bending moment of bridge piles.Then, the Simplified Bishop method is extended to analyze the stability of reinforced slope with piles by the author, herein a m is selected between [ a m] and 1/FS, namely a m ={[ aM ], l/FS}min, in which [ am] is the admissible a m of piles and FS is the safety factor of slope. In this way, the variation of safety factor (FS) and position of critical surface caused by placement of piles in rows can be taken into account simultaneously. The influence of d/D, ratio and the location of piles on the safety factor for an example of a slippery slope of landing pier are discussed, and a design procedure of reinforcing piles is also proposed.In order to verify the above extending Simplified Bishop method (EBM), this paper describes a finite element method (FEM) for analyzing FS of slopes reinforced by piles, in which the piles are represented by equivalent sheet-pile walls, and a plane strain analysis performed. Results from EBM show goodagreement with the data from FEM. It is deemed that EBM is valid over arbitrary range spacing while FEM is only valid over a limited spacing of the piles, since, at large spacing, the mechanism of sheet-pile walls is not the critical mode of flowing soil.Finally, cases of field loading tests about reinforcing schemes for a pile-supported pier constructed in soft-clay area are analyzed. Analysis of FS of landing pier slope, the displacement and bending moment along the piles of pier is also taken herein, and results from the methods proposed in this paper show good agreement with testing data.