Soil-pile Interaction Behavior Under Going Soil Lateral Movement Due To Surcharge Loading

The passive-pile problem often occurs because of soil lateral movement due to roadbed construction, bridge abutment construction or the surcharge loads, and so on. The carrying capacity of close-by piles decreases badly under passive load, especially in the industry workshop, which gives us much lesson in recent years. In order to study further the interaction mechanism between pile and soil due to surcharge load, the dissertation establishes a three dimensional finite element model by FLAC3D because of the soil arch effect and lateral flowing action between pile and soil. Firstly, much useful conclusion of recent years about the passive earth-pressure along the pile is summarized, including theory method, field test and the numerical analysis, and some typical distributed mode of earth-pressure is pointed out. Secondly, a three-dimensional FEM for single-row piles is set up. Some key parameters' effect on the piles, such as surcharge's value&dimension, pile' stiffness, property of interface between pile and soil, soil's engineering characters, reinforced effect of soft ground, and so on, is calculated and investigated. The distributing law of soil pressure along pile is summed up according to pile's moment value, and subsectional fitting curve is employed to simulate the distributing pile's lateral pressure in softclay. And then, a finite element model using FLAC3D for pilegroup is established, in which a few importance factors, for example, surcharge condition, pile's dimension, softclay's engineering properties, and so on, is discussed. In the same way, an experience model about lateral soil pressure is obtained by fitting curve method. A field surcharge test is modeled by FLAC, and the corresponding result of measure and FEM calculation is compared. For most engineers to master the working properties of passive pile, a convenient and easy method instead of complicated FEM is developed, improving Poulos' elastic theory via introducing the multilayer elastic theory under vertical load and fixate load inside the ground. Above method can take into account the multilayer soil and the together-action in three dimensions among surcharge, pile and clays. And, Matlab program is employed to carry out above idea. The total content of the disquisition is summed up in rear, and some facing difficulty and shortage about passive pile is discussed. Finally, the lookout is brought forward.