The Predigestion Analytical Study Of The High-Rise Structure's Pile Foundation

Pile is a usual foundation form in civil engineering, especially widely used in construction. Compared with shallow foundations, it has incomparable advantages in sharing load and settlement controling. However, with the fierce competition of construction in the market environment, controlling pile foundation's cost is imperative, especially by reducing overplus capacity. To achieve this objective, the first thing to do is estimating the foundation's maximum loading capacity accurately, which make the design capacity meet the actual capacity, so there could be fewest designed piles. Estimating single and group piles's ultimate bearing capacity accurately is a significant engineering issue.In this thesis, it starts from analyzing pile's theory, then adcanced a simplified algorithm which could improve the estimating accuracy. Besides, with the help of FEM program and tested the algorithm through engineering an indoor experiments, it finally comes with a series of meaningful results.In the research of simplified theory of single pile, it puts the accent on the effects on division of model's units'dimension and accuracy about beam and solid element under elastic and elastoplastic solid condition. This thesis demonstrated the possibility of replacing complicated solid element with simple beam element and also analysed verification results. The group piles' simplify theory uses Prof.Junfa Zhang's "Composite Model Theory" for reference and find simplification method, meanwhile, I programmed the computer to compute composite model's equivalent parameters and studied practical engineering by ANSYS. Furthermore, I did group piles model experiment in the structural laboratory of Xi'An University of Technolugy for further verification, which helped me study on simplification method's effectivity and Correctness about pile.The main results are as follows(1) As for solid and beam elements'dimension, different dimensions have obvious effect on Results Analysis.(2) The model's piles have rational relationship between axial force and pile's top sedimentation value. That means discretizing pile as beam element when considering the soil-pile interaction is feasible. (3) The simplified analysis results of pile's axial force and sedimentation, which is under elastoplastic solid condition, is close to practical values. This means simplified analysis method could reflect practical situation well and is feasible to estimate single pile's ultimate bearing capacity. In practical engineering, we could estimate single pile's ultimate bearing capacity accurately by taking geologic report and the DPs of cement concrete piles for reference.(4) Taking simplified analysis for group piles'composite model to simulate pile foundation'ssedimentation is more close to physical truth than specifications. As a matter of fact, composite model's FEM simulation is a effectual simplified method in estimating sedimentation.(5) The indoor experiment verifies the availability of simplified analysis method from another point.