Numerical Simulation Of Vertical Bearing Characteristic For Single Borehole Cast-in-place Concrete Pile

Pile foundations are widely used in civil engineering. There are several problems on the mechanics of vertical bearing capacity for a single pile. In this thesis, computation on the Borehole Cast-in-place Concrete Pile (BCCP) is performed by 3D static nonlinear FEM. Mechanics of bearing capacity for single pile is deeply analyzed from the aspects as follows: the settlement and the deformation of a single pile, the bearing capacity characteristics of a single pile, the displacement field and the strain field for single pile foundation. The main results are listed as follows:The reasonable length of a single pile is brought forward according to the calculation of the settlement and the deformation of a single pile varing with some factors (the length of pile, the ratio of length to diameter of pile, the type of subsoil around pile, the soil characteristics near pile tip). The relations of settlement of a single pile top and length of a single pile is analyzed. The determination method of reasonable pile length is given out by the relation of settlement and pile length (s-L) and the relation of load/settlement and pile length (q/s-L). This is main innovation of this thesis and it is useful for the theoretical study and the engineering application of pile foundation.The distribution rules of the lateral frictiongal resistance of pile and the tip resistance of a pile are analyzed according to the calculation of the settlement and the deformation of a single pile varing with some factors (the length of pile, the ratio of length to diameter of pile, the soil characteristics near pile tip). The exertion mechanics of tip resistance of a pile is given out. The reasonable thickness of the sediment under the pile tip is gained. The transformation rules of the lateral frictional resistance strengthened by the pile tip are analyzed. The differences of bearing capacity between friction pile and end load pile are analyzed. The results show the cause is the safety factor of pile design. The results can be offered to the engineering design and the engineering construction of pile foundation.They are analyzed that the distribution rules of the displacement field and strain field of a pile foundation. The causations of the mutation of the displacement in the area of a pile tip are given out. The method for the determination of the influence range of a single pile is given out by the displacement of a pile foundation. The area of the pile foundation is measured According to the characteristic of the soil strain field aroud a pile.The q-s curves of BCCP are simulated with the 3D nonlinear FEM. The simulation results using the numerical method are in agreement on the results based on the statics test of BCCP. The results show that numerical calculation is credible.