Research On Soil-pile Dynamic Interaction Of Sparse Pile Foundation

Since provided with better economic benefits and wider applied perspective as a new conception of pile design, the sparse pile foundation gained extensive utilization recently.Soil--pile dynamic interactions can not only modify the bearing capacity of piles, but also influence the dynamic responses of the superstructure. The influences of the soil--pile dynamic interactions must be considered when the analysis of the dynamic response of the superstructure is made. Existing research studies are only directly under the dynamic loads of pile--soil interaction which neglecting the axial force, shear deformation and pile lateral soil weakening effect, As for the sparse pile foundation, the vertical bearing capacity even near to limit status as the "elastic-plastic pile" or the "plastic piles", vertical stiffness much smaller than the initial stiffness, and it even close to zero, so, in such a premise, its vertical as well as the level of compression characteristics of dynamic stiffness is almost blank.This paper analyzed the main problems in the current teaching of the sparse pile--soil dynamic interaction , this paper makes thorough studies of the level and vertical dynamical impedance of single and interaction coefficients of grope piles include the following sever- al respect mainly:(1) With the summarization of lots of interrelated references , the studying actuality and developing level which about soil-pile interaction are presented ; the analytical ways of dynamic soil-pile interaction are summarized; the limitations, advantages and disadva- ntages existing in present researches are discussed too. Then, the basic research way and analyzing frame route related to soil-pile interaction in this paper is introduced.(2) Through the analysis of pile response characteristics under horizontal simple ham- onic loads which considering axial force, dynamic differential equation for the pile element is deduced, derived the influence law of axial force on the pile impedance function. Impor- ant influence on the Stiffness non-dimension parameters can't be ignored while the influe- nce of damping non-dimensional parameter values is smaller changed. Generally speaking, when the axial force is larger, it is appropriate to consider the axial force.(3) Through the analysis of pile response characteristics under the horizontal simple harmonic loads consider the axial force, dynamic differential equation for the pile element is deduced, analyzed the calculation results. A more rigorous analytical solution for lateral vibration of single pile in homogeneous soils is developed, in which the shear deformation of pile was considered for the first time. Based on parameters studies, it was proposed that the critical value of l/d is 8 beyond which the shear deformation can be ignored in common cases.(4) Through analysis of pile response characteristics under horizontal simple vertical loads consider the pile lateral soil weakening effect, dynamic differential equation for the pile elements is deduced . Based on the computing formula , the influence laws of the pile lateral soil weakening effect, slenderness ratio and stiffness ratio of pile to soil on the pile impedance function are studied。(5) Derived the horizontal and vertical interaction coefficients of two piles conceding the axial force, shear deformation and the pile lateral soil weakening effect, the influence law of these influencing factors on the interaction coefficients are studied。...