Study On A Simplified Method For Settlement Calculation Of Rigid Pile Composite Foundation

Currently, the practical, representative and authoritative method in engineering practice is still the specification methods for the settlement calculation of rigid pile composite foundation. However, those methods oversimplify the interaction between pile and soil which cannot reflect the real situation fully. While some methods are based on the modification of empirical coefficient, which will be quite different compared with the true settlement for the settlement calculation of rigid pile composite foundation in soft soil.In this paper, the pile and the soil of rigid pile composite foundation are considered as two independent stress systems. The settlement of the soil between piles was assumed linear due to the bearing capacity of soil between piles play a little in rigid-pile composite foundation. When the load level of pile is not high, the settlement of pile can be considered linear. If the pile may enter nonlinear even plastic, the load-settlement curve of pile was deemed to satisfy hyperbolic law which the nonlinear settlement process of the pile can be well considered. According to the mathematic property of hyperbolic equation, the nonlinear load-settlement equation could be deduced by the settlement under the characteristic values of bearing capacity of single pile. For the composite foundation with loading test of single pile, the hyperbolic equation of pile can be established directly by the loading test curve. Based on the deformation coordination between soil and piles and the static equilibrium equation, the actual foundation settlement can be calculated. On the whole, it is a simplified method for settlement calculation of rigid pile composite foundation.Two engineering examples are introduced in this paper in which the foundation settlement was calculated by this simplified method and compared with the measured data and the results by specification method. The feasibility of applicability of this simplified method was tested by the settlement calculation. It shows that the simplified method is superior and accurate, for the settlement calculation of rigid pile composite foundation in hard soil layer especially in deep soft soil.