Investigations of nonlinear p-y piles and pile groups in soft clay subjected to static loading-distributed parameter sensitivity analysis

For the design of a pile foundation, the engineer must take into account the axial loads and overturning moments. Although some structures deal with pile under axial load it is very common to see the utilization of piles subjected to lateral loads, especially in areas suitable for earthquakes or offshore platforms, bridges, high-rise structures, piers and so on.;A wide range of lengths and a large group of different boundary conditions were applied on single piles under static loadings, addressed to the pile head. In terms of structure, here the single piles are considered as one dimensional beam and the soil supporting selected is a soft clay and is defined by p-y relationship once under lateral load, deflection of the pile is directly dependent on the soil response and in this case the soil response is a nonlinear function of pile deflection and the depth of the soil below the surface. The p-y model mentioned above for soft clay was developed by Cox, Reese and Grubbs and has been used widely all over the world and is applied in the neighbourhood of the pile.;Under the broad variation of the boundary conditions the group of piles are also analyzed through the sensitivity approach and in this case the cap is considered as a plate and the pile members are recognized as one dimensional beam. The p-y relationship once more is the more appropriate model to understand and represent the behaviour of the pile-soil system. For the case of a group of piles, the utilization of a specific modifier fm factor had to be applied once the group of piles change with respect to spacing of the piles and also the location of the piles inside of the group.;The physical parameters of the soft clay and the stiffness of the pile used for the description of the p-y relationships are taken as the design variables of the continuous type. They are space dependent.;Laterally loaded piles embedded in soft clay bellow the water table under static load is presented in this study under the theoretical formulation and the numerical investigation of sensitivity analysis. In this study both single piles and pile groups are analyzed under the sensitivity approach.;To be able to analyze the sensitivity of the single pile and the group of pile subjected to lateral loads the adjoint method for nonlinear system is used. The first variation of the functional of maximum deformations as a result of the changes of the design variables is formulated based on the virtual work principle.;The variations of maximum generalized deflection located at the pile head as a result of the changes of the design variables are determined by sensitivity integrands and the design variables related. The sensitivity integrands are integrated and the numerical assessment of the outcomes are presented and discussed in details.;Although some specific design variable appeared in the sensitivity analysis of the deformation of the pile soil system each one as expected had demonstrated particular differences and significance through the analysis, and theses will be also part of the final discussion.