This paper is concerned with the study of a poroelastic soil layer under impulsive horizontal loading. Building upon Biot's general theory of poroelasticity, a comprehensive set of governing equations addressing three-dimensional transient wave propagation problem are established. Explicit general solutions for displacements and pore-pressures are derived by employing a sophisticated mathematical approach, incorporating decoupling transformation, Fourier series expansion, and Laplace-Hankel integral transform techniques. Subsequently, physical-domain components are numerically obtained by an enhanced Durbin method coupled with inverse Hankel transform. Comparisons the existing transient solutions for the ideal elastic half-space are made to validate the proposed formulations' reliability and precision. Through representative analyses for time-domain results, it is illustrated to study the influence of the soil thickness and types of loading pulse on the transient dynamic response of finite-thickness poroelastic soil layers. The results in comparative analysis show that the magnitudes of the horizontal displacement and pore water pressure can be affected and become more fluctuant when the thickness of the poroelastic soil layer decreases. The basic solutions may be attributed to a variety of wave propagation problems due to transient dynamic loading and illustrate the corresponding distinct wave features elegantly.

This paper proposes a new method for computing the undrained lateral capacity of Reinforced Concrete (RC) piles in cohesive soils, overcoming inherent conservativeness of classical Broms' theory. The proposed method relies on a new theoretical distribution for the limiting soil resistance, simple enough to derive closed-form solutions of the undrained lateral capacity, for different restraints at the pile head and for all possible failure mechanisms. After validation against numerical results and experimental data, the model is used to compute the failure envelope of RC piles under generalised loading. 3D FE analyses are used as benchmark to identify the main factors governing the ultimate response of RC piles. To this purpose, the Concrete Damaged Plasticity model is adopted to reproduce nonlinear concrete behaviour, which is an essential ingredient when modelling pile behaviour under horizontal loading. FE analyses show that, contrary to what observed for rigid and elastic piles, the ultimate response of RC piles relies on the soil strength mobilised at shallow depths, where the normalised lateral soil resistance basically depends on the sole adhesion factor. The proposed solutions are readily applicable to the design of single piles, as well as to the computation of three-dimensional interaction domains of pile groups.