A hypoplastic macroelement formulation for single batter piles in sand

Abstract

Summary Batter piles are widely used in geotechnical engineering when substantial lateral resistance is needed or to avoid the interference with existing underground constructions. Nevertheless, there is a lack of fast numerical tools for nonlinear soil‐structure interactions problems for this type of foundation. A novel hypoplastic macroelement is proposed, able to reproduce the nonlinear response of a single batter pile in sand under monotonic and cyclic static loadings. The behavior of batter piles (15°, 30°, and 45°) is first numerically investigated using 3D finite element modeling and compared with the behavior of vertical piles. It is shown that their response mainly depends on the pile inclination and the loading direction. Then, starting from the macroelement for single vertical piles in sand by Li et al (Acta Geotechnica, 11(2):373‐390, 2016), an extension is proposed to take into account the pile inclination introducing simple analytical equations in the expression describing the failure surface. 3D finite element numerical models are adopted to validate the macroelement that is proven able to reproduce the nonlinear behavior in terms of global quantities (forces‐displacements) and to significantly reduce the necessary computational time.

Study on the stiffness degradation and damping of pile foundations under dynamic loadings

“…When subjected to horizontal loading which causes rotation and translation of foundation, batter piles may have much more complicated nonlinear soil-pile interaction in both axial and lateral directions. This is in accordance with the numerical results from 3D nonlinear FEM simulations of Li et al [47]. It is found that under cyclic horizontal loading, batter pile has more important axial reaction force and energy loss due to plastic deformation.…”

A hypoplastic macroelement model for a caisson foundation in sand under monotonic and cyclic loadings

“…All the aforementioned macroelement models were developed within the framework of the classical (isotropic or anisotropic) theory of plasticity. Alternatively, macroelement models considering the rate-type constitutive equations of hypoplasticity [41][42][43] have been developed for shallow (Salciarini and Tamagnini [44], Tamagnini et al [45]) and pile foundations (Li et al [46,47]). The aim of this paper is to study the response of a caisson foundation in sand under static monotonic and cyclic loadings with a novel macroelement developed under the framework of hypoplasticity.…”

“…The hypoplasticity macroelement for shallow foundations and deep foundations introduced by Salciarini and Tamagnini [44] and Li et al [46,47] is used as a starting point to develop a hypoplastic macroelement for a caisson foundation in sand for static monotonic and cyclic loadings. The general framework is briefly given hereafter.…”

“…The flexibility of the lid and the skirt could be considered as suggested by Skau et al [49]. As was the case for pile foundations [46,47], the coupled effect between horizontal forces and moment must be considered for the caisson foundation because of the skirt.…”

A hypoplastic model for granular soils incorporating anisotropic critical state theory

“…Other recent development of hypoplastic models can be found for simulating frozen soils and rate‐dependency of granular soils . It is recognized that these models have been applied successfully in simulating a wide range of problems; see previous studies …”