Non-linear dynamic soil response underneath a vertical breakwater subjected to impulsive sea wave actions

A theoretical model of the soil-water-structure interaction involved in a breakwater structure subjected to sea wave actions is presented. The model includes i) soil skeleton-pore fluid interaction governed by the u − pw Generalized Biot formulation [1] including dynamic effects, ii) non-linear soil elastoplastic behaviour described by a novel Generalized Plasticity model [2] coupled with a conservative hyperelastic formulation for the dependence of the elastic stiffness on the stress [3], iii) coupling between the caisson and foundation through a non-linear contact with geometrical compatible formulation incorporating frictional behaviour. The numerical solution of the settled governing equations has been fully developed through the Finite Element Method. Furthermore, a program called ADÍNDICA has been created in M Matlab language. ADÍNDICA is a Spanish acronym for “Caisson Breakwater Dynamic Analysis”. Related numerical analyses are developed with reference to precise boundary value problems of specific physical nature. ADÍNDICA code has been able to reproduce adequately the principal characteristics of the caisson oscillations and instantaneous pore pressure generation relation deduced experimentally. Moreover, ADÍNDICA has been able to reproduce satisfactorily the accumulative settlement behaviour of a vertical breakwater structure subjected to series of sea wave impacts including the correlation between accumulated settlements and residual pore pressure

A FIC-based stabilized mixed finite element method with equal order interpolation for solid–pore fluid interaction problems

This is the peer reviewed version of the following article: [de-Pouplana, I., and Oñate, E. (2017) A FIC-based stabilized mixed finite element method with equal order interpolation for solid–pore fluid interaction problems. Int. J. Numer. Anal. Meth. Geomech., 41: 110–134. doi: 10.1002/nag.2550], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/nag.2550/abstract. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."A new mixed displacement-pressure element for solving solid–pore fluid interaction problems is presented. In the resulting coupled system of equations, the balance of momentum equation remains unaltered, while the mass balance equation for the pore fluid is stabilized with the inclusion of higher-order terms multiplied by arbitrary dimensions in space, following the finite calculus (FIC) procedure. The stabilized FIC-FEM formulation can be applied to any kind of interpolation for the displacements and the pressure, but in this work, we have used linear elements of equal order interpolation for both set of unknowns. Examples in 2D and 3D are presented to illustrate the accuracy of the stabilized formulation for solid–pore fluid interaction problems.Peer ReviewedPostprint (author's final draft

Using the scaled boundary finite element method to model 2D time-dependent geotechnical engineering problems

The scaled boundary finite element method caters well for soil-structure interaction problems, but the formulation does not cater for the presence of changing pore pressures with time, body loads and tractions. A detailed formulation is presented in this paper to consider the general 2D analysis case for modelling coupled consolidation, accounting for body forces and surface tractions in both the bounded and unbounded media. The advantages of this method compared to conventional methods are also explained in this paper

Modeling elastic wave propagation in fluid-filled boreholes drilled in nonhomogeneous media: BEM – MLPG versus BEM-FEM coupling

The efficiency of two coupling formulations, the boundary element method (BEM)-meshless local Petrov–Galerkin (MLPG) versus the BEM-finite element method (FEM), used to simulate the elastic wave propagation in fluid-filled boreholes generated by a blast load, is compared. The longitudinal geometry is assumed to be invariant in the axial direction (2.5D formulation). The material properties in the vicinity of the borehole are assumed to be nonhomogeneous as a result of the construction process and the ageing of the material. In both models, the BEM is used to tackle the propagation within the fluid domain inside the borehole and the unbounded homogeneous domain. The MLPG and the FEM are used to simulate the confined, damaged, nonhomogeneous, surrounding borehole, thus utilizing the advantages of these methods in modeling nonhomogeneous bounded media. In both numerical techniques the coupling is accomplished directly at the nodal points located at the common interfaces. Continuity of stresses and displacements is imposed at the solid–solid interface, while continuity of normal stresses and displacements and null shear stress are prescribed at the fluid–solid interface. The performance of each coupled BEM-MLPG and BEM-FEM approach is determined using referenced results provided by an analytical solution developed for a circular multi-layered subdomain. The comparison of the coupled techniques is evaluated for different excitation frequencies, axial wavenumbers and degrees of freedom (nodal points).Ministerio de Economía y Competitividad BIA2013-43085-PCentro Informático Científico de Andalucía (CICA

Flow-Induced Stresses and Displacements in Jointed Concrete Pipes Installed by Pipe Jacking Method

Transient flows result in unbalanced forces and high pressure in pipelines. Under these conditions, the combined effects of flow-induced forces along with sudden pipe displacements can create cracks in the pipeline, especially at the junctions. This situation consequently results in water leakage and reduced operational efficiency of the pipeline. In this study, displacements and stresses in a buried pressurized water transmission pipe installed by pipe jacking method are investigated using numerical modeling and considering interactions between fluid, pipe, and soil. The analyses were performed consecutively under no-flow, steady flow, and transient flow conditions, in order to investigate the effects of flow conditions on displacements and stresses in the system. Analyses of the results show that displacements and stresses in the jointed concrete pipes are significant under transient flow conditions. Moreover, because of pressure transient effects, maximum tensile stresses exceed the tensile strength of concrete at the junctions, leading to cracks and consequent water leakage

Analysis of Soil-Structure Interaction Effects of NPP Structures on Nonhomogeneous Subsoil

This paper describes the soil-structure interaction (SSI) effects to the Nuclear Power Plant (NPP) structure with reactor VVER-1200. The simplified 1D and numerical 3D FE models of the nonhomogeneous subsoil are investigated. The methodology of the calculation of the frequency dependent complex functions of the soil stiffness and damping is presented