Mekki Mellas

A numerical investigation into the behavior of geosynthetic-reinforced soil segmental retaining walls

Geosynthetic-reinforced soil segmental retaining walls are now an economical solution. The design of these structures is carried out according to the Association of State Highway and Transportation Officials or the Federal Highway Administration design guidelines, which are based on the limit equilibrium approach. Many experimental, analytical, and numerical studies have identified several sources of conservatism in these design guidelines. This article focuses on a numerical study undertaken using the finite difference code Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D), to investigate the influence of facing batter angle, soil/facing interface friction angle, and backslope angle on the behavior of geosynthetic-reinforced soil segmental retaining walls. The numerical results show that the design guidelines lead to overly conservative design where the soil/facing interface is rough and/or the backslope is present.

Bearing Capacity of Embedded Strip Footings on Cohesionless Soil Under Vertical and Horizontal Loads

In the last decades a few attention was given to the evaluation of the bearing capacity of embedded footing under inclined loads on a frictional soil. This paper focuses on a numerical study using the finite-difference code Fast Lagrangian Analysis of Continua (FLAC), to evaluate the bearing capacity of embedded strip footing on a frictional soil. The soil is modeled by an elasto-plastic model with a Mohr–Coulomb yield criterion and associative flow rule; the effect of non-associativity of the soil on the bearing capacity is also investigated. The effect of the embedment is estimated though a depth factor, defined as a ratio of the bearing capacity of a strip footing at a depth D to that of a strip footing at the ground surface. The inclination effect is estimated by inclination factors, defined as the ratio of the limit vertical load for a footing under inclined loading to that of the vertically loaded footing. Both swipe and probe analyses were carried out to identify the vertical force–horizontal force (V–H) failure envelope. The results have been compared with those available in the literature.

Probabilistic analysis of the bearing capacity of inclined loaded strip footings near cohesive slopes

ABSTRACTThe bearing capacity of strip footings has been widely investigated using deterministic methods . In practise, soil properties are spatially variable, which makes the use of the probabilist...

Numerical study of large-scale pull-out test of horizontal corrugated strips

Abstract The interaction between soil and geosynthetic plays an important role in the design and analysis of reinforced soil structures. Pullout tests are commonly used to simulate the soil reinforcement interaction mechanism along the interface. Thus, different types of reinforcements are used in these structures and present different behaviours. In this paper, we propose a new kind of reinforcement based on horizontal corrugated strips in order to improve the parameters interfaces between the soil and the reinforcement. To simulate the pullout interaction process of horizontal corrugated strips, we carry out a numerical study using the software package FLAC3D. We have modelled the soil as an elastic-perfectly plastic Mohr Coulomb and the reinforcement as linear elastic geogrid elements. In fact, the most important aim is to explain the horizontal corrugated reinforcement’s behaviour and to investigate the factors that affect the mechanical response (Confining pressure, friction angle, amplitude and number of the waves of the strip). A comparative study is also presented between the horizontal corrugated and planar strips. In our study, the numerical results showed that the confining pressure has significant influence on the interface properties of the horizontal strips corrugated. It also showed that the pullout shear stress on the head of horizontal corrugated strips is higher than the planar reinforcements.

The undrained bearing capacity of strip footings under eccentric loading: effect of soil-footing interface tensile strength

Abstract In order to satisfy the exceptional conditions imposed by the offshore structures, a particular attention should be paid to the stability of shallow foundations resting on purely cohesive soil. One important specification of the offshore foundations is their soil-footing interface which can sustain tension. This paper studies the effect of the tensile strength of this interface on the undrained bearing capacity of a strip footing and assesses the reliability of the effective width method under eccentric loading. This is done by a numerical modelling using the finite difference method. Failure envelopes, failure mechanisms and normal stress distribution at the interface are presented and compared with available results from literature. The results show that the effective width method is not reliable in the presence of the tensile strength at the interface. This strength yields supplementary stability and keeps the footing in contact with the soil even under low vertical loading.

Effect of the Slope on the Undrained Bearing Capacity of Shallow Foundation

The bearing capacity of shallow foundation near slope has always been one of the subjects of major interest in geotechnical engineering for researchers and practical engineers. This study focuses on the numerical analysis of the undrained bearing capacity for a strip footing near a slope, and subjected to a centered vertical load, using the explicit finite difference code FLAC (Fast Lagrangian Analysis of Continua). Theoretical and experimental studies confirm that, when a strip footing is near a slope, the bearing capacity must be assessed using reduction coefficients. In this study, several geometrical and mechanical parameters have been considered in order to evaluate the effect of the slope on the undrained bearing capacity. The numerical values have been compared with those available in the literature. The results show the influence on the undrained bearing capacity of the location of the footing with respect to the slope.

The Behaviour of Shallow Foundation Near Slope Under Inclined Loading

In civil engineering, major studies had examined the failure conditions of shallow foundations were based on the application of a combined state of loading in a homogeneous soil.

Bearing Capacity of Eccentrically Loaded Strip Footings Near a Slope

This paper presents a numerical investigation into the behavior of eccentrically loaded strip footings adjacent to a cohesionless slope. In this study, the finite-element software Plaxis 2D was used to evaluate the influences of load eccentricity on the bearing capacity, soil pressure distribution underneath the footing and the pattern of failure mechanism. The results are presented using the failure envelopes in vertical and moment loading plan. The obtained results are compared with those found in the literature.

Numerical Study of the Bearing Capacity of Embedded Strip Footings on Non-homogenous Clay Under Inclined Load

The present study investigates the undrained bearing capacity for embedded strip footings under inclined loading on non-homogeneous clay. Elasto-plastic finite-element analyses are carried out through Plaxis code for perfectly rough strip footings on Tresca material. This study examines the influence of strength non-homogeneity and footing embedment ratio D/B, on the bearing capacity factor N c * of rigid footings for different load inclinations α. The numerical results were compared with the available results published in the literature.