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CONTENTS
Volume 3, Number 4, December 2011
 

Abstract
Knowledge of seismic earth pressure against rigid retaining wall is very important. Mononobe-Okabe method is commonly used, which considers pseudo-static approach. In this paper, the pseudodynamic method is used to compute the distribution of seismic earth pressure on a rigid cantilever retaining wall supporting dry cohesionless backfill. Planar rupture surface is considered in the analysis. Effect of various parameters like wall friction angle, soil friction angle, shear wave velocity, primary wave velocity, horizontal and vertical seismic accelerations on seismic earth pressure have been studied. Results are presented in terms of tabular and graphical non-dimensional form.

Key Words
seismic earth pressure; retaining wall; Mononobe-Okabe method; pseudo-static approach; pseudo-dynamic method; seismic acceleration.

Address
Debabrata Giri: Department of Civil Engineering, Parala Maharaja Engineering College, Berhampur, BPUT University, Odisha, India

Abstract
The aim of the paper is to study the hydro-mechanical behaviour of a tuff and calcareous sand mixture. A first experimental phase was carried out in order to find the optimal mixture. This showed that the material composed of 80% tuff and 20% calcareous sand provides the maximum mechanical strength. The second experimental phase concerns the study of the drying- wetting behaviour of the optimal mixture. Triaxial shear tests in saturated and unsaturated states at constant water content were carried out on samples initially compacted at the MPO. Experimental results let to deduce the parameters necessary for the prediction of the hydro-mechanical behaviour of pavement formulated from tuff and calcareous sand mixtures, related to moisture. This optimal mixture satisfies the regulation rules and hence constitutes a good local eco-material, abundantly available, for the conception of pavements.

Key Words
tuff; sandy calcareous; road engineering; hydro mechanical behaviour; suction.

Address
Idriss Goual and Mohamed Sayeh Goual: Laboratoire de recherche de Genie Civil Universite Amar Teledji. BP.37 G Laghouat, Algeria
Said Taibi: Laboratoire Ondes et Milieux Complexes, FRE CNRS 1302, Universite du Havre, 53 rue de Prony,
76600 Le Havre, France
Nabil Abou-Bekr: Laboratoire Eau et Ouvrages dans Leur Environnement, Universite A. Belkaid, BP 230 - 13000 Tlemcen, Algeria

Abstract
This article employs Multivariate Adaptive Regression Spline (MARS) for determination of friction capacity of driven piles in clay. MARS is non-parametric adaptive regression procedure. Pile length, pile diameter, effective vertical stress, and undrained shear strength are considered as input of MARS and the output of MARS is friction capacity. The developed MARS gives an equation for determination of fs of driven piles in clay. The results of the developed MARS have been compared with the Artificial Neural Network. This study shows that the developed MARS is a robust model for prediction of fs of driven piles in clay.

Key Words
multivariate adaptive regression spline; driven pile; clay; friction capacity; artificial neural network.

Address
Pijush Samui: Centre for Disaster Mitigation and Management, VIT University, Vellore-632014, India

Abstract
The paper describes a simple numerical FLAC model that was developed to simulate the dynamic response of two instrumented reduced-scale model reinforced soil walls constructed on a 1-g shaking table. The models were 1 m high by 1.4 m wide by 2.4 m long and were constructed with a uniform size sand backfill, a polymeric geogrid reinforcement material with appropriately scaled stiffness, and a structural full-height rigid panel facing. The wall toe was constructed to simulate a perfectly hinged toe (i.e. toe allowed to rotate only) in one model and an idealized sliding toe (i.e. toe allowed to rotate and slide horizontally) in the other. Physical and numerical models were subjected to the same stepped amplitude sinusoidal base acceleration record. The material properties of the component materials (e.g. backfill and reinforcement) were determined from independent laboratory testing (reinforcement) and by back-fitting results of a numerical FLAC model for direct shear box testing to the corresponding physical test results. A simple elastic-plastic model with Mohr-Coulomb failure criterion for the sand was judged to give satisfactory agreement with measured wall results. The numerical results are also compared to closed-form solutions for reinforcement loads. In most cases predicted and closed-form solutions fall within the accuracy of measured loads based on

Key Words
reinforced soil walls; seismic; shaking table; numerical modelling; FLAC.

Address
Saman Zarnani: BGC Engineering, Vancouver, British Columbia, Canada
Magdi M. El-Emam: Department of Civil Engineering, College of Engineering, American University of Sharjah, Sharjah, United Arab Emirates
Richard J. Bathurst: GeoEngineering Centre at Queen

Abstract
Israel

Key Words
pressuremeter; cemented sand; standard penetration test; modulus of elasticity; cohesion; strain softening; numerical analysis.

Address
Sam Frydman: Faculty of Civil & Environmental Engineering, Technion – Israel Institute of Technology, Haifa, Israel


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