SUMMARYA new finite element model based on a large strain formulation has been developed to study cone penetration in normally consolidated sand. An auto-adaptive remeshing technique was utilized for handling the very large distortion of sand surrounding the cone tip. A frictional contact interface utilizing Mohr-Coulomb's theory was chosen to represent interactions between the surface of the cone and sand. To model the sand behaviour, the non-associated Drucker-Prager constitutive model was selected. ABAQUS, a commercial finite element software package, was used to implement the model. The explicit solution algorithm was chosen due to its effectiveness for complicated contact problems. Analysis results proved that the model successfully captured the cone penetration behavior in sand. In addition, a chart to predict internal friction angles based on cone tip resistance for different vertical effective stresses was provided. This paper also shows a typical distribution of sleeve resistance, tip resistance}penetration relationship, and typical contours of vertical, horizontal, and shear stresses in normally consolidated sand. Finally, a non-uniform resistance was found along the length of the friction sleeve.

Abstract. This paper describes, discusses and compares three new innovations of reinforcement systems for soft soils: (a) a combination of gridded matrass and piles of bamboo, (b) a combination of matrass and piles of bamboo, and (c) a group of mini piles connected by small H-beams with a compacted top layer to hold the top mini piles. First, illustrations and applications of the three types of reinforcement are described from three full-scale field works. Technical bases for the three types are presented, while technical comparisons are discussed next. Finally, conclusions are developed. The case studies, analysis results, and fullscale fieldwork verifications show that the three reinforcement systems have worked properly. Each system has its own advantages and disadvantages in terms of construction duration and cost, capability/effectiveness and material availability, especially in rural areas.

This paper presents a study result of peat behaviors through numerical analysis using the finite element method verified by full scale field measurements. Site investigation, construction, instrumentation and monitoring of a trial embankment on very compressible fibrous tropical peat layers at Bereng Bengkel in Central Kalimantan have been conducted by the Agency of Research and Development, the Indonesia Ministry of Public Works. Settlement responses of the embankment have been investigated by a series of finite element simulations using two different soil constitutive models: elastic perfectly plastic model with the Mohr-Coulomb criteria and hyperbolic Hardening-Soil model. A half space finite element model has been developed using the effective stress approach. Analyses were performed with the coupled static/consolidation theory. The soil parameters, embankment geometry, construction sequence and consolidation time of peats and clays were modeled in accordance with actual field trial embankment conditions. Implementation of the numerical model and simulations has completely been performed by a computer program, PLAXIS 2D. For ground settlement behavior at center of embankment, this study result shows that both soil constitutive models have reasonably produced suitable deformation behaviors. However, the settlement behaviors at embankment toes are not as accurate as they are at center.

Abstract. Piled raft foundation designs consider the contribution of the pile cap in transferring load to the ground and distributing load over the piles. The concept of a piled raft foundation requires a comprehensive evaluation of a number of factors that affect the performance of the foundation system. In this research the interaction among piles, pile cap and soil of a piled raft system on medium and stiff clays was studied. The effects of various distances between piles (s/d) in affecting load transfer mechanisms and deformation were considered. The study was performed by utilizing the 3D finite element method with a professional software package called Plaxis3D Foundation. A case study of the piled raft foundation performances of a foundation design for a high-rise building based on the soil stratification in Jakarta was also performed and is presented in this paper.

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