Case Study on Soft Soil Improvement Using Innovative and Cost-Effective Reinforcing Techniques

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 full-scale 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

Behaviors of Pipe-Soil Interaction on Unstable Slopes by Finite Element Simulation

Pipe-soil interaction plays an important role to the pipe stress analysis subjected to soil movement due to slope instability and/or slope failure. As the soils / slopes begin to fail, a single pipe or a group of pipes buried inside failure zone will bear additional loads which frequently lead to overstress or buckling. To study this phenomena, a case study was carried out by modelling a group of pipes subjected to ground movement in lateral direction. ABAQUS, a finite element software was employed to establish a 3 D numerical model of pipe-soil interaction during landslide event. Discussions of the results of this analysis are presented by focusing on the behaviors of displacement and stress of the pipes due to slope failure. Based on the analysis results, the length of failure zone becomes the major cause of the location of maximum stress during slope failure, it should be assessed carefully

Numerical and Experimental Studies of Wave Propagation Induced by Pile Driving

. This paper presents results of numerical and experimental studies to predict the peak particle velocity (ppv) induced by a pile driving. By utilizing a professional finite element software, Plaxis 2D Dynamic, this study analyzed ppv due to pile driving in clays for various soil stiffness and various embedded pile lengths. For verification, a full scale field test of pile driving was performed in East Kalimantan with installed instrumentations of accelerations. Results of both instrumentation and numerical analysis show that ppv depends on distance and soil rigidity. The closer the object to pile tip, the larger the ppv that will be produced. The more rigid the soils at the pile tip, the larger the ppv, too. The results also show that both field test and numerical analysis results are comparable. Finally, this paper proposes a chart to predict the ppv of soils due to pile driving in clays. The output of the proposed method is the predicted ppv for various distances from pile driving location