A Decision Support System for Ground Improvement Projects Using Gypsum Waste Case Study: Embankments Construction in Japan

This paper introduces a multi criteria decision making model to support the decision makers who work in the ground improvement projects such as embankments construction using stabilizer materials. The use of cement as a stabilizer material in embankments construction has a long history while the application of recycled gypsum in cooperation with cement as a stabilizer material is recently introduced in Japan. Four criteria and many factors are identified to compare the two stabilizer materials, cement only or gypsum-cement mixture, for the purpose of choosing one of them. The four criteria include: saving in cost, project scope achievement, durability, and geo-environmental impacts. The proposed model, which depends on the Analytic Hierarchy Process as a multi-criteria analysis method, is developed based on cost calculations, expert knowledge for achieving scope, and laboratory test results for durability and geo-environmental properties for each stabilizer material. It is applied on a real case study for embankments construction project in Japan. Based on the results of model application on the investigated case study, a decision introduced to Japanese construction market is that using gypsum-cement mixture as a stabilizer in ground improvement projects is better than using cement only by almost 50%. This result supports the application of recycled gypsum, produced from gypsum wastes, as a stabilizer in ground improvement projects to achieve the stability of society by reducing the quantities of wastes, meet sound environment, and reduce the cost of construction. Besides, the paper discusses in details the factors and reasons which have different effects on the two stabilizer materials and control the decision making. Keywords: Ground improvement; Decision making; Embankment construction; Gypsum waste; Gypsum-cement stabilizer; Multi-criteria analysi

Numerical Analysis for Seismic Behavior of a Slope Based on a Simple Cyclic Loading Model

A finite element simulation for dynamic centrifuge test of a slope is presented. The horizontal acceleration was applied to the base of the ground, and the response of the slope was measured. The residual deformation, accompanied with a clear slip surface, was observed after the testing. The main objective of this study is to investigate the validity of a new cyclic loading model, based on the strength parameters c - φ, and the G – γ, h - γ relationships. These features are thought to be very useful for practical usage