The hyperbolic model is a simple stress-strain relationship based on the concept of incrementally nonlinear elastic behavior. The hyperbolic stress-strain relationship was developed for use in finite element analysis of stresses and movements in earth masses. To estimate hyperbolic parameter values required for nonlinear finite element analysis, data used from the triaxial compression tests for the gypseous soils exposed to the effect of drying and wetting cycles carried out by (Mohammed, 1993). From these data, the parameters (C, φ, K, n, Rf), which are required by Duncan-Chang model, 1970 can obtained for analyses of dams, excavations and various types of soil-structure interaction problems. In addition, it can be found that the primary loading modulus, K, the exponent number, n, and the failure ratio, Rf, have random values during rewetting cycles for CU and UU triaxial compression tests
ABSTRACT:The gypseous soils are distributed in many regions in Iraq and other countries. Therefore, it is necessary to study the behavior of such soils due to the large damages that affects the structures founded and constructed in or on it.This research is concerned with studying the effect of leaching soil process on the stability of an embankment erected on foundation gypseous soil. The finite element method is adopted in this research. The analyses carried out using a nonlinear, increment, and stress-dependent finite element computer program. The hyperbolic stress-strain parameters used in the finite element analyses are estimated by the data collected from triaxial compression tests of some researchers. The analysis of the embankment problem carried out, shows that the leaching process for foundation gypseous soil increases the displacements and deformations of the embankment and its foundation. Finally, this research necessitate the success using of the finite element method in design and analyses of the important structures and buildings erected on gypseous soils that may expose to the effect of leaching process. This means that there is possibility to predicate the behavior of structure by a powerful means to establish the suitable solutions for any problems that may be occurred as a result of the present gypseous soil.
AbstractThe aim of this study is to analyze the slope stability for sections in Al-Furat River where engineering construction build on it, when a sudden decrease in the river water level happens. Two sections were chosen from the river in the area located about 35 km away from Ramadi city called Tel Aswad where undisturbed samples are taken and laboratory tests are done to obtain the soil parameters which are used in Geo-Slope program. The finite element method was applied in this study with elastic-plastic soil model. The analysis results show that the sections slope chosen from the river are stable. The second purpose of this analysis to reduce the risk of using earth structures when engineering construction build on it. Also, it is clear that the values of factor of safety calculated by the FEM are low compared with limit equilibrium methods.