Evaluation of pore water pressure foundation and core of Sivand dam after the first dewatering period in comparison with the actual instrument results

Increasing the pore water pressure in the body of dams will reduce the effective stress and thus reduce the shear strength of the body materials of the dam, which can lead to dangerous results and cause instability of earth dams. According to nonlinear behavior of earth dam, behavioral models of Mohr–Coulomb and hardening soil model are used to model the dam and body materials. In this study, using Plaxis and Geostudio finite element software, the results of instrumentation of the pore water pressure of the foundation and the core of the Sivand earth dam were calculated after the first dewatering period and compared with the results of the observational data. The study of hydraulic gradient variations and pore water pressure in Sivand dam showed that suitable permeability material was used in the construction of the dam. In addition, the results of evaluation of models with instrumentation data based on the root of the error and the relative standard error of more than 86 percent of the conformance show that the proper performance of the clay core and the cut off wall is due to changes in reservoir water level.