Study of the Arching Ratio in Earth Dam by Comparing the Results of Monitoring with Numerical Analysis (Case Study: Marvak Dam)

Abstract

Occurrence of arching phenomenon in the core of earth dams will reduce vertical stress, piping, and thus the destruction of the dam, so it is always considered an important issue in earth dams. In this study, GeoStudio software was used to investigate the total stress and the arching ratio of the Marvak earth dam at the construction and end of construction phase. In modeling the dam, the behavioral model of Mohr–Coulomb is used and the effect of layer-by-layer embankment construction is also considered. The results of total stress and arching ratio of instrumentation and numerical analysis in the construction and end of construction phase were evaluated and compared. Observational results and results of adaptive modeling show about 95%, which indicates the proper performance of the dam in terms of arching. The results show that with increasing embankment, the total stress also increases, and also, the highest percentage of arching from the beginning to the end of the construction phase is equal to 58% and occurred in the lower one-third of the core level. Due to the high impact of consolidation on arching, the speed and time of construction should be adopted in such a way that part of the consolidation of the lower embankment layers has been done, before the implementation and embankment of the upper layer. In the downstream of the clay core, a higher arching ratio (lower percentage of arching) is observed, which is due to the thicker filter and drainage areas.