Post Construction and Long Term Settlement of an Embankment Dam Computed with Two Constitutive Models

Abstract

For the settlement computation of an embankment dam, the soil stiffness is of great importance. Unfortunately, due to the lack of funds allocated for geotechnical investigation, stiffness parameters are commonly not evaluated as compared to strength properties. As a result, this may create hindrance in the use of advanced constitutive models such as Hardening Soil Model (HSM). In this study, the settlement with respect to depth and long term settlement of an embankment dam computed with Mohr-Coulomb Model (MCM) is compared with that of HSM applied to foundation soil only with limited data on stiffness. The results show that the MCM overestimated settlement in comparison with HSM. The settlement increment of MCM, in comparison with HSM, at the crest and at the depth of 120m was 53% and 82% respectively after the filling of the reservoir. The settlement computed with MCM and HSM were 2.9% and 1.35% of the dam height. It can be interpreted that the settlement predicted with MCM is unrealistically high due to the single constant value of modulus of elasticity (MOE), while the predictions of HSM are in agreement with the literature. In addition, the long term settlement computed using MCM is about 59% higher than that of HSM for the condition after the filling of the reservoir. This paper shows that the settlement of an embankment dam could be predicted reliably by using HSM even when a limited number of stiffness data is available.

A Comparative Study of the Dam Stability at Various Stages using Numerical Modeling and in Situ Measurements

“…We adjusted the fineness of the mesh (global coarseness), as shown in Figure 2. The Mohr-Coulomb model was used on all layers of the dam to calculate displacements and safety factors at the end of construction and during reservoir filling [10,16]. The settlements at the end of the construction of the hydraulic structure may vary significantly from one structure to another [11].…”

“…It is very well suitable for the modeling of earth dams by considering loading conditions, complex boundaries, irregular geometries, and material characteristics. It enables simulation of their behavior using various behavior laws, resulting in a more realistic imaging [10,11]. Based on these considerations, it can be concluded that the measurements provided by geotechnical and geodesic methods and the results obtained by FEM can only be complementary [12].…”

Numerical Analysis of Rapid Drawdown of an Embankment Dam

“…In addition, quick lowering of the reservoir could be necessary in a case of an emergency. The main parameters on which the safety of a dam depends are soil properties, pressure of water, and geometry [1][2][3]. In case of drawdown, pore pressures in the upstream side of the dam reduce which ultimately disturbs the equilibrium conditions of the dam.…”

Parametric Analysis of an Embankment Dam’s Stability

“…In order to ensure the safety of both the existing and the proposed dams in Pakistan, it is necessary to investigate the strength properties of local soils and their effects on the stability of the dams during their service life. There are very few case studies published on the stability issues of dams in Pakistan [3][4][5][6][7][8][9][10][11][12][13]. To the best of our knowledge no parametric analysis on the effects of strength properties on the stability of embankment dams with respect to local site conditions in Pakistan has been published.…”

“…Due to the low permeability of soils, excess pore pressure might develop gradually during raising and filling of the reservoir. This increase in excess pore pressure may lead to slope instability or dam failure [13].…”