Journal of Geomechanics and Geoengineering

Analysis of upstream slope stability during rapid drawdown - Sidi Abdelli dam as a case study

2022-06-15T15:36:21+00:00

Many factors, including soil permeability and mechanical properties, upstream side slope, drawdown ratio, and drawdown rate, influence the stability of an earth dam during sudden drawdown. This paper investigates the influence of rapid drawdown on earth dam upstream slope stability and its role in the change of pore water pressure at different locations and factor of safety of the upstream slope. To achieve the aim of this study, the Sidi Abdelli dam was taken as a case study by using the Geo-SLOPE/W program based on the limit equilibrium method. The results show that the pore water pressures are very low at the toe of the dam and then increase as the initiation of pore water dissipation from the dam and then decrease as the elevation, as well, the velocity vectors start to exit from the upstream side, the possible seepage face is on the upstream side. As well as, the factor of safety of the upstream slip surface decrease with the initiation of rapid drawdown, the upstream slope is no in a safe stability condition. But, after 13 days the factor of safety increases above value 1.00, that is means the upstream slope will be in a safe condition.

Transformation of the Equivalent Linear Method for solving soil-structure interaction problems in the time domain

2024-01-10T09:29:27+00:00

In the context of soil-structure interaction, often underestimated in design codes, accurate anticipation of dynamic amplification and foundation displacements has become increasingly crucial. Recent earthquakes like Mexico City (1985), Loma Prieta (1989), Port-au-Prince (2010), and Kumamoto (2016) highlighted the need for robust methods to analyze these complex nonlinearities. While both nonlinear and equivalent linear approaches offer valuable insights, limitations in computational efficiency and implementation can hinder their practical application. This paper addresses these challenges by presenting the formal development of a novel quasi-nonlinear method for real-time seismic response analysis, building upon the principles introduced by the author. This innovative approach, unlike traditional equivalent linear methods, dynamically calculates mean shear moduli and local secant stiffnesses, integrating them into a Newmark-based solution process. The paper further validates the method against the Santa Cruz earthquake (Loma Prieta 1989) on a sandy soil profile, demonstrating remarkable agreement with reference solutions obtained using established methods like Shake91 and Quad4m. This comprehensive formulation paves the way for accurate and efficient real-time reconstruction of seismic responses within a practical quasi-nonlinear framework.

Fast Lagrangian analysis of the short-term bearing capacity of shallow foundations in clays on the basis of the cone penetration test

2023-10-28T17:01:35+00:00

Based on a numerical modelling of the cone penetration test CPT as well as the vertical response of shallow foundation in saturated clays, derivation of the cone factor N_kled to propose a CPT-based method of computation of the bearing capacity. This study was carried out by launching a detailed parametric study using the software FLAC-2D (Fast Lagrangian Analyses of Continua) based on the finite difference method. The soil material was modeled as a homogeneous elastic-perfectly plastic medium obeying the Mohr-Coulomb criterion, and the effects of the soil rigidity index I_r, the cone-soil interface, and the initial depth of the penetration on the cone factor N_k were investigated leading to an analytical formulation of N_k. After a comparative study with those proposed in the literature, the cone factor N_k was used to derive the bearing capacity factor K_c of a shallow foundation. Compared to current CPT-based methods proposed in the literature, this method reasonably predicts the short-term bearing capacity of shallow foundations in saturated clayey soil.