Kambiz Hedayatnasab, Ahmad Adib, , ,
Volume 7, Issue 1 (8-2013)
Abstract
Various types of numerical analyses such as Finite Element Method, Boundary Element Method and Distinct Element Method, are used in rock mechanics and in engineering practices for designing rock structures such as tunnels, underground caverns, slopes, dam foundations and so on. In this paper, the results of back analysis of Koohin tunnel which is located in the first section of Qazvin-Rasht railway have been presented. The main purpose of this paper is to perform the back analysis of the mentioned tunnel with the use of numerical models. For modeling the tunnel, two different sections of 30+150 km and 30+900 km are analyzed with FLAC 2D software. To perform back analysis the suitable interval of geomechanical parameters according to the tests which were performed on the core drillings has been determined. With the use of direct method in back analysis, the errors of models have been corrected in several steps and finally the geomechanical parameters in 30+150 km station (Elastic Modulus = 0.3 GPa, Cohesion = 0.21 MPa and Internal Angle of Friction = 34°) and in 30+900 km station (Elastic Modulus = 0.3 GPa, Cohesion = 0.21 MPa and Internal Angle of Friction = 35°) have been achieved. The geomechanical parameters which obtained from back analysis are completely in the chosen interval and compliance with the results of tests which performed on core drillings. On the basis of geomechanical parameters obtained from back analysis with the parameters which used in the design of the tunnel, the tunnel design and the structure method were confirmed.
Mahdi Beshavard, Arash Adib, Seyed Mohammad Ashrafi,
Volume 16, Issue 3 (Autumn 2022)
Abstract
Droughts caused by precipitation deficits and increasing water consumption are intensifying worldwide, with negative economic and environmental consequences. The negative impacts can be mitigated by using optimized reservoir operation patterns and implementing rationing rules during droughts. These approaches involve meeting only a portion of total demand, allowing for water storage and accepting a small current deficit to mitigate severe future shortages. This research presents a case study to determine the operational command curves for Jareh Dam and to investigate the impact of reservoir operation under two management policies, Standard Operating Procedure (SOP) and rationing, on downstream drought indices, an aspect not previously studied. To achieve this, an optimization model coupled with a genetic algorithm was linked to a simulation model to determine the optimal values of command curves and rationing coefficients based on historical inflow data to the reservoir. The performance of the model was evaluated in the Allah River water resources system. In addition, the drought severity index (SDI), SOP performance, and rationing model performance during the base period were evaluated by calculating the objective function value or modified shortage index (MSI) and the resilience, vulnerability, and reversibility indices. The results showed that under the rationing model during the study period, the MSI value improved by 41% compared to the SOP method. In addition, the implementation of the rationing policy significantly improved the vulnerability of the system compared to the SOP method, reducing it from 64% to 26%.
