جستجوی مقالات مرتبط با کلیدواژه « Stability Analysis » در نشریات گروه « مهندسی معدن »

Inhomogeneity and discontinuities play a key role in the resistance and behavior of rock masses. Today engineers have a wide range of methods to analyze the stability of rock slopes. Due to its simplicity and speed of evaluation, static analysis methods continue to play a special role in the stability assessment of jointed rock slopes. One of the most well-known static methods used in the stability analysis of rock slopes is the Key Block method (KBM), which is based on key block finding and analysis. In this method, if none of the key blocks are unstable, it implies that rock mass is stable. Occasionally, the combination of several stable blocks has led to the formation of a group of blocks that sometimes leads to instability. Therefore, the stability analysis of the jointed rock masses leads to study groups of blocks that are potentially dangerous for the stability of a rock slope. The Key Group method (KGM), with its progressive approach, finds these critical groups and focuses the stability calculations on these groups. Until now, methods SKGM, PKGM, OKGM have been proposed to remove the limitations of this method and its development. In order to increase the efficiency, accuracy, and speed of this method and to develop it in three dimensions, it is decided to combine it with one of the numerical methods. The standard Discontinuous Deformation Analysis method (DDA) is an implicit method based on the finite element method. This is a sophisticated numerical method for modeling the quasi-static and dynamic behavior of rock block systems in discontinuous rock masses. The goal of this paper is to use the potency of the numerical method of DDA to analyze the candidate key group. For this purpose, the DDA computer program was developed with Mathematica programming language and combined with the KGM software. The resulting package, after selecting the key group by the KGM method, proceeds to analyze it with the DDA method. Two examples are solved illustrating the reasonable results and the efficiency of this developed method compared to that of the original KGM and SKGM. The results validated the proper accuracy and good performance of the procedure developed in this research.

The instability of the roof and walls of the tunnels excavated in coal mines has always attracted the attention of the miners and experts in this field. In this work, the instability of the main tunnels of the mechanized Parvadeh coal mine in Tabas, Iran, at the intersection with coal seam is studied. The main tunnels of this mine show significant horizontal displacements due to the complex ground conditions and great depth. The behavior of the rock mass surrounding the tunnel is investigated using various experimental methods, and according to the results obtained, the surrounding rock mass has squeezing conditions. In order to analyze the stability of the main tunnels, a series of 2D and 3D numerical modelings are performed using the FLAC2&3D finite difference software, and the results obtained are compared with the actual displacement values recorded in the walls of the main tunnels of the mine. The analysis results show that the tunnels under study are unstable with a steel frame support, and therefore, the use of different support systems for the stabilization is investigated. The results of modeling different types of support systems show that the use of shotcrete instead of galvanized sheet (as strut) does not have a significant effect on the reduced displacements. Also although the installation of steel sets is very effective in preventing the displacement of the walls, due to the swelling problems in the tunnel bottom and the placement of the conveyor and haulage rail, it cannot be used in practice. Finally, the use of truss bolt has yielded good results, and it can be proposed as a new support system in these tunnels. In addition, the modeling results show that in case the coal seam is higher than the tunnel foot, less displacement will occur in the tunnel walls compared to the other cases. In other words, changing the tunnel level in the future excavations can help reduce the displacements.

Ensuring the stability and integrity of underground gas storage salt caverns is a very complicated subject due to the non-linear and time-dependent behavior of rock salts under complicated thermal and mechanical loading conditions. For this reason, pressure and temperature fluctuations in the caverns and their surrounding strata must be integrated into the analysis and the numerical tools that are used for this purpose. LOCAS, a 2D axisymmetric finite-element code, dedicated to the stability analysis of underground salt spaces, was applied to assess the effects of various operating and geometrical parameters on the cavern behavior. In this paper, we aimed to give an overall assessment of the behavior of the salt caverns used for natural gas storage. In this work, some specific loading scenarios were considered first, followed by thorough parametric and sensitivity analyses to reveal the impacts of the geometrical parameters and operational parameters involved on the behavior of salt caverns using the modern stability criteria. The findings showed that the onset of dilation was more likely to happen within the first cavern life cycle when pressure dropped to the minimum level. As for the potential of tension occurrence in the surrounding rock, this is more likely to happen by increasing the number of operation cycles, especially in the upper one-third of the cavern wall. Finally, it was seen that the cavern depth and minimum cavern internal pressure had even more important influences than the others on the salt cavern behavior.