The impact of soil parameters and slope angle on the deformation and stability of cut slopes is critical for defining road project safety measurement. This study investigates the effect of soil properties and slope angle on the deformation and stability of cut slopes in general and the specific Arba Minch-Chencha upgrading road project. Forty-eight (48) analyses were carried out both in Slope/W and Plaxis 2D software for six cut slopes and analyzed for four different slope angles. Twenty-four (24) dataset samples were collected from six different cut-slope sites. These dataset samples were categorized in two situations, i.e., before and after water saturation for each cut slope. The limit equilibrium method (LEM) comparison clearly showed that the Spencer, Bishop, and Morgenstern-Price methods produced similar FOS. The Ordinary and Janbu approaches, on the other hand, underestimate the FOS. Most LEMs except Ordinary and Janbu methods that estimated higher FOS than finite element method (FEM) analysis. It is observed that the main reasons for the cut-slope instability were the provision of steep cut-slope angles, the existence of a high proportion of fine soil, and moisture content, which was observed in both Plaxis 2D (FEM) and Slope/W (LEM). It was concluded that the slope is more stable for the soil having few fine-grained fractions. Moreover, flattening the slope stabilizes the cut slopes based on the results obtained from both Plaxis 2D and Slope/W.
This study was focused on a case-based investigation and analysis of road projects at the Arba Minch-Chencha site. Representative soil samples from six selected sites were collected for laboratory testing to experiment index and engineering properties of the representative soil samples. Limit equilibrium was used to analyze slope stability. [5, 32, 33].
Slope Stability And Stabilization Methods Abramson Pdf 115
The Slope/W program was used to build the geometry. Morgenstern-Price, Ordinary, Spencer, Bishop, and Janbu methods were used to solve FOS. The slope stability was further assessed using Plaxis 2D, which is a finite element method, and the factor of safety was determined by the strength reduction technique.
The stability of the slopes was analyzed using the FEM and LEM for comparison and verification of the slope condition. Using the LEM and FEM software, factor of safety (FOS) and slope deformation were determined. The comparison was made using modeling data from Plaxis 2D (FEM-based) and Geo-Slope 2012 (LEM-based) software. Furthermore, the condition of the slope before saturation and after saturation was analyzed so that the stability of the slope and the deformation of the corresponding state of the soil were determined. The input parameters for both LEM and FEM analysis were carefully determined from both laboratory and field tests. The whole set of the input parameters for both Plaxis 2D and Slope/W software for specified slopes was used to model the geometry of the slope.
Slope/W analyzes the stability of the slope using the LEM. Five different methods (Sarma, Bishop, Ordinary, Janbu, and Morgenstern-Price) were taken to check the stability of the slopes. Each method analyzes the slopes based on equilibrium conditions, some methods considered equilibrium for the moment and force in the horizontal and vertical direction (Sarma and Morgenstern-Price), others considered only moment equilibrium (Ordinary and Bishop), and Janbu considered force equilibrium in the horizontal and vertical directions [2].
The steepness was the primary cause of instability and then are a lower factor of safety and a higher maximum predicted displacement of a cut slope. Moreover, flattening the slope from (1H: 1V) to (1.5H: 1V), (2H: 1V), and (2.5H: 1V) stabilizes the slopes in both Plaxis 2D and Slope/W.
The factors of safety and cut-slope displacements were calculated using finite element analysis methods and the two-dimensional limit equilibrium method. To provide a more realistic simulation of the problem, the slope side effect should be incorporated into three-dimensional finite element analysis methods.
Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method (FEM) in four stages. These stages are slope stability analyses for pre- and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-SSR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition to slope stability evaluation, the Rock Mass Rating (RMR), Rock Mass Quality (Q) and New Austrian Tunneling Method (NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses.
Abstract:The primary aim of every twenty-first century mining operation is to extract as much ore as possible in a safe and economical manner. Failure in mine excavation occurs when the shear stress acting on the rock is greater than the shear strength of the rock mass. The stability of rock slopes in open-pit mine and quarry operations is extremely important from both economic and safety points of view because unstable slopes can result in the loss of human life and damage to properties. This paper presents an overview of several case studies of slope failure in mining operations and explains various modes of failure in rock slopes, as well as factors that influence the stability of slope walls. With the aim of enforcing the importance of monitoring and evaluating slope stability in mining, both linear equilibrium and numerical modeling techniques were reviewed to elaborate their importance in designing stable slopes. In addition, the process of slope failure was discussed, and key signs of failure were indicated. In an effort to prevent mines from experiencing the hazards of slope failure, this study reports previous work performed in determining slope failure and the current state-of-the-art models, which entail the integration of analytical methods with artificial intelligence techniques. This innovation would help overcome the drawbacks of conventional prediction techniques that are cumbersome and ambiguous.Keywords: slope failure; in situ; shear stress; rockmass; mining; factor of safety
Protein stability in detergent or membrane-like environments is the bottleneck for structural studies on integral membrane proteins (IMP). Irrespective of the method to study the structure of an IMP, detergent solubilization from the membrane is usually the first step in the workflow. Here, we establish a simple, high-throughput screening method to identify optimal detergent conditions for membrane protein stabilization. We apply differential scanning fluorimetry in combination with scattering upon thermal denaturation to study the unfolding of integral membrane proteins. Nine different prokaryotic and eukaryotic membrane proteins were used as test cases to benchmark our detergent screening method. Our results show that it is possible to measure the stability and solubility of IMPs by diluting them from their initial solubilization condition into different detergents. We were able to identify groups of detergents with characteristic stabilization and destabilization effects for selected targets. We further show that fos-choline and PEG family detergents may lead to membrane protein destabilization and unfolding. Finally, we determined thenmodynamic parameters that are important indicators of IMP stability. The described protocol allows the identification of conditions that are suitable for downstream handling of membrane proteins during purification.
Several methods exist for assessment of protein stability of IMPs. GFP-tagged proteins can be monitored by fluorescent-detection SEC to address their aggregation state during expression and purification23,24. In addition, stability in detergents has been studied using analytical size exclusion chromatography18,25. Slotboom et al. have addressed the behavior of IMPs in detergent micelles and lipid/detergent micelles in SEC-LS (light-scattering) analysis compared to sedimentation equilibrium centrifugation experiments26. Other methods like differential filtration and ultracentrifugation assays4 address the stability by quantifying the remaining protein in solution. However, the lack of aggregation is not necessarily an indication for a properly folded protein. The thermal denaturation assay using the thiol-specific fluorochrome N-[4-(7-diethylamino-4-methyl-3-coumarinyl) phenyl-maleimide (CPM)27 links stability of the IMP to the accessibility of free cysteine residues that become exposed to the solvent upon denaturation. However, not all membrane proteins are suitable for this analysis due to the lack of compatible Cys residues. Thermal denaturation experiments provide information whether an IMP displays a cooperative unfolding transition following a two-state model28, providing evidence of the folded state. The inflection point in a standard denaturation curve, Tm, has been a recurrent parameter to compare protein thermodynamic stability. Other studies have evaluated the stability of membrane proteins following the change of intrinsic fluorescence during thermal denaturation using a differential scanning fluorimetry device for the screening of lipid-like peptides29 and ligands30,31,32,33. Recently, Nji et al. have developed an engineered thermal-shift screen for detecting IMP lipids preferences based on fluorescence-detection size-exclusion chromatography (FSEC-TS). By using GFP-fusion IMPs the authors compare the stabilization of bacterial and eukaryotic membrane proteins before and after purification, and after addition of selected lipids to the purified IMPs. The authors conclude that eukaryotic membrane proteins appear to be more sensitive to the presence of lipids than prokaryotic ones21. 2ff7e9595c
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