scholarly journals Rock Mass Characterization and Stability Evaluation of Mount Rushmore National Memorial, Keystone, South Dakota

2018 ◽  
Vol 24 (4) ◽  
pp. 385-412
Author(s):  
S. Lindsay Poluga ◽  
Abdul Shakoor ◽  
Eric L. Bilderback
Keyword(s):  
Rock Mass ◽  
Factor Of Safety ◽  
Static Condition ◽  
Seismic Load ◽  
Rock Mass Characterization ◽  
Calculation Results ◽  
Back Calculation ◽  
Wedge Sliding ◽  
The Mean ◽  
The Stability

Abstract The purpose of this study was to characterize the rock mass at Mount Rushmore National Memorial (MORU) and to evaluate the stability of the presidential sculptures. The sculptures are carved in granite, but quartz-mica schist and minor outcrops of pegmatite are also present within the site area. We divided the MORU area into four “regions” to collect discontinuity data. Since the sculptures were not accessible during this study, we used light detection and ranging (LiDAR) data and Split-FX software to determine the orientations of both the discontinuities and the slopes on the sculptures. The rock mass characterization results, using both the Rock Mass Rating system and the Q-system, indicate the granite, schist, and pegmatite classify as fair to good rock. Kinematic analysis results indicate that the potential for planar, wedge, and toppling failures exists for various slopes on each of the sculptures. The factor of safety (FS) values against planar and wedge sliding, ignoring cohesion, range from 0.1 to 0.8 and from 0.2 to 1.3, respectively. Since failures have not been observed at the memorial, we back-calculated the amount of cohesion required to raise the FS values to >1. The back-calculation results show that both cohesion and friction contribute to stability of the sculptures. Using the Slide program, we performed an overall slope probabilistic analysis for the slopes on which the MORU sculptures are located. The analysis determines the mean factor of safety (FSM), reliability index (RI), and probability of failure (PF) for the slopes. For the static condition, the analysis resulted in FSM, RI, and PF values ranging from 3.3 to 4.5 percent, 3.3 to 7.8 percent, and 0 percent, respectively. With a seismic load coefficient of 0.14 applied to the slopes, the corresponding values were: 2.6 to 4.1 percent, 2.9 to 4.7 percent, and 0 percent. For both the static and seismic conditions, the results indicate that, overall, the slopes of the sculptures are stable.

scholarly journals Analysis of Possible Origination of Domes in Longwalls

2019 ◽  
Vol 4 (1) ◽  
pp. 57-64
Author(s):  
R. I. Imranov ◽  
E. N. Khmyrova ◽  
O. G. Besimbayeva ◽  
S. P. Olenyuk ◽  
A. Z. Kapasova
Keyword(s):  
Rock Mass ◽  
Factor Of Safety ◽  
Coal Seams ◽  
Mining Operations ◽  
Compressive Stresses ◽  
Digital Modeling ◽  
Geological Conditions ◽  
The Stability ◽  
High Ash Coal ◽  
Borehole Log

The research is aimed at solving problems of assessing underground working stability in complicated mining and geological conditions to increase reliability and safety of mining operations. Analysis of geomechanical processes occurring in a rock mass during extraction of coal seams to determine the stability of mining block roof is the most important task. The performed digital modeling of the rock mass based on the structural logs for K1 seam and the nearest borehole log enabled highly detailed identifying the types of rocks occurred in the seam roof and their strength characteristics, compressive stresses. To determine the stability of a mining block roof, the factor of safety of the rocks was used, which was determined by modeling method using Phase 28.0 and Rockscince software. The carbonaceous argillite parting 0.09–0.12 m thick was taken as the contact of the longwall with the seam roof, and, for completeness of the analysis, the upper high-ash coal member in the seam roof up to 0.7 m thick was used. The modeling findings, presented in the graph of dependence between the safety factor and the distance between the belt heading and air drift, showed that the probability of dome formation in the longwall is high, as the factor of safety of the rocks is less than unity, that indicates the roof instability in the course of the coal seam block extraction. The modeling methods allowed assessing the mine working stability, based on which the measures to improve the reliability and safety of mining operations can be timely developed, and due technical and technological solutions shall be reached.

scholarly journals Rock Mass Characterization by UAV and Close-Range Photogrammetry: A Multiscale Approach Applied along the Vallone dell’Elva Road (Italy)

Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 436
Author(s):  
Maria Migliazza ◽  
Maria Teresa Carriero ◽  
Andrea Lingua ◽  
Emanuele Pontoglio ◽  
Claudio Scavia
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Small Scale ◽  
Stability Conditions ◽  
Multiscale Approach ◽  
Rock Mass Characterization ◽  
Geometrical Data ◽  
Close Range ◽  
The Stability ◽  
Kinematic Mechanisms

Geostructural rock mass surveys and the collection of data related to discontinues provide the basis for the characterization of rock masses and the study of their stability conditions. This paper describes a multiscale approach that was carried out using both non-contact techniques and traditional support techniques to survey certain geometrical features of discontinuities, such as their orientation, spacing, and useful persistence. This information is useful in identifying the possible kinematics and stability conditions. These techniques are extremely useful in the case study of the Elva valley road (Northern Italy), in which instability phenomena are spread across 9 km in an overhanging rocky mass. A multiscale approach was applied, obtaining digital surface models (DSMs) at three different scales: large-scale DSM of the entire road, a medium-scale DSM to assess portions of the slope, and a small-scale DSM to assess single discontinuities. The georeferenced point cloud and consequent DSMs of the slopes were obtained using an unmanned aerial vehicle (UAV) and terrestrial photogrammetric technique, allowing topographic and rapid traditional geostructural surveys. This technique allowed us to take measurements along the entire road, obtaining geometrical data for the discontinuities that are statistically representative of the rock mass and useful in defining the possible kinematic mechanisms and volumes of potentially detachable blocks. The main purpose of this study was to analyse how the geostructural features of a rock mass can affect the stability slope conditions at different scales in order to identify road sectors susceptible to different potential failure mechanisms using only kinematic analysis.

Comparing slope stability analysis using limit equilibrium and finite elements simulations of deep-seated landslides along the western margin of the Main Ethiopian Rift

2021 ◽  
Author(s):  
Tesfay Kiros Mebrahtu ◽  
Thomas Heinze ◽  
Stefan Wohnlich
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Strength Reduction ◽  
Ethiopian Rift ◽  
Seismic Load ◽  
Main Ethiopian Rift ◽  
Western Margin ◽  
The Stability

<p>Landslides and ground failures are among the common geo-environmental hazards in many of the tectonically active hilly and mountainous terrains of Ethiopia, such as in the western margin of the Main Ethiopian Rift in Debre Sina area. Besides the geological preconditioning, bi-modal monsoon and seismic events in the tectonically highly active region are usually suspected triggers. In order to minimize the damage caused by the slope failure events, a detailed investigation of landslide-prone areas using numerical modelling plays a crucial role. The aim of this study is to assess the stability of slopes, to understand the relevant failure mechanisms, and to evaluate and compare safety factors calculated by the different available numerical methods. The stability was assessed for slopes of complex geometry and heterogeneous material using the limit equilibrium method and the shear strength reduction method based on finite elements. Furthermore, numerical analysis was done under static and pseudo-static loading using the horizontal seismic coefficient to model their stability during a seismic event. The slope stability analysis indicates that the studied slopes are unstable, and any small scale disturbance will further reduce the factor of safety and probably causing failure. The critical strength reduction factors from the finite element method are significantly lower than the factor of safety from the limit equilibrium method in all studied scenarios, such as Bishop, Janbu Simplified, Spencer and Morgenstern-Price. The difference is especially evident for heterogeneous slopes with joints, which often are initiation points for the failure planes. The simulations show that slope stability of landslide prone hills in the study area strongly depends on the saturation conditions and the seismic load. The studied slopes are initially close to failure and increased pore-pressure or seismic load are very likely triggers.</p>

Comparing traditional geomechanical and remote sensing techniques for rock mass characterization 

2021 ◽  
Author(s):  
Angela Caccia ◽  
Biagio Palma ◽  
Mario Parise
Keyword(s):  
Rock Mass ◽  
Point Cloud ◽  
Laser Scanning ◽  
Quantitative Description ◽  
Present Contribution ◽  
Rock Mass Characterization ◽  
Rock Face ◽  
Remote Sensing Techniques ◽  
The Stability ◽  
Processing Techniques

<p>Analysis of the stability conditions of rock masses starts from detailed geo-structural surveys based on a systematic and quantitative description of the systems of discontinuities. Traditionally, these surveys are performed by implementing the classical geomechanical systems, available in the scientific literature since several decades, through the use of simple tools such as the geological compass to measure dip and dip direction directly on the discontinuity systems, and to fully describe their more significant physical characteristics (length, spacing, roughness, persistence, aperture, filling, termination, etc.). In several cases, this can be difficult because the discontinuities, or even the rock face, cannot be easily accessible. To have a complete survey, very often the involvement of geologists climbers is required, but in many situations this work is not easy to carry out, and in any case it does not cover the whole rock front.</p><p>Today, to solve these problems, traditional geomechanical surveying is implemented by innovative remote techniques using, individually or in combination, instruments such as terrestrial laser scanners and unmanned aerial vehicles to build a point cloud.</p><p>This latter permits to extract very accurate data on discontinuities for stability analyses, based on areal and non-point observations. In addition, the point cloud allows to map sub-vertical walls in their entirety in much shorter times than traditional surveying.</p><p>At this regard, two rock slopes were detected in the Sorrento Peninsula (Campania, southern Italy) with techniques that include traditional mapping, dictated by the guidelines of the International Society for Rock Mechanics, and the remote survey, through laser scanning and drone photogrammetry. The data obtained were processed automatically and manually through the Dips, CloudCompare and Discontinuity Set Extractor softwares.</p><p>In the present contribution we highlight the limits and advantages of the main data collection and the processing techniques, and provide an evaluation of the software packages currently available for the analysis and evaluation of discontinuities, in order to obtain a better characterization of the rock mass.</p>

scholarly journals Geostructural and Geomechanical Study of the Piastrone Quarry (Seravezza, Italy) Supported by Photogrammetry to Assess Failure Mode

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 64
Author(s):  
Sabrina Bonetto ◽  
Gessica Umili ◽  
Anna Maria Ferrero ◽  
Rodolfo Carosi ◽  
Matteo Simonetti ◽  
...  
Keyword(s):  
Rock Mass ◽  
Failure Modes ◽  
Three Dimensional ◽  
Point Clouds ◽  
Orientation Data ◽  
Rock Mass Characterization ◽  
Rock Bridges ◽  
Survey Techniques ◽  
Ornamental Stone ◽  
The Stability

The use of non-contact-techniques for rock mass characterization has been growing significantly over the last decade. However, their application to stability assessment of ornamental stone has not yet received much attention from researchers. This study utilizes rock mass data both in terms of slope orientations and degree of fracturing obtained from a point cloud, a set of three-dimensional (3D) points representing a rock mass surface, to (1) investigate the influence of geostructures at different scales and (2) assess quarry stability by determining areas susceptible to different failure types. Multi-resolution point clouds are obtained through several photogrammetric survey techniques to identify important structural elements of the site. By integrating orientation data of discontinuity planes, obtained with a traditional survey, and of traces, outlined on point clouds, several joint sets were identified. Kinematic tests revealed various potential failure modes of the rock slope. Moreover, an analysis of the influence of the discontinuity strength determined by the presence of rock bridges was carried out. The study revealed that the strength of the quarry face is governed by the presence of rock bridges that act to improve the stability condition of the rock fronts.

Research on Internal Force and Deformation of Supporting Rock-Socketed Piles Based on Ultimate Resistance Mechanics Theory

2010 ◽  
Vol 148-149 ◽  
pp. 108-111
Author(s):  
Fang Chen ◽  
Hao Qin ◽  
Chao Gao
Keyword(s):  
Rock Mass ◽  
Internal Force ◽  
Computing Methods ◽  
Force Balance ◽  
Deep Excavation ◽  
Mechanics Analysis ◽  
Calculation Results ◽  
The Stability ◽  
Ultimate Resistance ◽  
Theoretical Mechanics

At present there have rarely studies on internal force and deformation for rock-socketed piles of deep excavation. The current approaches still exist and have many deficiencies and all of them didn't consider the effect of rock-socketed length. Based on the theoretical mechanics analysis of rock mass resistance, the computing methods of ultimate resistance Pult is applied to the analysis of force balance of rock-socketed part, the paper has put forward the detailed procedure for computing internal force and deformation of supporting rock-socketed piles in view of the rock-socketed length, moreover, the influence of the stability of rockmass is comprehensive considered in this method. Finally, an example is analyzed according to the procedure, the calculation results show that the method is much feasibility. The internal force and deformation of the retaining piles computed according to the procedure mentioned above satisfies the stability of rockmass.

Injuries to the Coronoid Process of the Ulna with Involvement of the Lesser Sigmoid Notch

2020 ◽  
Author(s):  
Valentin Rausch ◽  
Sina Neugebauer ◽  
Tim Leschinger ◽  
Lars Müller ◽  
Kilian Wegmann ◽  
...  
Keyword(s):  
Fragment Size ◽  
Coronoid Process ◽  
Annular Ligament ◽  
Concomitant Injuries ◽  
Proximal Ulna ◽  
Sigmoid Notch ◽  
Coronoid Fractures ◽  
The Mean ◽  
The Stability ◽  
Arthritic Changes

Abstract Introduction This study aimed to describe the involvement of the lesser sigmoid notch in fractures to the coronoid process. We hypothesized that injuries to the lateral aspect of the coronoid process regularly involve the annular ligament insertion at the anterior lesser sigmoid notch. Material and Methods Patients treated for a coronoid process fracture at our institution between 06/2011 and 07/2018 were included. We excluded patients < 18 years, patients with arthritic changes or previous operative treatment to the elbow, and patients with concomitant injuries to the proximal ulna. In patients with involvement of the lesser sigmoid notch, the coronoid height and fragment size (anteroposterior, mediolateral, and craniocaudal) were measured. Results Seventy-two patients (mean age: 47 years ± 17.6) could be included in the study. Twenty-one patients (29.2%) had a fracture involving the lateral sigmoid notch. The mean anteroposterior fragment length was 7 ± 1.6 mm. The fragment affected a mean of 43 ± 10.8% of the coronoid height. The mean mediolateral size of the fragment was 10 ± 5.0 mm, and the mean cranio-caudal size was 7 ± 2.7 mm. Conclusion Coronoid fractures regularly include the lesser sigmoid notch. These injuries possibly affect the anterior annular ligament insertion which is important for the stability of the proximal radioulnar joint and varus stability of the elbow.

Instant 99mTc-Labelled Glucoheptonate Kit for Kidney Imaging

1983 ◽  
Vol 22 (05) ◽  
pp. 246-250 ◽  
Author(s):  
M. Al-Hilli ◽  
H. M. A. Karim ◽  
M. H. S. Al-Hissoni ◽  
M. N. Jassim ◽  
N. H. Agha
Keyword(s):  
Sodium Hydroxide Solution ◽  
Normal Subjects ◽  
Organ Distribution ◽  
Stable Complex ◽  
Scintillation Camera ◽  
Ph Adjustment ◽  
The Mean ◽  
The Stability ◽  
Kidney Imaging ◽  
Mean Concentration

Gelchromatography column scanning has been used to study the fractions of reduced hydrolyzed 99mTc, 99mTc-pertechnetate and 99mTc-chelate in a 99mTc-glucoheptonate (GH) preparation. A stable high labelling yield of 99mTc-GH complex in the radiopharmaceutical has been obtained with a concentration of 40-50 mg of glucoheptonic acid-calcium salt and not less than 0.45 mg of SnCl2 2 H2O at an optimal pH between 6.5 and 7.0. The stability of the complex has been found significantly affected when sodium hydroxide solution was used for the pH adjustment. However, an alternative procedure for final pH adjustment of the preparation has been investigated providing a stable complex for the usual period of time prior to the injection. The organ distribution and the blood clearance data of 99mTc-GH in rabbits were relatively similar to those reported earlier. The mean concentration of the radiopharmaceutical in both kidneys has been studied in normal subjects for one hour with a scintillation camera and the results were satisfactory.

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

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