Role of rock mass classifications in aiding effective support design in shallow workings at Koffiefontein Mine, South Western Free State, RSA

1993 ◽  
Vol 30 (1) ◽  
pp. A28
Keyword(s):  
Rock Mass ◽  
Free State ◽  
Support Design

Estimation of rockburst wall-rock velocity invoked by slab flexure sources in deep tunnels

2014 ◽  
Vol 51 (5) ◽  
pp. 520-539 ◽  
Author(s):  
Shili Qiu ◽  
Xiating Feng ◽  
Chuanqing Zhang ◽  
Tianbing Xiang
Keyword(s):  
Rock Mass ◽  
Seismic Source ◽  
Friction Angle ◽  
Wall Rock ◽  
Assessment Method ◽  
Source Mechanism ◽  
Uniaxial Tensile ◽  
Roughness Coefficient ◽  
Support Design ◽  
True Triaxial

For rock support in burst-prone ground, the wall-rock velocity adjacent to the surface of underground openings is a vital support design parameter, and depends on the seismic source mechanism inducing rockburst damage. In this study, to estimate the wall-rock velocity evoked only by rock slab buckling (an important rockburst source mechanism), a comprehensive velocity assessment method is proposed, using an excellent slab column buckling model with a small eccentricity, which relies on a novel compressive or tensile buckling failure criterion of rock slab. The true-triaxial loading–unloading tests and rockburst case analyses reveal that rock mass slabbing induced by high rock stress has major impacts on the evolution and formation of buckling rockburst in deep tunnels. Using a method based on the energy balance principle, the slabbing thickness of intact rock mass is also calculated by an analytical method, which indicates that the slabbing thickness parameter has a nonlinear relation to the following six parameters: uniaxial tensile strength (UTS), uniaxial compressive strength (UCS), normal stress (σn), length of joint (L), friction angle ([Formula: see text]), and joint roughness coefficient (JRC). These proposed models and methods have been quite successfully applied to rockburst and slabbing cases occurring in deep tunnels. These applications show that slab flexure is an important source mechanism invoking high wall-rock velocities and leading to severe rockburst damages in the area surrounding deep tunnels.

scholarly journals Automatic Monitoring System Designed for Controlling the Stability of Underground Excavation

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Piotr MAŁKOWSKI ◽  
Zbigniew NIEDBALSKI ◽  
Łukasz BEDNAREK
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Automatic Monitoring ◽  
Mass Movements ◽  
Support Design ◽  
Automatic Monitoring System ◽  
Underground Workings ◽  
The Stability ◽  
Technical Solutions ◽  
The Given

Ensuring the stability of mining excavations is a crucial aspect of underground mining. For thispurpose, appropriate shapes, dimensions, and support of workings are designed for the given mining andgeological conditions. However, for the proper assessment of the adequacy of the used technical solutions,and the calibration of the models used in the support design, it is necessary to monitor the behavior of theexcavation. It should apply to the rock mass and the support. The paper presents the automatic systemdesigned for underground workings monitoring, and the example of its use in the heading. Electronicdevices that measure the rock mass movements in the roof, the load on the standing support, and on bolts,the stress in the rock mass, are connected to the datalogger and can collect data for a long of time withoutany maintenance, also in hard-to-reach places. This feature enables the system to be widely used, inparticular, in excavations in the vicinity of exploitation, goafs, or in the area of a liquidated exploitationfield.

scholarly journals The role of modern geodynamic movements in the formation of geomechanical problems in subsoil use

2018 ◽  
Vol 56 ◽  
pp. 02010
Author(s):  
Anatoly Sashourin ◽  
Andrey Panzhin ◽  
July Konovalova ◽  
Vladimir Ruchkin
Keyword(s):  
Rock Mass ◽  
Secondary Structures ◽  
Mineral Deposits ◽  
Scientific School ◽  
Short Term ◽  
Fundamental Properties ◽  
Deformation Processes ◽  
Hazard Level ◽  
Proactive Measures

The paper describes the role of geomechanical processes and phenomena in the development and manifestation of hazardous situations in the development of mineral deposits, threatening the working personnel and the surrounding population. The studies of the Ural Scientific School of geomechanics functioning in the Institute of Mining of Ural Branch of RAS have established that the basis for the formation of hazardous geomechanical processes and phenomena are the fundamental properties of the rock mass - hierarchical blocking and constant mobility caused by the recent geodynamical movements. The constant mobility of hierarchical block medium of rock mass under the influence of trend and short-term recent geodynamical movements gives rise to the phenomenon of the secondary structuring. The recent geodynamical movements concentrate at the borders of the secondary structures and result in the deformations exceeding by 2 - 5 times the intrablock and integral deformations and representing the main source of the hazardous impact on the mining objects and on the surrounding population. The technology of the geological environment diagnostics for the forecast of hazardous mining situations is aimed at the identification of the boundary zones of secondary structures, the estimation of the hazard level of deformation processes and the adoption of proactive measures.

Tunnel reinforcement in columnar jointed basalts: The role of rock mass anisotropy

2015 ◽  
Vol 46 ◽  
pp. 1-11 ◽  
Author(s):  
Yossef H. Hatzor ◽  
Xia-Ting Feng ◽  
Shaojun Li ◽  
Gony Yagoda-Biran ◽  
Quan Jiang ◽  
...  
Keyword(s):  
Rock Mass

scholarly journals Formation of the Irish neutrality concept in the 1930s

2018 ◽  
pp. 210-226
Author(s):  
Olha Nahnybida
Keyword(s):  
Foreign Policy ◽  
Prime Minister ◽  
Free State ◽  
Irish Government ◽  
Formation And Evolution ◽  
Irish Free State ◽  
Practical Question

The article describes the specific aspects of the appearance, formation and evolution of the Irish neutrality as a foreign policy principle in the 1930s. The historical and geopolitical background of the formation of neutrality policy in the context of the struggle for independence and sovereignty of Ireland has been investigated. The role of Prime Minister Éamon de Valera as an ‘architect’ of neutrality policy of the Irish Free State and its foreign policy concept has been explored. It is emphasized that, unlike other neutral states, where the neutral status is legally secured, the neutrality of Ireland is of a traditional nature, since there are no clear legislative instructions according to which Ireland shall be obliged to adhere to the principle of neutrality in its foreign policy. The overcoming of the last obstacles to the proclamation of the neutral status of Ireland has been outlined, i.a. the elimination of the British naval presence in the Irish ports in 1938 and adoption of the Irish Constitution in 1937, which officially defined the annexation of Ulster. Finally, the influence of forthcoming WW2 has been explored. In the years of war, Ireland hoped to keep abstained not by adherence to some theoretical or abstract idea of neutrality, but by addressing to the practical question that the Irish government didn’t want to get involved in this conflict. They merely wanted to keep their people safe away from such consequences as they might appear when Ireland was directly involved in the war.

scholarly journals Previous classification of rock mass surrounding underground excavations and rock support design using block models

2021 ◽  
Vol 74 (4) ◽  
pp. 511-519
Author(s):  
Iure Borges de Moura Aquino ◽  
Rodolfo Renó ◽  
Roberto Mentzingen Rolo ◽  
André Cezar Zingano ◽  
Hernani Mota de Lima
Keyword(s):  
Rock Mass ◽  
Underground Excavations ◽  
Rock Support ◽  
Support Design ◽  
Block Models

scholarly journals Reliability Analysis of Rock Supports in Underground Mine Drifts: A Case Study

2021 ◽  
Author(s):  
Amoussou Coffi Adoko ◽  
Khamit Yakubov ◽  
Rennie Kaunda
Keyword(s):  
Rock Mass ◽  
Reliability Index ◽  
Probability Of Failure ◽  
Underground Mine ◽  
Mine Safety ◽  
Support Design ◽  
Rock Mass Quality ◽  
Reliability Method ◽  
East Kazakhstan ◽  
Rock Supports

Abstract Support failures in mine drifts represent potential hazards threatening underground mine safety and productivity. The aim of this study is to determine the reliability index associated with the rock supporting elements used in Ridder-Sokolny mine, an underground mine located in East Kazakhstan. Numerical simulations of the drift support and the first order reliability method (FORM) were employed to carry out the analysis. Several support cases were considered including; shotcrete, bolting, concrete, and combined bolting and concrete as well as unsupported drift case. For each support case, the factors of safety (FS), the reliability index (β) and the probability of failure (PF) were determined in accordance with the corresponding rock mass quality and excavation geometry. The results indicated the average FSs varied little for the different support cases (except for shotcrete); while β and PF vary more significantly between 0.62–3.25 and 0.05–27 (×103 %) factor depending on the rock conditions and support installed. The probability of failure of the rock support increases with a decrease in the rock mass quality. Similar trends were observed with an increase of the width/height ratio of the excavations for the same rock domain. These results illustrated that a single FS value obtained from a deterministic method may not always provide a sufficient indication of safety. This is in agreement with the field observations (many of the supports failed). Hence, on the basis of the reliability index of the supports, the requirement in terms of coefficient of variability of the rock mass quality to meet the target performance level was proposed. It is concluded that the results of this study could help improving the drift support design in Ridder-Sokolny mine.

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