2 edition of Stress-induced failures in mine roof found in the catalog.
Stress-induced failures in mine roof
James R Aggson
Bibliography: p. 16
|Statement||by James R. Aggson|
|Series||Report of investigations - Bureau of Mines ; 8338|
|Contributions||United States. Bureau of Mines|
|The Physical Object|
|Pagination||16 p. :|
|Number of Pages||16|
Strata control is the science (some would suggest art) of utilizing various techniques to prevent or control failure of the strata around mine openings at least for the period where access is required. For different locations in the mine this period may be for the life of the mine (which can be considered as permanent), such as the main mine. The proposed failure criterion, incorporating the scale effect for predicting stress-induced overbreak around excavations, combines the both rock mass and intact rock scales through a relation defining the B parameter. As presented previously, a scale effect is strongly evident at the intact rock scale, for boreholes that are less than 75 mm in Author: A. Delonca, J.A. Vallejos.
Chapter 1 Tension, Compression, and Shear Introduction Mechanics of Materials: to understand the behavior of solid bodies Materials that undergo large strains before failure are classified as ductile (f > 10%), such as mild steel, aluminum and its alloy, copper, lead Size: KB. The failure zone is formed when (ii) two continuous strain bands intersect with each other and with the excavation boundary, or (ii) if one continuous shear band which starts and ends at the boundary is formed. The failure, i.e., spalling of the rock is a progressive process that ends up in a final form that is most often triangular notch by:
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Stress-induced failures in mine roof. [Washington]: Dept. Stress-induced failures in mine roof book the Interior, Bureau of Mines, (OCoLC) Online version: Aggson, James R. Stress-induced failures in mine roof. [Washington]: Dept. of the Interior, Bureau of Mines, (OCoLC) Material Type: Government publication, National government publication: Document.
The roof failures predicted by the finite element analysis under known loading conditions correlate well with the roof failures observed underground.
The most probable failure modes are identified for the various loading conditions considered. Various failure preventive measures are discussed. Figure Horizontal, stress-induced roof failure that initiated between two pillars.
Arrows show measured direction of maximum horizontal stress. Figure Plan view showing the development of a stress-related roof fall in the.
Figure 3. Direction of failed roof normalized by drivage in a given direction 4. Stress induced cutter roof failure Direction and Magnitude of the Horizontal Stress Initially, to determine the direction of the maximum horizontal stress, the pattern of the roof falls was used.
The highest percentage of roof falls. As briefly discussed above, stress induced failures in the tunnel roof may result in large volumes of rock that need to be suspended in the upper zone of the roof.
In addition, some of these failures may result in significant shear displacements that may overload rock bolts. In the particular case of brittle failure Cited by: Summary. In an effort to minimize cutter roof failures in longwall development entries of a West Virginia coal mine, a three-entry system was developed with the center entry arched into the strata above the coal seam.
The purpose of the arched entry was to modify the horizontal stress envelope associated with the three-entry system Cited by: 2. Figure 4. Shallow stope failure, Moneta Mine .
Modeling such a large mine is complex and difficult. CANMET’s large 3D finite element code, ROCK3D  was used to model the entire upper stopes of the mine in order to obtain the impact on the existing stress field. The model was 6, m long and 3, m wide, containing at.
Stress path and instability around mine openings mine at ever increasing depths in a safe and efﬁcient manner. Yet, traditionally, mining at depth incurs rock mass failures that impact the economic and safety aspects of a mine.
Today many mines are gesting that for stress induced failure s = 0. The potential for instability in the rock surrounding underground mine openings is an ever-present threat to both the safety of men and equipment in the mine.
In addition, because of dilution of the ore due to rock falls, the profitability of the mining operation may be reduced if failures are allowed to develop in the rock surrounding a stope. Coal Operators’ Conference The AusIMM Illawarra Branch February INVESTIGATIONS INTO PREMATURE ROCK BOLT FAILURES IN THE AUSTRALIAN COAL MINING INDUSTRY Bruce Hebblewhite 1, Mike Fabjanczyk 2 and Peter Gray 3 ABSTRACT: An ACARP project was initiated in to address the observed phenomenon of premature failure of rock bolts in a.
sequence in the absence of horizontal stress, roof falls related to stackrock may indicate an increased horizontal stress is attacking the roof. The average depth of cover over the 6 mines is ft.
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conducted a field experiment using an integrated real time monitoring system with extensometers, stress-meters, and a.
Observations and analyses of roof guttering in a coal mine To eliminate, control, or minimize the risk of rockfalls, pillar failure, and roof and floor failure as a result of the instability associated with bord and pillar mining, it is necessary to understand the distribution of stress.
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Performance of Roof Support Under High Stress in a U.S. Coal Mine; Preventing Falls of Ground in Coal Mines With Exceptionally Low-Strength Roof: Two Case Studies; Rock Falls; Rock Mechanics Study of Lateral Destressing for the Advance-and-Relieve Mining Method; Safer Mine Layouts for Underground Stone Mines Subjected to Excessive Levels of Horizontal Stress; Utilizing the.
Tunnels in weak rock 2 Figure 1: Vertical section through a three-dimensional finite element model of the failure and deformation of the rock mass surrounding the face of an advancing circular tunnel.
The plot shows displacement vectors as well as the shape of the deformed tunnel profile. Analysis of cutter roof failure induced by clastic dikes in an underground coal mine (OCoLC) Material Type: Government publication, National government publication: Document Type: Book: All Authors / Contributors: Eric R Bauer; John L Hill; United States.
Bureau of Mines. Seismic activity intensifies before major roof displacement or stress changes are evident, and subsides in the later stage of roof failure when large roof displacement is visible. The seismic resonance frequencies decrease during roof failure by: Performance of roof support under high stress in a U.S.
coal mine The primary goal of the project was to obtain detailed data on the interaction between the mine roof and the support elements. Failure Criterion in Solid Mechanics To understand the mechanisms that contribute to stress-induced brittle failure (spalling, bursting, etc.), we need to understand the basic principals of rock strength and the initiation and propagation of brittle fractures.
Traditionally, there have been two approaches to .Stress induced miter mof failure Direction and Magnitude of the Horizontal Stress Initially, to determine the direction of the maximum horizontal stress, the pattern of the roof falls was used. The highest percentage of roof falls occurred in the N 30" W direction (figure 3).
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