Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-3 (of 3 Records) |
Query Trace: Tesarik D[original query] |
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User-friendly finite element design of main entries, barrier pillars, and bleeder entries
Pariseau WG , Larson MK , Lawson HE , Tesarik DR . Int J Min Sci Technol 2017 28 (1) 3-10 This contribution describes development and application of a user-friendly finite element program, UT3PC, to address three important problems in underground coal mine design: (1) safety of main entries, (2) barrier pillar size needed for entry protection, and (3) safety of bleeder entries during the advance of an adjacent longwall panel. While the finite element method is by far the most popular engineering design tool of the digital age, widespread use by the mining community has been impeded by the relatively high cost of and the need for lengthy specialized training in numerical methods. Implementation of UT3PC overcomes these impediments in three easy steps. First, a material properties file is prepared for the considered site. Next, mesh generation is automatic through an interactive process. A third and last step is simply execution of the program. Examples using data from several western coal mines illustrate the ease of using the application for analysis of main entries, barrier pillars, and bleeder entry safety. |
Effects of overburden characteristics on dynamic failure in underground coal mining
Lawson HE , Tesarik D , Larson MK , Abraham H . Int J Min Sci Technol 2016 27 (1) 121-129 Dynamic failures, or bumps, remain an imperative safety concern in underground coal mining, despite significant advancements in engineering controls. The presence of spatially discrete, stiff roof units are one feature that has been linked to these events. However, an empirical stratigraphic review indicates that no significant difference exists in the relative commonality of discrete units between bumping and non-bumping deposits. Instead an apparent relationship exists between reportable bumping and the overall stiffness of the host rock. However, this initial study is too simplistic to be conclusive; to weight the relative impact of changes in a single variable, such as the thickness or location of sandstone members, it must be examined in isolation-i.e., in a setting where all other variables are held constant. Numerical modelling provides this setting, and the effects of variability in a stiff discrete member in a hypothetical longwall mining scenario are investigated within the context of three stratigraphic types, Compliant, Intermediate and Stiff. A modelling experiment examines changes in rupture potential in stiff roof units for each stratigraphic type as discrete unit thickness and location are manipulated through a range of values. Results suggest that the stiff-to-compliant ratio of the host rock has an impact on the relative stress-inducing effects of discrete stiff members. In other words, it is necessary to consider both the thickness and the distance to the seam, within the context of the host rock, to accurately anticipate areas of elevated rupture-induced hazard; acknowledging the presence of a discrete unit within the overburden in general terms is an insufficient indicator of risk. This finding helps to refine our understanding of the role of individual stiff, strong roof members in bumping phenomena, and suggests that a holistic view of overburden lithology and site-specific numerical modelling may be necessary to improve miner safety. |
Long-term stability of a backfilled room-and-pillar test section at the Buick Mine, Missouri, USA
Tesarik DR , Seymour JB , Yanske TR . Int J Rock Mech Min Sci 2009 46 (7) 1182-1196 Rock mechanics instruments have been providing data in a backfilled room-and-pillar test section of the Buick Mine near Boss, Missouri, USA, for nearly 16 years. Host rock instruments include borehole extensometers installed in the mine roof and pillars, and biaxial stressmeters used in pillars and abutments. Embedment strain gauges, extensometers, and earth pressure cells were installed in the cemented backfill. The instruments monitored stability of the test section for two years while the pillars were extracted, and 14 years after pillar extraction to monitor long-term stability. Of the transducers that were not mined out when the pillars were extracted, 68% still function. Data from these instruments demonstrate that backfill improves long-term underground safety by supporting the mine roof and maintaining the strength of support pillars. For example, backfill significantly limited the dilation of a remaining support pillar by providing confinement on one side of the pillar. Post-mining stress and strain in the backfill account for 35% and 28% of the total stress and strain that was measured, respectively. Earth pressure cell stress measurements confirmed visual observations that the backfill remained stable. Post-mining stress measurements from the earth pressure cells fit natural log equations as a function of time with r-squared values ranging from 0.76 to 0.98. Natural log equations also described post-mining strain behavior of the backfill with r-squared values ranging from 0.30 to 0.99. Stresses calculated for the backfill by a three-dimensional numerical model of the test area were consistent with those that were measured by earth pressure cells. Published by Elsevier Ltd. |
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