Title page for ETD etd-06062008-171333

Type of Document Dissertation
Author Akram, Muhammad
URN etd-06062008-171333
Title Stability assessment of entry roofs in underlying multiple seam mines
Degree PhD
Department Mining and Minerals Engineering
Advisory Committee
Advisor Name Title
Haycocks, Christopher Committee Chair
Faulkner, G. J. Committee Member
Karfakis, Mario G. Committee Member
Karmis, Michael E. Committee Member
Luttrell, Gerald H. Committee Member
  • Mine roof control
Date of Defense 1993-06-07
Availability restricted

Entry roofs in underlying multiple seam mines are vulnerable to failure under the influence of stress transferred from the upper seam workings. Overburden depth, innerburden thickness, percentage of hard rock in the innerburden and relative location of pillars in the two seams are some of the factors known to influence stress transfer and ensuing instability in the lower seam. This study was undertaken to quantify the effects of these factors and to develop a comprehensive roof stability assessment model capable of predicting any instability in the lower seam entry roofs under given conditions of geology and loading.

The finite element analysis technique was used to model a range of loading conditions and innerburden lithology. The innerburden thickness was varied from 50 to 20 feet. The innerburden lithology was varied in terms of percentage of sandstone and its location in the innerburden. Various loading conditions were simulated by changing the relative location of pillars in the two seams and by varying overburden depths from 300 feet to 1500 feet. Excessive horizontal stresses and unsymmetric loading were also simulated. The effects of these factors were quantified in terms of safety factors across the entry span.

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