2015-02-26_REPORT - C1982056 (3)

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Panel Ribside I I I I I I I I I I Vertical Stress I Re -distribution 1 / 1 f Panel Yield Pillar "Rigid' or Abtatment Pillar (a) After Development Figure I Generalized Vertical Stress Change and Displacement during Longwall Mining (Derived using information from Mark, 1992. Bienawski, 1992, Shadbolt. 1977) Pillar Yeid and Floor Punching (load transier to cure) so 3 e 100 Floor Heave (b) After Longwall Extraction 1. Empirical Methods: Graphical Methods, Profile Functions, Influence Functions and Zone Area Methods. 2. Analytical Methods: Mechanistic Models, Finite Element, Boundary Element, and Hybrids. Panel Extension Compression �® I ®I I I Zone of Vertical Extension I (bed separation) I I I Q Zone of Bed Separation II ✓ �� Zone of Caving I r ®® 2 If "p O — — 1 3-5m Zone of Incomplete Convergence (c) Zones of Fracturing (Singh, 1986) EXPLANATION: M = Extracted seam thickness S = Subsidence av = In -situ weNcat stress Or = Side abutment stress +E = Extension •E = Compression Table 1 provides a summary of the relative capability of each method with regard to the prediction of subsidence, displacement, and strain. The interested reader is referred to the citations for a detailed description of each method. Table 1. Relative capability of the methods to predict subsidence, displacement and strain. PREDICTION METHOD METHOD OF PREDICTING (REFERENCE) Subsidence (S) Displacement Strain (E) Graphical Method Graphical based on w/h & Not predicted, however, Figure Maximum strains predicted (Ref: NCB, 1975) tabulated profile data 64 provides a monogram for using Smax/h multiplier. Strain calculating the change in length profile predicted using tabulated of a subsided surface structure. & araphical data. Profile Functions Uses mathematical equation Calculated from predicted Calculated from predicted (Karmis, 1992; Singh, 1992) based on empirical data. slope. curvature Zone Area Method Subsidence factor calculated by Calculated from predicted Calculated from predicted (Karmis & Hacocks, 1983; superposition of the proportional slope. curvature. Marr, 1975) extraction of a finite number of concentric rings forming the area of influence. Influence Functions Profiles constructed by Calculated from predicted Calculated from predicted (VPI, 1987; Salamon, 1992) integrating the influence function slope. curvature. (see eq. 3 -7 to 3 -11) Mechanistic Models Subsidence predicted based on Not addressed. Not addressed. composite beam deflections. Finite & Boundary Element Subsidence & related parameters Produced as model output. Computed from modeled Models simulated directly through displacements. (Su, 1992; Summers, 1990) analysis of the rock mass response to undermining.