A Simple Program for Estimating Multiple Seam Interactions

A Retrospective on LaModelorDr. Heasleys Wild RideDr. Keith A. HeasleyProfessorDepartment of Mining EngineeringWest Virginia UniversityKeith.Heasley@mail.wvu.edu(304) 293-3842It doesnt look so bad with my eyes closed1DevelopmentApplicationEnhancementA Retrospective on LaModel2MULSIMNIOSHBoundary Element Program for Displacement and Stress Analysisin Coal Mines3Boundary-ElementDisplacement Discontinuity Method

4Homogeneous OverburdenCoal SeamGround SurfaceHPz5Longwall Panel ConvergenceDistance from Center of Panel (m)Convergence (m)0204060801000.500.400.300.200.100.00Homogeneous Elastic OverburdenLaminated (t=15) OverburdenCL0100LM6Surface SubsidenceDistance from Center of Panel (m)Surface Subsidence (m)-200-1000100200-1.5-1.0-0.50.0LLCMHLaminated (t=5.3)EmpiricalOverburdenSubsidence CurveHomogeneous Elastic Overburden7Laminated OverburdenHPj01j-1j+1nn+1n-1tjEjvjzGround SurfaceCoal Seam8Longwall Panel ConvergenceDistance from Center of Panel (m)Convergence (m)0204060801000.500.400.300.200.100.00Homogeneous Elastic OverburdenLaminated (t=15) OverburdenCL0100LM9Surface SubsidenceDistance from Center of Panel (m)Surface Subsidence (m)-200-1000100200-1.5-1.0-0.50.0LLCMHLaminated (t=5.3)EmpiricalOverburdenSubsidence CurveHomogeneous Elastic Overburden10LaModelLaminated Boundary Element Program for Displacement and Stress Analysisin Coal Mines11Uses a Laminated Overburden ModelMore Realistic Stresses and Displacements

Used to Model:Multiple SeamsVariable TopographyComplex Mining Geometriesetc.LaModel12Case Study

13Upper Mine:Room-and-PillarOverburden 500 to 1300 ft (855 ft)Seam Thickness 5.0 ft7 Entry Rooms, Retreated

Lower Mine:Room-and-PillarInterburden 45 ftSeam Thickness - 5.0 ft7 Entries 60 by 70 ft PillarsCase Study14Overburden Stress

15Single Seam Stress

16Multiple Seam Stress

17Total Vertical Stress

18Stress Hazard Map

19Displacement and Stress CalculationsMultiple SeamsMultiple Mining Steps26 Different Seam Materials6 Non-Linear Seam Models

Basic Features20Material ModelsElastic Plastic32Strain Softening1Linear Elastic6Linear Elastic Gob5Strain-Hardening4Bi-Linear Hardening21Graphical Post-Processing (1996)Graphical Grid Generation (1999)Coal Wizard (2000)Grid Size IncreasesPillar Safety Factors (2006)Lam2D (2003)Stability Mapping (2006)LaModel Enhancements22LamPlt

23Grid Editor

24Grid Size

Keith;I need bigger grids, and more seamsGrid Size 250 x 250 (1996)400 x 400 (2000)1000 x 1000 (2004)2000 X 2000 (2010)25Grid Generator

26Grid Generator

27Pillar Safety Factor

28Energy Calculations

29Lam2D

Keith:2D is the way to go.

30Stability Mapping

31

Mine CollapseCrandall Canyon32Final Model

33Final Model

34Developed a procedure that calibrated:

The Rock Mass Stiffness against the extent of the abutment zoneThe Gob Stiffness against the expected gob loading (21 abutment angle)The Coal Strength with empirically determined pillar strength (900 psi).LaModel Calibration35Thickness Wizard

36Calibrated Database37Calibrated Safety Factor:

Keep the Safety Factor > 1.4 and

< 10% chance of failureCalibration Results38Calibrate to shallow coverRe-examine Abutment ExtentLocal Mine Stiffness CalculationARMPS-LAMImprove the speed of the Multiple-Seam calculationFuture Developments39

ARMPS-LAMKeith:You should build the laminated model into ARMPSIncorporate a laminated overburden loading model into the ARMPS program40Calibrate to shallow coverRe-examine Abutment ExtentLocal Mine Stiffness CalculationARMPS-LAMImprove the speed of the Multiple-Seam calculationFuture Developments41Dr. Heasleys Wild RideWhere to next?

42Questions?

Maybe, if I close my eyes, I wont have to ask questions4344Boundary-ElementDisplacement Discontinuity Method

45Boundary-ElementDisplacement Discontinuity Method

46Boundary-ElementDisplacement Discontinuity Method

47Boundary-ElementDisplacement Discontinuity Method

48