A retrospective on lamodel or dr heasley s wild ride
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A Retrospective on LaModel or Dr. Heasley’s Wild Ride. It doesn’t look so bad with my eyes closed. Dr. Keith A. Heasley Professor Department of Mining Engineering West Virginia University [email protected] (304) 293-3842. A Retrospective on LaModel. Development Application

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A Retrospective on LaModelorDr. Heasley’s Wild Ride

It doesn’t look so bad with my eyes closed

Dr. Keith A. Heasley

Professor

Department of Mining Engineering

West Virginia University

[email protected]

(304) 293-3842


A Retrospective on LaModel

  • Development

  • Application

  • Enhancement


MULSIM

NIOSH

Boundary Element Program for

Displacement and Stress Analysis

in Coal Mines


Boundary-ElementDisplacement Discontinuity Method


Ground Surface

H

z

P

Coal Seam

Homogeneous Overburden


0.00

Homogeneous Elastic Overburden

0.10

C

L

L

0.20

M

Convergence (m)

100

0

0.30

0.40

Laminated (t=15) Overburden

0.50

0

20

40

60

80

100

Distance from Center of Panel (m)

Longwall Panel Convergence


0.0

Homogeneous Elastic Overburden

-0.5

Surface Subsidence (m)

H

-1.0

Laminated (t=5.3)

Overburden

Empirical

Subsidence Curve

C

-1.5

L

L

M

-200

-100

0

100

200

Distance from Center of Panel (m)

Surface Subsidence


Ground Surface

0

H

1

z

P

j-1

j

t

E

v

j

j

j

j+1

n-1

n

Coal Seam

n+1

Laminated Overburden


0.00

Homogeneous Elastic Overburden

0.10

C

L

L

0.20

M

Convergence (m)

100

0

0.30

0.40

Laminated (t=15) Overburden

0.50

0

20

40

60

80

100

Distance from Center of Panel (m)

Longwall Panel Convergence


0.0

Homogeneous Elastic Overburden

-0.5

Surface Subsidence (m)

H

-1.0

Laminated (t=5.3)

Overburden

Empirical

Subsidence Curve

C

-1.5

L

L

M

-200

-100

0

100

200

Distance from Center of Panel (m)

Surface Subsidence


LaModel

Laminated

Boundary Element Program for

Displacement and Stress Analysis

in Coal Mines


LaModel

  • Uses a Laminated Overburden Model

    • More Realistic Stresses and Displacements

  • Used to Model:

    • Multiple Seams

    • Variable Topography

    • Complex Mining Geometries

    • etc.


Case Study


Case Study

  • Upper Mine:

    • Room-and-Pillar

    • Overburden – 500 to 1300 ft (855 ft)

    • Seam Thickness – 5.0 ft

    • 7 Entry Rooms, Retreated

  • Lower Mine:

    • Room-and-Pillar

    • Interburden 45 ft

    • Seam Thickness - 5.0 ft

    • 7 Entries – 60 by 70 ft Pillars


Overburden Stress


Single Seam Stress


Multiple Seam Stress


Total Vertical Stress


Stress Hazard Map


Basic Features

  • Displacement and Stress Calculations

  • Multiple Seams

  • Multiple Mining Steps

  • 26 Different Seam Materials

  • 6 Non-Linear Seam Models


1

3

5

Strain-Hardening

Linear Elastic

Elastic Plastic

2

4

6

Linear Elastic Gob

Bi-Linear Hardening

Strain Softening

Material Models


LaModelEnhancements

  • Graphical Post-Processing (1996)

  • Graphical Grid Generation (1999)

  • Coal Wizard (2000)

  • Grid Size Increases

  • Pillar Safety Factors (2006)

  • Lam2D (2003)

  • Stability Mapping (2006)


LamPlt


Grid Editor


Grid Size

Keith;

I need bigger grids, and more seams

  • Grid Size

    • 250 x 250 (1996)

    • 400 x 400 (2000)

    • 1000 x 1000 (2004)

    • 2000 X 2000 (2010)


Grid Generator


Grid Generator


Pillar Safety Factor


Energy Calculations


Lam2D

Keith:

2D is the way to go.


Stability Mapping


Crandall Canyon

Mine Collapse


Final Model


Final Model


LaModel Calibration

  • Developed a procedure that calibrated:

    • The Rock Mass Stiffness against the extent of the abutment zone

    • The Gob Stiffness against the expected gob loading (21° abutment angle)

    • The Coal Strength with empirically determined pillar strength (900 psi).


Thickness Wizard


Calibrated Database


Calibration Results

  • Calibrated Safety Factor:

    • Keep the Safety Factor > 1.4 and

    • < 10% chance of failure


Future Developments

  • Calibrate to “shallow cover”

  • Re-examine Abutment Extent

  • Local Mine Stiffness Calculation

  • ARMPS-LAM

  • Improve the speed of the Multiple-Seam calculation


ARMPS-LAM

Keith:

You should build the laminated model into ARMPS

  • Incorporate a laminated overburden loading model into the ARMPS program


Future Developments

  • Calibrate to “shallow cover”

  • Re-examine Abutment Extent

  • Local Mine Stiffness Calculation

  • ARMPS-LAM

  • Improve the speed of the Multiple-Seam calculation


Dr. Heasley’s Wild RideWhere to next?


Questions?

Maybe, if I close my eyes, I won’t have to ask questions


Boundary-ElementDisplacement Discontinuity Method


Boundary-ElementDisplacement Discontinuity Method


Boundary-ElementDisplacement Discontinuity Method


Boundary-ElementDisplacement Discontinuity Method


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