1 / 11

Estimating Mining Induced Stress

Estimating Mining Induced Stress. Penny Stewart BEng(Mining) PhD. Estimation of Elastic Stress. All empirical design tools, across all disciplines of engineering have one thing in common – They must be applied consistently

unity
Télécharger la présentation

Estimating Mining Induced Stress

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Estimating Mining Induced Stress Penny Stewart BEng(Mining) PhD

  2. Estimation of Elastic Stress • All empirical design tools, across all disciplines of engineering have one thing in common – They must be applied consistently • Now that 3D models are commonly used, it is worth checking how this affects 2D derived mining induced stresses upon which stability charts are based. • 1980s to late 1990s, induced stresses were estimated using 2d plain-strain charts (Stewart and Forsyth, 1995)- Kirsch equation closed form linear elastic solution. • Charts not applicable for low aspect ratios in the database • Map3d boundary element • Most authors used 2d stress estimation methods  Need to check Map3d against 2d model eg Phases2d

  3. Example: South Crofty mine: Stope320 15H Map3d Stress Estimation Span = 32 m Hangingwall Width = 17m Stress Resolution Grid 3 Height = 75 m 3 -0.94 MPa

  4. Example: Stope 320 15HPhases 2d Stress Estimation 3 -3.2 MPa 3

  5. Estimation of Elastic Stress II • 2d Phases hybrid boundary element/finite element estimated larger tensile stresses than Map3d • Difference between Phases2d and Map3d could not be explained for stopes approaching 2d geometry • ie. Aspect ratio >5

  6. Estimation of Elastic Stresses III • Further investigation required • South Crofty case study used to compare numerical modelling programs • High aspect ratio = 83 (strike span to width)  Theoretically, 2d should be very similar to 3d model results • Compare FLAC3D (finite element) with Map3d (boundary element)

  7. FLAC3D Stress Estimation Stope 3=-1.99 MPa 3=-7.59 MPa

  8. Some difference between FLAC3D and FLAC Comparison of Stress Estimation Method: South Crofty

  9. Comparison of Stress Estimation Methods @ Bottom of Stope Bottom of stope less sensitive to element size

  10. Conclusions: Comparison of Stress Estimation Methods • FLAC3d, 2d FLAC and Map3d produce similar values Map3d stress estimates of induced stresses will be used, not Phases2d • Further investigation is required to explain why Phases2d is predicting larger tensile stresses than Map3d, FLAC3d and 2d FLAC • Comparison of codes

More Related