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design procedure geotek untuk pembelajaran prosedur dari desain pada batuan ketahannan
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Underground Geotech Design and Procedures
Tembagapura, 21 June 2006
Flow chart for Geotechnical Design
• Pillar design• Ground support• Excavation
design
Pillar Design
Extraction level
Data collection
Wilson Pillar analysis (use FOS > 2.2)
Numerical modeling
Sill pillar
Crown pillar
• Rock mass classification
• Dimension of pillar
• Required life and long term plan
• Purpose of the excavation
• Caving and Mining Stress
• Expected personnel exposure
• Maximum allowable deformation
Pillar stability
Monitoring and Evaluation
Pillar Reinforcement
• Heavy support in medium to good ground
(Bolts + Mesh (two layers) + Shotcrete (2 layers) + T/bars
• Special support in poor ground
Steel set + concrete
Pillar Performance
• Partial closure at DrawpointsThe sill pillar failure was due to load from compacted muck in surrounding draw points.
The ground was classified as poor ground and regular ground support (bolts + Mesh + t/bar) was recommended
• Partial closure of panel Crown pillar failure occurred due to load from compacted muck.
The support is concrete but without steel set
• Slight damage at drawpoint pillarThe sill pillar is still stable though several of the surrounding drawpoints were compacted.
Special support with concrete and steel set was installed.
Pillar stability monitoring
P11-DP 5E/W P11-DP 5E/W
Condition Feb,14,2006 Condition Mar,07,2006
Mucking DB5 P10/11 Vs Conv.
Shutdown
Field Inspection
Convergence Monitoring
Recommendation/Action plan
Ground Support Design
Extraction/Undecut/Truck Haulage Level
Data collection
Ground support tables
Wedge analyses
Support FOS > 2.0 for Undercut level
Support FOS > 2.0 for Extraction level
Support FOS > 1.2 for other areas
Development support
Permanent support
Monitoring and Evaluation
• Rock mass classification
• Dimension of pillar
• Required life and long term plan
• Purpose of the excavation
• Caving and Mining Stress
• Expected personnel exposure
• Maximum allowable deformation
Minimum Required Standard Support
Classes of Minimum Ground Support
Classes of Minimum Ground Support
Light Support (Class 1A)Only Bolts
Not used anymore
Medium Light Support (Class 2)
Regular Support (Class 3)
Heavy support (Class 4) Extra heavy support (Class 5) Special support (Class 6)
Types of Development Ground Support
Map of extraction level showing Minimum Ground Support
Requirement
Quality control inspection
Monthly Goal
- New excavation
Monthly ground support
recommendation
Weekly Heading Check inspection/
Quality Inspection
Weekly Ground Support
recommendation
Collecting data
Collecting data Actual
To engineering and operation for improving the
installation
Not enough grout Loose Plate Short hole Protruding bolts
Laubscher’s Chart - Hydraulic Radius
CNI PREDICTION ACTUAL
Actual Hydraulic radius
UG Geotech inputs to Mine Operations
• Assistance in development of draw order based on convergence monitoring results
• Recommendations for minimizing the impact of abutment stress loading through additional blasting and/or re-support
• Evaluation of wet muck status and potential• Assistance in the sequencing of cave blasting based on
convergence monitoring and damage mapping• Sequencing the closure of draw points• Recommendations for the acceleration of development or
sequence for Underground Development• Review of ground support requirements in all production areas