Ground Control Design Considerations for Reducing Longwall?Induced Stress and Seismicity Associated with Massive Sandstone under Deep Cover

Su, Daniel W.H.
Organization: International Conference on Ground Control in Mining
Pages: 9
Publication Date: Jan 1, 2014
Thick, massive sandstone present in close proximity of the mining horizon can create difficult longwall caving issues, which may lead to severe face loading and subsequent face roof control problems. Under deep cover, such delayed caving and overhang not only impose additional loading on the gate road pillar system, but they also increase the potential for large seismic events. Such a combination of thick, massive sandstone geology and deep cover was present over a portion of a southwestern Virginia coal mine, which was confirmed via detailed in-mine roof scoping and mapping. Large seismic events were recorded over a district of 1,000-foot-wide longwall panels. This paper presents the ground control design changes implemented to reduce longwall-induced stresses in the sandstone, to reduce longwall abutment pressures in the gate road pillars, and to reduce the magnitude of mining-induced seismic events. A series of two-dimensional finite element models were constructed and analyzed to evaluate the longwall-induced stresses in the sandstone above the gate road pillars and the abutment pressures within the gate road pillars. Results from the analyses indicated that reducing the panel width from 1,000 to 700 feet reduced the longwall-induced stresses in the sandstone by a factor of 2.0. Specifically the probability of sandstone stability improved from 29% for the 1,000-foot-wide panel district to over 95% for the 700-foot-wide panel districts. Also, the subcritical 700-foot-wide panel, coupled with a change in pillar design, considerably reduced the longwall-induced abutment pressures in the gate road pillars, which significantly increased the gate road pillar stability factor. Surface subsidence measurements conducted over the 1,000-foot-wide panel district and two new 700-foot-wide panel districts were in very good agreement with those predicted by the finite element models. In addition, results from the models indicated that wider panels with a smaller district may produce the same probability of sandstone stability. One four-panel district and one five-panel district with the new ground control design changes have been mined successfully. The panel width was found to be the most influential factor in determining the longwall-induced stresses in the sandstone and in the gate road pillars. The thickness and massive nature of the sandstone, the proximity of the sandstone, and the strength of the sandstone were also found to be important factors. Seismic monitoring over the two mining districts that employed 700-foot-wide panels confirmed the reduction of one order of seismic magnitude when compared with those measured over the 1,000-foot-wide panel district.
Full Article Download:
(1834 kb)

Additional chapters/articles from the SME-ICGCM book 33rd International Conference on Ground Control in Mining

Development of the 3D Numerical Modeling of Roof Bolts for S
Development and Application of the TT Anti?Friction Washer f
A Comparison Between ARMPS and the New ARMPS?LAM Programs
Multi?stage Testing Procedures, Verification, and Results fo
The Caterpillar HW300 Quickscan
Underground Mining Technology in Chinese Coal Mines
Rock Characterization Using Time - Series Classification Alg
Ground Control in the Underground Coal Mines of Colombia
Investigating the Contributing Factors to Rib Fatalities Thr
Analyses of De-Confinement Mechanisms of Unstable Failures i
Photogrammetric Monitoring of Rock Mass Behavior in Deep Vei
Development of An Enhanced Methodology for Ground Movement P
Estimating Coal Strength Based on Historical Laboratory Test
Experimental Observations and Interpretations on Fracture Ne
Overburden Failure Characteristics of Extra?Thick Seam Using
FlexKnot: An Innovation in Roof and Rib Surface Control
Learning Our Geotechnical Limits and Pushing Our Longwalls T
Three Dimensional Analysis of Strain and Ground Surface Disp
Use of a Plate Loading Device to Quantitatively Evaluate Wea
Ground Control Design Considerations for Reducing Longwall?I
Mechanics of Horizontal Movements Associated with Coal Mine
Roof Geotechnical Properties for Roof Control Purposes in Il
Update: Analysis and Case Study of Impact?Resistant Steel Se
The Implementation of Rock Mechanics Into a Multiple Level L
A Case Study for Multiple Seam Calibration of LaModel in Bum
A Liquid Settlement System for Measuring Roof Sag During Dev
Ground Response As a Longwall Advances Into a Backfilled Rec
A Case Study of a Low Overburden Longwall Recovery with Pre?
To What Extent the Mechanical Properties of Coal Play Role i
Mine Water Vs. Drinking Water?Technical Execution and Legal
Mitigation of a Massive Sandstone Channel?s Impact on Longwa
Study on the Modified Model of Probability Integra Method
Multi?Seam Mining Over Old Workings with Small Pillars - A C
Development of Mechanized Ground Support Installation Equipm
Understanding and Optimizing the Performance of Passive Prim
Validation of Overburden Failure Zone in Complex Extra Thick
The Impact Factors of Overburden Movement in Longwall Mining
Fiber Reinforced Polymer Rockbolts for Ground Control in a S
Introduction of a Measurement Based Ground Control Managemen
Application of Various Probing Methods for Rock Characteriza
Risk Analysis and Risk Ranking in Tunneling: A Case Study
Development of Road Header Roof Bolting Module
Combined Effects of Rock Bedding Orientation and Topography
Challenges of Room and Pillar Mining at 900 M Depths in the
Sandy Creek Waterfall?Case Study of Successful Management of
Overburden Strata Movement for the Longwall Mining of Shallo
Rock Slope Stability Comparison Between Deterministic and Pr
Stability of a Gateroad Used Simultaneously for Two Retreati
Meeting the Challenges of Floor and Sidewall Strata Control
Strata Control Investigations During Fully Mechanized Coal P
Strata Movement Around Large Mining Height Face Area with Fu
A Case Study of Topography?Related Stress Rotation Effects o
Introduction of a New Superior Coating on Ground Support Pro
Suspension Designs Required in the Logical Framework
A Novel and Effective Method to Develop Tension in a Roof Bo
Time Dependent Mining Induced Subsidence Measured by Differe
Tracking and Tracing in Terms of Transportation Logistics of