Assessment of Ground Conditions Near a Mine Portal Using Ground Penetrating Radar

Trevits, Michael
Organization: International Conference on Ground Control in Mining
Pages: 8
Publication Date: Jan 1, 2005
The NIOSH Lake Lynn Laboratory (LLL) is a unique research facility, located about 50 miles southeast of Pittsburgh, Pennsylvania, that is designed to provide a full-scale mining environment for testing and evaluation of mine health and safety technologies. The LLL occupies more than 400 acres and is composed of surface test and training areas and an underground mine. The Lake Lynn Experimental Mine (LLEM) was built at an abandoned commercial limestone quarry where surface mining ceased in the late 1960's. Later, new underground development was constructed to simulate modern-day coal mining scenarios; including room-and-pillar and longwall mining layouts. In January 1994, a sinkhole opened southeast of the No. 4 Portal of the LLEM and since then, the area of the underground failure and surface deformation has continued to expand and now includes several interconnected sinkholes. A concern developed that the overburden instability could expand and affect the structural integrity of the nearby highwall and the No. 4 Portal. It was unsafe to conduct a detailed underground survey of the mine in this area because the mine roof conditions near the No. 4 Portal had deteriorated significantly. It was decided to investigate the overburden conditions near the No. 4 Portal using ground penetrating radar (GPR). A GPR survey grid was located along an access road that passes over the top of the portal. To delineate the mine conditions near the portal, antennas whose frequency spectra produced pulses centered near 100- and 200-MHz were used. The results of the GPR survey suggests that the overburden rock units appear to be laterally consistent to a depth of about 15-ft. Below that point, the overburden appears to be significantly disturbed and it was hypothesized that this area contains a large roof fall. A follow-up ground truth survey of the mine roof conditions was conducted from the mouth of the portal. It is concluded that the observations and measurements made from the radar records appear to be correct as a large roof fall was observed and measured from the mine portal area.
Full Article Download:
(11812 kb)

Additional chapters/articles from the SME-ICGCM book 24th International Conference on Ground Control in Mining (ICGCM) 24th

Keynote Address at the 23rd International Conference on Grou
Analysis and Design of Rib Support (ADRS) a Rib Support Desi
Evaluation of the Impact of Standing Support on Ground Behav
Half a Career Trying to Understand Why the Roof Along the Lo
Forecasting Roof Falls with Monitoring Technologies - A Look
Analysis of Seismic Source Parameters of Roof Falls in Time
A System to Provide Early Warning on Impending Goaf
Outcomes of the Landmark Longwall Automation Project with Re
Application of Phenolic Foam in Longwall Mining
Multiple Seam Mining Interactions: Case Histories from the H
Analysis of Entry Stability Associated with Multi-seam Minin
Failure Mechanics of Multiple Seam Mining Interactions
Engineering Classification of Ultra-close Multiple Seam Roof
Definition of Ultra-close Multiple-seams and its Ground Pres
Depillaring and Roof Bolting Practices at Quinsam Coal Mine
Seam Structure - An Important Criterion for Coal Pillar Desi
Mitigating Longwall Subsidence Effects on a Large Industrial
Impacts of Longwall Mining on Hydrology, Soil Moisture, and
Basics on the Dimensioning and the Extraction of Shaft Safet
Modeling the Arc-effect of a Coal Mine Roof
Recent Advances in Numerical Simulation of Cutter Roof Failu
Test Method for Assessing Water Degradation Potential of Coa
Geotechnical Strata Characterisation Using Geophysical Boreh
A Method for Quantitative Void/Fracture Detection and Estima
Implication of Highly Anisotropic Horizontal Stresses on Ent
Ground Control of a Mine Stope in Weak Rocks Subjected to Hi
Analysis of Highwall Mining Stability - The Effect of Multip
Highwall Mining in a Multiple-seam, Western United States Se
The Slope Stability Assessment in the Wall Overlooking the S
Numerical Modeling as a Tool to Predict Pillar Condition and
Development and Testing of a New Roof Prop
Stability Mapping System
Using Foaming Grout to Stabilize a Ventilation Raise in Very
Roof Control and Roadway Support Design in the #9 Coal Seam,
Non-confirmation Mathematics for Wall Rock Classification fo
The Influence of the First Layer Thickness of Immediate Roof
Studies on Distribution Pattern of and Methane Migration Mec
Development of a New Roof Bolt Technology to Improve Gate- R
Improved Pull out Strength of Fully Grouted Roof Bolts throu
Experimental and Numerical Methodology Assessment of Load Tr
An Investigation into the Support Systems in South African C
Investigation of Fully Grouted Roof Bolts Installed Under In
Development of the Laboratory Short Encapsulation Pull Test
A Resin Quality Testing Procedure for Collieries
Determination of Load Transfer Characteristics of Gloved Res
Fully Grouted Torque Tension Bolts Successfully Support Pitt
Shear Bond Characteristics in Grouted Cable Bolts
Overcoring Techniques to Assess in Situ Corrosion of Galvani
Development of a Laboratory Facility for Testing Shear Perfo
Mechanical Response of Split-Set Rock Bolts in Squeezing Gro
Mechanisms of Rib Sloughing and Methods of Controlling Thick
Supporting Method of the Bolted Strata in Large Deformation
Assessment of Ground Conditions Near a Mine Portal Using Gro
Detection of Abandoned Mines and Air Passages/Burning Center
Detecting Abandoned Coal Mine Entries by High Resolution Ear