Application Of Mechanical And Groundwater-Flow Models To Predict The Hydrogeologic Effects Of Longwall Subsidence - A Case Study

Roosendaal, Danny J. Van
Organization: International Conference on Ground Control in Mining
Pages: 9
Publication Date: Jan 1, 1995
An investigation was undertaken to determine hydrogeological effects of subsidence over a longwall coal mine in the Illinois Basin. At this mine, approximately 200 ft of bedrock overburden is overlain by up to 150 ft of glacial till and localized water-bearing glacial sediments within a buried bedrock valley that overlies the longwall panel. A finite-element mechanical model of the subsided longwall panel shows sufficient strain to enhance permeability throughout the bedrock portion of the overburden. However, examination of the actual surface subsidence profile indicates that the overburden deformation is localized in narrow zones at the panel edges. The aquifer units at the base of the glacial sediments are confined by glacial clays (above) and weathered shales (below). Elevated water levels were observed in the glacial aquifers during subsidence, which indicates that the clays and shales maintained confinement as the overburden subsided and deformed. A three-dimensional ground-water flow model was used to simulate the effects of subsidence on the hydrogeologic system and to estimate inflows into the mine. Longwall retreat was simulated by several model runs, each representing a new longwall face position. Simulated heads and mine inflows were calibrated with recorded water levels and observed inflow conditions by modifying the hydraulic conductivity of particular model layers. Model calibration indicates that the permeability of certain lithologies, such as plastic underclays and weathered shales, is not significantly enhanced by subsidence. A worst-case scenario was simulated by inserting a deeply incised, sandfilled valley into the model, which had only minimal impact on the simulated mine inflows.
Full Article Download:
(2530 kb)

Additional chapters/articles from the SME-ICGCM book Proceedings of 14th International Conference on Ground Control in fining

Truss Systems For Longwall Tailgate Support - Update
Cable Support Systems For Longwall Gate Road Stability
Innovative Tailgate Support For Heavy Ground: 11 Left Longwa
Parameters Affecting Resin-Anchored Cable Bolt Performance:
Roof Support Performance In High Stress Conditions
Regional Horizontal Stress And Its Effect On Longwall Mining
Deformation Development Around Mine Roadways And Simulation
Monitoring Mobile Roof Supports
Analysis Of Retreat Mining Pillar Stability
Planning And Design For Barrier Pillar Recovery Three Case H
Influence Of Partings In A Coal Seam On Long Term Pillar Sta
A Cooperative Study Of Gate Entry Designs Welbeck Colliery (
Comparative Case Study Of Yielding And Critical Coal Pillar
Comparison Of Empirical, Analytical, And Numerical Methods O
Nonlinear Approach For Determining Design Criteria For Yield
In-Situ Coal Strength Determination - Case Studies
The Design And Application Of Propsetter? In Underground Coa
Renewed Interest In Prop Supports As A Replacement For Wood
Improved Intersection Design And Monitoring In The Sydney Co
Drivage System In Retreat Longwall Gateroad
Case Study Of Stability Investigations Related To Shallow Un
Analysis Of Rockbolt Performance At The Waste Isolation Pilo
Continuous Improvement In Cuttable Coal Rib Support In Austr
Floor Failure Induced By Lateral Stress Ahead Of Longwall Su
Towards A Method Of Determining Floor Quality In An Undergro
Chinese And North American High-Extraction Underground Coal
Integration Of CAD-Based Mine Planning And Subsidence Engine
Development Of A Subsidence Database And Determination Of Su
Statistical Regional Calibration Of Subsidence Prediction Mo
Subsidence Monitoring Results, Thick Seam Longwall Mining In
Application Of Mechanical And Groundwater-Flow Models To Pre
The Application Of Underground In-Seam Seismic Methods (UISS
Vertical Stress Redistribution Around A Retreating Longwall
Entry Stability Monitoring & Analysis For Longwall & Continu
A Case Study Of A Deformation Mechanism Around A Two-Entry G
Multiseam Mining On South African Collieries
Design And Planning Of Lower Seam Longwall Gateroads
Optimizing Pillar Design In A Multi-Seam Environment