Application of time-domain reflectometry to subsidence monitoring. Final technical report
The report describes how reflected voltage pulses from coaxial antenna cable grouted in rock masses can be employed to quantify the type and magnitude of rock mass deformation (movements) during abandoned mine subsidence events. The cable signal generated can differentiate between both extension and shear deformation. It performs the same task as a combined full profile extensometer (to measure local extension) and inclinometer (to measure local shearing). Rock mass movements locally deform the grouted cable, which changes cable capacitance and thereby the reflected wave form of an induced voltage pulse. By monitoring changes in these reflected signatures, it is possible to monitor rock mass deformation. The project encompassed two sequential phases of work. First, laboratory determinations were made to quantify signal changes with shear and tensile cable deformation, and to select cable diameter and grout mix. Secondly, field installation and monitoring procedures were tested at two active planned subsidence mining operations and over one abandoned mine with an active subsidence event. The paper also develops the electromagnetic wave theory necessary to quantitatively relate changes in cable geometry to changes in reflected voltage signatures. The results of these analyses are employed to extract new information from previously collected field data and to analyze cable signature results from cables installed over the two planned subsidence mining operations and one abandoned mine.
- Research Organization:
- Illinois State Geological Survey, Champaign, IL (United States)
- OSTI ID:
- 5215268
- Report Number(s):
- PB-91-228411/XAB; CNN: HQ51-CT6-01537
- Resource Relation:
- Other Information: Sponsored by Office of Surface Mining Reclamation and Enforcement (DI), Washington, DC
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
47 OTHER INSTRUMENTATION
ABANDONED SHAFTS
GROUND SUBSIDENCE
MONITORING
WELL LOGGING EQUIPMENT
PERFORMANCE
BENCH-SCALE EXPERIMENTS
CAPACITANCE
COAL MINES
COAXIAL CABLES
DEFORMATION
ELECTROMAGNETIC RADIATION
EXPERIMENTAL DATA
FIELD TESTS
FINITE ELEMENT METHOD
GROUTING
MINING ENGINEERING
OPERATION
REFLECTION
ROCK MECHANICS
STRATA MOVEMENT
TEST FACILITIES
WAVE PROPAGATION
CABLES
CONDUCTOR DEVICES
DATA
ELECTRIC CABLES
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ENGINEERING
EQUIPMENT
INFORMATION
MECHANICS
MINE SHAFTS
MINES
NUMERICAL DATA
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
RADIATIONS
SHAFT EXCAVATIONS
TESTING
UNDERGROUND FACILITIES
011000* - Coal
Lignite
& Peat- Reserves
Geology
& Exploration
440400 - Well Logging Instrumentation