Monitoring and modelling of microseismicity associated with rock burst and gas outburst hazards in coal mines
File(s)
Author(s)
Cao, Wenzhuo
Type
Thesis
Abstract
This thesis aimed at establishing a better understanding of the mechanisms involved and methods for forecasting, prevention and control of rock bursts and gas outbursts in underground coal mining.
After a comprehensive review of relevant literature, the thesis first presents experimental investigations into the seismic response of coal blocks to stress and fracturing under true-triaxial stress conditions. The dynamic response of coal seams to longwall face advance has been investigated through continuous microseismic monitoring of several longwall panels over the research period. A conceptual model has been developed to interpret the recorded microseismicity based on the fracture slip seismicity-generation mechanism. Based upon the monitoring results and the conceptual model, a statistical short-term forecasting methodology was developed to estimate the probability of hazardous microseismicity during longwall coal mining. In addition, a discrete fracture network (DFN) based microseismic modelling methodology was developed to simulate Longwall Top Coal Caving (LTCC) mining induced microseismicity in a probabilistic framework through the combination of deterministic stress and failure analysis and stochastic fracture slip evaluation. The modelling methodology was further employed to investigate the impact of lithological heterogeneity on microseismic characteristics.
Further on, rock bursts and coal and gas outbursts are generalised as problems of dynamic instability under excavation unloading conditions. The role of excavation unloading as a source of dynamic stress perturbations in contributing to rock bursts was quantified. A coal and gas outburst model based on fracture mechanics and gas dynamics was formulated and further numerically implemented to simulate coal and gas outbursts during roadway developments. Key factors affecting outburst initiation and its temporal evolution were also identified.
After a comprehensive review of relevant literature, the thesis first presents experimental investigations into the seismic response of coal blocks to stress and fracturing under true-triaxial stress conditions. The dynamic response of coal seams to longwall face advance has been investigated through continuous microseismic monitoring of several longwall panels over the research period. A conceptual model has been developed to interpret the recorded microseismicity based on the fracture slip seismicity-generation mechanism. Based upon the monitoring results and the conceptual model, a statistical short-term forecasting methodology was developed to estimate the probability of hazardous microseismicity during longwall coal mining. In addition, a discrete fracture network (DFN) based microseismic modelling methodology was developed to simulate Longwall Top Coal Caving (LTCC) mining induced microseismicity in a probabilistic framework through the combination of deterministic stress and failure analysis and stochastic fracture slip evaluation. The modelling methodology was further employed to investigate the impact of lithological heterogeneity on microseismic characteristics.
Further on, rock bursts and coal and gas outbursts are generalised as problems of dynamic instability under excavation unloading conditions. The role of excavation unloading as a source of dynamic stress perturbations in contributing to rock bursts was quantified. A coal and gas outburst model based on fracture mechanics and gas dynamics was formulated and further numerically implemented to simulate coal and gas outbursts during roadway developments. Key factors affecting outburst initiation and its temporal evolution were also identified.
Version
Open Access
Date Issued
2019-04
Date Awarded
2019-07
Copyright Statement
Creative Commons Attribution Non-Commercial No Derivatives licence
Advisor
Durucan, Sevket
Shi, Ji-Quan
Sponsor
UK Engineering and Physical Sciences Research Council (EPSRC) PhD scholarship awarded by the Faculty of Engineering at Imperial College London
Publisher Department
Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)