As described by Brady and Brown (2005), a rational subsidence predictive
methodology can only be achieved through understanding the mechanisms in-
volved in the phenomenon. In this thesis, mechanism of the strata movement
due to multi-seam longwall mining and characteristics of the multi-seam sub-
sidence are investigated by means of physical modelling, numerical modelling
and factual subsidence data analysis. Outcomes of this investigation are then
employed for characterisation of multi-seam subsidence and modification of
a conventional subsidence predictive methodology in order to achieve reliable
multi-seam subsidence predictions. On this basis, the main objectives of this
thesis can be defined as:
a) understanding the strata movement mechanisms and characteristics of the
multi-seam subsidence profile; and
b) characterisation and prediction of the multi-seam subsidence.
To achieve the main objectives of this thesis, seven chapters − after this
introduction − are outlined in the following format:
Chapter 2 Single-seam mining-induced subsidence. In this chapter, general
aspects of the mining-induced subsidence, subsidence parame-
ters and their definitions together with conventional subsidence
prediction methods are reviewed.
Chapter 3 Multi-seam mining-induced subsidence. In this chapter, the most
of the multi-seam subsidence are studied from the available ob-
servational data, articles and reports in the literature. This
review helps understanding the key parameters influencing the
characteristics of the multi-seam subsidence as well as providing
the required information for tailoring the physical and numerical
modelling approaches.
After reviewing the multi-seam observations, suggested modi-
fications of the conventional subsidence prediction methods by
other researchers to account for the specific characteristics of
the multi-seam subsidence are critically reviewed.
Chapter 4 Physical modelling of multi-seam subsidence. In this chapter,
physical modelling techniques are used for evaluating the multi-
seam subsidence characteristics as a result of changing some of
the multi-seam mining variables, which affect the characteristics
of the generated subsidence.
Chapter 5 Numerical modelling of multi-seam subsidence. In this chap-
ter, numerical modelling techniques are employed for simulat-
ing the multi-seam subsidence as a supplement to the physical
modelling techniques and an alternative method to investigate
the strata movement mechanism and subsidence characteristics
due to multi-seam mining. These techniques are also utilised
for evaluating some of the multi-seam subsidence parameters,
which are difficult, costly or impossible to investigate via phys-
Chapter 6 Multi-seam subsidence observations and analysis. In this chap-
ter, multi-seam subsidence observations from a case study in
Australia are thoroughly investigated. This case study for its
specific arrangement of the panels in the two coal seams creates
various multi-seam mining scenarios along different survey lines,
which help understanding the characteristics of the multi-seam
subsidence. Also, where appropriate, multi-seam subsidence ob-
servations are compared with the physical and numerical mod-
elling results.
Chapter 7 Characterisation and prediction of multi-seam subsidence. In
this chapter, findings from the previous chapters are utilised for
characterisation of the multi-seam subsidence. This characteri-
sation is then used for modification of a prediction method. Af-
ter this, the proposed method is employed to predict the multi-
seam subsidence in an example case study and its prediction
results are discussed and compared with a few other conven-
tional subsidence prediction methods.
Chapter 8 Conclusions. In this chapter, main conclusions of this thesis
and its contribution to improving the knowledge and reliability
of prediction of the multi-seam subsidence are summarised. In
addition, key points for future investigations of the characteris-
tics and prediction of the multi-seam subsidence are outlined.
Based on the main body of this thesis (Chapters 4 to 7), a total num-
journals, local and international conferences. These articles include five pub-
lished and three under review works as follow:
• Ghabraie, B. and Ren, G. (2013). “Discussion on mining subsidence factors for multiple seam longwall mining.” In: The 6th International
Symposium on Green Mining. Ren, T. and Jialin, X. University of
Wollongong, NSW, Australia. 24-26 November, 96-100.
• Ghabraie, B. and Ren, G. (2014). “Investigating characteristics of strata movement due to multiple-seam mining using a sand-plater phys-
ical Model.” In: 9th Triennial Conference Proceedings - Mine Subsi-
dence: Risk Management In Action. D. Kay and G. Li. Sebel Kirkton
Park, Pokolbin, NSW, Australia, Mine Subsidence Technological Soci-
ety. 11-13 May, 1: 169-174.
• Ghabraie, B., Ren, G., Zhang, X. and Smith, J.V. (2015). “Physical modelling of subsidence from sequential extraction of partially overlap-
ping longwall panels and study of substrata movement characteristics.”
International Journal of Coal Geology 140(0): 71-83.
• Ghabraie, B., Ren, G., Smith, J.V. and Holden, L. (2015). “Application of 3D laser scanner, optical transducers and digital image processing
techniques in physical modelling of mining-related strata movement.”
International Journal of Rock Mechanics and Mining Sciences 80: 219-
230.
• Ghabraie, B. and Ren, G. (2016). “Mechanism and Prediction of
In: 35thInternational Conference on Ground Control in Mining (ICGCM).
Morgantown, WV, USA, 26-28 July: 304-310.
• Ghabraie, B., Ghabraie, K., Ren, G. and Smith, J.V. (2016). “Numeri- cal modelling of multi-stage caving processes: insights from multi-seam
longwall mining-induced subsidence.” Accepted in: International
Journal for Numerical and Analytical Methods in Geomechanics.
• Ghabraie, B., Ren, G. and Smith, J.V. (2016). “Characterising the multi-seam subsidence due to varying mining configuration, insights
from physical modelling.” Submitted to: International Journal of
Rock Mechanics and Mining Sciences.
• Ghabraie, B., Ren, G., Barbato, J. and Smith, J.V. (2016). “Discrete Influence Function Method, a predictive methodology for multi-seam
mining-induced subsidence.” Submitted to: International Journal of
C H A P T E R 2
Single-seam mining-induced
subsidence
2.1
Introduction
In this chapter, relevant literature to general aspects of the single-seam long-
wall mining-induced subsidence are reviewed. The underlying ground move-
ment mechanism that leads to formation of the ground surface subsidence is
briefly discussed. The most important subsidence parameters, which shape
the subsidence profile, are then reviewed for the single-seam subsidence pro-
files. Later in this chapter, different conventional subsidence prediction meth-
ods available for single-seam subsidence predictions are reviewed.