Introduction

 

Mine Subsidence Engineering Consultants provide subsidence predictions based on monitored subsidence movements over previously mined areas and it is therefore, necessary to compare observed subsidence measurements against predicted ground movements and to regularly review and update the prediction curves and profiles. These regular reviews enable us to provide the best possible predictions of subsidence and assessments of damage to our clients.

 

The Company research programme includes regular reviews of measured data as well as major research projects to achieve specific objectives. Examples of these major projects follow:

 

NERDDP Funded Project No. 1446

Effects of Subsidence on Steep Topography and Cliff Lines

 

In 1989 Don was awarded a grant under the Commonwealth Government’s National Energy Research, Development and Demonstration Program, from which the Report entitled ‘Effects of Subsidence on Steep Topography and Cliff Lines’, resulted.

 

Incremental Profile Method

 

Through many years of analysis and enquiry, Don Kay and Arthur Waddington have conducted considerable research in the field of the effects of underground mining on surface infrastructure and topography. This research resulted in the formulation of the Incremental Profile Method of prediction.

 

This unique method has since evolved with application to real life situations and is entirely based upon detailed, site specific data.  The method has received wide critical acclaim and has been proven to be the most accurate methodology presently available.

 

The method was initially used in a September 1994 Report entitled ‘Empirical Prediction of Subsidence, Strain, Tilt and Curvature due to the Proposed Longwall Extraction at Appin and Tower Collieries’. ‘The data was used to establish a method of subsidence prediction based upon the increments of subsidence which occur after individual longwall panels are mined.  This method allows the maximum incremental subsidence from each longwall panel to be predicted and the shape of the transverse incremental profile for each panel to be determined.’

 

‘The first step in the development of the model was to study detailed records of subsidence movements, which had been observed over previous longwalls at Appin and Tower Collieries and over longwalls at neighbouring mines, including Tahmoor, West Cliff, Cordeaux and South Bulli Collieries.

 

The measured subsidence data was plotted in a variety of ways in order to establish whether any regular patterns of ground behaviour could be found.  The most significant patterns were illustrated in the shapes of the incremental subsidence profiles measured along survey lines transversely across the longwalls.

 

The incremental subsidence profile, for each longwall, was derived by subtracting the initial subsidence profile, measured before mining the longwall, from the final subsidence profile, measured after mining the longwall.  The incremental subsidence profile for a longwall therefore shows the change in the subsidence profile caused by the mining of the longwall.

 

The consistency in the shape of the incremental subsidence profiles led to the development of the Incremental Profile Method.’ (WKA96 2001)

 

The benefits of the Incremental Profile Method are:

· Predictions are provided at all positions across the series of panels.

· The method can be used even where the seam thicknesses, pillar and panel widths and the cover depths vary from panel to panel across a series of longwalls.

· The method can be used even if some panels are stopped short near survey cross lines.

· This method provides improved predictions of the tilts, curvatures and general background strains.

 

The method is useful as a mine planning tool, to enable consideration of the effects of alternative pillar and panel configurations.

 

ACARP Projects

 

Refinement of the method is ongoing and in 1998 Arthur and Don successfully applied for research funding from the Australian Coal Association Research Program (ACARP). This grant was supported by BHP Coal Illawarra Collieries; Austral Coal Ltd, Tahmoor Colliery; Powercoal, Angus Place Colliery; Oakbridge Coal Division, Baal Bone Colliery; and  Springvale Coal Pty Ltd, Springvale Colliery, with research contributions coming from BHP, Waddington Kay & Associates (now MSEC), CSIRO Division of Petroleum Resources and the University of New South Wales.

 

The Report No.74 dated March 2001 on ‘Research into the Impacts of Mine Subsidence on the Strata and Hydrology of River Valleys and Development of Management Guidelines for Undermining Cliffs, Gorges and River Systems’, was the result of Stage I of this research project.

 

Stage II was completed in 2002.

 

In 2004 Arthur and Don successfully applied for another ACARP grant to investigate the Building Impact Assessment process in the Tahmoor area of the Southern Coalfield.

 

Arthur is also a contributor to an ACARP project researching Watercourse Remediation with Ken Mills.

Mine Subsidence Engineering Consultants Pty Ltd

Consultants in Civil, Structural, Environmental, Mine Infrastructure & Subsidence Engineering

Research