Analysis of slope stability at Goonyella Mine

Abstract

Since the commencement of mining at the strip coal mine at Goonyella, Queensland, Australia, serious stability problems have been experienced in both the spoil piles and the highwalls. A collaborative investigation was commenced in 1974 and the significant factors influencing stability have now been defined. This paper outlines the results of field and laboratory studies associated with the investigation and describes the various numerical methods used to analyse stability. The main conclusions, which are similar for both the spoil piles and the highwalls, are that the failures generally occur along two or three planar surfaces; that the shear strength in the basal areas is controlled by the sensitivity of the materials to moisture and shear strain prior to failure; and that tensile cracking due to stress relief and blasting is the dominant factor in the upper or escarpment areas. Possible control and remedial measures are discussed briefly.

Leaching of potential hazardous elements of coal cleaning rejects

“…Waste dump instability and failure (Richards et al 1981;Stead and Singh 1989;Speck et al 1993;Singh and Kant 2007;Steiakakis et al 2009;; Silva and DaBoit 2010) 2. Spontaneous combustion and subsequent deleterious emissions to the atmosphere Zhao et al 2008; 3.…”

Stability and characterisation of spoil heaps in European surface lignite mines: a state-of-the-art review in light of new data

“…This progressive failure mode is often caused by the continual saturation of the spoil heap, due to seasonal rainfall and water infiltration within the spoil dump, which is made worse by inadequate or non-existing drainage infrastructure. Richards et al (1981) observed similar progressive failure mechanisms in spoil heaps, pointing out that the strength of basal materials of heaps has a greater influence on the stability of the structure than that of the bulk of the spoil heap. In addition, due to the high levels of heterogeneity associated with spoil materials, more than one failure mode can occur within the same heap (Okagbue 1984).…”

“…There have been a number of efforts to numerically model the stability of spoil heaps. Richards et al (1981) used a finite element model to simulate the progressive failure of a spoil heap, taking into account residual shear strength of soil, ensuing from soil strain-softening and wet-softening phenomena. They concluded that slope failure in the Goonyella mine spoil heap in Australia was initiated by weakening of a moisture-sensitive material at the base of the slope, and the subsequent cracking of bulk spoil material was due to settlement and compaction movements.…”

“…In addition, typical failure mechanisms and case histories of large instabilities in lignite spoil heaps are discussed, and the advantages and shortcomings of slope stability analysis methods applied to spoil heaps are reviewed. Modelling techniques that are usually applied for stability of spoil heaps are also critically discussed based on a review of examples within the literature that use limit equilibrium analyses (Nguyen et al 1984;Steiakakis et al 2009;Ulusay et al 1996), numerical models (Poulsen et al 2014;Richards et al 1981), and probabilistic analyses (Cheng and Usmen, 1987;Chowdhury et al 1986;Nguyen et al 1984). Finally, important research gaps and key shortcomings in the methods of design and analysis of spoil heap slopes in lignite mines are summarised.…”

Bulking and Subsequent Self-Weight and Saturation Settlements, and Geotechnical Stability of High Coal Mine Spoil Piles

“…Subsequent probabilistic analyses undertaken by Nguyen and Chowdury (1984) revealed that the relatively low design factor of safety of spoil piles in the Bowen Basin Coalfields correspond to a reasonably high simulated probability of failure of up to 15%. Williams (2012) noted that failure was initially assumed to take place under drained conditions (Richards, Coulthard and Toh 1981;Davies 1983;Dunbavan 1983). This was subsequently evidenced in Seedsman, Richards and Williams (1988) as being undrained, due to the rapid onset of failure.…”