22nd August 2016 Fall MG 101 21-22 ct MRE GROSVENOR
POINTS TO NOTE
Reported to duty Inspector Graham Callinan (Rocky area?) on weekend. No time of report indicated.
Over 1 hour since the Management were aware, I would guess. Inspector does not arrive for 2 days after.
Assume he has seen surface subsidence and is not just taking their word for it.
Makes little sense to me to be front abutment pressure, due to timing. Face has gone 250m past. Maybe side abutment pressure.
Looking at Pillar thickness as well as Megabolt density of the area of the fall would make more sense to me
Assume he has seen surface subsidence and is not just taking their word for it.
Where are the tell tales every 15m from previous falls?
Fall found by (Shift Supervisor) and A Seccombe (Geotechnical Engineer)
Mine on 3rd major roof fall in 6 weeks allowed to make its own decisions about how and what was done and will be dealt with in future, with no DNRME input.
NORTH GOONYELLA and MORANBAH NORTH learnt the hard way years ago
Cut throughs in gateroads already have lots of secondary support, are taking weight visually but have not fallen yet. (No mention of telltales every 15m again). They will fall when they take weight from the longwall.
Typical Goonyella Upper roof failure. Takes a bit of weight, bit of roof flake near rib, the road crack down the centre (above bolted horizon of 1.8m) and then fails quickly when it decides, hours, or days. That is why those mine megabolt as part of normal roof support and the centre line of roadways on the advance.
More bolts will do nothing. Only passive support has a slim hope. Big wooden props, steel cans and pigsty’s.
Dead Weight Bolting. is. Megabolts, long tendons, cable bolts they all apply to getting 8 or more metres long. The 8m length I would guess have just been adopted from both operations as what actually works, though not the when and where.
BULL has worked at North Goonyella and Moranbah North.
Not the first time the roof deterioration has occurred and it got secondary support of failed area.
Area’s only secondary supported as they fail not as part of fixing previous longwall fall 2 weeks earlier.
Not one Directive, nothing.
Not one hint of DNRME suspending any mining pending investigation.
22.08.2016 Fall MG 101 21-22 ct MRE – Grosvenor Coal Mine + comments
