1. This report summarises the fall of ground dangerous
occurrences and major injury accidents at mines during the
2002/2003 reporting year.
2. All statistics are provisional.
3. "Any fall of ground not being part of the normal
operations at a mine, which results from a failure of an
underground support system and prevents persons from travelling
through the affected area by a fall of ground or which otherwise
exposes them to danger", was introduced as a dangerous
occurrence at Part II/40 in RIDDOR 1995, with effect from April
1996.
4. Six falls of ground dangerous occurrences were reported at
mines, three at coal mines and 3 at one miscellaneous mine.
5. In coalmines two falls of ground occurred at the one mine at
junction areas of roadways that were over 20 years old, one
supported by steel and the other by props and bars. The immediate
roof had degraded and caused the support to fail. The roadways
had been used as auxiliary airways and were not needed
strategically for the ventilation of the mine. If the roads are
not needed then they should be sealed off. The other fall
occurred on a face line, supported by passive steel supports
supplemented with roof bolts. The tell tale monitoring showed
increasing levels of dilation. The tell tale readings were
ignored because it was mistakenly thought that the steel support
would support the roof and no action needed to be taken. When
mixed support systems are used any movement recorded by
monitoring should be acted upon to stabilise the affected
area.
6. Three falls occurred at one miscellaneous mine. The falls occurred in roadways driven in 1997 in roadways driven below the main mining horizon. In one roadway remedial work had been recommended by the mine geotechnical engineer but not carried out. The omission was not detected and the road subsequently collapsed. In another a fall occurred in a cross connection off a main road. The mine risk assessment programme was to be extended to include these types of roadways. The support strategy at this mine was to be reviewed and detection skills of supervisors improved.
| Type of Support | |
|---|---|
| Miscellaneous | 3 |
| Steel arch | 2 |
| Mixed systems | 1 |
| Total | 6 |
| Warning of Collapse | |
|---|---|
| Less than 24 hours | 1 |
| Over 24 hours | 2 |
| No warning | 3 |
| Total | 6 |
| Age of Excavation | |
|---|---|
| Recently driven | 1 |
| 6 - 12 months | - |
| 2 to 3 years | - |
| Over 5 years | 5 |
| Total | 6 |
| Type of Excavation | |
|---|---|
| Junction -girders | - |
| Junction - natural support | - |
| Junction - props and bars | - |
| Roads - arches | 2 |
| Roads - props and bars | 1 |
| Roads - rockbolts | 3 |
| Roads - mixed systems | - |
| Total | 6 |
7. There were no fatal accidents recorded during the year.
8. Two major injuries were recorded at coal mines this year
compared to five last year. There were no major injuries recorded
at miscellaneous mines, two were recorded last year.
9. Both major injuries at coal mines occurred in roadways
supported by passive steel supports. There were no injuries
recorded in roadways supported by rock bolts.
10. One accident occurred when a workman was setting a German TH type arch leg and a stone fell from the roof and struck him. The other occurred when a workman was assisting to install a large junction girder when a stone fell and slid down a mesh panel and struck him. Then introduction of temporary support systems (similar to mesh cages in roof bolted systems) to prevent injuries from falls of the roof or sides when passive arch type supports are being installed.
| 2001/2002 | 2002/2003 | |||
|---|---|---|---|---|
| All mines fall of ground accidents | Fatal | Major injury | Fatal | Major injury |
| Coal mines - free standing supports | 1 | 2 | - | 2 |
| Coal mines- powered supports | - | 1 | - | - |
| Coal mines- rockbolts | - | 2 | - | - |
| Miscellaneous mines | - | 2 | - | - |
| Total | 1 | 7 | - | 2 |
| 2001/2002 | 2002/2003 | |||
|---|---|---|---|---|
| Coal Mines - place of accident | Fatal | Major injury | Fatal | Major injury |
| Longwall face | - | 1 | - | - |
| Headings | 1 | 4 | - | 2 |
| Elsewhere | - | - | - | - |
| Total | 1 | 5 | - | 2 |
11. There were no fatal accidents reported during the year.
12. There has been a reduction in major injuries from seven last
year to two this year. An industry wide working group is pursuing
the provision of temporary support systems to prevent injury in
roads supported by passive supports.
13. There were no accidents reported in roadways supported by
rock bolts even though this support system is used to support
approximately 80% of all roads being driven.
14. The incidence of falls of ground reported in coal mines has
increased from one to three. One particular fall of ground
occurred on a face line supported with steel supports
supplemented with roof bolts where monitoring information was
ignored. If roof bolts are used as part of the support system
then tell tales should be installed and action taken if dilation
above accepted levels is recorded. The other two were in old
roads. Surveys should be carried out and any roads not required
should be sealed off.
15. The incidence of falls of ground in miscellaneous mines has remained at three. This is concerning because the three falls of ground all occurred at the same mine and in similar circumstances. This mine also accounted for two of the falls of ground reported last year, again in similar circumstances. Remedial work recommended by the geotechnical engineer is being prioritised and acted upon and systems implemented to check that the work has been carried out.