S 1: Fractured Rock in Stope Face After Blasting
Blasting as well as mining induced stresses causes the hanging wall to fracture. Mostly fracturing is also taking place during the shift. This together with dilatational movement of the rock result in the deterioration of the hanging wall throughout the shift. Therefore even if the making safe measures were taken in the beginning of the shift the hanging wall conditions could become unsafe during the shift.
S 2: Presence of Geological Features and Brows
The presence of geological features combined with mining induced stress fractures and bedding planes often results in the formation of unstable blocks of ground and brows, which are hazardous unless identified and sufficiently supported or otherwise made safe.
S 3: Friable Hangingwall due to Poor Marking, Drilling, Charging up and Timing of Blast Holes
Poor drilling and charging up of blast holes result in unnecessary blast damage to the rock surfaces and create cross fracturing and friable hanging wall conditions thus increasing the likelihood of falls of ground both in stope panels and in gullies. Furthermore poor drilling and charging up practices result in unnecessary large spans across dip and strike gullies.
S 4: Stoping in the Vicinity of Old Workings or Holing into Adjacent Workings
Stoping in the vicinity of old workings as well as holing into adjacent workings result in abnormal fracture pattern created by the fracturing induced by the previous as well as the current mining activities. Such ground conditions are particularly vulnerable for shake down damage due to possible seismicity as well as for gravity driven falls of ground.
S 5: Excavation Instability When Opening up of Collapsed Panels and/or Entering Old Workings or recently blasted workings
Due to the time dependent deterioration of rock and the deterioration of timber support the ground conditions in old workings or in panels not blasted for a period of time are often friable and unsafe.
S 6: Incorrect Face Configuration When Negotiating Geological Features
When faults and dykes are not negotiated with an insufficiently acute angle the possibility exists that poor ground conditions may affect relatively large areas.
S 7: In Stope Pillars not Cut to the Correct Dimensions
If the in stope crushes pillars are cut too small the required support resistance is not achieved and hence the likelihood of falls of ground is increased. If the said pillars are cut too large there is a possibility of pillars strain bursting and injuring workers.