2.5 Mining Methods

Factor related to method of mining and affecting stability of slope include method used for preparation of foundation, method of stripping, placement and rehandling of dump material.  Important factors with regard to dump configuration, zonation, potential failure surface, engineering properties of dump material and pore water pressure are also very significant. The density of the waste dump is also controlled by the manner of deposition gradation and loading history. This in turn can affect the shear strength of waste dump. Further the type of equipment used for dumping of over burden also affects its compaction. A combination of shovel and dumper along with the use of bulldozers for leveling creates a waste dump of maximum compaction, which gives maximum strength of dump materials. In contrast to it, the bucket wheel excavator alone or in conjunction with spreaders places the material of low strength in a very loose state. The dragline places the spoil dump material in dumps from height and thus, causes some compaction to take place. Therefore, the material in dragline waste dumps show densities in between the above two categories.