Abstract: An undercut excavation method is provided, which is particularly suitable as an undercut-and-fill mining method, wherein concrete posts are inserted into holes drilled in the ground and are used to support a concrete floor poured on their top ends, which serves as a roof for the lower excavation level. The bottom ends of these posts rest on resilient elements to provide protection against seismic events or excessive ground movements. Excavation beneath such roof is thereby safely carried out in areas prone to seismic events such as rock bursts or earth quakes or to excessive ground movements. The concrete posts may be attached to the resilient elements at their bottom ends, thereby producing yielding posts suitable for such excavation. For still greater safety, a double post system may be used, which involves placing a second post beside the first after excavation on a given level and tying them all together with the concrete used to make the floor/roof for the next lower level of excavation.

Abstract: An excavation method is provided, which is particularly suitable as an undercut-and-fill mining method, wherein posts are inserted into the ground and are used to support a concrete floor of the upper level which serves as a roof for the lower excavation level. Excavation beneath such roof is thereby safely carried out. Also, for mining operations, the excavation is very efficient since it removes essentially 100% of the ore in a single pass. The posts are preferably made of concrete and are inserted into holes drilled in the ground. For greater safety a double post system can be used, which involves placing a second post beside the first and tying them all together with the concrete used to make the floor/roof at any given level of excavation.