Formation of cover for hollow underground formations - utilises hole, whose axis coincides with the water flow, for drainage

摘要

Holes are drilled from the surface into the hollow formation. At least one hole, intended for drainage, is equipped with an open casing pipe. The other holes are used for injecting strengthening solution. Before injection, cavities are filled with rock while water is drained. The intensity of drainage is boosted by pumps. - In the water entry and discharge zones, regions of low hydraulic resistance are created using large-sized rocks. The inter-zone region is filled with finely graded material of high hydraulic resistance. The holes for feeding the materials are filled with a strengthening solution to complete the formation of the water covering zone.