METHOD OF UPKEEP OF DEVELOPMENT WORKINGS Russian patent published in 1997 - IPC

FIELD: protection of repeatedly used district second workings in pillarless development and mining of coal seams. SUBSTANCE: each frame of arched support is installed with shifting of its vertical axis to the side of rock mass through angle α equalling 5-6 deg by installing on the side of the first adjacent face of additional leg together with frame prop ensuring high yield between prop and leg when approaching the first face. At the junction of the first face with working, the prop is dismantled together with additional leg. In so doing, incomplete frame turns relative to prop base on the side of rock mass to vertical axis under the action of load obliquely directed from the side of the first face, and side load from the side of rock mass. Upon passage of face, dismantled prop is reinstalled without additional leg with provision of symmetrical shape of frame relative to its vertical axis owing to installation of yielding units on the same level from the working floor. In so doing, transformation of asymmetric shape of the frame into symmetric one preserves the preset parameters and quality of support for the period of further service. EFFECT: higher efficiency. 2 dwg