FLEXIBLE SANDING DEVICE FOR CYLINDER ROCK SPECIMEN

    公开(公告)号:US20190168357A1

    公开(公告)日:2019-06-06

    申请号:US16208592

    申请日:2018-12-04

    Abstract: A rock sanding device includes a base, a bottom sanding plate, an adjustable connecting rod, an elastic loader, a connector, a side sanding brush, a top sanding plate, an inner rod, a prong and a drill rod. The top of the drill rod is fixedly connected with the rotating shaft of the external water drilling rig and the external water drilling rig has a water inlet joint to introduce water into the drill rod. The inner rod and drill rod are connected and fixed coaxially, and the bottom of the drill rod is symmetrically welded with four prongs. The rock specimen is placed in the center of the side sanding brush. The top sanding plate and the bottom sanding plate are provided in the top side and bottom side of the rock specimen, respectively.

    I-PATTERNED FILLING METHOD FOR INITIAL STAGE OF COAL MINING BASED ON ROOF FRACTURE FEATURE CHARACTERITICS

    公开(公告)号:US20240209734A1

    公开(公告)日:2024-06-27

    申请号:US18595263

    申请日:2024-03-04

    CPC classification number: E21C41/18 E21C2100/00

    Abstract: An I-patterned filling method for an initial stage of coal mining based on roof fracture characteristics is provided. A relationship between an overburden load borne by a main roof and an overhang size is determined based on principle of virtual work and a surgery theory when an overhang distance of the main roof reaches an initial weighting interval to enter a plastic limit state with an advance of a working face to obtain the initial weighting interval. An initial fracturing interval of an immediate roof is obtained in the same way. According to a subsidence law of the main roof in an inverted hip roof form, the filling is performed at a key position around an internal plastic hinge line through I-patterned three-strip filling. Size parameters of the I-pattered filling are designed to prevent the immediate roof and the main roof from being fractured.

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