Mine roof support is a kind of support measure commonly involved in tunnel construction. The construction quality of roof support directly affects the installation, progress and enterprise image.
The mine roof support shall be installed immediately after the preliminary spraying of excavation is completed. According to the position measured, each steel frame is connected with bolts on the palm face, and the connecting plate should be closely affixed. In order to ensure that each section of the steel arch frame is placed on a solid foundation before the whole ring is closed, the bottom of each section of the steel frame should be removed before installation of the empty ballast and debris. At the same time, two anchor pipes (rods) with locking feet were installed on each side to lock them. After the bottom excavation was completed, the initial support at the bottom was timely followed up to close the whole ring of the steel frame. Ⅴ level of surrounding rock in the arch of steel frame footing in a channel to increase the bearing capacity of basement.
In order to ensure the accurate placement of mine roof support , grooves of connecting plates are reserved at the joints of steel frames during tunnel excavation. At the beginning of shotcrete, the wooden wedge is driven into the groove to set apart the connection plate (and channel steel) position for erecting the steel frame. The steel support shall be installed according to the design position. In the installation process, when there is a large gap between the steel frame and the initial spray layer, precast concrete blocks shall be used for wedge every 2m, and the back of the steel frame shall be filled with shotcrete. The steel frame is longitudinally connected with steel tubes (reinforcement bars) at an annular interval of 1m.
