LIN Jian,ZHOU Yiqun,WANG Zhengsheng,SHI Yao
1.Coal Mining and Designing Department，Tiandi Science and Technology Co.，Ltd.，Beijing ，China；2.Coal Mining and Designing Research Branch，China Coal Research Institute，Beijing ，China
bolt support; pre-stress; wooden plate; pre-stress loss
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Aiming at the common phenomenon of adding wooden plate under the bolt trays of many mines in China, the laboratory test method was used to reveal the influence of wooden plate on the pre-stress of bolt by using the self-developed bolt support stress field test rig. The pre-stress loss, preload torque conversion and pre-stress distribution of the bolt under the action of the wooden plate were studied and compared with the metal trays. The results show that in the dry environment, the first hour loss rate of the bolt prestress of the wooden plate is up to 23%, and the coefficient of the preload torque convert to pre-stress of the bolt is reduced by 23%. The range of pre-stress fields formed by bolt support in the surrounding rock is greatly reduced, the area of each stress contour is reduced by 27% on average, and the peak of pre-stress is reduced by 38%. It is also pointed out that in the environment where the humidity of the mine exceeds 90%, the influence of the wooden plate on the working load of the bolt will be greatly increased.
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