Analysis on bending moment property of hard roof influenced by elastic，hardening and softening zone of coal seam
PAN Yue1，GU Shitan2，3，LI Wenshuai2，3
(1. School of Civil Engineering，Qingdao Technological University，Qingdao，Shandong 266520，China；2. State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology，Shandong University of Science and Technology，Qingdao，Shandong 266590，China；3. College of Mining and Safety Engineering，Shandong University of Science and Technology，Qingdao，Shandong 266590，China)
Abstract：It was usually considered that the yield soften state of coal seam was derived from coal wall to abutment pressure peak in coal seam and coal seam was in elastic state in front of the abutment pressure peak. The hardening state between the soft and elastic state was neglected. Given this above，the coal seam was divided into the softened zone near the coal wall，the hardened zone in front of peak abutment pressure and the elastic zone ahead again. Then expressions of abutment pressure in hardened and softened zone of coal seam were proposed and determination methods of abutment pressure in each section of coal seam were continuous. On the basis of reference [13]，expressions of deflection of hard roof supported by elastic zone，hardened zone and softened zone of coal seam were derived before periodic weighting. According to the expressions，cases of abutment pressure of coal seam to roof and corresponding bending moment distribution curve of hard roof were given by Matlab when the elastic，hardening and softening zone parameters were changed. From the above，the changeable parameters of any section of the coal seam could cause the change of abutment pressure in other sections. Pre-distance of bending moment peak of the roof was 6.04 m which had crossed the softening zone and was in coal seam hardening section under the assumption that the coal seam residual strength was 0. Compared the cases with abutment pressure and corresponding roof bending moment under the assumption that only supported by elastic and softening zones，the roof deflection，peak bending moment and pre-distance of bending moment peak of the former were significantly greater than the corresponding value of the latter. After the analysis of abutment pressure of coal seam and the corresponding roof bending moment data of the former，an important understanding was obtained that anti bending moment formed by abutment pressure of softening zone in coal seam was small，the corresponding peak value of bending moment and pre-distance of bending moment peak of the roof were large. The explanation was that roof and coal seam was a community which supported overlying load together. When the anti- bending moment caused by the abutment force of softening zone of coal seam was small，bending degree and bending scope of the roof would increase to resist its overlying load，which led that the roof peak value of bending moment and pre-distance of bending moment peak increase.
潘 岳1，顾士坦2，3，李文帅2，3. 煤层弹性、硬化和软化区对顶板弯矩特性影响分析[J]. 岩石力学与工程学报, 2016, 35(S2): 3846-3857.
PAN Yue1，GU Shitan2，3，LI Wenshuai2，3. Analysis on bending moment property of hard roof influenced by elastic，hardening and softening zone of coal seam. , 2016, 35(S2): 3846-3857.
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2016, Vol. 35 
