When subjected to shear loading condition,a steel rock bolt will become bent in the field close to the loading point in situ.The bolt is deformed as the joint displacement increases,which can mobilize a normal load an...When subjected to shear loading condition,a steel rock bolt will become bent in the field close to the loading point in situ.The bolt is deformed as the joint displacement increases,which can mobilize a normal load and a shear load on the bolt accordingly.In this work,the relationship analysis between the displacing angle and loading angle is carried out.By considering elastic andplastic states of rock bolt during shearing,the rotation of bolt extremity can be calculated analytically.Thus,the loading angle isobtained from displacing angle.The verification of analytical results and laboratory results from reference research implies that theanalytical method is correct and working.In terms of in-situ condition,the direction of the load acting on steel bolt can be predictedwell according to the direction of the deformed rock bolt with respect to original bolt axis.展开更多
The prevention and forecast of coal and gas outburst has always been one of the key issues in coal mining safety.By simulating the process of tunneling in coal seam with different dip angle through FLAC3D software,the...The prevention and forecast of coal and gas outburst has always been one of the key issues in coal mining safety.By simulating the process of tunneling in coal seam with different dip angle through FLAC3D software,the dangerous zone in which outburst may occur and the probability of outburst near the working face were predicted through the distribution of stress,displacement and plastic zone.Then we discussed the size of unstable area in the surrounding rock through the distribution of stress and the variation curve of the displacement on the roadway wall.The results show that,with an increase of the coal seam dip angle,the risk of outburst in the working face rises gradually.And the dangerous areas in which may outburst occur moves to the upper part of coal seam.The size of unstable area in the surrounding rock increases with the increase of coal seam dip angle.展开更多
美国材料实验协会(American Society of Testing Materials,ASTM)F2052-21标准(对应中文标准YY/T 0987.2)规定了磁共振环境中医疗器械磁致位移力的标准测试方法,在国际上被广泛接受和应用。该方法是用细线将被测植入物悬挂于磁场中,测...美国材料实验协会(American Society of Testing Materials,ASTM)F2052-21标准(对应中文标准YY/T 0987.2)规定了磁共振环境中医疗器械磁致位移力的标准测试方法,在国际上被广泛接受和应用。该方法是用细线将被测植入物悬挂于磁场中,测量悬线相对竖直方向的偏转角,从而计算磁致位移力相对重力的大小。然而,当该方法应用于极轻型植入物测试时,很难满足悬线质量小于植入物质量的1%的要求。该文提出了一种基于配重修正的极轻型植入物磁致位移力测试方法:使用质量超出待测植入物质量的1%的悬线和夹持物,按照标准方法测量偏转角度,再使用待测植入物质量在被测物总质量中的占比对偏转角度进行修正,从而获得准确的测量结果。该文对配重修正法进行了理论计算和实验验证,结果表明,所提出的配重修正法能够有效测量极轻型植入物的磁致位移力偏转角。展开更多
基金Projects(51604299,51274249,51474252)supported by the National Natural Science Foundation of ChinaProject(2016YFC0600706)supported by the State Key Research Development Program of China+4 种基金Project(2015CX005)supported by the Innovation Driven Plan of Central South University,ChinaProject(2016M600636)supported by China Postdoctoral Science FoundationProject supported by the Postdoctoral Science Foundation of Central South University,China
文摘When subjected to shear loading condition,a steel rock bolt will become bent in the field close to the loading point in situ.The bolt is deformed as the joint displacement increases,which can mobilize a normal load and a shear load on the bolt accordingly.In this work,the relationship analysis between the displacing angle and loading angle is carried out.By considering elastic andplastic states of rock bolt during shearing,the rotation of bolt extremity can be calculated analytically.Thus,the loading angle isobtained from displacing angle.The verification of analytical results and laboratory results from reference research implies that theanalytical method is correct and working.In terms of in-situ condition,the direction of the load acting on steel bolt can be predictedwell according to the direction of the deformed rock bolt with respect to original bolt axis.
文摘The prevention and forecast of coal and gas outburst has always been one of the key issues in coal mining safety.By simulating the process of tunneling in coal seam with different dip angle through FLAC3D software,the dangerous zone in which outburst may occur and the probability of outburst near the working face were predicted through the distribution of stress,displacement and plastic zone.Then we discussed the size of unstable area in the surrounding rock through the distribution of stress and the variation curve of the displacement on the roadway wall.The results show that,with an increase of the coal seam dip angle,the risk of outburst in the working face rises gradually.And the dangerous areas in which may outburst occur moves to the upper part of coal seam.The size of unstable area in the surrounding rock increases with the increase of coal seam dip angle.
文摘美国材料实验协会(American Society of Testing Materials,ASTM)F2052-21标准(对应中文标准YY/T 0987.2)规定了磁共振环境中医疗器械磁致位移力的标准测试方法,在国际上被广泛接受和应用。该方法是用细线将被测植入物悬挂于磁场中,测量悬线相对竖直方向的偏转角,从而计算磁致位移力相对重力的大小。然而,当该方法应用于极轻型植入物测试时,很难满足悬线质量小于植入物质量的1%的要求。该文提出了一种基于配重修正的极轻型植入物磁致位移力测试方法:使用质量超出待测植入物质量的1%的悬线和夹持物,按照标准方法测量偏转角度,再使用待测植入物质量在被测物总质量中的占比对偏转角度进行修正,从而获得准确的测量结果。该文对配重修正法进行了理论计算和实验验证,结果表明,所提出的配重修正法能够有效测量极轻型植入物的磁致位移力偏转角。
