The center cutter of a hard rock tunnel boring machine(TBM) is installed on the cutterhead at a small radius and thus bears complex side force.Given this fact,the formation mechanism and change law of the side force s...The center cutter of a hard rock tunnel boring machine(TBM) is installed on the cutterhead at a small radius and thus bears complex side force.Given this fact,the formation mechanism and change law of the side force suffered by the center cutter were studied.Based on the rock shear failure criterion in combination with the lateral rolling width,a model for predicting the average side force was set up.Besides,a numerical analysis model of the rock fragmentation of the center cutter was established,and the instantaneous load changing features were investigated.Results shows that the inner side of the center cutter can form lateral rolling annulus in rock during the rotary cutting process.The smaller the installation radius is,the greater the cutter side force will be.In a working condition,the side force of the innermost center cutter is 11.66 k N,while it decreases sharply when installation radius increases.Variation tends to be gentle when installation radius is larger than 500 mm,and the side force of the outermost center cutter is reduced to 0.74 k N.展开更多
The cutter layout of a full-face tunnel boring machine(TBM)directly affects its tunneling efficiency.The revolving diameter of the center cutter is small,and the double-edged design results in its rock breaking mechan...The cutter layout of a full-face tunnel boring machine(TBM)directly affects its tunneling efficiency.The revolving diameter of the center cutter is small,and the double-edged design results in its rock breaking mechanism and force characteristics being significantly different from those of the single-edged cutter.The gage cutter is installed on the transition arc of the cutterhead,and the installation inclination complicates its movement and force.In this paper,by taking sandstone as the research object,the composite rock breaking models of the center cutter group and the gage cutter group of a compound TBM are separately established based on the three-dimensional particle discrete element method.The numerical models are verified by comparing results with the full-scale rotary cutting laboratory test.From the view point of the force characteristics of a single cutter,the propagation of rock cracks between adjacent cutters,the overall mechanical properties of the cutterhead,the load characteristics and layout form of the double-edged center cutter,and the installation angle range of the gage cutter were studied.Results demonstrate that the use of a cross-shaped center cutter layout can reduce the force of a single cutter ring and the overall load of the cutterhead,which is conducive to TBM stability during tunneling.Therefore,it is recommended that a cross-shaped layout for the double-edged center cutter of a rock formation compound TBM should be used.To improve the stability and service life of the cutter,we recommend setting the installation angle of the innermost gage cutter of the rock formation compound TBM to about 9°,and the installation angle of the outermost gage cutter should not exceed 70°.展开更多
为进一步优化数据机房的整体布局,提升综合的数据处理效率,扩大实际的执行范围,研究了互联网数据中心(Internet Data Center,IDC)数据机房布局设计与安装。首先进行IDC密闭冷通道框架的构建,设计机架与柱网布置,以此为基础,完成电阻封...为进一步优化数据机房的整体布局,提升综合的数据处理效率,扩大实际的执行范围,研究了互联网数据中心(Internet Data Center,IDC)数据机房布局设计与安装。首先进行IDC密闭冷通道框架的构建,设计机架与柱网布置,以此为基础,完成电阻封锁的布局,以通信楼分层建立的方式实现IDC数据机房的布局。然后,通过机房定点定位放线的方式,构建标定的机房安装空间,在辅助截面的承接之下安装辅助吊架,形成一个完整、关联性较强的安装承接口,进行顶框及附件的安装,最终实现对数据机房的设计与实践安装,一定程度上为数据机房的应用营造更为稳定、安全的环境。展开更多
基金Project (2013CB035401) supported by the National Basic Research Program of ChinaProject (51475478) supported by the National Natural Science Foundation of ChinaProject (2012AA041803) supported by the High-Tech Research and Development Program of China
文摘The center cutter of a hard rock tunnel boring machine(TBM) is installed on the cutterhead at a small radius and thus bears complex side force.Given this fact,the formation mechanism and change law of the side force suffered by the center cutter were studied.Based on the rock shear failure criterion in combination with the lateral rolling width,a model for predicting the average side force was set up.Besides,a numerical analysis model of the rock fragmentation of the center cutter was established,and the instantaneous load changing features were investigated.Results shows that the inner side of the center cutter can form lateral rolling annulus in rock during the rotary cutting process.The smaller the installation radius is,the greater the cutter side force will be.In a working condition,the side force of the innermost center cutter is 11.66 k N,while it decreases sharply when installation radius increases.Variation tends to be gentle when installation radius is larger than 500 mm,and the side force of the outermost center cutter is reduced to 0.74 k N.
基金the National Natural Science Foundation of China(No.U1934213)the Sichuan Science and Technology Program(No.2019YFG0460)。
文摘The cutter layout of a full-face tunnel boring machine(TBM)directly affects its tunneling efficiency.The revolving diameter of the center cutter is small,and the double-edged design results in its rock breaking mechanism and force characteristics being significantly different from those of the single-edged cutter.The gage cutter is installed on the transition arc of the cutterhead,and the installation inclination complicates its movement and force.In this paper,by taking sandstone as the research object,the composite rock breaking models of the center cutter group and the gage cutter group of a compound TBM are separately established based on the three-dimensional particle discrete element method.The numerical models are verified by comparing results with the full-scale rotary cutting laboratory test.From the view point of the force characteristics of a single cutter,the propagation of rock cracks between adjacent cutters,the overall mechanical properties of the cutterhead,the load characteristics and layout form of the double-edged center cutter,and the installation angle range of the gage cutter were studied.Results demonstrate that the use of a cross-shaped center cutter layout can reduce the force of a single cutter ring and the overall load of the cutterhead,which is conducive to TBM stability during tunneling.Therefore,it is recommended that a cross-shaped layout for the double-edged center cutter of a rock formation compound TBM should be used.To improve the stability and service life of the cutter,we recommend setting the installation angle of the innermost gage cutter of the rock formation compound TBM to about 9°,and the installation angle of the outermost gage cutter should not exceed 70°.
文摘为进一步优化数据机房的整体布局,提升综合的数据处理效率,扩大实际的执行范围,研究了互联网数据中心(Internet Data Center,IDC)数据机房布局设计与安装。首先进行IDC密闭冷通道框架的构建,设计机架与柱网布置,以此为基础,完成电阻封锁的布局,以通信楼分层建立的方式实现IDC数据机房的布局。然后,通过机房定点定位放线的方式,构建标定的机房安装空间,在辅助截面的承接之下安装辅助吊架,形成一个完整、关联性较强的安装承接口,进行顶框及附件的安装,最终实现对数据机房的设计与实践安装,一定程度上为数据机房的应用营造更为稳定、安全的环境。
