随着开采深度的不断增加,巷道围岩破坏程度也逐渐增大,巷道稳定性成为相关工作人员关注的焦点。矿产资源处于地层较深处,开采环境复杂,特别是在构造应力复杂的情况下,巷道的稳定性面临巨大挑战。对深部巷道围岩在不同的侧压系数下,水平...随着开采深度的不断增加,巷道围岩破坏程度也逐渐增大,巷道稳定性成为相关工作人员关注的焦点。矿产资源处于地层较深处,开采环境复杂,特别是在构造应力复杂的情况下,巷道的稳定性面临巨大挑战。对深部巷道围岩在不同的侧压系数下,水平位移、垂直位移、最大应力分布以及塑性区的变化特征进行了研究,并运用3DEC(3 Dimension Distinct Element Code,三维离散单元法程序)软件进行数值模拟研究。研究结果表明:巷道两帮的水平位移会随着侧压系数的增大逐渐变大;顶底板的垂直位移也在增大,并向两帮扩展;此系数对巷道顶底板塑性区的影响较为明显,出现剪切形式的破坏范围呈增长趋势,两帮塑性区破坏形式主要为剪切破坏。通过3DEC数值模拟研究,为深部巷道处于复杂应力环境时的巷道支护提供参考。展开更多
A high efficiency sliding screw driver is introduced. It can improve drivingefficiency obviously. As the material strength of the nut in this structure is low and the nut isthe most dangerous part, so it is important ...A high efficiency sliding screw driver is introduced. It can improve drivingefficiency obviously. As the material strength of the nut in this structure is low and the nut isthe most dangerous part, so it is important to master the structure's characters of deformation andstress. The deformation and stress of this structure are researched by finite element method(FEM),and the changing law of stress concentration coefficient of the structure is gained. So the exactstress of nut teeth with highest load can be calculated directly based on this result.展开更多
The probability distributions of the critical threshold chloride concentration Ccr, the chloride diffusion coefficient D, and the surface chloride concentration Cs are determined based on the collected natural exposur...The probability distributions of the critical threshold chloride concentration Ccr, the chloride diffusion coefficient D, and the surface chloride concentration Cs are determined based on the collected natural exposure data, and the probability estimation of reinforcement depassivation in concrete is presented using Monte-Carlo simulation. From sensitivity analysis of mean value for ccr, cs, and D on the depassivation probability of reinforcement, it is found that ccr, cs, and D respectively has the greatest, smaller, and the lowest effect on the probability of depassivation. Finally the effect of stress state of concrete on the reinforcement depassivation probability is analyzed. It is found that the influence of stress state becomes apparent as exposure time increases.展开更多
文摘随着开采深度的不断增加,巷道围岩破坏程度也逐渐增大,巷道稳定性成为相关工作人员关注的焦点。矿产资源处于地层较深处,开采环境复杂,特别是在构造应力复杂的情况下,巷道的稳定性面临巨大挑战。对深部巷道围岩在不同的侧压系数下,水平位移、垂直位移、最大应力分布以及塑性区的变化特征进行了研究,并运用3DEC(3 Dimension Distinct Element Code,三维离散单元法程序)软件进行数值模拟研究。研究结果表明:巷道两帮的水平位移会随着侧压系数的增大逐渐变大;顶底板的垂直位移也在增大,并向两帮扩展;此系数对巷道顶底板塑性区的影响较为明显,出现剪切形式的破坏范围呈增长趋势,两帮塑性区破坏形式主要为剪切破坏。通过3DEC数值模拟研究,为深部巷道处于复杂应力环境时的巷道支护提供参考。
文摘A high efficiency sliding screw driver is introduced. It can improve drivingefficiency obviously. As the material strength of the nut in this structure is low and the nut isthe most dangerous part, so it is important to master the structure's characters of deformation andstress. The deformation and stress of this structure are researched by finite element method(FEM),and the changing law of stress concentration coefficient of the structure is gained. So the exactstress of nut teeth with highest load can be calculated directly based on this result.
基金Funded by National Natural Science Foundation of China (Nos.50908148and 50925829)Research Project of Ministry of Housing and Urban-Rural Development of China (Nos.2009-K4-23, 2010-11-33)National KeyTechnologies R&D Program of China (No.2006BAJ02B04)
文摘The probability distributions of the critical threshold chloride concentration Ccr, the chloride diffusion coefficient D, and the surface chloride concentration Cs are determined based on the collected natural exposure data, and the probability estimation of reinforcement depassivation in concrete is presented using Monte-Carlo simulation. From sensitivity analysis of mean value for ccr, cs, and D on the depassivation probability of reinforcement, it is found that ccr, cs, and D respectively has the greatest, smaller, and the lowest effect on the probability of depassivation. Finally the effect of stress state of concrete on the reinforcement depassivation probability is analyzed. It is found that the influence of stress state becomes apparent as exposure time increases.
