To investigate the interaction of the bolt-reinforced rock and the surface support,an analytical model of the convergence-confinement type is proposed,considering the sequential installation of the fully grouted rockb...To investigate the interaction of the bolt-reinforced rock and the surface support,an analytical model of the convergence-confinement type is proposed,considering the sequential installation of the fully grouted rockbolts and the surface support.The rock mass is assumed to be elastic-brittle-plastic material,obeying the linear Mohr-Coulomb criterion or the non-linear Hoek-Brown criterion.According to the strain states of the tunnel wall at bolt and surface support installation and the relative magnitude between the bolt length and the plastic depth during the whole process,six cases are categorized upon solving the problem.Each case is divided into three stages due to the different effects of the active rockbolts and the passive surface support.The fictitious pressure is introduced to quantify the threedimensional(3D)effect of the tunnel face,and thus,the actual physical location along the tunnel axis of the analytical section can be considered.By using the bolt-rock strain compatibility and the rocksurface support displacement compatibility conditions,the solutions of longitudinal tunnel displacement and the reaction pressure of surface support along the tunnel axis are obtained.The proposed analytical solutions are validated by a series of 3D numerical simulations.Extensive parametric studies are conducted to examine the effect of the typical parameters of rockbolts and surface support on the tunnel displacement and the reaction pressure of the surface support under different rock conditions.The results show that the rockbolts are more effective in controlling the tunnel displacement than the surface support,which should be installed as soon as possible with a suitable length.For tunnels excavated in weak rocks or with restricted displacement control requirements,the surface support should also be installed or closed timely with a certain stiffness.The proposed method provides a convenient alternative approach for the optimization of rockbolts and surface support at the preliminary stage of tunnel design.展开更多
目的对比分析应用移动卒中单元(MSU)行院前静脉溶栓与常规静脉溶栓对急性缺血性卒中(AIS)的治疗效果。方法回顾性连续纳入曲靖市第一人民医院神经内科2022年2月至2022年12月行静脉溶栓的AIS患者。收集患者的一般资料及临床资料,包括年...目的对比分析应用移动卒中单元(MSU)行院前静脉溶栓与常规静脉溶栓对急性缺血性卒中(AIS)的治疗效果。方法回顾性连续纳入曲靖市第一人民医院神经内科2022年2月至2022年12月行静脉溶栓的AIS患者。收集患者的一般资料及临床资料,包括年龄、性别、吸烟史、高血压病、糖尿病、高脂血症、既往卒中史、心房颤动史、发病时间、静脉溶栓时间、基线美国国立卫生研究院卒中量表(NIHSS)评分、静脉溶栓后48 h症状性颅内出血、静脉溶栓后7 d NIHSS评分、静脉溶栓后90 d改良Rankin量表(mRS)评分、静脉溶栓后90 d死亡及静脉溶栓过程中是否发生任何过敏反应或其他系统出血等。应用MSU进行院前静脉溶栓的AIS患者为MSU溶栓组,院内阿替普酶静脉溶栓(普通急救车入院或自行来院)的AIS患者为常规溶栓组。观察终点指标包括时间指标、疗效指标和安全性指标。时间指标为发病至静脉溶栓时间;疗效指标为静脉溶栓后7 d NIHSS评分、90 d mRS评分;安全性指标包括静脉溶栓后48 h症状性颅内出血、静脉溶栓过程中发生任何过敏反应或其他系统出血及静脉溶栓后90 d患者死亡。结果共纳入151例应用阿替普酶行静脉溶栓的AIS患者,其中男94例(62.3%),女57例(37.7%),年龄39~86岁,中位年龄为67(58,77)岁。MSU溶栓组50例,常规溶栓组101例。两组患者一般资料中年龄、性别、高血压病、高脂血症、心房颤动、吸烟史、卒中史及基线NIHSS评分差异均无统计学意义(均P>0.05),糖尿病史差异有统计学意义(P=0.024)。MSU溶栓组发病至静脉溶栓时间较常规溶栓组明显缩短[93.0(64.5,136.5)min比153.0(118.5,193.5)min,Z=-5.058,P<0.01]。MSU溶栓组溶栓后7 d NIHSS评分低于常规溶栓组[1.0(0.0,3.0)分比2.0(1.0,4.0)分,Z=-2.464,P=0.013],且静脉溶栓后90 d mRS评分较常规溶栓组低[0.0(0.0,0.5)分比0.0(0.0,1.0)分,Z=-2.037,P=0.042]。两组静脉溶栓后48 h症状性颅内出血发生率及90 d内病死率差异均无统计学意义(均P>0.05)。两组患者静脉溶栓过程中均未出现过敏及其他系统出血。结论基于MSU的AIS院前静脉溶栓可以显著缩短发病至静脉溶栓时间,对改善患者神经功能和提高临床疗效具有一定的作用。展开更多
如何为建成区居民提供支持性蓝色空间,是维护居民身心健康状况的新议题。基于Web of Sience核心数据库,回顾近10年45篇英文实证研究文献,从环境暴露行为中介作用视角探讨蓝色空间健康效应、分析影响因素、评价当前研究方法。结果表明:...如何为建成区居民提供支持性蓝色空间,是维护居民身心健康状况的新议题。基于Web of Sience核心数据库,回顾近10年45篇英文实证研究文献,从环境暴露行为中介作用视角探讨蓝色空间健康效应、分析影响因素、评价当前研究方法。结果表明:环境暴露行为可以概念化为3种类型,蓝色空间的内部环境和周边联系共同决定了环境暴露行为的健康效应,并受到个体差异的调节,通过潜在暴露行为测量和显性暴露行为调查2种研究方法测度环境暴露行为的中介作用。最后,针对当前数据获取与分析尚存的不足,建议未来研究在数据采集、研究方法、实践应用方面予以完善,以期为健康导向下的蓝色空间规划提供借鉴和参考。展开更多
Longitudinal cracks on the tunnel lining significantly influence the performance of tunnels in operation.In this study,we propose a semi-analytical method that provides a simple and effective way to calculate the inte...Longitudinal cracks on the tunnel lining significantly influence the performance of tunnels in operation.In this study,we propose a semi-analytical method that provides a simple and effective way to calculate the internal forces of tunnel linings with multiple cracks.The semi-analytical solution is obtained using structural analysis considering the flexural rigidity for the cracked longitudinal section of the tunnel lining.Then the proposed solution is verified numerically.Using the proposed method,the influences of the crack depth and the number of cracks on the bending moment and modified crack tip stress are investigated.With the increase in crack depth,the bending moment of lining scetion adjacent to the crack decreases,while the bending moment of lining scetion far away from the crack increases slightly.The more the number of cracks in a tunnel lining,the easier the new cracks initiated.展开更多
基金funding support from the Fundamental Research Funds for the Central Universities(Grant No.2023JBZY024)the National Natural Science Foundation of China(Grant Nos.52208382 and 52278387).
文摘To investigate the interaction of the bolt-reinforced rock and the surface support,an analytical model of the convergence-confinement type is proposed,considering the sequential installation of the fully grouted rockbolts and the surface support.The rock mass is assumed to be elastic-brittle-plastic material,obeying the linear Mohr-Coulomb criterion or the non-linear Hoek-Brown criterion.According to the strain states of the tunnel wall at bolt and surface support installation and the relative magnitude between the bolt length and the plastic depth during the whole process,six cases are categorized upon solving the problem.Each case is divided into three stages due to the different effects of the active rockbolts and the passive surface support.The fictitious pressure is introduced to quantify the threedimensional(3D)effect of the tunnel face,and thus,the actual physical location along the tunnel axis of the analytical section can be considered.By using the bolt-rock strain compatibility and the rocksurface support displacement compatibility conditions,the solutions of longitudinal tunnel displacement and the reaction pressure of surface support along the tunnel axis are obtained.The proposed analytical solutions are validated by a series of 3D numerical simulations.Extensive parametric studies are conducted to examine the effect of the typical parameters of rockbolts and surface support on the tunnel displacement and the reaction pressure of the surface support under different rock conditions.The results show that the rockbolts are more effective in controlling the tunnel displacement than the surface support,which should be installed as soon as possible with a suitable length.For tunnels excavated in weak rocks or with restricted displacement control requirements,the surface support should also be installed or closed timely with a certain stiffness.The proposed method provides a convenient alternative approach for the optimization of rockbolts and surface support at the preliminary stage of tunnel design.
文摘目的对比分析应用移动卒中单元(MSU)行院前静脉溶栓与常规静脉溶栓对急性缺血性卒中(AIS)的治疗效果。方法回顾性连续纳入曲靖市第一人民医院神经内科2022年2月至2022年12月行静脉溶栓的AIS患者。收集患者的一般资料及临床资料,包括年龄、性别、吸烟史、高血压病、糖尿病、高脂血症、既往卒中史、心房颤动史、发病时间、静脉溶栓时间、基线美国国立卫生研究院卒中量表(NIHSS)评分、静脉溶栓后48 h症状性颅内出血、静脉溶栓后7 d NIHSS评分、静脉溶栓后90 d改良Rankin量表(mRS)评分、静脉溶栓后90 d死亡及静脉溶栓过程中是否发生任何过敏反应或其他系统出血等。应用MSU进行院前静脉溶栓的AIS患者为MSU溶栓组,院内阿替普酶静脉溶栓(普通急救车入院或自行来院)的AIS患者为常规溶栓组。观察终点指标包括时间指标、疗效指标和安全性指标。时间指标为发病至静脉溶栓时间;疗效指标为静脉溶栓后7 d NIHSS评分、90 d mRS评分;安全性指标包括静脉溶栓后48 h症状性颅内出血、静脉溶栓过程中发生任何过敏反应或其他系统出血及静脉溶栓后90 d患者死亡。结果共纳入151例应用阿替普酶行静脉溶栓的AIS患者,其中男94例(62.3%),女57例(37.7%),年龄39~86岁,中位年龄为67(58,77)岁。MSU溶栓组50例,常规溶栓组101例。两组患者一般资料中年龄、性别、高血压病、高脂血症、心房颤动、吸烟史、卒中史及基线NIHSS评分差异均无统计学意义(均P>0.05),糖尿病史差异有统计学意义(P=0.024)。MSU溶栓组发病至静脉溶栓时间较常规溶栓组明显缩短[93.0(64.5,136.5)min比153.0(118.5,193.5)min,Z=-5.058,P<0.01]。MSU溶栓组溶栓后7 d NIHSS评分低于常规溶栓组[1.0(0.0,3.0)分比2.0(1.0,4.0)分,Z=-2.464,P=0.013],且静脉溶栓后90 d mRS评分较常规溶栓组低[0.0(0.0,0.5)分比0.0(0.0,1.0)分,Z=-2.037,P=0.042]。两组静脉溶栓后48 h症状性颅内出血发生率及90 d内病死率差异均无统计学意义(均P>0.05)。两组患者静脉溶栓过程中均未出现过敏及其他系统出血。结论基于MSU的AIS院前静脉溶栓可以显著缩短发病至静脉溶栓时间,对改善患者神经功能和提高临床疗效具有一定的作用。
文摘如何为建成区居民提供支持性蓝色空间,是维护居民身心健康状况的新议题。基于Web of Sience核心数据库,回顾近10年45篇英文实证研究文献,从环境暴露行为中介作用视角探讨蓝色空间健康效应、分析影响因素、评价当前研究方法。结果表明:环境暴露行为可以概念化为3种类型,蓝色空间的内部环境和周边联系共同决定了环境暴露行为的健康效应,并受到个体差异的调节,通过潜在暴露行为测量和显性暴露行为调查2种研究方法测度环境暴露行为的中介作用。最后,针对当前数据获取与分析尚存的不足,建议未来研究在数据采集、研究方法、实践应用方面予以完善,以期为健康导向下的蓝色空间规划提供借鉴和参考。
基金The authors gratefully acknowledge the financial support by the Key Project of High-speed Rail Joint Fund of National Natural Science Foundation of China(Grant No.U1934210)the Natural Science Foundation of Beijing,China(Grant No.8202037).
文摘Longitudinal cracks on the tunnel lining significantly influence the performance of tunnels in operation.In this study,we propose a semi-analytical method that provides a simple and effective way to calculate the internal forces of tunnel linings with multiple cracks.The semi-analytical solution is obtained using structural analysis considering the flexural rigidity for the cracked longitudinal section of the tunnel lining.Then the proposed solution is verified numerically.Using the proposed method,the influences of the crack depth and the number of cracks on the bending moment and modified crack tip stress are investigated.With the increase in crack depth,the bending moment of lining scetion adjacent to the crack decreases,while the bending moment of lining scetion far away from the crack increases slightly.The more the number of cracks in a tunnel lining,the easier the new cracks initiated.
