极高地应力软岩隧道超前导洞应力释放及多层支护变形控制技术

为了解决极高地应力软岩隧道大变形控制难题,以兰渝铁路木寨岭隧道岭脊核心段施工为例,通过现场试验和数据分析,得到如下主要结论:1)提出了"先放后抗,抗放结合,锚固加强"的变形控制理念;2)得出了该隧道岭脊核心段"超前导洞应力释放+圆形4层支护结构+径向注浆+长锚杆+长锚索"综合变形控制方案;3)超前导洞应力释放效果明显,正洞累计变形减小幅度约为34%;4)得到了圆形多层支护结构变形规律;5)累计变形均控制在设计预留变形量内,保证了该隧道岭脊核心段大变形控制效果。     

Magneto-rheological suspensions for improving ground vehicle’s ride comfort,stability, and handling

ABSTRACT

A state-of-the-art discussion on the applications of magneto-rheological (MR) suspensions for improving ride comfort, handling, and stability in ground vehicles is discussed for both road and rail applications. A historical perspective on the discovery and engineering development of MR fluids is presented, followed by some of the common methods for modelling their non-Newtonian behaviour. The common modes of the MR fluids are discussed, along with the application of the fluid in valve mode for ground vehicles’ dampers (or shock absorbers). The applications span across nearly all road vehicles, including automobiles, trains, semi-trucks, motorcycles, and even bicycles. For each type of vehicle, the results of some of the past studies is presented briefly, with reference to the originating study. It is discussed that Past experimental and modelling studies have indicated that MR suspensions provide clear advantages for ground vehicles that far surpasses the performance of passive suspension. For rail vehicles, the primary advantage is in terms of increasing the speed at which the onset of hunting occurs, whereas for road vehicles – mainly automobiles – the performance improvements are in terms of a better balance between vehicle ride, handling, and stability. To further elaborate on this point, a single-suspension model is used to develop an index-based approach for studying the compromise that is offered by vehicle suspensions, using the H₂ optimisation approach. Evaluating three indices based on the sprung-mass acceleration, suspension rattlespace, and tyre deflection, it is clearly demonstrated that MR suspensions significantly improve road vehicle’s ride comfort, stability, and handling in comparison with passive suspensions. For rail vehicles, the simulation results indicate that using MR suspensions with an on-off switching control can increase the speed at which the on-set of hunting occurs by as much as 50% to more than 300%.     

监控量测在姚村坦隧道施工险情预报中的应用

以景(德镇)婺(源)黄(山)高速公路姚村坦连拱隧道施工中出现的险情为例,结合地表沉降、洞内净空收敛及拱顶下沉进行观测及现场观察,针对隧道出口段围岩失稳导致中导洞右侧工字钢严重内敛现象进行了动态预报,从而为及时采取有效措施排除险情争取了时间,避免了重大事故的发生,以此进一步说明了监控量测在隧道修建过程中的必要性。     

真空预压排水板有效真空压力变化规律

针对竖向排水板中有效真空压力分布模式存在的争议,基于流体力学相关理论对真空度和负压概念加以分析,指出排水板中孔隙水压力的变化量便是有效真空压力大小。通过计算排水板中孔隙水的总势能,并利用水具有趋向于更低能量状态的趋势原理,分析了孔隙水的运动机制及流动全过程,进而得到有效真空压力变化规律。研究表明,排水板中有效真空压力变化规律与初始地下水位、膜下真空度及排水板变形量紧密相关;有效真空压力的简化分布模式为折线形,转折点在与初始地下水位线交汇处;在地下水位线以上时,有效真空压力变化大,衰减梯度达10 k Pam;在地下水位线以下时,有效真空压力基本保持不变;排水板变形量越大,排水阻力越大,如果出现折管现象,可能导致膜下真空压力无法向下传递。     

防空装备战场抢修保障模型研究*

防空武器装备作战任务重、遭受打击强,给装备保障工作提出了较高的要求。在分析了其战场环境下受损规律的基础上,对防空武器装备战场抢修任务组织实施流程进行了研究,并运用Ex tendSim平台进行了仿真,对进一步开展防空武器装备战场抢修组织决策的研究具有一定的帮助。     

铜合金接触线禁用承导双架施工方法的建议

通过分析高速悬挂系统的特点和工艺标准,从施工效率、施工质量、施工工艺等方面对采用承导双架施工方法进行探讨,认为承导双架施工方法对施工效率的提高不明显、质量存在隐患且工艺上易产生不可克服的缺陷,建议在使用锡(镁)铜合金接触线或新线一次建设电气化工程中禁止采用承导双架施工方法.     

改善刚柔过渡区域弓网关系的探讨

对刚柔过渡区域刚性和柔性接触网的弹性不同及接触线高度不等情况进行了定性及定量分析,找出该区域弓网关系恶劣的原因,并针对原因提出改善刚柔过渡区域弓网关系的解决方案。     

遥控单索无动力开闭抓斗技术分析

遥控单索无动力开闭抓斗具有技术先进性和实用性,使用这种抓斗,可以起到简化装卸工艺、降低生产成本、缓解门机压力等多重作用,可以在低投入的情况下有效地提高综合性码头的散货装卸效率.     

广州地铁2号线大面积软土地基处理监测分析

介绍了广州地铁2号线大面积软土地基处理施工工艺和施工监测.通过对软土地基处理施工监测数据分析结果表明:①新采用的软土地基处理手段合理,软土地基加固处理效果明显;②软土地基处理监测能及时发现问题采取措施,保障了软土地基处理工程的顺利进行;③土体水平位移测斜是判断土体及边坡稳定与否的重要指标;④要使水平位移率和水平位移实测值控制在设计允许范围内,以保证软土地基处理工程安全有序.     

汽车电气自燃影响因素浅谈

详细论述汽车导线的负载能力及过载试验情况,导线过载、短路时会出现的严重后果;熔断丝技术参数及导线上选配合适熔断丝的物理意义,提出汽车上除搭铁线外所有线路都需要经过熔断丝;简单介绍插接件、线束安装、电器件、内饰材料阻燃等对汽车自燃的影响。