A Study of Prevention Techniques for Tunnel Lining Defects北大核心CSCD

Defects of tunnel lining, such as inadequate thickness, voids, cracks, rock falling and water leakage etc., endanger the safety of railway tunnel operation. Based on the site construction, an analysis of the reasons for lining defects was conducted; technical measures against lining defects were proposed and tests were carried out at site. The results show that these measures are reliable and effective, and the purposes of prevention and treatment are re⁃ alized. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

车身壁板自由阻尼层稳健性优化设计

在车身壁板自由阻尼层的优化设计中,提出了考虑阻尼材料参数不确定性波动的稳健性优化设计方法。首先,在车身防火墙、地板和顶棚等区域全敷阻尼材料;其次,以等效辐射声功率(ERP)为优化目标对阻尼层布局进行拓扑优化并验证优化效果;最后,以阻尼层厚度为随机设计变量,损耗因子和弹性模量为随机变量,质量最小为优化目标,并结合径向基函数(RBF)近似模型、蒙特卡洛模拟(MCS)和序列二次规划算法(SQP)对阻尼层进行6σ稳健性优化设计。结果表明,优化后车身自由阻尼层的总质量减少了50.45%,并且车身结构噪声性能达到了6σ质量水平,实现了保证车身轻量化要求下的阻尼层稳健性优化的目标。     

基于荣乌高速烟威段的生态建设和修复技术研究

高速公路建设的迅速发展在带来很高的社会效益和经济效益的同时,对路域自然环境、对生态平衡造成的影响日益突出。本文以荣乌高速烟威段实施的绿化工程为案例,对路堑边坡、路侧裸地、受损湿地生态系统修复技术进行了探讨和研究。     

On Safety in Dismantling Temporary Strut of Super-large Tunnels with Double-layer Primary Support北大核心CSCD

More and more multiple-track tunnels and super-large section tunnels have been built, and disman- tling of temporary strut is a weak point of the whole structure during force transfer when the secondary lining is con- structed. It is significant to guarantee structure safety during dismantling of temporary strut. Little systematic re- search on safety in dismantling of temporary strut of the super-large section tunnel with double-layer primary support has been conducted, so the internal force and security of the two-layer primary support of the Xinkaotang tunnel were analyzed by a numerical analysis and site measurement, and it proves the effect of two-layer primary support on the safety during strut dismantling. The research results indicate that: (1) with constant support thickness and one-time longitudinal dismantling length, the safety factor of secondary primary support is larger than that of the first primary support, and the safety factor of the first primary support is larger than that of the single-layer primary support. Change range of safety factor for the first primary support is smaller than that of the single-layer primary support, and the safe factor for the single-layer primary support is smaller than that of the secondary primary support; (2) with the same support pattern, the safety factors increase firstly and then decrease with an increase of the onetime dismantling length. The calculated results of various cases show that the reasonable one-time dismantling length for this project is about 9 m. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

木寨岭隧道炭质板岩流变力学特性研究

为深入探究木寨岭隧道工程中炭质板岩的流变力学特性,在不同条件下,对现场取得的岩样进行单轴和三轴压缩蠕变试验,并对炭质板岩的蠕变特性进行分析,描述了炭质板岩的流变特性,得出了瞬时应变占总应变的比例为80%~90%,以及高围压下的流变多为等速流变等结论;采用Burgers流变本构模型,对试验数据进行参数拟合分析,得出了3组不同围压下炭质板岩流变本构方程的弹性模量、黏性模量、黏滞系数等主要参数。     

一种减轻装有EPS汽车转向扭矩的控制策略

本文提出了一种新的电动助力转向系统的控制策略,以减小车辆静止时改变方向所需的转向力。以前尝试通过减少不良的转向振动来减少转向扭矩失败的原因是因为高辅助增益往往会产生震荡或增加噪声敏感性。为了消除此种振动,开发出一种基于控制齿轮角速度的控制策略,它是在简化的转向模型的基础上开发出来的。这个实验获得了很好的齿轮角速度的估计值,这样就有可能消除方向盘所有旋转速度下的振动。实验证明在方向盘大转速变换下,转向扭矩显著降低,无振动传输给司机。所提出的控制策略使用一个辅助来获得超过原来的三倍以上的增益。此外,所提出的控制策略不需要补充传感器。     

基于正交实验法的车身侧面碰撞性能优化

建立车身有限元模型进行仿真分析.输出B柱加速度曲线并与实车侧面碰撞结果对标,使有限元模型能够表征物理样车,仿真结果具有可信性及预测性.进行CAE侧面碰撞仿真,采用正交试验法分析车身侧面结构中的7个零件,考核各零件对车身侧面碰撞性能指标的影响,寻找出对车身侧面碰撞性能影响较大的零件及区域.进行优化设计,利用CAE仿真手段来验证优化方案.通过该方法,能够判断对车身侧面碰撞性能影响较大的零件和区域,以及影响因子.能够快速、合理、有针对性地进行车身结构优化,达到优化目标.     

厦门石渭头污水处理厂改扩建工程设计总结

厦门市石渭头污水处理厂一期已建规模10万m3/d,二期扩建10万m3/d,同时进行一期工程的改造,改扩建后总规模20万m3/d同步达标排放。本着充分利用一期已有构筑物和设备的原则,将原一期10万m3/d出水二级排放标准的生物反应池升级改造为5万m3/d一级B标准的好氧池和缺氧池,同时新建15万m3/d完整的A2/O池+5万m3/d厌缺氧池,通过连接管道使一、二期构筑物有机结合,确保出水同步达标排放。该文就污水处理厂一期存在的问题;二期扩建与一期升级改造衔接方案;改扩建工程设计等方面进行总结,可供同行参考。     

基于有限元法的某商用车驾驶室力学性能仿真研究

文章基于有限元法,采用Nastran软件,对某商用车驾驶室系统进行了CAE模态,弯曲扭转刚度和强度分析,结果显示,驾驶室前四阶模态有效避开了发动机怠速频率,而弯曲和扭转刚度满足设计目标,同时,驾驶室四工况下最大塑性应变达成设计目标,综合评估该商用车驾驶室力学性能符合设计要求.     

汽车理论非标准答案教学改革的研究

文章针对车辆工程专业核心课程—汽车理论,结合我校该专业的定位和社会对该专业人才的实际需求,根据地方院校应用型人才培养的目标和要求,在我校进行了汽车理论课程非标准答案教学改革的探索,提出了该课程采用非标准答案教学的改革思路,并从非标准答案教学的意义、非标准答案教学改革的内容与形式、具体实施步骤以及评分标准等方面进行了细致...