高地应力软岩隧道圆形断面扩挖施工围岩及支护受力特征研究

针对高地应力软岩隧道开挖时围岩大变形问题,以某隧道圆形扩挖段为背景,采用三台阶法施工和3层初期支护+小导管注浆+二次衬砌的复合结构支护,并通过现场监测、数值模拟和理论计算研究开挖过程中的围岩变形及支护结构受力。结果表明:上、中台阶开挖时的隧道围岩变形速率较大,在仰拱封闭和第3层初期支护施作完成后,隧道变形趋于稳定;采用3层初期支护结构可有效改善隧道周边围岩应力,3层初期支护基本都是受压结构,拱腰和边墙处竖向应力最大,拱顶处水平应力最大;二次衬砌拱腰、拱顶、拱脚和边墙处安全系数均大于规范要求,保证隧道结构安全。     

耐久试验中不同测试循环下排放规律研究

采用标准台架循环(SBC)和标准道路循环(SRC)两种方式,分别对催化器进行耐久试验,并在不同耐久里程时分别进行排放试验。采用SBC方式时,随耐久里程增加,CO排放无明显变化,NO_x明显增大,THC有小幅增大;CO瞬态曲线由单峰态变为双峰态,双峰态峰值小于单峰态峰值;NO_x为双峰态,第1个峰值总体上呈增大趋势,第2个峰值无明显规律;THC为明显的单峰态,峰值总体上呈增大趋势。采用SRC方式时,随耐久里程增加,CO排放明显增大,NO_x也呈增大趋势,THC先增大后减小;CO瞬态曲线始终为单峰态,峰值呈增大趋势;NO_x为双峰态,第1个峰值与第2个峰值总体上均呈增大趋势;THC为明显的单峰态,峰值先增大后减小。     

独立板凳平台在无覆盖层海域灌注桩施工中的应用

为了便利在不良地质的海域进行海洋工程,创建了独立板凳平台。以菲律宾某电站码头为背景,结合无覆盖层海域的实际地质情况,分别介绍板凳平台的设计、制作、起吊和运输、安装和应用。该板凳平台具有诸多优点,可供类似工程参考。     

基于中条山隧道的台阶法几何参数优化分析

为提高台阶法在软岩条件下施工时的安全性,充分发挥其施工高效的固有优势,以中条山隧道为工程依托对该法施工时几何参数的选取进行优化分析。分析采取数值模拟结合现场监测数据的方法,以初期支护结构安全性、掌子面稳定性以及施工便利性作为优化选择的依据。根据研究成果可知:在软岩条件下隧道采用台阶法施工时,上台阶长度控制在4~5 m时隧道初期支护结构受力合理,施工机械操作便利;上台阶高度取值为0.6H(H为隧道高度)时能较好地兼顾隧道的施工效率以及掌子面的稳定性,但是在围岩条件较差如Ⅴ级围岩掌子面出水或浅埋情况下,其取值应适当提高但也不宜超过0.7H。     

基于AVL台架的ISG混合动力客车扭矩优化

介绍了ISG混合动力客车各动力部件扭矩加载速率变化的设计优化过程及整车控制策略的优化,重点阐述了基于AVL台架验证扭矩加载速率变化对部件的寿命以及加速性能的影响。     

超大跨度隧道上台阶CD法中隔壁力学计算模型及施工力学行为研究

为研究超大跨度隧道分部开挖法施工中隔壁结构的施工力学行为,以山东滨莱高速公路改扩建工程双向八车道乐疃隧道为依托,基于初期支护钢架与中隔壁钢架之间的内力传递、变形协调及拱脚变位,将支护体系等效为支座可移动的三次超静定无铰拱-梁固接结构,建立了上台阶先导初期支护钢架-中隔壁钢架共同承载变位力学计算模型,采用理论分析、现场测试和力学模型计算相结合的方法,对超大跨度隧道上台阶CD法施工时中隔壁的力学行为进行分析。研究结果表明:拱顶沉降和周边收敛主要经历急剧增长、缓慢变形和趋于稳定3个阶段,且各变形值均小于设计预留变形量150 mm;受施工工序和结构约束条件变化的影响,钢架内外侧应力整体呈现出先急剧变化后逐渐趋于稳定的规律,各测点应力小于型钢屈服强度235 MPa;力学模型计算结果和现场实测数据的平均相对误差为12.6%,且规律基本一致;钢架轴力在上台阶施工过程中始终为受压,且最大值均在钢架拱脚处,受后导开挖影响,中隔壁钢架轴力增大,初期支护钢架轴力减小;先导开挖时钢架弯矩大部分部位为正,拱顶部位为负,受后导开挖影响,中隔壁钢架正弯矩值及正弯矩区域减小,同时初期支护钢架正弯矩区域减小,钢架拱脚附近弯矩出现负值;钢架结构整体处于偏心受压状态,受后导开挖影响,中隔壁钢架和初期支护钢架小偏心受压区域均发生移动,且两者钢架小偏心受压长度占比增大。     

交流牵引传动系统及牵引电机台架试验负载反馈方案的比选

对交流牵引传动系统及牵引电机台架试验的几种负载反馈方案进行了分析和比较，探讨了转向架或整车无需陪 电气设备进行台架功率试验的负载反馈方法，同时也提出了通过行星差动传动箱联结异步牵引电机的负载反馈试验的方案。     

高压共轨系统压力控制策略研究

开发了一种柴油机高压共轨系统压力控制策略,从目标轨压选取入手,建立轨压的闭环控制策略,并确定了各轨压控制状态间的转换条件。为实现轨压快速响应,增加了轨压前馈算法;为改善轨压控制瞬态特性,建立了双环控制算法;针对特殊工况,采用开环控制策略。通过发动机台架试验证明,该控制策略能够实现轨压的稳定控制以及快速响应,各工况之间过渡柔和,突变工况下也能够达到安全控制的要求。     

An optical tire contact pressure test bench

An optical tire contact pressure test bench developed by the IMMa group is described. The measurement system is based on the frustration of total internal reflection (FTIR) of light. The test bench allows performing normal pressure distribution and patch contact shape measurements on passenger car tires. The system is based on the use of a laterally illuminated glass on which the tire leans. Between them a plastic interphase is located that will cause the FTIR of light. A video camera catches the formed shining image through the glass. The brightness level in each pixel of the image can be related to the existing normal pressure. The study of the contact patch provided by the bench makes it possible to characterize tire behaviour under different loading states, inflation pressure, tire defects and toe and camber angles. The bench incorporates a computerized load and control system of the tire operation parameters, an image acquisition module and a data acquisition system that allow monitoring and acting on the experimental variables of interest in the tests such as load on the tire and environmental conditions. A supporting mechanical system incorporated to the bench allows providing the tire with variable toe and camber angles. From the images obtained with this system, the maximum normal pressure points, total force, size and shape of the patch can be determined, which are related to the tire-use conditions. As an application example, results that show the patch size and shape under different load and tire inflation pressures are presented. A further application, which is the use of the system for the detection and study of defective tires is also presented.     

Rotational vibration absorber for the mitigation of rail rutting corrugation

Torsional vibrations of metro wheel sets are known to be involved in the wavelength-fixing mechanism of the rutting-type rail corrugation. In the first part of this paper, the basic conditions for this type of wear to appear are established using a theory developed in the frequency domain. The efficiency of a dynamic vibration absorber tuned to the first torsional resonance of the wheel set to mitigate rutting corrugation is evaluated numerically. In the second part, the phenomenon is studied on a quarter-scale test bench. The scaling laws for wheel–roller wear predictions are established. The efficiency of the dynamic vibration absorber is evaluated on the scaled bench. The results are compared with theoretical predictions from a linear model. Additionally, the measurements are compared with numerical results from a multi-body model portraying the experiment.