回流区水流运动三维数值模拟

建立了三维有限元水流模型,模型中采用了高分辨率计算格式。依此模型计算了突扩引起的回流,获得的掺混区流速分布和回流区固定点水位、流速非恒定过程与实测结果基本一致。     

砂层地铁车站暗挖施工技术研究

北京地铁5号线磁器口车站主体结构大部分位于粉细砂、细砂及中粗砂层中,结构埋深10m左右,采用中洞法施工。由于地质条件多为砂层,施工环境复杂,对地表沉降要求严格,主要阐述车站主体的施工方法,对施工各阶段地表沉降原因进行分析,提出车站施工中的相关建议。     

湘潭市湘江四桥系杆锚固区局部应力分析

针对湘潭市湘江四大桥主跨结构为(120 400 120)m的斜拉钢管混凝土系杆拱桥,该桥系杆锚固于混凝土边主梁上,系杆锚固区受力状态复杂的情况,基于有限元分析,发现设计结构存在局部拉应力过大的现象,为了解决该问题,对系杆锚固区的结构设计进行修改及进一步力学分析,提出减小锚固槽壁及支座对锚下变形约束的结构设计思路和具体措施,以实现减小局部应力的目的。所得结论和建议可供同类结构设计参考。     

从水质水量联合角度评价鉴江流域可用水资源量

首先介绍满足流域水功能区水质目标的可用水资源量联合评价方法。该方法通过水量平衡和污染物质的质量平衡原理,建立单元系统的水量水质模型,依据水质水量资料确定模型参数;然后利用模型推求单元系统的可用水资源量;最后推广应用到河流多区段系统。将该评价方法应用到广东鉴江流域,计算该流域的可用水资源量。结果表明,可用水资源量与水质污染现状、水功能区的水质目标、河道生态需水量等有关。     

寒冷地区客车的防寒设计

根据25T型铁路客车在寒冷地区的运用,分析了列车防寒的主要因素,包括车体的密封性、防寒材料的薄弱部位和热绝缘等。结合运用结果,提出了寒冷地区列车防寒结构方案的改进设计。     

Fatigue design for plug/ring type gas welded joints of sts301l including welding residual stresses

This paper presents a fatigue design method for plug and ring type gas welded joints, which incorporates welding residual stress effects. A non-linear finite element analysis (FEA) was first performed to simulate the gas welding process. The numerically predicted residual stresses of the gas welds were then compared to experimental results measured using a hole drilling method. In order to evaluate the fatigue strength of the plug and ring type gas welded joints, a stress amplitude (σ _a ) _R taling the welding residual stress of the gas weld into account was introduced and is based on a modified Goodman equation incorporating the effect of the residual stress. Using the stress amplitude (σ _a ) _R , the ΔP-N _f relations obtained from fatigue tests for plug and ring type gas welded joints having various dimensions and shapes were systematically rearranged into (σ _a ) _R -N _f relations. It was found that the proposed stress amplitude (σ _a ) _R could provide a systematic and reasonable fatigue design criterion for the plug and ring type gas welded joints.     

预应力束张拉顺序对锚下局部应力影响分析

预应力混凝土构件中通常布置有多束预应力束,在施工设计中需要考虑预应力束的张拉顺序,合理的进行预应力筋的张拉。采用有限元程序ANSYS对不同的预应力束张拉顺序下某大桥主粱被动锚固区的局部应力进行分析计算,计算结果对同类桥梁的设计施工有一定的参考价值。     

城市群核心城市对外交通规划

伴随着城市化进程的加快和区域经济的一体化,以大城市为核心的城市群发展迅猛,必须对核心城市的对外交通进行合理的规划。以成都市为例,对成都市的对外交通需求进行预测,并重点对成渝方向的客运交通方式进行划分,从成渝城市群的角度出发,科学地研究成都市对外交通的发展战略,合理地规划成渝通道的发展。     

Driver behavior formulation in intersection dilemma zones with phone use distraction via a logit-Bayesian network hybrid approach

Use of cellular phone while driving is one of the top contributing factors that induce traffic crashes, resulting in significant loss of life and property. A dilemma zone is a circumstance near signalized intersections where drivers hesitate when making decisions related to their driving behaviors. Therefore, the dilemma zone has been identified as an area with high crash potential. This article utilizes a logit-based Bayesian network (BN) hybrid approach to investigate drivers' decision patterns in a dilemma zone with phone use, based on experimental data from driving simulations from the National Advanced Driving Simulator (NADS). Using a logit regression model, five variables were found to be significant in predicting drivers' decisions in a dilemma zone with distractive phone tasks: older drivers (50–60 years old), yellow signal length, time to stop line, handheld phone tasks, and driver gender. The identified significant variables were then used to train a BN model to predict drivers' decisions at a dilemma zone and examine probabilistic impacts of these variables on drivers' decisions. The analysis results indicate that the trained BN model was effective in driver decision prediction and variable influence extraction. It was found that older drivers, a short yellow signal, a short time to stop line, nonhandheld phone tasks, and female drivers are factors that tend to result in drivers proceeding through intersections in a dilemma zone with phone use distraction. These research findings provide insight in understanding driver behavior patterns in a dilemma zone with distractive phone tasks.     

车站基坑揭露断层带注浆加固效果数值模拟研究

为研究注浆对明挖基坑揭露断层带的加固效果,以南京地铁上元门车站基坑工程为背景,考虑基坑开挖过程中渗流场与围岩应力场的相互耦合作用,建立相应的有限元分析模型,对软弱破碎层、注浆加固带、基坑地下连续墙以及围岩所组成的耦合系统进行模拟,研究注浆加固前后围岩渗流场、位移场以及应力场的特征,最终获得基坑地下连续墙的水平位移、基坑外地表沉降、围岩塑性区分布、基坑内围岩变形以及基坑内涌水量变化规律。研究结果表明： 1）通过对基坑底部断层带的注浆加固,基坑侧向位移及基坑外地表沉降均得到有效控制,相比于注浆加固前,其最大水平位移和地表累计沉降量减小50%以上,满足工程要求; 2）基坑底部区域内塑性区范围明显减少,基坑外塑性区扩散也得到有效抑制; 3）基坑底部断层带注浆改变了渗流场分布,有效降低了基坑涌水量,基坑治理区域涌水量由最初的94 m3/h逐渐减小到4 m3/h,堵水率达96%; 4）注浆结束后现场钻孔取芯率达到75%~80%,开挖揭露大量劈裂作用形成的浆脉,验证了注浆可有效治理明挖基坑所揭露的软弱断层破碎带。