基坑开挖对邻近管线的位移影响分析

隧道基坑常位于地下管线数量较多的闹市区,为避免施工过程中对周边管线的破坏,如何准确分析基坑开挖对周边管线的影响至关重要。利用三维有限元软件MIDAS GTS对基坑周边不同管线进行计算,通过对计算数据的观察分析,归纳总结基坑开挖对不同管线所造成的位移变形特点,为隧道基坑周边管线的合理保护优化提供了重要依据。     

不同改性剂改性沥青性能分析

通过常规试验和SH RP沥青试验,对国内外常用的几种不同改性剂改性沥青的性能进行了对比研究,同时结合相应改性沥青混合料的高温性能、低温性能和疲劳性能研究,比较了不同改性沥青的路用性能。     

浅埋偏压连拱隧道先行洞数值模拟分析

浅埋偏压连拱隧道先行洞选择问题是施工中首先要解决的问题,先行洞的选择与围岩条件和地质构造等密切相关,目前学术界和工程界尚没有形成共识。连拱隧道穿越坡积体地形,由此导致的偏压、潜在滑坡、潜在坍塌等问题,使得先行洞的选择更为复杂。虽然按照工程经验建议先施工右侧埋深较大的一侧,但为了提供可靠的理论依据,使决策更科学,以某连拱隧道为工程依据,通过有限元数值模拟方法对先施工深埋侧和先施工浅埋侧进行了对比分析,取得了较好的结论,从而更加科学地引导施工。     

高速公路改扩建边坡工程的稳定性数值分析

针对某高速公路改扩建过程中对边坡工程的二次开挖卸荷的稳定性问题进行分析,采用有限元软件midas／gts对边坡的开挖支护过程进行模拟,得出了开挖边坡过程中的应力场变化规律,开挖同时应对边坡及时支护。并求得了支护后的边坡安全系数。     

横隔板缺口形式对正交异性钢桥面板力学性能的影响

文章运用有限元模型和静力分析方法,分析了正交异性梯形加劲钢桥面板轮载作用下连接细节处的应力分布情况,并比较了横隔板的不同缺口形式对结构体系力学性能指标的影响。     

大型活动的交通调查及分析

随着我国经济的不断发展,全国各地举行的大型活动越来越多。大型活动产生突增交通量造成周边地区的交通拥挤,而分析大型活动带来的交通拥挤则是以对大型活动的交通调查为基础的。以长春市南岭体育场周围的道路交通系统为基础,对举行足球比赛产生的观众到达高峰和离开高峰进行了实地调查,并通过问卷的方式对观众出行方式及其他与此活动相关的特性进行了分析。     

大体积混凝土凝固过程中的温度控制

进行大体积混凝土施工时必须根据混凝土水化热的具体情况,配备相应的监控系统—混凝土温度测试系统,对大体积混凝土凝固过程中的水化热进行实时温度检测,并对凝固过程进行全程检测和控制,采取相应的控制措施。     

Railway reforms: do they influence operating efficiency?

This paper considers railway operations in 23 European countries during 1995–2001, where a series of reform initiatives were launched by the European Commission, and analyses whether these reform initiatives improved the efficiency of the railway systems. Efficiency is measured using Multi-directional Efficiency Analysis, which enables investigation of how railway reforms affect the inefficiencies of specific cost drivers. The main findings are that the reform initiatives generally improve technical efficiency but potentially differently for different cost drivers. Specifically, the paper provides empirical evidence that accounting separation is important for improving the efficiency in the use of both material and staff costs, whereas other reforms only influenced one of these factors.

Multiple criteria optimization method for the vehicle assignment problem in a bus transportation company

A vehicle assignment problem (VAP) in a road, long‐haul, passenger transportation company with heterogeneous fleet of buses is considered in the paper. The mathematical model of the VAP is formulated in terms of multiobjective, combinatorial optimization. It has a strategic, long‐term character and takes into account four criteria that represent interests of both passengers and the company's management. The decision consists in the definition of weekly operating frequency (number of rides per week) of buses on international routes between Polish and Western European cities. The VAP is solved in a step‐wise procedure. In the first step a sample of efficient (Pareto‐optimal) solutions is generated using an original metaheuristic method called Pareto Memetic Algorithm (PMA). In the second step this sample is reviewed and evaluated by the Decision Maker (DM). In this phase an interactive, multiple criteria analysis method with graphical facilities, called Light Beam Search (LBS), is applied. The method helps the DM to define his/her preferences, direct the search process and select the most satisfactory solution.