共查询到20条相似文献,搜索用时 46 毫秒
1.
采用管道失效评估方法可评估静载荷作用下缺陷是否满足适用要求。但在内压等交变载荷作用下,输油管道环焊缝仍存在疲劳破坏的可能。为评估管道环焊缝缺陷的疲劳寿命,进行管道母材和环焊缝疲劳裂纹扩展速率试验,并分析和统计管道实际运行压力数据以及环焊缝缺陷开挖验证数据,采用BS7910标准方法计算疲劳寿命值。结果显示在仅考虑管道内压波动情况下,管道环焊缝平面型缺陷的疲劳寿命结果满足管道设计使用要求。 相似文献
2.
3.
4.
5.
6.
7.
8.
采用悬臂弯曲试验的方法,研究了平均应力对两种焊管结构疲劳特性的影响,满角焊管的疲劳强度随平均应力而改变,但对接焊管的疲劳强度则不随平均应力而改变,满角焊管的疲劳裂纹从外表面的焊趾开始,而对接焊管则人催表面的咬边开始,测定疲劳裂纹的扩展速率及测定残余应沿管壁分布的结果表明,满角焊管和对焊接管疲劳特性之所认不同,其原因是焊接引起的内表面残余应力和外表面的残余压应力,这就意识着沿内表面造成残余压力将是改 相似文献
9.
文中介绍了核电厂硼伴热系统的设计原理,根据核电厂的工艺要求和实际设备情况,建立了管道热损计算模型,对管道支撑件、阀门等管道附属件的热阱效应进行了折算考量,并应用于某核电厂硼酸再循环泵出口管道电加热装置设计缺陷处理,确保了核电厂系统与设备的稳定运行。系统的实际运行结果表明,所建立的热损计算模型以及基于经验得出管道附属件热阱效应折算考量模型正确可靠,其为硼伴热系统的设计提供了参考。 相似文献
10.
11.
12.
"超限超载"的产生与发展,蕴藏着深层的内在运作机理,包含着复杂的经济社会原因.其中道路货物运输价格体系的长期扭曲失衡与成本结构的有欠合理是一个不容忽视的根本原因.为此,公路所开展了货运市场运价与成本"治超"专项研究,先后历时一个多月,行程数千公里,深入7省市运输一线,对21家典型企业和个体业户的23辆货车、24条线路进行了跟踪调查,获取了大量的第一手资料与原始数据,并对此进行了解析. 相似文献
13.
14.
Ngila Mwase† 《运输评论》2013,33(3):191-206
Zambia has attempted to reduce her excessive transport dependency on her traditional transport routes via South Africa and the former Portugese colonies. The costly construction of the Tanzania‐Zambia Railway (TAZARA) was part of this diversification strategy. This article examines the nature, extent and direction of Zambian traffic, including its historical evolution. It explores further the place of TAZARA among the various routes to Mozambican, Angolan and South African ports, and the ensuing actual and potential competition. Future traffic patterns will be influenced not only by the direct and service‐oriented costs of the different lines, but also by the region's volatile and uncertain political climate. 相似文献
15.
16.
17.
18.
Robert E. Paaswell 《Transportation》1973,2(4):351-371
An examination of current population statistics shows that in the U.S. more than half of the population is without immediate access to a car, and in the U.K. more than three-fifths of the population is without access to a car. This phenomenon has been accentuated by national investment in both countries in major highway programs. The term carless refers to more than just households that own no cars. It extends, in households with cars to those without licenses (old and young), the handicapped, and even the licensed drivers who have no access to the family car when it is in use elsewhere (e.g. at work). The most severely effected are those in urban areas and especially the urban poor. Transportation expenses are limited for the poor when other family expenditures (food, shelter) take a high priority. Once the work trip has been satisfied, money for other trips, for the poor, is not always available. One solution to cost-free travel is pedestrianism (walking), but this too is difficult in urban areas where the pedestrian has been overlooked in favor of the car. Solutions to problems of the carless include dial-a-ride, better public transit, and better design of urban form. 相似文献
19.
针对海中箱梁现浇施工中的工程量大、工期紧迫、悬臂法施工不能满足工期要求和施工难度大等问题,文章结合青岛海湾大桥箱梁现浇施工实践,介绍以钢管桩支撑作为承载基础,采用贝雷梁与碗扣式支架相结合的支架,成功地解决现浇箱梁施工难题的方法。 相似文献
20.
章简略地分析了单线循环固定抱索器索道抱索器移位及索道频繁开停车对索道运载索、驱动机减速器、制动器等部件使用寿命的影响,并提出了相应的减轻这些影响的技术对策。 相似文献