斜拉索对钢管混凝土桁式组合拱桥力学性能的影响

位于湖南省永连公路上的天子山大桥是目前世界上第一座钢管混凝土桁式组合拱桥,其设计上的一个创新是用斜拉索代替了原来的刚性斜杆.制作了天子山大桥1∶20的铝合金模型,用模态分析的方法对钢管混凝土桁式组合拱桥的动力特性进行了研究,探讨了斜拉索对钢管混凝土桁式组合拱桥力学性能的影响.     

极软岩作为路堤填料施工工艺的模糊评判

随着高等级公路建设突飞猛进,软岩在公路建设中如何使用就成为工程技术人员普遍关注的问题。在广西修建的许多高速公路需要利用极软岩作为公路填料。工艺试验研究表明:极软岩可以作为高速公路的填料,在进行了综合试验后,通过模糊评判表明,适用它的最佳松铺厚度为35cm。对于极软岩应用于其它高速公路上也具有重要的借鉴意义。     

预应力混凝土先简支后连续梁静、动力试验研究

简要介绍预应力混凝土先简支后连续梁1∶5模型设计、试验方法。根据弹性试验、开裂试验和破坏试验结果,研究分析该类结构的工艺特点、正常使用荷载作用下结构受力变形特征、结构特别是湿接缝截面的抗裂性、开裂区域裂缝发展分布规律以及结构极限承载力。在对模型梁体系转换前、后和先简支后连续梁破坏前、后动力测试与理论分析的基础上,校核模型梁的刚度、制作精度,最后初步探讨了先简支后连续梁的动力性能。     

低剂量水稳基层防治薄面层沥青路面反射裂缝研究

采用低剂量水泥稳定碎石基层作为防治薄面层沥青路面反射裂缝的主要方案,利用室内试验和试验路工程分别得到不同剂量水泥稳定碎石基层的收缩特性以及强度发展规律。力学分析和观测结果都证明该方法可以有效防治薄面层沥青路面反射裂缝。     

多孔材料垂直渗透系数测定装置的研究

在对渗透系数影响因素的分析研究基础上,针对原有渗透仪在侧漏、低水头下测量困难等缺点,就测压管位置、测压管直径、测量用水及试件尺寸方面规范化多孔渗透系数测定仪。为减少试件表面附着的气泡,采用抽真空后,而不采用分层浸泡的方法。最后就渗透测定仪装置提出几条改进建议:用充气气囊代替柔性侧壁,用差压计代替微压计。实践证明本仪器使用稳定,数据重复性高。     

振荡压实对桥梁结构物的影响研究

振荡压实是利用在材料厂中产生的快速交变剪应力使材料的颗粒重新排列而变得更加密实。通过振荡压实与振动压实对桥梁结构的振动的对比试验，分析了这2种作业方式对桥梁结构物的影响．论证了振荡压路机在桥梁压实中的优越性。     

西南红层软岩地区铁路滑坡形成机理分析及治理措施

红层软岩地区铁路工程建设中滑坡问题突出。本文结合西南地区一铁路红层滑坡治理工程,利用该地区红层滑坡的现场调查结果,从红层软岩特性、地层岩性、地质地貌、水文地质条件、深孔位移监测数据等多方面对该地区铁路滑坡形成机理进行分析,并论述红层滑坡与一般滑坡的不同点,分析红层软岩岩体力学特性、地层主要成分以及红层软岩中的粉砂质泥岩在不同风化程度下的力学特性。根据分析结果提出治理措施,并对治理措施进行评价。总结得出地层岩性、地质水文、人为因素是导致红层滑坡病害发生的主要因素。     

Changes in fuel economy: An analysis of the Spanish car market

This paper estimates the role that technological change and car characteristics have played in the rate of fuel consumption of vehicles over time. Using data from the Spanish car market from 1988 to 2013, we estimate a reduced form equation that relates fuel consumption with a set of car characteristics. The results for the sales-weighted sample of vehicles show that energy efficiency would have improved by 30% and 42% for petrol and diesel cars respectively had car characteristics been held constant at 1988 values. However, the shift to bigger and more fuel-consuming cars reduced the gains from technological progress. Additionally, using the results of the fuel equation we show that, besides a natural growth rate of 1.1%, technological progress is affected by both the international price of oil and the adoption of mandatory emission standards. Moreover, according to our estimations, a 1% growth in GDP would modify car characteristics in such a way that fuel consumption would increase by around 0.23% for petrol cars and 0.35% for diesel cars.     

地下工程注浆技术研究新进展

注浆是土木、水利和矿山等工程建设中重要的防渗和加固技术。文章基于国内外注浆技术研究文献,总结了水泥等颗粒性浆液的“渗滤效应”及“黏度时空变异性”等理论研究成果,论述了非水反应高聚物、CW环氧树脂和微生物菌液等注浆新材料的应用现状及发展前景,介绍了细观力学数值模拟研究的突破性进展,可为地下工程注浆技术发展提供借鉴和启发作用。     

Driving cycle prediction model based on bus route features

Bus fuel economy is deeply influenced by the driving cycles, which vary for different route conditions. Buses optimized for a standard driving cycle are not necessarily suitable for actual driving conditions, and, therefore, it is critical to predict the driving cycles based on the route conditions. To conveniently predict representative driving cycles of special bus routes, this paper proposed a prediction model based on bus route features, which supports bus optimization. The relations between 27 inter-station characteristics and bus fuel economy were analyzed. According to the analysis, five inter-station route characteristics were abstracted to represent the bus route features, and four inter-station driving characteristics were abstracted to represent the driving cycle features between bus stations. Inter-station driving characteristic equations were established based on the multiple linear regression, reflecting the linear relationships between the five inter-station route characteristics and the four inter-station driving characteristics. Using kinematic segment classification, a basic driving cycle database was established, including 4704 different transmission matrices. Based on the inter-station driving characteristic equations and the basic driving cycle database, the driving cycle prediction model was developed, generating drive cycles by the iterative Markov chain for the assigned bus lines. The model was finally validated by more than 2 years of acquired data. The experimental results show that the predicted driving cycle is consistent with the historical average velocity profile, and the prediction similarity is 78.69%. The proposed model can be an effective way for the driving cycle prediction of bus routes.