大山塘隧道小净距优化设计与施工技术分析

在隧道工程施工设计中,小净距隧道凭借施工技术要求低、投资成本较小等优点获得广泛应用。文章以河池市境内的G210线大山塘隧道为工程实例,介绍了小净距隧道的间距设计方法,阐述了小净距隧道开挖及支护的关键施工技术,为类似隧道施工提供技术参考。     

金旗山小净距隧道施工技术要点

位于福建省京福高速公路上的金旗山隧道是一座典型的双线双洞、小净距公路隧道,其双洞中心线间距为17.519 m.文章以该隧道为例,介绍小净距隧道的洞身开挖和施工顺序以及中夹岩柱加固、锚喷支护、监控量测等关键工序的施工方法和技术要点,为小净距隧道设计与施工的工程类比积累了经验.     

小净距隧道开挖方法浅论

小净距隧道是介于普通隧道和连拱隧道之间的一种隧道结构形式,正以其独特的优点引起了隧道界的关注.文章论述了间距为5 m左右的小净距隧道的围岩特点、开挖方法及工程实例.     

爆破振动下小净距隧道围岩的力学行为分析

文章运用数值分析计算软件,对小净距隧道中既有隧道受邻近隧道爆破震动影响的动力响应特性进行分析,得出了爆破地震波作用下,隧道周边围岩应力、位移和振动速度的分布规律,为小净距隧道的设计与安全施工提供科学依据。     

穿越易滑岩层小净距隧道开挖与量测控制要点

在我国中西部铁路扩建复线工程中,由于地质条件限制,不得不穿越滑坡区段,新建隧道施工时易引起隧道变形与滑坡体变形.小净距隧道是双洞隧道净距介于连拱隧道与规范要求上下行分离式隧道最小净距之间的一种特殊隧道结构形式,由于隧道净距小,施工时双洞相互影响较大,对隧道围岩,特别是中夹岩岩体稳定性有很大的影响.因此,探讨安全、合理、经济的高速公路小净距隧道施工方法十分必要.     

小净距隧道爆破施工对中夹岩影响分析

结合泉厦高速公路扩建工程大坪山隧道振动监测,研究小净距隧道爆破对工作面前后中夹岩的影响规律,得出了爆破地震波质点振动峰值在小净距隧道中夹岩衰减公式及V-p曲线,结果可为类似条件下小净距隧道的爆破控制和现场监测提供参考。     

偏压及非均质性地层对小净距隧道安全稳定性的影响

采用大比例(1:20)物理相似模型试验和数值计算,模拟了在Ⅳ、Ⅴ级围岩中净距6 m、坡率为1:1的小净距隧道开挖过程,研究了初期支护状态下偏压小净距隧道的地中位移、洞周位移增量、围岩压力规律,对比分析了不同围岩组合对小净距隧道安全稳定性的影响;得出了不同围岩情况下偏压隧道的基本力学特性,优化了隧道开挖顺序,为小净距偏压隧道优化设计和施工提供了科学依据.     

双洞小净距隧道施工控制要点

在现行的隧道设计施工规范中,还没有明确规定小净距隧道的设计、施工规程.文章结合工程实例介绍了小净距隧道的开挖顺序和围岩支护加固方式,以及中央岩柱加固、监控量测等关键工序,对小净距隧道施工质量的控制作了初步探讨.     

高地应力软岩大变形小净距隧道支护形式及施工顺序探讨

山岭铁路受地形影响及车站设置需要,车站延伸到隧道的实例越来越多,燕尾式的隧道平面布置形式是其中最常见的一种,在小净距隧道施工时由于后行隧道对先行隧道的影响,造成初期支护、二次衬砌开裂及仰拱隆起等问题。文章以兰渝铁路新城子隧道两单线小净距段施工为例,分析探讨了高地应力、软岩大变形、小净距隧道支护形式及左右洞仰拱与二次衬砌的施工顺序,可为类似隧道施工与管理提供借鉴。     

浅谈小净距浅埋偏压富水段隧道施工技术

文章结合靖西至龙邦高速公路龙邦隧道工程实例,对小净距浅埋偏压富水隧道施工技术进行研究,从地表冲沟处理、超前地质预报、洞身开挖、复合式衬砌支护及监控量测等施工环节,介绍了小净距浅埋偏压富水隧道的施工方案。     

A multioutput cost function for the services of Spanish ports' infrastructure

A long run multioutput cost function for the infrastructure services of Spanish ports is estimated using 286 observations on 26 ports during 11 years. Cargo specific marginal costs and the degree of economies of scale and scope are calculated up to a port level. Results show that liquid bulk and non-containerised general cargo present the lowest and largest marginal cost, respectively. Increasing returns to scale are present in general and for each and every port. A scope analysis indicates that port specialisation is not appropriate from the viewpoint of infrastructure.     

Assessment of an eastern European city's public transport system

The paper examines the present quality of public transport services in Budapest and compares that to the impact of growing car ownership. A review is made of the city's transport plans and future investment proposals and these are assessed in light of public transport's present and likely future competitive position compared to private cars. The paper concludes that much of the proposed investment in a metro system will not maintain public transport's competitive position in the face of rising car ownership and that other measures and investments might be more effective.     

VPD技术在中国汽车工业中的应用

从汽车构造的四个方面举例说明了VPD技术在现阶段中国汽车工业中的应用,以及VPD技术对汽车工业发展的意义。     

On a mean field game approach modeling congestion and aversion in pedestrian crowds

In this paper we present a new class of pedestrian crowd models based on the mean field games theory introduced by Lasry and Lions in 2006. This macroscopic approach is based on a microscopic model, that considers smart pedestrians who rationally interact and anticipate the future. This leads to a forward-backward structure in time. We focus on two-population interactions and validate the modeling with simple examples. Two complementary classes of problems are addressed, namely the case of crowd aversion and the one of congestion. In both cases we describe the model and present numerical solvers (based on the optimization formulation and the partial differential equations respectively). Finally we present numerical tests involving anticipation phenomena and complex group behaviors such as lane formation.     

Japanese perspective of driver information systems

A perspective view of of Japanese R&D activities of Driver Information Systems is given from the standpoint of developing joint projects by public and private sectors. First, a brief history of the R&D activities is illustrated from above mentioned standpoint. Then, two major projects, AMTICS and RACS, and the social backgrounds of these projects are explained. In order to give a clear idea of both projects some technical details are treated.Based on the history and the present status of the developments, the basic design conceptions of Japanese Driver Information Systems are explained and several factors or reasons which have influenced to the design conception are discussed. Then, the promoting systems of the R&D activities are generally explained and present status of the projects and future problems in developing more advanced systems are also handled. A brief discussion on the establishment of international standard is also mentioned as a final comment.     

The role of the discount rate in tendering highway concessions under the LPVR approach

Flexible-term highway concessions are becoming quite popular around the world as a means of mitigating the traffic risk ultimately allocated to the concessionaire. The most sophisticated mechanism within flexible-term concession approaches is the least present value of the revenues (LPVR). This mechanism consists of awarding the concession to the bidder who offers the least present value of the revenues discounted at a discount rate fixed by the government in the contract. Consequently, the concession will come to an end when the present value of the revenues initially requested has been eventually reached. The aim of this paper is to evaluate the effect that the discount rate established by the government in the bidding terms has on the traffic-risk profile ultimately allocated to the concessionaire. To analyze this effect, a mathematical model is developed in order to obtain the results. I found that the lower the discount rate the larger will be the traffic risk allocated to the concessionaire. Moreover, I found that, if a maximum term is established in the contract, the lower the discount rate, the less skewed towards the downside will be the traffic-risk profile allocated to the concessionaire.     

超声波流量计的研究和应用

系统地阐述了超声波流量计的组成、工作原理及使用范围，比较各种流量计的优缺点，并对超声波流量计误差进行了详细的分析，简略介绍了流量计的标定和应用范围，对当前的研究应用具有一定指导作用。     

海上输油管道腐蚀穿孔仿真新方法——元胞自动机

文中介绍了元胞自动机的基本理论和它作为一个物理系统模型的优点,提出了采用元胞自动机对海上输油管道腐蚀穿孔进行仿真的重要性和可行性,最后介绍了元胞自动机在该领域已经取得的成果,并提出了元胞自动机模拟海上输油管道腐蚀穿孔过程的建模步骤。     

The development of civil aviation in new China

The article reviews the development of the Civil Aviation Administration of China from its foundation, describing its history, major achievements and present scale, and the guiding principles under which the achievements have been made.     

长输管道环焊缝的射线数字成像检测技术应用

文中分析了长输油气射线数字成像检测的3种技术类型,及其在油气管道环焊缝检测方面的优缺点和发展趋势.开展了在役输油管道动火作业中射线数字成像检测技术(DR)的现场应用试验,初步验证了在役管道环焊缝DR检测的技术可行性和对缺陷检测的较高灵敏度.结合中俄东线输气管道建设,进行了传统射线胶片照相检测技术(RT)和DR检测技术工...