公路隧道塌方成因分析及处治方案设计

文章基于对隧道塌方成因及各种类型塌方处治方法的总结,分析了依托工程冒顶塌方的成因,提出了地表与洞内相结合的处治设计方案,为公路隧道塌方处治提供参考。     

大跨度隧道特大塌方处治技术探讨

文章结合某大跨度隧道特大型塌方事故,分析了塌方产生的原因,提出了针对性的监控量测方案和处治原则,并制定了塌方处治方案,为类似大跨度隧道工程的塌方处治提供参考。     

浅埋偏压黄土隧道塌方处治及效果分析

为研究软弱黄土隧道塌方处治效果,文章以宝天高速某隧道洞口段塌方治理工程为依托,分析了隧道塌方的主要原因,提出采用超前大管棚与注浆小导管相结合、洞内与地表共同治理的综合处治措施,并通过现场实测与数值计算相结合的方法详细分析了处治效果。结果表明:地形浅埋偏压、设计偏于不安全、降雨通过地表裂缝浸泡围岩等因素最终导致隧道坍塌、地表塌陷;处治后塌方段初期支护和二次衬砌的变形及受力在20 d后趋于稳定,且均未发生异常变化,处治效果良好;现场监测和数值计算的拱顶沉降和周边收敛规律基本一致,相关变化值都在规范的允许范围之内,处治后隧道结构处于稳定状态。研究结果可为类似隧道工程塌方处治提供借鉴。     

隧道冒顶塌方的结构稳定性分析及处治措施

文章基于河南某隧道工程的冒顶塌方情况及其主客观原因,通过建立有限元数值分析模型,模拟分析了隧道通过冒顶塌方段的结构稳定性及施工力学行为,并提出了相应的处治措施,为今后隧道的冒顶塌方施工提供了依据。     

浅埋大断面隧道塌方机理分析与处治建议

文章结合某浅埋大断面隧道冒顶塌方情况,分析了塌方体形态特征,指出地形地貌、地质构造、地层岩性、水文地质是隧道塌方的影响因素,并从力学角度阐述了塌方的机理,开展了塌方段围岩稳定性评价,提出了相应的处治建议,可为今后类似工程提供参考。     

风化砂岩隧道塌方处治及智能应力应变监测分析

在风化砂岩地区修建的隧道由于围岩结构层之间粘聚力低,容易出现掉块及滑塌等现象。文章以广西某高速公路隧道施工为背景,针对隧道施工中出现的塌方现象,分析了塌方成因与处治措施,并采用智能应力应变监测技术,收集病害处治处实时的隧道围岩应力与应变数据以及支护结构健康情况等信息,反馈支护结构工作状态,以判断支护结构的稳定性,为后续类似隧道工程提供参考。     

上坪格隧道塌方原因分析及处治措施研究

针对福建省漳永高速公路上坪格隧道塌方案例,文章在分析其塌方机理的基础上提出了相应的工程处治措施,并采用荷载-结构法对变更后塌方段初期支护和二次衬砌强度进行了验算。分析结果表明:不良地质、较差施工质量和不合理开挖工法是导致隧道塌方的主要原因;在塌方荷载作用下,初期支护和二次衬砌弯矩较大值发生在拱顶、左右拱腰、左右拱脚和仰拱部位,这些部位在施工中应给予足够的重视;初期支护危险截面的最小安全系数为1.93。二次衬砌危险截面的最小安全系数为2.43。均大于国家隧道规范规定值,满足工程安全性要求。     

吉庆隧道断层破碎带水压力分布及塌方涌水处治研究

基于流固耦合和三维数值模拟,文章研究了吉庆隧道断层破碎带富水隧道中水压力的分布规律,预测了渗水量。结果表明:隧道开挖后,因扰动而产生超静孔隙水压力和地应力耦合,使拱腰部位出现的应力集中最为显著,其次是拱顶部位。针对该段出现的病害,采用帷幕注浆与超前预支护相结合的处治方法,处理了塌方和涌水病害,可为类似工程提供技术参考。     

隧道施工中塌方的预防和处理

通过分析隧道施工产生塌方的原因,详细介绍了隧道施工塌方的预防、塌方出现的前兆以及塌方的处理,为今后隧道施工塌方的预防和处理提供参考.     

王家岭双连拱隧道右线塌方处理

文章结合宜万铁路王家岭隧道双连拱施工与右线塌方处理方案,分析了隧道塌方的原因,着重介绍了隧道塌方处理措施及施工中的关键环节。     

高坡冲隧道冒顶原因分析及处理方案

文章介绍了广西岑罗高速公路第5标段高坡冲隧道的冒顶塌方情况,分析了隧道冒顶的原因,提出了相应的冒顶处理方案,并探讨了方案的实施效果。     

公路隧道溶洞冒顶处理方案

文章根据红岩山隧道水文地质情况及冒顶塌方现场具体状况,从排水及加固角度提出了针对性的隧道溶洞坍塌冒顶处理方案,并对方案的加固处理效果进行了监控量测。监测结果证明,该方案能有效处理隧道溶洞坍塌冒顶问题。     

Temporal stability of travelers' activity choice and home-stay duration: Some empirical evidence

This paper explores the temporal stability of activity type-choice models and models of travelers' home-stay duration. To empirically evaluate this stability, a nested logit model of activity-type choice and a proportional hazards model of home-stay duration are estimated using data from two-day travel diaries collected in the fall of 1989 and again, from the same individuals, in the fall of 1990. The results show that the models are not temporally stable over the one year time period separating the two travel-diary samples. A number of possible reasons for this instability are discussed.     

浅谈隧道浅埋软弱地质段塌方处理技术

文章以十天高速公路石庄隧道施工为例,对该隧道浅埋软弱地质段的塌方冒顶情况进行了介绍,分析了塌方产生的原因,提出了内外结合的塌方处理方案,并阐述了方案的关键技术措施及注意事项。     

预应力锚索桩板墙在高速公路中的应用

梅(州)河(源)高速公路K95 940~K96 170段地形横坡陡峻,该边坡在开挖失去支撑情况下产生整体或局部滑动变形破坏,采用了预应力锚索桩板墙支挡处治措施,对于类似路基横向陡边坡处治提供借鉴与参考。     

Bus accidents,bus deregulation and London

Local bus services were deregulated in October 1986 in all areas of Britain except London. Government policy is to extend deregulation to London, though not in the current parliament. This paper analyses statistics on bus accidents from the national road accident database from 1981 to 1991 to compare results for London and the rest of Great Britain, and to consider whether deregulation has affected safety. The conclusions depend on the assumption that accident recording practice was not itself affected by deregulation.Bus accident rates are higher in London than on built-up roads elsewhere, partly apparently because of road traffic conditions in London, and partly because open-platform buses have higher accident rates involving occupants, including boarding and alighting accidents, than buses with doors.The main safety effects of deregulation operate through its effects on bus activity, though there is also some evidence that the rate per bus-kilometre of accidents involving other road users fell slightly. This may be due in part to the trend towards smaller buses associated with deregulation. Deregulation has led to a fall in bus patronage, and thus to a fall in occupant casualties; and to a rise in bus-kilometres, and thus to a rise in casualties among other road users in accidents involving buses. The number of fatal and serious casualties among other road users involved in bus accidents is larger than the number among bus occupants, so deregulation in London could lead on balance to a small rise in fatalities involving buses. On the other hand, the number of slight casualties among other road users involved in bus accidents is smaller than the number among bus occupants, so deregulation in London could lead to a fall in the number of slight casualties involving buses.Although there were fears that changes in the management of bus operations or financial pressures might lead to increased accident rates following deregulation, there no evidence in the findings to support such fears.This paper was first presented at the 3rd International Conference on Competition and Ownership in Surface Public Transport at Mississauga, Canada on 25–29 September 1993. The author is grateful to the Department of Transport for the speed and efficiency with which they provided special tabulations from the road accident database for this study.     

On measuring the efficiency of public enterprises: Bus operating companies in the San Francisco Bay area

It is important to be able to say whether or not an enterprise in the public sector is efficient and to measure this aspect of its performance. Public enterprises sometimes have legitimate reason to treat efficiency as secondary, but they also may resist efficiency measurement for other reasons.Statistical cost functions containing experience from similar enterprises provide useful yardsticks for public administrators. A purported cost function can be inadequate, however, as is shown in one example.Statistical cost functions allow comparison of bus properties by giving a range within which costs of an efficient property should fall. While random influences cannot be excluded, if observed costs fall outside two standard errors of prediction, there is a good case to say the property is inefficient. The usefulness of the standard error of prediciton as a measure of precision is explored.Nationally estimated cost functions were used to investigate the bus operations only of three San Francisco companies. Two were found within sampling error, one was significantly more costly on its motorbus operations than average experience in the nation. A closer look would then be in order by those funding this property. Several years' experience is explored showing changes over time as well as across companies.This material was prepared with the support of National Science Foundation Grant No. GI-37181 to the University of California. The results and views are the independent product of university research and are not necessarily concurred in by the National Science Foundation. The Institute of Urban and Regional Development at U.C. Berkeley facilitated research herein.     

格拉成品油管道优化运行有关问题探讨

针对落差大,存在翻越点,目前根据有时需要仍采用旁接油罐流程的格拉长输成品油管道的特点,提出利用减阻剂和合理调节流量解决翻越点方法;主泵串联运行在降低能耗等方面更具有优势;依据实际运行参数和约束条件,拟定预定方案的工况调节方法来指导实际输油操作更符合该管道的实际,在这方面做了一定的探讨论述。     

Long-term behavior of particulate matters at urban roadside and background locations in Seoul,Korea

The concentrations of particulate matter, PM_2.5, PM₁₀, and TSP at an urban roadside and an urban background station are analyzed. Data collected over a 10 year period are analyzed. The concentrations of the particulates measured at the urban site are systematically larger than at the background station. The mean PM values at the former also exhibit a slight fall over the decade unlike those at the background station. Overall, the particulate matters at both locations are in an intermediate range of global level, e.g., approximately two times lower than those in other Asian regions but higher than in Europe.