偏压浅埋连拱隧道施工过程的三维数值模拟

针对一座浅埋偏压条件下的双连拱隧道，分别按三导洞先墙后拱法和中导洞法对其施工过程进行了三维弹塑性有限元模拟分析。计算结果揭示了该条件下双连拱隧道衬砌结构的受力和变形以及围岩的塑性区分布都具有明显的非对称特性，衬砌内侧的拱部和内外侧仰拱承受了较大的拉应力而成为结构的薄弱环节，中隔墙因在不对称水平推力作用下发生偏转成为影响衬砌结构稳定的关键因素，并在此基础上对提高结构的稳定性提出了建议。     

合福铁路浅埋偏压隧道溜坍分析及整治方案研究

以合福铁路客运专线浅埋偏压隧道为例,对其溜坍事故原因进行分析,研究提出施工整治方案并对实施效果进行评价.首先,通过现场调研与有限元模拟对事故原因进行分析,结果显示,该隧道施工过程受力复杂,软弱围岩自稳性差,洞口临时支护不足及施工期发生强降雨是本次事故的主要原因.然后,结合工程实际和有限元模拟结果提出了加强支护、减少开挖步长等具体整治措施.后续施工中隧道围岩变形收敛较快,洞口稳定得到有效控制,开挖进展顺利,表明该整治方案合理可行.研究思路和方法可为同类工程施工和事故处理提供参考.     

Understanding the role of the forecast-maker in overestimation forecasts of policy impacts: The case of Travel Demand Management policies

Forecasting the impacts of a proposed policy is an important component of the transportation planning and decision making process. Although scientific tools are often used in transportation forecasts, biases and, more specifically, overestimations of the expected impact are often observed. This study explores the correlations between forecast-maker’s characteristics and forecast bias creation and reduction. The study examines two transport-related policies aiming at the reduction of car use: telecommuting and carsharing. Both are Travel Demand Management (TDM) policies, which attract much attention from transport experts. We tested the extent to which the forecast-maker’s beliefs about the policy at stake affected the forecast bias. We found that attitudes and beliefs associates not only with overestimation bias but also with its reduction over time. We also tested the extent to which the forecast-maker’s affiliation, the performing institute and the publication type were correlated with the biases of the forecast and with the forecaster attitudes and beliefs. These characteristics are intuitively used by the forecast user as tools to assess the ‘objectivity’ of the forecast, but our analysis found no association between these characteristics and the forecast bias.     

浅埋偏压隧道洞口段加固方案计算分析

采用虚拟内力计算方法,以FLAC2D为计算工具,对洞冲里隧道的浅埋偏压段拟采用的加固方法进行了计算分析。结果表明：采用侧向管棚治理洞口段偏压无论整体沉降、结构受力均优于正面管棚的加固方法。在随后的监控量测的数据分析中也证明了该加固方案的有效性。