Regulation of the informal transport sector in Rio de Janeiro,Brazil: welfare impacts and policy analysis

In Brazil, the explosion of informal transport activity during the past decade has had profound effects on formal public transport systems and is a source of great controversy in the urban transportation sector. A variety of policies have been proposed to manage the growth of the sector. This study seeks to understand how proposed policies will impact the users of these systems. A corridor in Rio de Janeiro with substantial informal activity was used as a case study. Measures of welfare changes in a discrete choice framework were used to estimate proposed policies’ impacts on users. Eleven candidate policies were evaluated, ranging from the eradication of the informal modes and investment in formal modes, to the legalization of the informal modes. Benefits were compared with costs and the distribution of benefits across income classes was explored. Net benefits from some policies were found to be substantial. Legalizing the informal sector was found to benefit users slightly but further investments in the sector are probably inefficient. Users benefited most from improvements in formal mass transit modes, at roughly 100–200 dollars per commuter per year. Finally, policies to foster a competitive environment for the delivery of both informal and formal services were shown to benefit users about 100 dollars per commuter per year. Together, the regulation of the informal sector and investments in the formal sector serve to reinforce the movement towards competitive concessions for services and help reduce the impacts of cartelization and costly in-road competition.

双管同沟技术中的土壤温度场的计算

用数值模拟来研究冷成品油管对恒稳态热油管热量的传递问题,使用西部管道作为研究对象.在研究中,主要使用新疆北部的埋地管道和90#汽油.通过导热方程计算不同条件下的成品油管和原油管土壤温度场的变化情况.用三节点单元格对管道土壤进行模拟.根据模拟图得出结论.     

软土地区盾构越江隧道地质灾害风险分析

结合工程案例,从风险源识别及风险控制措施等方面对软土地区盾构隧道的地质灾害进行定性的风险分析,并利用风险分析矩阵对地质灾害进行风险等级评价。     

地下商城静压群桩施工对紧邻地铁车站影响的控制技术

介绍了上海轨道交通9号线二期工程6A标段——徐家汇地下商城向下加层工程中低净空条件下的静压钢管群桩施工对周边环境的影响。通过严谨、合理的施工工艺、压桩工序以及施工监测,确保了压桩施工的顺利进行,可供类似条件下的静压桩施工参考。     

地铁隧道管片混凝土免蒸养技术研究及其发展

针对蒸汽养护对混凝土可能产生不可逆转的结构破坏和能耗大的问题,采用聚羧酸外加剂的接枝共聚技术,开发出了超早强型的聚羧酸减水剂,并进行了管片混凝土的制备。结果表明,采用超早强型聚羧酸能明显加速水泥的水化进程,促进早期强度的发展,在低温（10℃～20℃）条件下实现管片混凝土的免蒸养,12h可达到管片拆模吊起所需要的强度,这对降低管片混凝土的生产成本、节约能源具有积极的意义     

复杂地层地铁旁通道冻结孔施工技术

在复杂地层中,对地铁旁通道采用水平冻结法施工是一种有效手段,而冻结孔施工又是旁通道工程的关键工序之一.结合上海地铁十一号线祁连山-真南路站区间旁通道施工实例,介绍了含承压水的砂性土复杂地层中旁通道冻结孔的施工技术,包括壁后预注浆加固、冻结孔开孔以及夯管等技术,对类似地质条件下旁通道冻结孔施工具有一定的参考价值和指导意义.     

小净距隧道洞口通风交叉污染的数值分析及工程处治措施

在小净距隧道通风过程中,会出现排出的污染空气被吸人到邻近隧道中的交叉污染,严重影响隧道通风的性能和效率.文章以北固山隧道洞口段及隧道外空气域为分析对象,采用k-ε双方程紊流模型及组分传输方程组,借助Fluent软件,模拟不同速度自然风,针对现有洞口设计、洞口外设置中隔墙以及出口施做明洞3种情况,研究隧道洞口以外污染物扩散对邻近隧道的影响.研究表明:隧道洞口接一段距离的明洞,对缓解通风交叉污染效果是非常明显的.     

管棚超前支护在平顶直墙隧道中的优化设计

管棚法作为浅埋暗挖隧道的一种辅助工法在防止隧道塌方、控制地层位移方面发挥着重要作用.管棚设计需要确定两个基本参数--间距、截面尺寸.而管棚的设计理论还不够成熟.文章引入土拱原理可以计算管棚的最大间距;而对于截面尺寸.提出在弹性地基梁法的基础上,考虑隧道开挖影响并结合增量法进行计算较为合理.同时认为,两个基本参数的相互影响必须综合考虑,假定管棚直径进行间距设计,应根据管棚受力分析进行校核,通过多次循环假定、计算、校核以得到较为合理的管棚设计参数.