Stress and deformation due to embankment widening with different treatment techniques

A two-dimensional (2-D) finite element (FE) model was developed to analyze the deformation and stress of embankment on soft ground due to widening with different treatment techniques. It is found that the embankment widening induces transverse gradient change due to differential settlements and horizontal outward movements at the shoulder of the existing embankment. Embankment widening also increases the shear stress along the slope of the existing embankment, especially at the foot of slope. The failure potential due to embankment widening may increase with the increase of widening width when the widening width is smaller than 8.5 m, but may decrease with the increase of widening width as the widening width is greater than 8.5 m. The effectiveness of four ground and embankment treatment techniques, including geosynthetic reinforcement, light-weight embankment, deep mixed columns, and separating wall were compared. The results indicate that these treatments reduce the differential settlements and improve the stability. The light-weight embankment has the most effectiveness among four treatments. By using the fly-ash backfill material in widening, the transverse gradient change decreases from 0.5%–1.3% to 0.26%–0.8% and the maximum horizontal displacement decreases from 2.76 cm to 1.44 cm.     

Lewis Mumford and Norman Bel Geddes: the highway,the city and the future

Lewis Mumford’s life spanned the era in which American cities were rebuilt for the automobile and his writings addressed that theme from the 1920s to the 1970s. Norman Bel Geddes achieved fame during the 1930s for his imaginative evocations of future urban and regional landscapes designed for high‐speed auto travel, culminating in the Futurama exhibit at the 1939 World’s Fair. Both of these men were influential figures during the period (1935–45) when the basic contours of American urban highway policy were codified. Mumford advocated a careful integration of street, highway and landscape in order to tame the destructive impacts of the automobile. By the 1950s he had become a fervent opponent of both central city freeway building and auto‐dependent suburban sprawl. Norman Bel Geddes embraced the emerging world of automobiles and freeways, and poured his energies into the creation of exhibits, models, plans and books showing how high‐speed motorways could shape a new metropolis. This paper compares these two men along multiple dimensions and argues that the contrasting styles of Mumford and Bel Geddes embody a recurring split in the American attitude toward cities and urban planning.     

既有桥梁拼宽方案分析与对比

面对日益增长的桥梁通行需求,既有桥梁的拼宽处理势在必行.既有桥梁承载能力决定着桥梁拼宽的方式,文中以某工程项目为例,探讨了既有桥梁拼宽形式的合理选取方法.利用Midas Civil建立有限元模型,提取结构的内力,结合老桥检测结果,在对相关系数折减基础上,进行相应结构检算,明确整体拼宽及分离拼宽的适用条件及检算方式,为该...     

软土地基上高速公路扩建的沉降变形规律分析

通过选取代表性断面,对南京绕城公路扩建工程不同处理方式下的新老地基变形规律进行了分析,分析表明,扩建工程的路基的沉降变形规律不同于新建工程,为扩建工程的设计和施工提供了科学依据。     

高速公路加宽工程路堤结合部及地基处理探讨

就如何控制新路堤的工后沉降量,以及由此引起的新老路堤不均匀沉降做了探讨,重点介绍了高速公路加宽工程路堤结合部的衔接措施以及新路堤软土地基的处理方法,为今后相关工程提供了参考借鉴。     

河口治导线放宽率的计算

根据潮汐河口河床形态关系，推导了河口治导线放宽率的计算式．利用已有的河口河床形态系数及长江口北槽的有关数据，估算了长江口北槽深水航道治导线的放宽率，且与定床物理模型试验值基本相符．     

谈高速公路改扩建加宽方式

针对如何选择最佳的高速公路改扩建加宽方式的问题,介绍了主要的改扩建加宽方式,以列表形式对主要加宽方式的控制性因素进行了对比分析,并结合工程实例进行了探讨,具有一定的现实指导意义。     

新老路基相互作用分析与数值模拟

基于有限元法,对路基拼宽后新老路基的相互作用进行了分析,结果表明:新路基的垂直、水平位移均大于旧路基的垂直、水平位移,导致在结合处出现纵向裂缝;新路基土体的弹性模量越大,垂直位移越小;新路基土体的重度越大,垂直位移越大;路基拼宽时,应选用变形模量大、重度小的土体作为路基拼宽的填料。     

上海市内环高架道路(宛平南路—瑞金南路)拓宽方案探讨

内环高架道路是上海市高架快速路网的重要组成部分。随着上海市中心城区交通量增长,内环线的通行能力已越来越不相适应。针对内环高架道路(宛平南路—瑞金南路)拥堵路段,分析了拓宽建设的可行性,并提出拓宽改建方案及比选。     

拓宽路基差异沉降有限元分析及控制技术研究

针对高速公路的扩建加宽中由于旧路路基已沉降多年基本趋于稳定,而新建路基沉降时间较短,新老路基结合部位常会产生差异沉降的现象,利用有限元方法进行了模拟分析,并在此基础上,从设计上提出了对差异沉降的控制措施,为公路拓宽的设计提供借鉴。