《公路工程》PPT课件

在公路路面以下的基础是路基，所以路基（或基层土壤）可被定义为支撑路面 及其特殊下层的结构。路面的作用是提供一个任何气候条件下车辆都可能通过的平 滑的表面。由于天然地形凹凸不平，为了让道路平顺，挖方和填方都需要改变自然 地形。路基被分类成 路堤，路堑，半挖半填路基。
horizontal alignment
公路线形包括平面线形和纵断面线形。
平面线形
道路的平面线形显示在平面图和一系列的直线称为圆ve曲rt线ic连al接a切li线gn。me目nt前在
实际操作中，一般在切线和圆曲线之间插入缓和曲线或螺纵旋断曲面线线。形平面线形的组成
是切线（直），圆曲线和过渡曲线，如图中下面的图27-1t。angent切线
① Clover-leaf Interchan苜ge蓿叶
② Diamond Interchange ③ Rotary Interchange
菱形 环形 喇叭形
④ Trumpet Interchange
立体交叉口
普通公路与高速公路的转弯线形的比较 高速公路
When roads intersect or a railroad spans across a road, the road intersections are needed. The intersection can be at-grade intersection and grade-separated junction. The freeways only adopt the latter intersection. The typical at-grade crossings are cross roads, T intersection, and rotary intersection, as shown in following Fig. 27-3.
线形必须一致c（on平si面st线en形t一和致纵断面线形）。必须避免平地突然变化为急 弯以及很长的切线l后ik紧ew跟is着e同锐样曲地线，否则就会产生事故风险。同样地把不同 半径的圆曲线尾尾r相ad连ii、半或径两条曲线之间插入短切线是不良做法，除非曲线 之间有适当的缓和曲线。
Long, flat curves are preferable at all times, as they are pleasing in appearance and decrease possibility of future obsolescence. Long, flat curves should be used for small changes in direction, as short curves appear as 'kink'. Also horizontal and vertical alignment must be considered together, not separately. For example, a sharp horizontal curve beginning near a crest can create a serious accident hazard.
intersect 交叉 junction 连接 rotary 环形
当相交的道路或铁路横跨道路时， 需要设置道路交叉口。交叉口可以是平 面交叉的和立体交叉。该高速公路仅采 用后者的交叉口。典型的平面交叉口的 十字路口，T形交叉，及环形交叉，如 图下所示 27-3。
作业：将下段英文翻译成汉语。
The foundations under pavement of highways are subgrade, so highway subgrade(or basement soil) may be defineБайду номын сангаас as the supporting structure on which pavement and its special under courses rest. The purpose of a pavement is to provide a smooth surface over which vehicles may pass under all climate conditions. Because natural terrains are uneven, to get smooth road, cutting and filling are needed to change the natural terrain. Subgrades are classified into embankment, cutting, and part-cut part-fill subgrade, 。
circular curve圆曲线
Curve line
Straight line
The vertical alignment of a road is shown on the cutaway view. The elements of the vertical alignment are tangents, vertical curves. Usually there are two type of vertical curve: convex vertical curve and concave vertical curve, as shown in following Fig. 27-2.
side friction侧向摩擦力
When roads intersect or a railroad spans across a road, the road intersections are needed. The intersection can be at-grade intersection and grade-separated junction. The freeways only adopt the latter intersection. The typical at-grade crossings are cross roads, T intersection, and rotary intersection, as shown in following Fig. 27-3.
车辆在弯曲道路行驶受到离心力。这个平衡通过大小相等方向相反的超高和
侧向摩擦力来达到。从公路设计的观点来讲，超高和侧向摩擦力都不能超过某个
最大值，这些控v制eh值ic设le置车了辆曲线锐度限值，曲线锐度限值可以与设计速度建立联
系。
centrifugal force离心力 superelevation超高
intersect 交叉 junction 连接 rotary 环形
当相交的道路或铁路横跨道路时， 需要设置道路交叉口。交叉口可以是平 面交叉的和立体交叉。该高速公路仅采 用后者的交叉口。典型的平面交叉口的 十字路口，T形交叉，及环形交叉，如 图下所示 27-3。
Gradeseparated junctions
道路的纵断面线形显示在剖视图。纵断面线形的 组成是切线，竖曲线。通常有两种类型的竖曲线：垂 直凸竖曲线和凹竖曲线，如图以下所示27-2。
cutaway 剖面 convex 凸的 concave 凹的
Alignment must be consistent. Sudden changes from flat to sharp curves and long tangents followed by sharp curves must be avoided; otherwise, accident hazards will be created. Likewise, placing circular curves of different radii end to end(compound curves) or having a short tangent between two curves is poor practice unless suitable transitions between them are provided.
1.Alignment（线形）
The alignment of a road includes horizontal alignment and vertical alignment.
The horizontal alignment of a road is shown on the plan view and is a series of straight lines called tangents connected by circular curves. In modern practice it is common to interpose transition or spiral curves between tangents and circular curves. So the elements of the horizontal alignment are tangent, circular curve, and transition curve, as shown in following Fig. 27-1.
Lesson 27
HIGHWAY ENGINEERING
公路工程
Introduction
Transportation has always been one of the most important aspects of civil engineering. One of the greatest accomplishments of Roman engineers was the high way system that made rapid communication possible between Rome and the provinces of the empire. Modern highways are built according to the principles laid down in the eighteenth and early nineteenth centuries. Generally speaking, alignment, subgrade, and pavement are the most basic three parts of the modern highways.
A vehicle traveling in a curved path is subject to centrifugal force. This is balanced by an equal and opposite force developed through superelevation and side friction. From a highway design standpoint, both superelevation and side friction cannot exceed certain maximums, and these controls place limits on the sharpness of curves that can be used with a design speed.
accomplishment成就 alignment线性 subgrade路基 pavemen路面 交通一直是土木工程中最重要的方面之一。一位罗马工程师的最伟大的成就 是公路体系，其使快速通讯成为可能。现代公路的修建是根据十八和十九世纪 初所定下的原则。一般而言，线性，路基，路面是现代公路的最基本的三个部 分。
obsolescence报废 crest高峰
在任何时候都长且平坦的曲线都是优选，因为它们在外观上令人愉悦并能减少将 来报废的可能性。长，平面曲线应该用于在方向上的微小变化，如短的曲线显示 为“扭结”。同时平面线形和纵断面线形必须一起考虑，而不是分开。例如，一 个锐的平曲线的开始接近高峰时可能会产生严重事故的危险。