UNIT 3 Embankment Dams.pptx

UNIT 3 Embankment Dams;In general, there are two types of embankment dams: earth （earthfill dam） and rockfill（rock fill dam）. The selection is dependent upon the usable materials from the required excavation and available borrow. 一般来说，土石坝有两种类型：土坝和堆石坝。坝型的选择取决于能从需要开挖的地点和可用的料场（料场 stock ground）（borrow area 取土面积; 采料场）处取得合用材料的情况。;It should be noted that rockfills can shade into soil fills depending upon the physical character of the rock and that no hard and fast system of classification can be made. 应当指出的是（注意），根据岩石的物理特性，堆石可以逐渐变化为填土，因而不能对土石料作出严格而固定的分类。;Rocks which are soft and will easily break down under the action of excavation and placement can be classified with earthfills. Rocks which are hard and will not break down significantly are treated as rockfills. 那些软弱的和在开挖填筑时容易破碎的岩石可被归入填土类。而坚硬和不会大量破碎的的岩石，则列为堆石类。 ;The selection and the design of an earth embankment are based upon the judgement and experience of the designer and is to a large extent of an empirical nature. The various methods of stability and seepage analysis are used mainly to confirm the engineer’s judgement. 一座土坝的选定和设计都有赖于设计人员的判断和经验，而且在很大程度上是属于经验性的。各种稳定和渗透分析方法，主要是作为证实工程师的判断而使用的。 ;All earth dams must have sufficient extra height known as freeboard to prevent overtopping by the pool. The freeboard must be of such height that wave action, wind setup, and earthquake effects will not result in overtopping of the dam. 所有的土坝都必须有一个足够的额外高度，称为超高，以防止水库漫顶。超高的高度必须足以在波浪作用、风浪壅高和地震影响下，不会导致坝的漫顶。;The width of the earth dam top is generally controlled by the required width of fill for ease of construction using conventional equipment. In general, the top width should not be less than 30 ft. 土坝的坝顶宽度一般用常规设备便于施工的填筑宽度来控制。通常，坝顶宽度应不小于30英尺。;If a danger exists of an overtopping wave caused either by massive landslides in the pool or by seismic block tipping, then extra top width of erosion resistive fill will be required. 如果存在着大规模塌方进入水库，或者有因地震使岩块倒落而引起波浪漫顶的危险，则需要采用抗冲刷的材料填筑更宽的坝顶高度。;The alignment of an earthfill dam should be such a