1、附 录 英文论文 The characteristics of earth-rock DAMS and technical control 1. selection of embankment type In general, there are two types of embankment dams: earth （ earth fill dam） and rock fill（ rock fill dam） . The selection is dependent upon the usable materials from the required excavation and avai
2、lable borrow. It should be noted that rock fills 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. Rocks which are soft and will easily break down under the action of excavation and placement can be classified
3、with earth fills. Rocks which are hard and will not break down significantly are treated as rock fills. The selection and the design of an earth embankment are based upon the judge ment and experience of the designer and is to a large extent of an empirical nature. The various methods of stability a
4、nd seepage analysis are used mainly to confirm the engineers judge ment 2. freeboard 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 ov
5、ertopping of the dam. In addition to freeboard, an allowance must be made for settlement of the embankment and the foundation which will occur upon completion of the embankment. 3. top width The width of the earth dam top is generally controlled by the required width of fill for ease of construction
6、 using conventional equipment. In general, the top width should not be less than 30 ft. 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. 4.alignment The alignment of
7、 an earth fill dam should be such as to minimize construction costs but such alignment should not be such as to encourage sliding or cracking of the embankment. Normally the shortest straight line across the valley will be satisfactory, but local topographic and foundation conditions may dictate oth
8、erwise. Dams located in narrow valleys often are given an alignment which is arched upstream so that deflections of the embankment under pool load will put the embankment in compression thus minimizing transverse cracking. 5. Abutments Three problems are generally associated with the abutments of ea
9、rth dams: seepage, instability, and transverse cracking of the embankment. If the abutment consists of deposits of pervious soils it may be necessary to construct an upstream impervious blanket and downstream drainage measures to minimize and control abutment seepage. Where steep abutments exist, es
10、pecially with sudden changes of slopes or with steep bluff, there exists a danger of transverse cracking of the embankment fills. This can be treated by excavation of the abutment to reduce the slope, especially in the impervious and transition zones. The transition zones, especially the upstream, s
11、hould be constructed of fills which have little or no cohesion and a well-distributed gradation of soils which will promote self-healing should transverse cracking occur. 6. stage construction It is often possible, and in some cases necessary, to construct the dam embankment in stages. Factors dictating such a procedure are: a wide valley permitting the construction of the diversion or outlet works and part of the embankment at the same time； a weak foundation requiring that the embankment not be built too rapidly to prevent
