. Principles of irrigation engineering, arid lands, water supply, storage works, dams, canals, water rights and products. pth or extent such as to clean out aU of the poorermaterials, filling in the cavitiesthus made with carefully placedconcrete or masonry. The rockin place after being stripped in thisway is left as rough as possible inorder to make a good joint and iscarefully washed to remove all ofthe smaller particles and enablethe mortar to effect a completebond. Section.—The cross-section ofa modern masonry dam has devel-oped into a somewhat conven-tional form following certain Fig- 47—
. Principles of irrigation engineering, arid lands, water supply, storage works, dams, canals, water rights and products. pth or extent such as to clean out aU of the poorermaterials, filling in the cavitiesthus made with carefully placedconcrete or masonry. The rockin place after being stripped in thisway is left as rough as possible inorder to make a good joint and iscarefully washed to remove all ofthe smaller particles and enablethe mortar to effect a completebond. Section.—The cross-section ofa modern masonry dam has devel-oped into a somewhat conven-tional form following certain Fig- 47—Typical section of masonrygeneral assumptions. On the dam, Boise Project, Idaho, upper or water side the dam is nearly vertical, having in some in-stances a light batter or forward projection of about i ft. horizontalto 20 vertical. On the down-stream side, the slope is about i to from to 2 ft. vertical. It is generally a straightline, or may be gently curved, the batter or slope being increaseddownward from about the middle height of the dam as shown inFig. 47- Homonral Radius 662 Cl&Siiri. Maximum Cross Section 236 PRINCIPLES OF IRRIGATION ENGINEERING This form of section has been developed from theoretical considera-tions, verified by practical results. There are two principal forces tobe considered: first, the downward pressure, or weight due to gravityof each portion of the dam acting upon the foundation or upon eachhorizontal layer or section of the dam; and second, the horizontalpressure or force of the water tending to push the dam down-stream oroverturn it. There are other forces, such as uplift and ice thrust,of less immediate importance, but which are to be considered. To compute the resultant of the two main forces, the dam is con-sidered as consisting of an indefinite number of portions formed bytaking successively lower and lower sections from the top down to thefoundation. Beginning, for example, with the first lo ft. of the top
Size: 1408px × 1775px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectirrigat, bookyear1913
