Stresses in Masonry Dams

Abstract

THE stresses in masonry dams, to which much attention has recently been devoted in our correspondence columns, formed the subject of three papers read before the Institution of Civil Engineers on January 21. In the first, Sir John W. Ottley, K.C.I.E., and Dr. A. W. Brightmore described some experiments, occupying about fourteen months, made with plasticine models of a dam of typical triangular section under perfect conditions. The height of the model was 30 inches, and the length of the dam 12 inches. From the results of the experiments the following conclusions were drawn:—(1) If a masonry dam be designed on the assumption that the stresses on the base are uniformly varying, and that these stresses are parallel to the resulting force acting on the base, the actual normal and shearing stresses, on both horizontal and vertical planes, would (in the absence of stresses due to such factors as changes in temperature, unequal settlement,. &c.) be less than those provided for. There can be:no tension on any plane at points near the outer toe. There will be tension on planes other than the horizontal plane hear the inner toe, the maximum intensity of such tension being generally equal to the average intensity of shearing stress on the base, and the inclination of its plane of action being about 45°.