US2407952A - Dam structure - Google Patents

Description

Sept 17, 1946. E. D. DEL @AS1-@LLC Y ESPANOL 2,407,952

19AM STRUGTURE Sept. 117, 194e. E, D. DEL CASTILLO Y ESPANOL 2,407,952

DAM STRUCTURE Filed May 12, 1943 2 Sheets-Sheet 2 Patented Sept. 17, 1946 DAM STRUCTURE Eugenio Diaz del Castillo y Espaol, Buenos Aires., Argentina Application May 12, 1943, Serial No. 486,717 In Argentina March 20, 1943 3 Claims.

The present invention relates to dams and more particularly to dams composed of sections which are soarranged relative to one another and to the ground, as to prevent sliding and to reduce the quantity of building material required to re strain a water head of any given magnitude.

The gravity type dam, which may be defined as a dam which does not depend on arch action to resist the forces imposed upon it, while'wdely used, fis subject to the disadvantage that to prevent sliding and bad distribution of the loads produced'by the weight of the dam itself and the water restrained thereby, it is necessary to employ very large quantities of building material which render the completed structure unduly costly from the lpoint of View of both labor time consumed and material used.

It is therefore an object of this invention to provide a dam which will mitigate the economic disadvantages of theknown type gravity dam and which is characterized by a construction which is adaptable to solid construction, buttress construction, multiple arch construction, or the like.

Other objects and advantages of this invention will be apparent from the following detailed description of preferred embodiments thereof in conjunction with the annexed drawings wherein:

Figure 1 is a fragmentary plan view of a dam constructed in accordance with this invention, the view being limited to the portion of the dam which extends from the center line of the stream over one hillside;

Figure 2 is an elevational view showing the upstream face of the construction of Figure 1;

Figure 3 is a view in cross section taken along the line 3-3 of Figure 1, reference planes for certain mathematical considerations being rendered in chain lines;

Figure 4 is a perspective view of a modified type of dam constructed in accordance with this invention taken from a downstream direction; and

Figure 5 is a fragmentary view in perspective of a dam section illustrating the application of this invention to buttress construction. i

Referring now in greater detail to the drawings and particularly to Figures 1 to 4 inclusive, it will be noted that the dam of this invention is composed of sections IIJ which are in the over-al1 form of truncated prisms. It can be seen that if the sections I0 are set in position across the valley which is to be dammed in such relation to each other that angular open spaces II facing downstream are provided at each of a plurality of relcl. erf-so) CII entrant angles I2 on the upstream side. It can be seen that if the sections .III are so disposed relative to one another as to define a dam crown line I3 of a broken character including line components I4, I5 and I6, each extending in a different direction, said line components being oblique in each case to the horizontal projection Il, Figure 1, o-f the lines I8 of maximum slope of the hillside, see Figure 2, a dam will be obtained consisting of a plurality of prisms I0 more or less `truncated depending upon the ground contour. i

The direction of flow of the Water of the stream or river to be dammed is shown by an arrow in Figure 1. It is noted that the dam axis line I3 extends in an upstream direction from the center line of the stream so that the bases of the sections II), while having a general slope toward the center of the stream Will, transversally to their axes, slope in the upstream direction.

To facilitate consideration of the foregoing, the angles and slopes that must be taken into consideration in the construction of a vdam in accordance with this invention, have been set `forth in Figures 1, 2 and 3 of the drawings. The angles ,81, 182, s and .fn are defined between the slope of the ground at the particular point and the vertical. The angle a, see Figure 3, is the apex angle of the dam. -n is the angle defined 'between the horizontal and the line of slope of the base of a section I 9 transversally of its axis. 0 and @-11 are dam sliding angles. The angles fy1, fyz, we, and 'v4 are defined between the horizontal projections I1 of the line I8 of maximum slope and the axis lines I4, I5 and IE respectively of the dam sections. ry and 11 in Figures 4 and 5 refer to the same angles. The slope of the base 2| of each section I0 transversally of its axis results in a narrower base for the sections I since, in the absence of this slope, the cross section of the dam section at any point would be a right triangle, see the broken line 22 of Figure 3, while, with the slope, the angle between` the wetted face of the section and the base thereof is always less than Hence, for

,any given section apex angle a a narrower section results from the construction of this invention.

The narrowness of the section resulting from the inclination of the base transversally of its axis has the concomitant advantage that the height of the downstream face 23 of the section is reduced. 'Ihe over-all gain in reduction in volume can Ibe appreciated by comparing the full line cross section of Figure 3 with the broken vline cross section which would result if the base of the section were not sloping transversely of its axis.

It is, of course, to be understood that the economy of material apparent from Figure 3 is somewhat reduced due to the fact that the over-all length of the dam of the present invention must somewhat exceed the over-all length of a conventional dam at the same site.

It is apparent that the construction of the present invention affordsv a high degree of stability against sliding due to the fact that the ground affords horizontal reactions in an upstream direction which contribute to resisting the. thrust of the water.

At the bottom of the valley and in those zones o-f the hillsides in which the slopeincreases as the ground rises, it is apparent that the angles defined between the components of the line I3 will, in general, be reentrant on the upstream side and, between the sections which are in contact with each other at the wetted face, there will be angular open spaces at l-i.r facing in a downstream direction.

Of .the spacesI l I, the most important, although beit not always lthe largest, is the one at the fbottom of the valley which affords economy in themost difficult and expensive part of the foundation. The joints between the sections lll will be beveled -and made watertight by any known means.

In those areas where the slope of the hillside diminishes, the angles of the axis line i3 will project outwardly in an upstream direction as indicated .at 29 in FigureV 1.. There will be virtual superposition of the ends of the sections of the dam corresponding to a smaller resultant of the thrust of the water in these areas. These projecting angles at 2d can., oi' course, be replaced by'curves. By selecting a correct axis line, bearing'in'mind the slopes of the hillsides in any particularV case, it is possible to obtain a minimum over-all volume of building material whereby economies in construction are effected.

The selectionv of an axis line can be utilized not only as the basis for the. construction o-f a dam of minimum structural volume, but also may be utilized for obtaining a greater inclination of the bases of the sections so as to achieve improved disposition of the stresses to which the dam is subjected or an improved stability against sliding. If, starting from; the Obliquity of the axis whichis'required for a damof minimum structural volume, the axis Obliquity, i. e.: the angle y, is increased, one will eventually arrive at an axis obl-iquity where thegreater over-all length of the dam is compensated for by the lesser cross sectionalarea of its component sections. If the dam would lie at 24 and would dene an angle 0 with a line 25 lying at right angles to the assumed base 22. The actual sliding angle of the present dam is represented by @-11 and is defined ibetween a line 26 representing the resolved forces acting on the dam and a line 21 at right angles to the base 2l. It can be seen that 0 1; is always smaller than 0 since the tendency of 0 to increase with the dam of the present invention is more than compensated for by the increase of n. Ac-

cordingly, the resistance to sliding of the present invention is great compared to a conventional dam. In solid dams, the division of the dams into sections with some open spaces between suppresses substantially all longitudinal reactions to the ground. There remains to be considered the 'longitudinal stresses which may arise from the pressure of the water on those surfaces of thedam which are in contact with the ground. The importance of this pressure is different from that', of the subpressures because it is much easier to eliminate it by efficient drainage, of theground applied to surfaces of the terrain not loaded by the dam. 'I'heangularspaoes arising in the construction of the dam of the vpresent in-l vention facilitate drainage. In buttressor multiple arch dams the ready elimination of longitudinal pressures is even more clearly seen.

It is apparent that the foregoing remarks apply not only to masonry dams or the like, which have a vertical o-r substantially vertical wetted face, but also to dams of! the lbuttress type havingv a substantially inclined wetted face, see Fig-ure 5. In the latter case, a further advantage results from the diminution of theweight of water required for stability. Compensation for this diminution is afforded by the inclinationo-f the base of each section transversally of -its axis, see angle n in Figure 5.

What is claimed isf 1. A dam structure having a broken line axis comprisinga plurality of sections substantially in the over-al1 form o-f truncated prisms; the horizontal axes of said prisms beingoblique tothe horizontal projections of the line of maximum slope ofthe hillsides; the foundation base ofeach section being declivent, transversallyto the section axis, toward upstream; whereby to affordV foundation reactions opposite to water pressure, stability against sliding, reduced foundation Width, and downstream reduction of height and accordingly diminution of the stresses; said sections being set in angular relationship v.with each other, defining between-them at the Areentrant" upstream angles of the dam angular open spaces facing downstream, providing fordrainageand freecontraction; ,and imperviousjoints atthe upstream contact of these sections. 1

2. A dam as claimed in claimV l'having solid sections. Y

,.3.. A dam asfclaimed in claim l having sections ofthe buttresstype. -f

-EUGENIODLAZDEL eAsr-rrLLo-Y-EsPAon.

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