US 1885057 A
Description (OCR text may contain errors)
Oct. 25, 1932.
A. v. KARPOV DAM ' Filed May 26, 1950 2 Sheets-Sheet 1 Oct. 25, 1932. A. v. KARPOV 1,885,057
' DAM Filed May 26, 1950 2 Sheets-Sheet 2 Bcenfer )ine of the section Patented Oct. 25, 1932 UNITED ST ALEXANDER v. imnrov,
OF PITTSBURGH, BENNSYLVANIA [DAM Application filed May 26, 1930. Serial No. 455,532. Y
M invention relates to dams such as are emp oyed for retaining the water of streams or reservoirs and more particularly to dams of. the arch. type, that is,'dams which are of 5 curved form with the convex side of the curve upstream or against the head of the water pressure. a 1' ,j t v V v I I .The usual arch dam designs do not represent the most favorable designs, due to the factlthat' no full advantage is taken of the gravity action or weightot the dam material and because the dams in their vertical and'horizontal cross sections have arbitrahi h stresses in some partsand in uneconom ca lylow stresses in some other parts of the dams.
The most favorable design is to be obtained by taking full advantage of the gravity action, by using arches tor thehorizontal dam sections that 'are' relieved from any bending moments, and such shapes for the vertical damv sections that,-under water load,
Vertical sections. H
Still another object otmy inventionis to provide a dam of such' form that it is relieved of bending moments resulting from water load, or from contraction of 0ncre te, displacement of abutments or foundations. etc. Some of the Yways in "which my invention may be practised are shownin the accompanying drawings, wherein Figurel isa' diagrammatic view showing across section of adamfor' purposes of description Fig. 2 is a horizontal sectional view taken on the line IIII oflFi'g. 5; 3 is view taken on the line III-IIIofFigb Fig. 4 isa View taken "on the line IV'IV' 0f-Fig.' 5; Fig. 5
1s a vertical sectlonal view 811111181 .to Fig.
rily-chosen shapes that result in excessivelythey'will develop the largest horizontal dethereof taken care of by the weight of the.
1, but'showing a particular form which the dam may take in actual practice; Fig. 6 is a graphic illustration of. the forces exerted in the structure of Fig. 5, and Fig. 7 shows a modification ot a portion of the structure 55 of Fig. 5.
As indicated above, I have designed a dam of such form that the weight of the dambody isso directed that it will oppose the pressure of the water to an increasing extent vertically from a point below the top of the dain toward the basethereof where the water pressure is of course greatest. I Infthe drawings, I have used thelegends 'as follows: f 1 W PlV'=Water pressure PC=Part of water pressure taken by the A, vertical element v I P.=Part of water taken by the horizon- I ,tal element I .Willfirst describe the manner in which the, weightis distributed'to counteract the water pressure. In Fig. 5-,the vertical center line of the dam structure is represented at- 8, while the numeral 9 represents what might be called the line. of equilibrium or thecenter line of gravity of the mass. The line 10 indicates the water load plus the .Weight, and the relation of the line 9 to the line 10.indicates the extent to which the water pressure is opposed by the weight of the materialfin the dam, this weight resistance to water pressure being of course greatest at p the base of the dam. t For purposes of illustration, the dam is indicated as composed of blocks ranging from 87 teetin horizontal Width at the bottom to 10'. feet at the top, the dam structure being shown as approximately 200 feet high.
' As shown more clearly in Fig. 6, the dam near its top offers no weight resistance to the water pressure, as indicated by the letter P,which shows that all of the water pressure is there taken by the horizontal element. The
amount of resistance offered by the horizontal sections of the dam to the water pressure decreases toward the bottom of the dam, and the weight resistance to the water pressure increases, as indicatedby the lines PC and P near the mid point of Fig. 6. 1w
. bv the horizontal arches.
In Fig. 5, near the upper portion thereof, the weight line 9 is indicated at the right hand or down stream side of the physical center line of the dam so that instead of the weight resistance being offered to water pres sure at this upper portion of the dam, the weight exerts a down stream pressure with the water pressure, for a purpose to be hereinafter explained, in connection with the provision for deflection of the dam under stresses.
At the higher elevations, the vertical sections of the dam in any given horizontal plane develop a down-stream pressure that is greater than the water pressure at such points, and at the lower elevations the pressure developedby the weight of the dam is smaller than the water pressures at such points as indicated graphically by the line 12a in Fig. 1, the straight line 13a representing the water pressure and the line 12a representing the pressure-resisting weight of the materials compared to the water pressure.
Referring now more particularly to Figs.
2 to 4:, I show means providing compensation for various stresses or bending moments which may take place in the concrete or other dam material, such as those stresses arising from contraction of the concrete, displacement of abutments, temperature changes, etc. To this end, I provide notches or angular spaces between the blocks 15, the notches near the mid-point of the arch being provided in the upstream side, as indicated at 16, and the notches adjacent to the ends being provided at the down-stream side, as indicated at 17, so that bending movements of the dam will be distributed equally throughout the horizontal sections to compensate for such stresses, without rupture. Comparison of Fig. 2 with Fig. 4:, which indicates upper and lower horizontal sections respectively, shows that the notches or clearance spaces near the bottom of the dam are smaller or narrower than at higher portions thereof. This difference is provided because the distortional stresses will ordinarily be greater near the top of the dam than at the bottom, since the weight-force of the dam is utilized to compensate for increased stresses toward the bottom. The points at which horizontal forces are normally greatest on the blocks 15 are their points of abutting engagement, as viewed in Figs. 2 to 4.
It will be seen, therefore, that in providing the notches in this manner, the compensation for the deflecting stresses of the horizontal arches on various points thereof, and at various elevations is proportional to the part of the loading taken care of at such points Further, the centers of bending moments of the arches are indicated at 18 18, 1919 and2020 respectively, in Figs. 2, 3 and 4, no bending moments will ordinarily occur at such points. Since the loading pressure is directed against the convex side of the arches, I prefer to dispose the notches between the blocks on the convex side of the arches to permit equal distribution of the deflecting stresses throughout the arch between the centers of bending moment; while below such centers the notches are disposed at the concave side of the arches to receive the stresses imparted thereto, thereby equally distributing the deflecting stresses throughout the entire horizontal sections of the arches.
The notches can be provided in various ways. For instance, wedge-shaped filling blocks as at 17 a may be mounted in the molds or forms in which the blocks are poured, or the blocks may be assembled in position upon the dam and filling material such as asphalt placed between the vertical surfaces of the blocks at 17a to hold certain portions thereof in properly spaced relation.
In Fig. 7, I have shown a modification of the structure of Fig. .5. In this figure, the numeral 30 represents the lower portion of the vertical section of a dam. The distribution of weight in this section is indicated by the lines 8a, 9a and 10a, which correspond to the lines 8, 9 and 10 of Fig. 5. A saving of material is effected in making the dam of this form, since approximately the same support is afforded against pressures as in the case of Fig. 6.
In order to prevent the dam falling upstream during construction, I provide a bracing element 31 of concrete, stone or any other suitable material which may be either temporary or permanent. This bracing element 31 need not necessarily extend across-the full length of the dam.
I claim as my invention 1. Dam structure comprising a wall of curved form whose convex side faces toward the source of pressure, the convex surface of the wall between vertical sections adjacent to mid portions of the curve having clearance spaces flared toward said convex side, and the vertical sections at the concave surfacev of the wall, between the said mid portion of the curve and the ends of the curve, having clearance spaces that flare toward the concave side of the wall the clearance spaces being of dimiililished width toward the bottom. of the wa 2. Dam structure comprising a wall of curved form whose convex side faces toward the source of pressure, the convex surfaceof the wall having vertically-extending clearance spaces that are flared toward the convex side of the wall, the vertical wallsectionsthus defined normally contacting with one another at the concave surface of the wall. y
3. Dam structure comprising a wall of curved form whose convex side faces toward the source of pressure, the convex surface of the wall having vertically-extending clearance spaces that are flared toward the convex side of the wall, and are of diminished width toward the bottom of the wall, the vertical wall sections thus defined normally contacting with one another at the concave surface of the wall.
4. Dam structure comprising a wall of curved form whose convex side faces toward the source of pressure, the convex surface of the wall between vertical sections adjacent to mid portions of the curve having clearance spaces that flare toward said convex side, and the vertical sections at the concave surface of the wall, between the said mid portion of the curve and the ends of the curve having clearance spaces that flare toward the concave side of the wall.
In testimony whereof I, the said ALEXAN- DER V. KARPOV have hereunto set my hand.
ALEXANDER V. KARPOV.