CN1696412A - Method for designing practical weir in broadband and coarse vacuum - Google Patents

Abstract

The present invention discloses a design method of broad base low-vacuum practial weir. Said invention includes system design mentality, weir surface curve design, flood carrying capacity calculation method, finite element stress check calculation and technical economic comparison of new weir type and WES weir. The most key of said design includes three factors of flood carrying capacity, weir surface pressure and volume of dam body, and its concrete design calculation method includes two portions of body type designand discharge coefficient definition.

Description

The method for designing of broadband low vacuum practical weir

Technical field

The present invention relates to the method for designing of flood discharge overfall dam, a kind of specifically design method of broad base low-vacuum practial weir.

Background technology

Practical weir is one of topmost building of Ba Gongzhong, has dash and sluicing double action concurrently, therefore, the safe and reasonable, also good hydraulic characteristic(s) will be arranged on requiring its structure.Broadband low vacuum practical weir belongs to Hydraulic and Hydro-Power Engineering dam flood-discharge new technology.Content relates to the most important building that Ba Gongzhong has dash and sluicing double action concurrently---the design of practical weir.

More than one since century, the hydraulic engineering expert of countries in the world has proposed a plurality of overflow weir bodily forms, wherein most representative is by the WES weir of CE, US Army water channel experiment station proposition and the Krieger one Ao Feicailuofu weir of former Soviet Union's proposition (being called for short gram weir difficult to understand), the former is extensively adopted by the U.S., Japan and the Western European countries, and among income China's " design of spillway standard " SL253-2000, the latter then is put into former Soviet Union's " hydraulic structure design specifications ".Restrain weir difficult to understand, it is the former Soviet Union's a kind of practical weir commonly used and that be put into its hydraulic structure design specifications, also be the weir type of China's 50～sixties through using always, the weir surface curve mainly is made up of five line segments, it is the upstream vertical section, the curved section of weir kept man of a noblewoman portion straightway, weir crest upstream and downstream face, abrupt slope straightway and anti-segmental arc are formed, and mainly tabling look-up by X/Hd and Y/Hd during design draws.AUS engineering water channel experiment station proposes standard weir type: the WES weir, extensively adopt in the U.S., Japan and the Western European countries, also be widely adopted in China the eighties, and income China's " design of spillway standard ", it is more small and exquisite that WES weir build restrains weir difficult to understand, and its weir surface curve depends on typing head Hd fully.The institute of Yangtze River Water section of China proposed the long I type practical weir that grinds in 1973,1981～nineteen eighty-two enriches the back and forms the weir surface curve similar to the WES weir, and only the power exponent with weir, downstream face changes 1.80 into by 1.85, and weir body mentality of designing is basic identical with the WES weir; Nanjing Shui Keyuan utilizes binary potential barrier Mathematical Modeling, find the axial ratio of an optimum, make that curve interior pressure distribution in weir crest upstream is comparatively even and negative pressure value is minimum, pressure distribution in the weir crest downstream curve is comparatively even and negative pressure value is minimum, weir crest downstream face curve and WES weir are very approaching, and this weir is called as the extremal practical weir; China Jiang Yu dragon, the medium people of Guo Zi are after the weir crest downstream curve of collecting domestic and international multiple weir type, and respective coordinate value is in addition average, and the curve that obtains a kind of match is called the resultant curve practical weir; It is a biquadratic equation that the airfoil type weir surface curve that proposes behind the airfoil type weir of the empty Advisory Board of U.S.'s boat (NACA) has been analyzed in the examination of China Hohai University, mainly is applicable to the face design of flood spillway weir, bank.

In sum, present practical weir all has the flood discharge capacity deficiency or flood discharge capacity does not also reach ideal range, the negative pressure value of weir face such as but can't bear at problem, and improving the flood discharge capacity of dam, the cavitation resistive property that strengthens dam facing, the engineering quantity etc. that reduces overfall dam is the important technology difficult problem that present Ba Gongjie waits to capture.

Show from the interrelated data retrieval that comprises Chinese patent, at present the relevant report of still not having the application example of broadband low vacuum practical weir both at home and abroad and not finding flood discharge capacity higher under equal hydraulics as yet.

Summary of the invention

In order to overcome present practical weir flood discharge capacity deficiency, problem such as dam facing vacuum band is unreasonable the invention provides a kind of design method of broad base low-vacuum practial weir.

The technical solution adopted for the present invention to solve the technical problems is: the present invention includes general design idea, the design of weir surface curve, flood discharge capacity computational methods, finite Element Stress are checked calculating and new weir type and WES weir Technological Economy and are relatively waited part.The design most critical of weir type three key elements, i.e. discharge capacity, weir surface pressure and dam body volume arranged.And these three key elements are mutual restriction to each other.Feature of the present invention is: broadband low vacuum practical weir, and the specific design computational methods are divided two parts, and the one, the build design, the 2nd, discharge coefficient is determined.The build design mainly is to determine oval major and minor axis length A, B and power curve COEFFICIENT K.

Head ellipse ${\left(\frac{x}{a{H}_{\max }}\right)}^2+{(1-\frac{Y}{b{H}_{\max }})}^2=1$

Power curve y=CX ^1.85

By known maximum weir head H _MaxWith permission weir face max vacuum force value ha, obtain coefficient k by following formula, C.

$\left(1\right)---K=-0.88\frac{\mathrm{ha}}{H_{\max }}+0.5$

$C=\frac{K}{{H_{\max }}^{0.85}}=K\·{H_{\max }}^{-0.85}$

2. obtain coefficient a value according to the K value by following formula

a＝0.1984-0.2571ogk

3. obtain coefficient b value according to the K value by following formula

b＝0.2502-0.1804k

4. transverse length A=aH _Max

Ellipse short shaft length B=bH _Max

5. by $m=0.5250-0.03922\ln \left(\frac{P}{H}\right)$ Obtain the integrated flow rate coefficient.

The wide zone of described band shape: the maximum operating head polishing H of weir face _MaxWith the ratio of weir face vacuum belt length L be H _Max/ L=0.77～1.11; High dam H _Max/ L gets big value, and weir gets the small value.

Described height of dam is at the high dam of 70～130m, and weir face head ellipse long axis length can be determined by following formula

A＝(0.1984-0.25701ogk)H _max

Minor axis length: B=(0.2502-0.1804k) H _Max

Weir face equation Y=CX ^1.85

Coefficient $K=0.5-0.88\frac{\mathrm{ha}}{H_{\max }}$ Ha is for allowing negative pressure value (m water column)

Coefficient C=KH ^-0.85 _Max

Integrated flow rate coefficient (counting the side direction effect of contraction)

$m=0.5252-0.03922\ln \left(\frac{P}{H}\right)$

P is that height of weir (m) H is weir head (m)

Above formula application conditions:

P/H＝4.6～20.0

Storehouse, overfall dam water inlet face width degree B _{The storehouse}With water inlet overflow clear span B _OnlyRatio

B _{The storehouse}/ B _Only=3.0～5.0

Flood discharge capacity has than quantum jump

Big discharge coefficient M can reach 0.5261～0.5465, and big by 5～7.8% than the WES weir, more antivacuum gram weir difficult to understand is big by 4.4～7.2%.

The invention has the beneficial effects as follows: the weir surface pressure presents the wider nothing harm low pressure in zone and distributes, and promptly so-called low pressure broadband distributes; The peak suction value of weir face is controlled in the safe range of standard permission; This weir type has bigger flood discharge capacity, its discharge coefficient international WES weir maximum at present can improve 5.0～7.8%, gram one antivacuum weir difficult to understand than the former Soviet Union improves 4.4～7.2%, can reach 0.5261～0.5465, reservoir level can reduce by 0.36～0.92m, and its effect is by improving WES weir type or improving the gate pier head type and improve 10 times that flood discharge capacity tells on.Moreover, the broadband low vacuum practical weir bodily form is small and exquisite, and the basal area of weir body can reduce 6.8% than the WES weir, is a kind of new weir type that good economic benefit and application prospect are arranged.At present, this new technology has been successfully applied to the weir face design of the major works dam of Fujian Province's key project dam design and height of dam 128m, and is respond well.Therefore, weir of the present invention body has big flood discharge capacity, and the harmfulness negative pressure does not take place the weir face, and engineering quantity is few, characteristics such as reduced investment.

Description of drawings

The present invention is described in more detail below in conjunction with drawings and Examples.

Fig. 1 is a broadband of the present invention low vacuum practical weir cross section view.

Fig. 2 is a terminal layout of the present invention.

Fig. 3 is an overfall dam sectional drawing of the present invention.

Fig. 4 is an overfall dam plan view of the present invention.

Dam body slime flux face weir crest upstream curve 1 among the figure, weir, weir crest downstream surface curve 2 (by weir crest to abrupt slope section initial point), weir surface curve 3 is anti-segmental arc (initial point is an abrupt slope section end), gate pier 4, gate 5.

The specific embodiment

Embodiment 1:

Overfall dam weir crest curve (1) is designed to as shown in Figure 1:

${\left(\frac{X}{2.912}\right)}^2+{(1-\frac{Y}{1.579})}^2=1$

Weir, weir crest downstream surface curve is 2 to be designed to:

Y＝0.0803X ^1.85；

Weir surface curve 3 is radius 20m, and central angle is 83 ° a circular arc;

Gate pier 4 is a long 30m, thick 2.5m cuboid, and two is the column of radius 1.25m;

Gate 5 is the camber steel gate of a radius 16m.

Claims (3)

1. design method of broad base low-vacuum practial weir, it is characterized in that: broadband low vacuum practical weir specific design computational methods are divided two parts, and the one, the build design, the 2nd, discharge coefficient is determined; The build design mainly is to determine oval major and minor axis length A, B and power curve COEFFICIENT K;

Head ellipse ${\left(\frac{X}{{\mathrm{aH}}_{\max }}\right)}^2+{(1-\frac{Y}{b{H}_{\max }})}^2=1$

Power curve y=CX ^1.85

By known maximum weir head H _MaxWith permission weir face max vacuum force value ha, obtain coefficient k by following formula, C;

① $K=-0.88\frac{\mathrm{ha}}{H_{\max }}+0.5$

$C=\frac{K}{{H_{\max }}^{0.85}}=K\·{H_{\max }}^{-0.85}$

2. obtain coefficient a value according to the K value by following formula

a＝0.1984-0.257logk

3. obtain coefficient b value according to the K value by following formula

b＝0.2502-0.1804k

4. transverse length A=aH _Max

Ellipse short shaft length B=bH _Max

5. by $m=0.5250-0.039221n\left(\frac{P}{H}\right)$ Obtain the integrated flow rate coefficient.

2. the method for designing of broadband according to claim 1 low vacuum practical weir is characterized in that: the wide zone of described band shape is: the maximum operating head polishing H of weir face _MaxShould be H with the ratio of weir face vacuum strip length L _Max/ L=0.77～1.11; High dam H _Max/ L gets big value, and weir gets the small value.

3. the method for designing of broadband according to claim 1 low vacuum practical weir is characterized in that: described height of dam is at the high dam of 70～130m, and weir face head ellipse long axis length can be determined by following formula

A＝(0.1984-0.2570logk)H _max

Minor axis length: B=(0.2502-0.1804k) H _Max

Weir face equation Y=CX ^1.85

Coefficient $K=0.5-0.88\frac{\mathrm{ha}}{H_{\max }}$ Ha is for allowing negative pressure value (m water column)

Coefficient C=KH ^-0.85 _Max

Integrated flow rate coefficient (counting the side direction effect of contraction)

$m=0.5252-0.039221n\left(\frac{P}{H}\right)$

P is that height of weir (m) H is weir head (m)

Described formula application conditions:

P/H＝4.6～20.0

Storehouse, overfall dam water inlet face width degree B _{The storehouse}With water inlet overflow clear span B _OnlyRatio

B _{The storehouse}/ B _Only=3.0～5.0

Flood discharge capacity has than quantum jump

Big discharge coefficient M can reach 0.5261～0.5465, and big by 5～7.8% than the WES weir, more antivacuum gram weir difficult to understand is big by 4.4～7.2%.

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