CN102251504A - Facility for eliminating negative pressure of bottom plate at torrent diffusion slope-variable section of flood discharging tunnel - Google Patents

Abstract

The invention relates to a facility for eliminating the negative pressure of a bottom plate at a torrent diffusion slope-variable section of a flood discharging tunnel, The facility comprises a step-down floor and pressing holes, wherein the step-down floor is arranged in front of a negative pressure region of the bottom plate at a diffusion section of the flood discharging tunnel; the pressing holes are arranged at two ends of the step-down floor outside a side wall of the flood discharging tunnel; a hollow cavity formed between a jet flow surface generated by discharged water in the flood discharging tunnel flowing across the step-down floor and a step-down floor bottom plate surface is communicated with air through the pressing holes so that the negative pressure of the bottom plate of the flood discharging tunnel is reduced and partial damage of the bottom plate of the flood discharging tunnel is avoided. In general, the step-down floor height is 0.30-1.00m, and the sizes of the pressing holes are determined by factors, such as the step-down floor height, step-down floor aerating capacities, a negative pressure region range and the like. A physical model test result shows that the pressing facility provided by the invention can be used for effectively eliminating a negative pressure value of the bottom plate at the torrent diffusion section of the flood discharging tunnel, increasing water flow aerating concentration and improving the energy dissipation effect of a stilling basin.

Description

Eliminate the facility that the diffusion of flood discharging tunnel torrent becomes slope section base plate negative pressure

Technical field

The present invention relates to eliminate in the Hydraulic and Hydro-Power Engineering measure of flood discharging tunnel base plate negative pressure, more specifically say so and eliminate the measure that high Froude number flood discharging tunnel torrent diffusion becomes slope section base plate negative pressure.

Background technology

Flood releasing structure is the important component part in power station, accounts for about 1/3 of its gross investment, so the security of operation of flood releasing structure is very important for whole Hydropower station pivotal.Main flood releasing structure comprises spillway on dam body (spout hole), bank flood spillway (flood discharging tunnel) and emptying tunnel etc. at present.For the bank flood discharging tunnel,, its base slope build is arranged as the linking form that becomes sloping curve according to actual landform usually in order to reduce the excavation investment.When taking disspation through hydraudic jimp, flow into the single wide power in pond (absorption basin) to reduce downstream energy dissipating pressure in order to reduce water, flood discharge hole outlet to absorption basin section is typically designed to the flaring form, and reduces into pond discharge per unit width and increase energy dissipation rate with this, thus the investment of saving the power facility that disappears.

Become the slope section from flood discharge hole outlet to the diffusion between the absorption basin, high water head flood discharging tunnel water velocity can reach more than the 35m/s, this high flow rate, shallow water is dark and the current of big base slope gradient (being high Froude number), cause diffusion to become slope section base plate easily and form local decompression's district (and negative pressure value is relatively large) in certain limit, this negative pressuren zone is under the acting in conjunction of base plate uplift pressure and negative-pressure sucking, cause the coal seam floor failure of flood discharging tunnel easily, thereby influence the safety of whole outlet structure escape works.

Before the present invention finished, the inventor did not also find to become the measure of subduing flood discharge hole outlet torrent diffusion change slope section base plate negative pressure that sloping section adopts the present invention to propose in the diffusion of flood discharge hole outlet torrent.

Summary of the invention

The high Froude number flood discharging tunnel torrent diffusion that the present invention is directed to the disspation through hydraudic jimp pattern becomes slope section base plate negative pressure destruction is easily taken place, suitable position design concora crush facility in this diffusion becomes the slope section has been proposed, to eliminate the base plate negative pressure destruction that this negative pressuren zone produces under the acting in conjunction of base plate uplift pressure and negative pressure.

Basic thought of the present invention is to become to be provided with before slope section base plate negative pressure produces the position in the diffusion of flood discharging tunnel torrent to fall bank;, bottom water flow forms the concora crush cavity so that taking place to separate; the concora crush cavity is communicated with atmosphere by the concora crush hole; to eliminate the base plate negative pressure that the diffusion of flood discharging tunnel torrent becomes the slope section, the safety of protection flood discharging tunnel facility.

Elimination flood discharging tunnel torrent diffusion disclosed by the invention becomes the facility of slope section base plate negative pressure, comprise that being arranged on falling bank and being arranged on before the flood discharging tunnel diffuser base plate negative pressuren zone falls the bank two ends and be positioned at the outer concora crush hole of flood discharging tunnel side wall, flood discharging tunnel sluices down to flow through and falls jet face that bank produces and fall the cavity that forms between the bank base plate face and be communicated with atmosphere by the concora crush hole, and promptly the concora crush hole is passed the flood discharging tunnel side wall and fallen bank base plate superjacent air space and be communicated with.

Elimination flood discharge hole outlet torrent diffusion disclosed by the invention becomes the facility of slope section base plate negative pressure, both become slope section base plate and be Parabolic flood discharging tunnel applicable to the torrent diffusion, also become the flood discharging tunnel that slope section base plate is connected anti-arc shaped form after into wet strange curve, be applicable to that equally also the torrent diffusion becomes the flood discharging tunnel that slope section base plate is connected the abrupt slope type after into anterior gentle slope applicable to torrent diffusion.When the diffusion of flood discharging tunnel torrent became slope section base plate into parabolic type, the described bank that falls should be designed to vertically fall bank; When flood discharging tunnel torrent diffusion became slope section base plate and is connected anti-arc shaped form after into wet strange curve, the described bank that falls should be designed to bank groove mating type; When flood discharging tunnel torrent diffusion becomes slope section base plate and is connected the abrupt slope type after into anterior gentle slope, can fall the bank downstream base plate gradient with the jet face that increases that sluicing down flows through and fall bank and produce and fall the cavity length that forms between the bank base plate face by increase.

In technique scheme of the present invention, when sluicing down to flow through, flood discharging tunnel falls jet face that bank produces can not cover flood discharging tunnel diffuser base plate negative pressuren zone the time, can highly be not more than the bank of choosing of 0.30m by design one before falling bank, sluice down to flow through and fall jet face that bank produces and fall the cavity scope that forms between the bank base plate face to increase flood discharging tunnel, promptly increasing sluices down flows through and falls the jet face length degree of bank generation.The height of choosing bank is preferably in 0.10～0.20m scope.

In technique scheme of the present invention, fall the bank height and preferably be controlled at 0.30～1.00m scope.The exit position in concora crush hole can be positioned at outside the flood discharging tunnel side wall, also can be arranged on the suitable position of flood discharging tunnel side wall.The concora crush hole can be by single wide throughput 12～15m ³/ (s.m), wind speed designs less than 60m/s.The concora crush hole dimension is by falling the bank height, falling bank and hold the decision of factors such as gas ability and base plate range of negative pressure, its basal area A under the arm _αCan calculate by following formula.

In the formula:

Q _a-total throughput, Q _a=Bq _a, m ³/ s;

Q _a-single wide throughput, $q_a=0.023{\mathrm{\&mu;}}_1{L}_c\sqrt{\cos \mathrm{\&alpha;}},{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="HDA0000067336090000012.png"\; state="\{\{state\}\}">m</figure-callout>}}^3/(s.m)$

B-concora crush facility flow section width, m;

μ ₁-concora crush facility falls flow velocity on the bank, m/s;

L _c-concora crush ventilation cavity length, m;

α-downstream base plate the gradient;

-air vent wind speed coefficient, 0.67～0.82;

ρ _w, ρ _aThe density of-water and air, p _w/ ρ _a=773;

Δ h _aPermission negative pressure value in the-cavity is no more than the 0.5m water column;

L _cCalculating see following projectile theoretical formula (2):

$L_c=L_{\max }(1-0.4\sqrt{\mathrm{\&Delta;}\stackrel{\&OverBar;}{p}}),\mathrm{\&Delta;}\stackrel{\&OverBar;}{p}=\frac{\mathrm{\&Delta;p}}{\mathrm{\&gamma;}{h}_0};$

$L_{\max }=\frac{\mathrm{<figure-callout\; id="2"\; label="F\; r"\; filenames="HDA0000067336090000012.png,HDA0000067336090000031.png"\; state="\{\{state\}\}">F</figure-callout>}{r}^{}{}^2\stackrel{\&OverBar;}{\mathrm{\&theta;}}{h}_0}{\cos \mathrm{\&alpha;}}[1+\sqrt{2+\frac{2T\cos \mathrm{\&alpha;}}{{\left(\stackrel{\&OverBar;}{\mathrm{\&theta;}}\mathrm{Fr}\right)}^2}}];$

T＝(Δ+y ₀)/h ₀， $\begin{array}{cc}\stackrel{\&OverBar;}{\mathrm{\&theta;}}=\mathrm{\&theta;}\sqrt{\mathrm{th}\left(\frac{\mathrm{\&Delta;}}{\mathrm{\&theta;}{h}_0}\right)},& \mathrm{Fr}=\frac{{\mathrm{\&mu;}}_1}{\sqrt{g{h}_0}}\end{array}---\left(2\right)$

In the formula:

L _MaxThe maximum cavity length that-impelling water body forms, m;

Δ p-negative pressure and cavity, pa;

-revised negative pressure and cavity coefficient;

h ₀-concora crush facility bank headwater depth, m;

Δ-concora crush facility falls bank height, m;

y ₀-concora crush facility is chosen bank height, m;

θ-concora crush facility is chosen the bank angle;

-revised concora crush facility is chosen the bank angle;

For this concora crush cavity length, obtain following fit equation according to model testing and prototype measurement achievement:

$\frac{{\mathrm{<figure-callout\; id="1"\; label="L\; c\; h"\; filenames="HDA0000067336090000041.png,HDA0000067336090000052.png"\; state="\{\{state\}\}">L</figure-callout>}}_c}{h_{}}=-0.0996{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="HDA0000067336090000041.png,HDA0000067336090000052.png"\; state="\{\{state\}\}">X</figure-callout>}}_1^2+3.5326X_1-1.3523---\left(3\right)$

${\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="HDA0000067336090000041.png,HDA0000067336090000052.png"\; state="\{\{state\}\}">X</figure-callout>}}_1=\frac{{\mathrm{\&mu;}}_1}{\sqrt{g{h}_0}}\sqrt{\frac{\mathrm{\&Delta;}}{h_0}}\frac{1}{\cos \mathrm{\&alpha;}\cos \mathrm{\&theta;}}$

X ₁Be the comprehensive parameters of comprehensive each factor to the cavity length influence, it is the same respectively to meet meaning in the formula.

The design in concora crush hole is a control criterion to eliminate cavity and flood discharging tunnel base plate negative pressure, determines the size in concora crush hole.

Concrete enforcement of the present invention, its process at first are to judge that the diffusion of flood discharging tunnel base plate torrent becomes the slope section and whether produces negative pressure, and range of negative pressure, and this need determine by physical experiments; If base plate has negative pressure, then need to be provided with this concora crush facility, the bank height that falls of concora crush facility is generally 0.3～1.0m, and sluicing instantly flows through falls jet face that bank produces can not cover diffuser base plate negative pressuren zone the time, can set up 0.1～0.2m again and choose bank for a short time.The concora crush hole dimension can be calculated by top described formula to be determined, and the consideration that combines with actual conditions.Adopt in engineering before the concora crush facility of the present invention's proposition, need subdue the effect of base plate negative pressure by physical experiments optimization and checking concora crush facility, and the concora crush facility shape.

For high flow rate, shallow water is dark and the flood discharging tunnel of big base slope gradient (being high Froude number), becomes the facility that the slope section is provided with elimination base plate negative pressure disclosed by the invention in diffusion, can produce following ten minutes beneficial technical effects.

1,, avoided base plate to produce greatly negative pressure and gone to pot owing to sluice down to flow through and fall the cavity that forms between jet face that bank produces and the base plate and effectively be communicated with atmosphere.

2, can reduce flood discharge hole outlet to the absorption basin diffuser along the journey pressure change, promptly reduce its barometric gradient, thereby effectively avoid shearing the possibility of cavitation.

3, the cavity behind the concora crush facility can form the bottom aeration, forms the aeration form of forcing with the surface from aeration, can effectively reduce or remit flood discharging tunnel base plate and side wall generation cavitation or cavitation erosion.

4, increase the aeration concentrater of current before the pond, the inflow of high concentration aerated water can increase the energy dissipation rate of absorption basin behind the pond, thereby can reduce absorption basin length.

Description of drawings

Accompanying drawing 1: the torrent diffusion becomes slope section base plate and is parabolic type, and the downstream is connected falls bank underflow type absorption basin, and wherein Fig. 1-1 is the vertical profile schematic diagram; Fig. 1-2 is a floor map.

Accompanying drawing 2: torrent diffusion becomes slope section base plate and is connected anti-arc shaped form after into wet strange curve, and the downstream is connected falls bank underflow type absorption basin, wherein Fig. 2-1 vertical profile intention; Fig. 2-2 is a floor map.

Accompanying drawing 3: torrent diffusion becomes a slope section base plate and is parabolic type, and the torrent diffusion becomes the slope section and is provided with the concora crush facility, the concora crush facility fall bank for vertically falling bank, wherein Fig. 3-1 is the vertical profile schematic diagram; Fig. 3-2 is a floor map; Fig. 3-3 is the partial enlarged drawing of A part among Fig. 3-1; Fig. 3-4 is the partial enlarged drawing of B part among Fig. 3-2; Fig. 3-5 is provided with the vertical profile schematic diagram of choosing bank for before falling bank; Fig. 3-6 is the partial enlarged drawing of C part among Fig. 3-5; Fig. 3-7 is connected abrupt slope type vertical profile schematic diagram behind the anterior gentle slope; Fig. 3-8 is the partial enlarged drawing of D part among Fig. 3-7.

Fig. 4: torrent diffusion becomes slope section base plate and is connected anti-arc shaped form after into wet strange curve, and the torrent diffusion becomes the slope section and is provided with the concora crush facility, and the bank that falls of concora crush facility is a bank groove mating type, and wherein Fig. 4-1 is the vertical profile schematic diagram; Fig. 4-2 is a floor map; Fig. 4-3 is the partial enlarged drawing of E part among Fig. 4-1; Fig. 4-4 is the partial enlarged drawing of F part among Fig. 4-2; Fig. 4-5 is provided with the vertical profile schematic diagram of choosing bank for before falling bank; Fig. 4-6 is the partial enlarged drawing of the G part among Fig. 4-5.

Fig. 5: be the vertical profile schematic diagram of a specific embodiment of the present invention, the torrent diffusion becomes slope section base plate and is parabolic type.

Fig. 6: concora crush facility front and back Bottom Pressure value correlation curve figure is set for torrent diffusion shown in Figure 5 becomes slope section base plate.

In above-mentioned accompanying drawing, the sign of each shown by reference numeral is to liking:

Water surface curve in the 1-flood discharging tunnel torrent diffuser; The 2-absorption basin; 3-flood discharging tunnel torrent diffuser; 4-falls bank (groove); 5-concora crush air vent; 6-concora crush cavity; 7-chooses bank.

The specific embodiment

Provide embodiments of the invention below in conjunction with the explanation of accompanying drawing drawing, and the present invention is further illustrated by embodiment.What be necessary here to specify is, the specific embodiment of the present invention is not limited to the form among the embodiment, according to content disclosed by the invention, the person of ordinary skill in the field can also take other concrete mode to implement, therefore, embodiment can not be interpreted as it is the specific embodiment that the present invention only can implement.

Case history

This case history is certain large-scale power station bank flood discharging tunnel, and its outlet absorption basin form is for falling the bank disspation through hydraudic jimp, and its torrent diffusion becomes slope section base plate and is parabolic type, and parabolic equation is

As shown in Figure 5, when in this parabolic segment, not establishing the concora crush facility, let out 2+0640～let out in pile No. and can produce 0 in the 2+0688 scope～-negative pressure of 0.6m.In order to eliminate this negative pressure, in the parabolic segment pile No. is to let out the 2+0644.961m place to be provided with by falling the concora crush facility that bank and concora crush hole constitute, the concora crush hole is arranged on the flood discharging tunnel side wall body, pass the flood discharging tunnel side wall and fall bank base plate superjacent air space and be communicated with, falling the bank height is 0.9m, and the concora crush hole dimension is 1.5 * 2.0m.Fig. 6 contrasts for this torrent diffuser base plate negative pressure value before and after the concora crush facility is set.Fig. 6 explanation, be provided with in this parabolic segment after the concora crush facility, flood discharging tunnel has that equal pressure is not all malleation when pressing the section base plate, hour the most all pressure be 0.1 (* 9.8KPa), show that this concora crush facility with the elimination of the negative pressure in the former negative pressure section, has the effect of eliminating torrent diffuser base plate negative pressure preferably.

Claims (10)

1. eliminate the facility that the diffusion of flood discharging tunnel torrent becomes slope section base plate negative pressure for one kind, it is characterized in that comprising that being arranged on falling bank and being arranged on before the flood discharging tunnel diffuser base plate negative pressuren zone falls the bank two ends and be positioned at the outer concora crush hole of flood discharging tunnel side wall, flood discharging tunnel sluices down to flow through and falls jet face that bank produces and fall the cavity that forms between the bank base plate face and be communicated with atmosphere by the concora crush hole.

2. elimination flood discharging tunnel torrent diffusion according to claim 1 becomes the facility of slope section base plate negative pressure, it is characterized in that the described bank that falls is for vertically falling bank when the diffusion of flood discharging tunnel torrent becomes slope section base plate into parabolic type.

3. elimination flood discharging tunnel torrent according to claim 1 diffusion becomes the facility of slope section base plate negative pressure, it is characterized in that when the diffusion of flood discharging tunnel torrent become slope section base plate into wet strange curve after during the anti-arc shaped form of linking, the described bank that falls is a bank groove mating type.

4. elimination flood discharging tunnel torrent diffusion according to claim 1 becomes the facility of slope section base plate negative pressure, it is characterized in that when flood discharging tunnel torrent diffusion becomes slope section base plate and is connected the abrupt slope type after into anterior gentle slope, fall the bank downstream base plate gradient by increase and increase that sluicing down flows through and fall the jet face that bank produces and fall the cavity length that forms between the bank base plate face.

5. spread the facility that becomes slope section base plate negative pressure according to the described elimination flood discharging tunnel of one of claim 1 to 4 torrent, it is characterized in that falling jet face that bank produces can not cover flood discharging tunnel diffuser base plate negative pressuren zone the time when flood discharging tunnel sluices down to flow through, design one highly is not more than the bank of choosing of 0.30m before falling bank.

6. elimination flood discharging tunnel torrent according to claim 5 diffusion becomes the facility of slope section base plate negative pressure, and the height that it is characterized in that choosing bank is 0.10～0.20m.

7. according to the facility of the described elimination flood discharging tunnel of one of claim 1 to 4 torrent diffusion change slope section base plate negative pressure, it is characterized in that falling the bank height is 0.30～1.00m.

8. elimination flood discharging tunnel torrent diffusion according to claim 6 becomes the facility of slope section base plate negative pressure, and it is characterized in that falling the bank height is 0.30～1.00m

9. according to the facility of the described elimination flood discharging tunnel of one of claim 1 to 4 torrent diffusion change slope section base plate negative pressure, it is characterized in that the concora crush hole is by single wide throughput 12～15m ³/ (s.m), wind speed is determined less than 60m/s.

10. elimination flood discharging tunnel torrent diffusion according to claim 8 becomes the facility of slope section base plate negative pressure, it is characterized in that the concora crush hole is by single wide throughput 12～15m ³/ (s.m), wind speed is determined less than 60m/s.

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