Design method for energy dissipation and scour prevention downstream of steel dam gate

Abstract

The application discloses a design method for energy dissipation and impact prevention downstream of a steel dam gate, and determines the minimum length of the energy dissipation structure downstream of the steel dam gate according to the farthest distance of the overflow water tongue of the steel dam gate. The actual impact and rolling area range can be included, the situation that the end of the bottom plate of the steel dam gate is hollowed out is avoided, the length of the stilling basin or the water cushion pond is set according to the value, the engineering construction amount can be reduced, the construction cost is reduced, and the safety of the energy dissipation structure behind the gate can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel dam gate, in particular to a design method for energy dissipation and scour prevention downstream of a steel dam gate. BACKGROUND

[0002] The steel dam gate is a new type of adjustable overflow gate, which is composed of a civil structure, a steel gate body with a fixed shaft, and hoist equipment. Since it can be designed to be relatively wide, the pier of the gate hole can be omitted, so not only the structure is simple, but also the civil investment can be saved, the water can be stored by standing the gate, the flood can be discharged by lying the gate, the water level can be adjusted by appropriately opening the gate, and the artificial waterfall landscape effect can be formed by passing water through the gate top.

[0003] However, when the steel dam gate is discharged, due to the unique discharge form of the steel dam gate and the water tongue projection range and water flow oscillation characteristics behind the gate, the water flow directly scours the bottom plate of the steel dam gate, which will hollow out the lower end of the steel dam gate bottom plate, forming a safety hazard. Therefore, the existing conventional method is to set a stilling basin or a water cushion pond or a scouring bottom plate downstream of the gate to solve the problem of hollowing out the lower end of the steel dam gate bottom plate. However, there is no corresponding specification requirement and calculation method at present to clearly require the length of the stilling basin or the water cushion pond or the scouring bottom plate to be set, so at present only the conventional energy dissipation formula can be used for calculation. However, the water flow form corresponding to the conventional energy dissipation formula is different from the water flow form corresponding to the steel dam gate, so although this calculation method can solve the problem of hollowing out the lower end of the steel dam gate bottom plate, the length of the stilling basin or the water cushion pond or the scouring bottom plate calculated by using this method will be very long, directly leading to an increase in engineering construction amount and an increase in construction cost. Therefore, a design method for energy dissipation and scour prevention downstream of a steel dam gate is proposed to solve the problems existing in the prior art. SUMMARY

[0004] The purpose of the present application is to provide a design method for energy dissipation and scour prevention downstream of a steel dam gate to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following scheme: the present application provides a design method for energy dissipation and scour prevention downstream of a steel dam gate, which specifically comprises the following steps:

[0006] S1, determining the farthest distance L of the overflow water tongue of the steel dam gate 抛 :

[0007] L 抛 = L s + L p (1)

[0008] wherein,

[0009] L s is the horizontal projection length of the gate during the opening process (unit: m).

[0010] L p The maximum distance that the water flow hits the bottom plate horizontally (unit: m);

[0011] S2. Determine the length L of the energy dissipation structure downstream of the steel dam gate 池 :

[0012] L 池 =ζ1×L 抛 (2)

[0013] in,

[0014] L 池 is the distance between the tail of the downstream energy dissipation structure of the steel dam gate and the center of the gate shaft (unit: m);

[0015] ζ1 is the calculation coefficient of energy dissipation and anti-impact range.

[0016] Preferably, it also includes:

[0017] S0. Set up a water retaining sill upstream of the steel dam gate and determine the distance H from the top of the water retaining sill to the top of the gate (unit: m);

[0018] S01. Determine the height difference Δ1 between the center of the steel dam gate shaft and the top of the upstream retaining sill (unit: m);

[0019] S02. Determine the gate's rotation radius R:

[0020] R=H+Δ1 (3)

[0021] S03. Determine the height difference Δ2 between the center of the steel dam gate's rotation axis and the downstream riverbed (unit: m);

[0022] S04. Determine the overflow head height Δh of the steel dam gate (unit: m).

[0023] Preferably, according to formula (3), the horizontal projection length L of the gate during the gate opening process is s :

[0024] L s =R×SINθ (4)

[0025] Where θ is the vertical angle of gate opening;

[0026] According to formula (3), the maximum distance L that the water flow can hit the bottom plate is p :

[0027]

[0028] According to formula (1), formula (4) and formula (5), the maximum distance L that the overflow water tongue of the steel dam gate can hit is 抛 :

[0029]

[0030] The minimum length of the energy dissipation structure downstream of the steel dam gate is determined according to formula (2) and formula (6).

[0031] Preferably, the calculation formula of the calculation coefficient of the energy dissipation and scour prevention range is as follows:

[0032]

[0033] According to formula (2), formula (6) and formula (7), the following is obtained:

[0034]

[0035] L 池 The minimum length of the energy dissipation structure downstream of the steel dam gate.

[0036] The present application discloses the following technical effects:

[0037] The minimum length of the energy dissipation structure downstream of the steel dam gate determined by the steel dam gate downstream energy dissipation and scour prevention design method provided by the present application can include the actual impact and rolling area, avoid the situation that the end of the steel dam gate bottom plate is hollowed out, and the length of the stilling basin or the flip bucket can be set according to the value, so that the engineering construction amount is reduced, the construction cost is reduced, and the safety of the energy dissipation structure downstream of the gate is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] Figure 1 It is a schematic diagram of the projection of the overflow water tongue when the steel dam gate is closed;

[0040] Figure 2 It is a schematic diagram of the projection of the overflow water tongue when the gate of the steel dam gate is inclined downstream after being opened;

[0041] Figure 3 It is a schematic diagram of the horizontal projection of the overflow water tongue;

[0042] Figure 4 It is a relationship diagram of the 3.35m high gate, 0.5m overflow projection water tongue and energy dissipation and scour prevention range of the combination of the steel dam gate and the pump station;

[0043] Figure 5 It is a relationship diagram of the 3.9m high gate, 0.5m overflow projection water tongue and energy dissipation and scour prevention range of the combination of the steel dam gate and the pump station;

[0044] Figure 6 The steel dam gate and pump station combined arrangement door high 4.5m, overflow 0.4m water tongue and energy dissipation and anti-scour range relationship diagram is provided;

[0045] Figure 7 The steel dam gate and pump station combined arrangement door high 4.5m, overflow 0.5m water tongue and energy dissipation and anti-scour range relationship diagram is provided;

[0046] Figure 8 The steel dam gate and pump station combined arrangement door high 4.5m, overflow 0.5m water tongue and energy dissipation and anti-scour range relationship diagram is provided;

[0047] Figure 9 The steel dam gate and pump station combined arrangement door high 4.5m, overflow 0.5m water tongue and energy dissipation and anti-scour range relationship diagram is provided;

[0048] Figure 10 The steel dam gate and pump station combined arrangement door high 4.5m, overflow 0.5m water tongue and energy dissipation and anti-scour range relationship diagram is provided;

[0049] Figure 11 The steel dam gate and pump station combined arrangement door high 4.5m, overflow 0.5m water tongue and energy dissipation and anti-scour range relationship diagram is provided;

[0050] Figure 12 The steel dam gate and pump station combined arrangement door high 4.5m, overflow 0.5m water tongue and energy dissipation and anti-scour range relationship diagram is provided. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0052] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0053] The present application provides a steel dam gate downstream energy dissipation and anti-scour design method, specifically comprising the following steps:

[0054] S1, determining the farthest distance L of the steel dam gate overflow water tongue 抛 :

[0055] L 抛 = L s + L p (1)

[0056] wherein,

[0057] L s is the horizontal projection length of the gate during the opening process (unit: m);

[0058] L p is the farthest distance of the flat impact of the water flow to the bottom plate (unit: m);

[0059] S2, determining the length L of the energy dissipation structure downstream of the steel dam gate 池 :

[0060] L 池 = ζ1×L 抛 (2)

[0061] wherein,

[0062] L 池 is the distance from the tail of the energy dissipation structure downstream of the steel dam gate to the center of the gate rotation shaft (unit: m);

[0063] ζ1 is the calculation coefficient of the energy dissipation and scour prevention range.

[0064] Further, it further comprises:

[0065] S0, setting a water retaining ridge upstream of the steel dam gate, and determining the distance H from the top of the water retaining ridge to the top of the gate (unit: m);

[0066] S01, determining the height difference Δ1 between the center of the rotation shaft of the steel dam gate and the top of the upstream water retaining ridge (unit: m);

[0067] S02, determining the rotation radius R of the gate:

[0068] R = H + Δ1 (3)

[0069] S03, determining the height difference Δ2 between the center of the rotation shaft of the steel dam gate and the bottom of the river downstream (unit: m);

[0070] S04, determining the overflow water head height Δh of the steel dam gate (unit: m).

[0071] Further, according to formula (3), the horizontal projection length L of the gate during the opening process s :

[0072] L s = R × SINθ (4)

[0073] wherein, θ is the vertical angle of the gate opening;

[0074] When the steel dam gate is closed (0° opening), the overflow water is thrown to the downstream and can be calculated by the parabolic trajectory model, i.e. the water flow is in the horizontal direction with uniform velocity and in the vertical direction with free fall, the horizontal direction of the parabolic trajectory has only initial velocity v0 without acceleration, so the horizontal displacement x = v0t, and the horizontal velocity v x = v0, the vertical direction of the parabolic trajectory is equivalent to the free fall with initial velocity 0, x the vertical direction of the parabolic trajectory is equivalent to the free fall with initial velocity 0, v y = gt, the vertical direction of the parabolic trajectory is equivalent to the free fall with initial velocity 0,

[0075] When the steel dam gate is opened, the gate is tilted downstream and the top of the gate moves backward, and the backward distance is the horizontal projection length of the gate during the opening process. Therefore, the throwing distance of the overflow water tongue of the steel dam gate is determined by the sum of the horizontal projection length of the gate generated by the opening angle of the gate and the horizontal distance of the water flow generated by the overflow water head.

[0076] According to formula (3), the farthest distance L p of the water flow to the bottom plate by the parabolic trajectory is:

[0077]

[0078] According to formula (1), formula (4) and formula (5), the farthest distance L 抛 of the overflow water tongue of the steel dam gate to the bottom plate is:

[0079]

[0080] According to formula (2) and formula (6), the minimum length of the downstream energy dissipation structure of the steel dam gate is determined.

[0081] Further, the calculation formula of the energy dissipation and scour prevention range coefficient is:

[0082]

[0083] According to formula (2), formula (6) and formula (7), it is obtained that:

[0084]

[0085] L 池 is the minimum length of the downstream energy dissipation structure of the steel dam gate.

[0086] The derivation of the simulation interval of the stilling basin aims to introduce the impact jump and flip interval caused by the water tongue overflow of the steel dam gate, including within the stilling basin, to avoid insufficient energy dissipation, which leads to water jumping and flipping outside the stilling basin, and causes the instability and damage of the downstream apron. If the downstream water depth is large and the water level amplitude is small, there is enough water cushion, and the stilling basin can also not be set. The test and simulation results of the stilling basin setting interval of the steel dam gate under typical operating conditions and the jump and flip interval after the water tongue hits the bottom plate are shown in Tables 1-9.

[0087] Embodiment

[0088] The steel dam gate (gate width 6.0 m) pump gate combined arrangement scheme gate height 3.35 m, 3.9 m, 4.5 m, and the steel dam gate (gate width 12.0 m) single hole arrangement scheme gate height 5.5 m, 6.5 m, 7.5 m, different overflow water head, different gate opening, different upstream and downstream water depth, the recommended stilling basin tailgate horizontal distance L from the center of the gate shaft under each operating condition 池 and the test data of the water tongue hitting the bottom plate position are shown in Tables 1-9.

[0089] L 3min The minimum value of the horizontal distance from the center of the steel dam gate shaft to the centerline point of the water tongue hitting the bottom plate is (unit: m);

[0090] L 3max The maximum value of the horizontal distance from the center of the steel dam gate shaft to the centerline point of the water tongue hitting the bottom plate is (unit: m);

[0091] L Bmin The minimum value of the horizontal distance from the center of the steel dam gate shaft to the rolling range of the water tongue hitting the bottom plate is (unit: m);

[0092] L Bmax The maximum value of the horizontal distance from the center of the steel dam gate shaft to the rolling range of the water tongue hitting the bottom plate is (unit: m).

[0093] Table 1 Steel dam gate + pump station combined arrangement gate height 3.35 m, benefit flow 0.5 m water tongue and energy dissipation and anti-erosion range

[0094]

[0095] Table 2 Steel dam gate + pump station combined arrangement gate height 3.9 m, benefit flow 0.5 m water tongue and energy dissipation and anti-erosion range

[0096]

[0097] Table 3 Steel dam gate + pump station combined arrangement gate height 4.5 m, benefit flow 0.4 m water tongue and energy dissipation and anti-erosion range

[0098]

[0099] Table 4 Steel dam gate + pump station combined arrangement door height 4.5m, overflow 0.5m, jet water tongue and energy dissipation and scour protection range

[0100]

[0101] Table 5 Steel dam gate single hole arrangement door height 5.5m, overflow 0.5m, jet water tongue and energy dissipation and scour protection range

[0102]

[0103]

[0104] Table 6 Steel dam gate single hole arrangement door height 6.5m, overflow 0.5m, jet water tongue and energy dissipation and scour protection range

[0105]

[0106] Table 7 Steel dam gate single hole arrangement door height 7.5m, overflow 0.5m, jet water tongue and energy dissipation and scour protection range

[0107]

[0108] Table 8 Steel dam gate door height 6.5m, opening 30°, overflow 0.5m, jet water tongue and energy dissipation and scour protection range

[0109]

[0110]

[0111] Table 9 Steel dam gate opening angle 30°, different overflow water head, jet water tongue and energy dissipation and scour protection range

[0112]

[0113] According to the test results, the position of the stilling basin tailgate calculated by the fitting formula is basically consistent with the impact and rolling area of the overflow water tongue, and the actual impact and rolling area range is included, the length of the stilling basin or the water cushion is set according to the value, the engineering quantity of the designed stilling basin is saved by 7% to 58%, and the safety of the energy dissipation structure behind the gate can be ensured.

[0114] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0115] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.

Claims

1. A design method for energy dissipation and anti-scour of downstream of steel dam gate, characterized by: The specific steps include: S1. Determine the maximum distance L of the overflow water tongue of the steel dam gate 抛 : L 抛 =L s +L p (1) in, L s is the horizontal projection length of the gate during the gate opening process (unit: m); L p The maximum distance that the water flow hits the bottom plate horizontally (unit: m); S2. Determine the length L of the energy dissipation structure downstream of the steel dam gate 池 : L 池 =ζ1×L 抛 (2) in, L 池 is the distance between the tail of the downstream energy dissipation structure of the steel dam gate and the center of the gate shaft (unit: m); ζ1 is the calculation coefficient of energy dissipation and anti-impact range; Also includes: S0. Set up a water retaining sill upstream of the steel dam gate and determine the distance H from the top of the water retaining sill to the top of the gate (unit: m); S01. Determine the height difference Δ1 between the center of the steel dam gate shaft and the top of the upstream retaining sill (unit: m); S02. Determine the gate's rotation radius R: R=H+Δ1 (3) S03. Determine the height difference Δ2 between the center of the steel dam gate's rotation axis and the downstream riverbed (unit: m); S04. Determine the overflow head height Δh of the steel dam gate (unit: m); According to formula (3), the horizontal projection length L of the gate during the gate opening process is s : L s =R×SINθ (4) Where θ is the vertical angle of gate opening; According to formula (3), the maximum distance L that the water flow can hit the bottom plate is p : According to formula (1), formula (4) and formula (5), the maximum distance L that the overflow water tongue of the steel dam gate can hit is 抛 : According to formula (2) and formula (6), the minimum length of the energy dissipation structure downstream of the steel dam gate is determined; The calculation formula for the energy dissipation and impact prevention range coefficient is: According to formula (2), formula (6) and formula (7), we can get: L 池 It is the minimum length of the energy dissipation structure downstream of the steel dam gate.

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