Annular overflow weir vertical shaft spillway structure with trapezoidal cofferdams

Abstract

The utility model discloses an annular downflow weir vertical shaft spillway structure with a trapezoid cofferdam, which comprises an annular downflow weir, a vertical shaft connected to the bottom of the inner side of the annular downflow weir, a round-to-square section connected to the bottom of the vertical shaft, a stilling well connected to the bottom of the round-to-square section, a discharge hole arranged on the side surface of the stilling well, and a pressure slope connected to the discharge hole on the side surface of the stilling well. And the pressure slope structure further comprises a trapezoidal cofferdam, and the trapezoidal cofferdam is arranged on the periphery of the side wall of the annular overflow weir. The annular downflow weir vertical shaft spillway structure with the trapezoidal cofferdam solves the problem that due to the fact that a traditional annular downflow weir vertical shaft spillway tunnel is affected by asymmetric terrains, the flow state of water flow entering a vertical shaft is not uniform, and the phenomenon of water flow bias in the vertical shaft is serious.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of water conservancy project spillway structure, and specifically relates to annular overflow weir shaft spillway structure with trapezoidal cofferdam. BACKGROUND

[0002] The traditional annular overflow weir shaft spillway structure has the following technical defects under the condition of complex asymmetric topography: when the topography causes a large included angle between the direction of incoming flow and the axis of the shaft, the annular overflow weir which is axisymmetric cannot effectively adjust the direction of the flow, resulting in a significant circumferential velocity gradient when the flow enters the shaft, which is specifically manifested as the flow continuously impacting one side of the shaft wall. If operated for a long time, the shaft will be damaged due to the intensified flow turbulence, which threatens the safety of the structure. In terms of discharge capacity, the traditional annular overflow weir shaft is difficult to adapt to the variable water level condition, which seriously restricts the efficiency of the spillway under high water head conditions. SUMMARY

[0003] The utility model discloses a kind of annular overflow weir shaft spillway structures with trapezoidal cofferdam, solve the problem that the traditional annular overflow weir shaft spillway structure is influenced by asymmetric topography, flow state is not uniform when flow enters shaft, resulting in the serious problem of water flow deflection in shaft well.

[0004] The utility model discloses the technical scheme in the application is annular overflow weir shaft spillway structure with trapezoidal cofferdam, including annular overflow weir, annular overflow weir inside bottom is connected with shaft, shaft bottom is connected with circle changes square section, circle changes square section bottom is connected with stilling well, and the side of stilling well is equipped with discharge hole, and the side of stilling well is connected with pressure slope at discharge hole, and the other end of pressure slope is connected with water tunnel, further including trapezoidal cofferdam, trapezoidal cofferdam is located in annular overflow weir side wall periphery.

[0005] The utility model has the characteristics that:

[0006] The water inlet of annular overflow weir is horn-shaped water inlet, and the inner diameter of the bottom of annular overflow weir is the same as the inner diameter of the shaft.

[0007] The trapezoidal cofferdam, annular overflow weir and shaft form a circular ring structure, and the center of the trapezoidal cofferdam coincides with the center of the annular overflow weir and the shaft.

[0008] The height ratio of the trapezoidal cofferdam to the annular overflow weir is 1:2-3:4.

[0009] The trapezoidal cofferdam includes an inner side wall, and the distance from the bottom of the inner side wall to the side wall of the annular overflow weir is 1:2.5 times the inner diameter of the shaft.

[0010] The trapezoidal cofferdam includes an outer side wall, and the distance from the bottom of the outer side wall to the side wall of the annular overflow weir is 1:0.7 times the inner diameter of the shaft.

[0011] The trapezoidal cofferdam comprises a trapezoidal cofferdam bottom plate, and a ratio of a width of the trapezoidal cofferdam bottom plate to an inner diameter of the shaft is 1:2.5.

[0012] The trapezoidal cofferdam comprises a trapezoidal cofferdam top, which is composed of a trapezoidal cofferdam inclined line type top structure, a trapezoidal cofferdam inner side circular arc type top structure and a trapezoidal cofferdam outer side circular arc type top structure, the trapezoidal cofferdam inner side circular arc type top structure is tangent to the trapezoidal cofferdam inclined line type top structure and the trapezoidal cofferdam inner side wall, a slope of the trapezoidal cofferdam inner side wall is 1:11-1:7, the trapezoidal cofferdam outer side circular arc type top structure is tangent to the trapezoidal cofferdam inclined line type top structure and the trapezoidal cofferdam outer side wall, and a slope of the trapezoidal cofferdam outer side wall is 1:12-1:8.

[0013] The trapezoidal cofferdam inclined line type top structure is arranged as an inner low and outer high structure along a water flow direction, a slope ratio of the trapezoidal cofferdam inclined line type top structure is 1:2, and a length-width ratio of the trapezoidal cofferdam inclined line type top structure to the trapezoidal cofferdam bottom plate is 1:2.85.

[0014] The trapezoidal cofferdam inner side circular arc type top structure and the trapezoidal cofferdam outer side circular arc type top structure have the same radius, a circular arc radius of the trapezoidal cofferdam inner side circular arc type top structure, a circular arc radius of the trapezoidal cofferdam outer side circular arc type top structure and a length of the trapezoidal cofferdam inclined line type top structure all have a ratio of 1:3.5.

[0015] The trapezoidal cofferdam has the following beneficial effects:

[0016] The annular overflow weir shaft spillway structure with the trapezoidal cofferdam has the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic view of the annular overflow weir shaft spillway structure with the trapezoidal cofferdam of the utility model;

[0018] Figure 2 is a top view of the annular overflow weir shaft spillway structure with the trapezoidal cofferdam of the utility model;

[0019] Figure 3 is a sectional view of the trapezoidal cofferdam of the utility model.

[0020] In the diagram, 1. Annular overflow weir, 2. Trapezoidal cofferdam, 3. Trapezoidal cofferdam oblique crest structure, 4. Trapezoidal cofferdam inner arc-shaped crest structure, 5. Trapezoidal cofferdam outer arc-shaped crest structure, 6. Trapezoidal cofferdam inner sidewall, 7. Trapezoidal cofferdam outer sidewall, 8. Trapezoidal cofferdam bottom plate, 9. Vertical shaft, 10. Circular-to-square section, 11. Stilling well, 12. Slope, 13. Drainage tunnel, 14. Trapezoidal cofferdam crest. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] The present invention provides a ring-shaped overflow weir vertical shaft spillway structure with a trapezoidal cofferdam, such as... Figure 1 As shown, the system includes an annular overflow weir 1, with a vertical shaft 9 connected to the bottom of the inner side of the annular overflow weir 1. A circular-to-square section 10 is connected to the bottom of the vertical shaft 9, and a stilling well 11 is connected to the bottom of the circular-to-square section 10. A discharge hole is provided on the side of the stilling well 11, and a slope 12 is connected to the discharge hole on the side of the stilling well 11. A drainage tunnel 13 is connected to the other end of the slope 12. The system also includes a trapezoidal cofferdam 2, which is located outside the sidewall of the annular overflow weir 1 to facilitate slowing the water flow and ensuring uniform water flow into the annular overflow weir 1. The inlet of the annular overflow weir 1 is a funnel-shaped inlet to facilitate water flow. The inner diameter of the bottom of the annular overflow weir 1 is the same as the inner diameter of the vertical shaft 9. Figure 2 As shown, the trapezoidal cofferdam 2, together with the annular overflow weir 1 and the vertical shaft 9, forms a circular structure. The center of the trapezoidal cofferdam 2 coincides with the center of the annular overflow weir 1 and the vertical shaft 9. The height ratio of the trapezoidal cofferdam 2 to the height of the annular overflow weir 1 is 1:2-3:4. The trapezoidal cofferdam 2 includes an inner sidewall 6, and the ratio of the distance from the bottom of the inner sidewall 6 to the sidewall of the annular overflow weir 1 to the inner diameter of the vertical shaft 9 is 1:2.5. The trapezoidal cofferdam 2 also includes an outer sidewall 7, and the ratio of the distance from the bottom of the outer sidewall 7 to the sidewall of the annular overflow weir 1 to the inner diameter of the vertical shaft 9 is 1:0.7. Figure 3As shown, the trapezoidal cofferdam 2 includes a trapezoidal cofferdam base plate 8, the width of which is in the ratio of 1:2.5 to the inner diameter of the shaft 9; the trapezoidal cofferdam 2 includes a trapezoidal cofferdam crest 14, which is composed of a trapezoidal cofferdam inclined crest structure 3, an inner arc-shaped crest structure 4, and an outer arc-shaped crest structure 5. The trapezoidal cofferdam inclined crest structure 3 ensures smoother water flow. The inner arc-shaped crest structure 4 is tangent to the trapezoidal cofferdam inclined crest structure 3 and the inner sidewall 6. The slope of the inner sidewall 6 is 1:11-1:7. The outer arc-shaped crest structure 5 is tangent to the trapezoidal cofferdam... The inclined weir crest structure 3 and the outer sidewall 7 of the trapezoidal cofferdam are tangent to each other. The slope of the outer sidewall 7 of the trapezoidal cofferdam is 1:12-1:8. The inclined weir crest structure 3 of the trapezoidal cofferdam is designed with an inner lower and outer higher structure along the water flow direction. The slope ratio of the inclined weir crest structure 3 of the trapezoidal cofferdam is 1:2. The ratio of the length of the inclined weir crest structure 3 of the trapezoidal cofferdam to the width of the bottom plate 8 of the trapezoidal cofferdam is 1:2.85. The inner arc-shaped weir crest structure 4 of the trapezoidal cofferdam and the outer arc-shaped weir crest structure 5 of the trapezoidal cofferdam have the same radius. The ratio of the arc radius of the inner arc-shaped weir crest structure 4 of the trapezoidal cofferdam and the arc radius of the outer arc-shaped weir crest structure 5 of the trapezoidal cofferdam to the length of the inclined weir crest structure 3 of the trapezoidal cofferdam is 1:3.5.

[0023] Example 1

[0024] The annular overflow weir vertical shaft spillway structure with trapezoidal cofferdam proposed in this embodiment, such as... Figure 1 As shown, it includes an annular overflow weir 1, a vertical shaft 9 connected to the bottom of the inner side of the annular overflow weir 1, a circular-to-square section 10 connected to the bottom of the vertical shaft 9, a stilling well 11 connected to the bottom of the circular-to-square section 10, a discharge hole opened on the side of the stilling well 11, a pressure slope 12 connected to the discharge hole on the side of the stilling well 11, and a drainage tunnel 13 connected to the other end of the pressure slope 12. It also includes a trapezoidal cofferdam 2, which is located on the outer periphery of the sidewall of the annular overflow weir 1.

[0025] Example 2

[0026] The annular overflow weir vertical shaft spillway structure with trapezoidal cofferdam proposed in this embodiment, such as... Figure 1 As shown, it includes an annular overflow weir 1, a vertical shaft 9 connected to the bottom of the inner side of the annular overflow weir 1, a circular-to-square section 10 connected to the bottom of the vertical shaft 9, a stilling well 11 connected to the bottom of the circular-to-square section 10, a discharge hole opened on the side of the stilling well 11, a pressure slope 12 connected to the discharge hole on the side of the stilling well 11, and a drainage tunnel 13 connected to the other end of the pressure slope 12. It also includes a trapezoidal cofferdam 2, which is located on the outer periphery of the sidewall of the annular overflow weir 1. The inlet of the annular overflow weir 1 is a funnel-shaped inlet, and the inner diameter of the bottom of the annular overflow weir 1 is the same as the inner diameter of the vertical shaft 9.

[0027] Example 3

[0028] The vertical shaft spillway structure with the ring overflow weir and the ladder-shaped cofferdam provided by the embodiment includes a ring overflow weir 1, a vertical shaft 9 connected to the inside bottom of the ring overflow weir 1, a round-to-square section 10 connected to the bottom of the vertical shaft 9, a stilling well 11 connected to the bottom of the round-to-square section 10, a flow hole formed in the side of the stilling well 11, a pressure slope 12 connected to the side of the stilling well 11 at the flow hole, and a water outlet tunnel 13 connected to the other end of the pressure slope 12. Figure 1 The vertical shaft spillway structure with the ring overflow weir and the ladder-shaped cofferdam provided by the embodiment includes a ring overflow weir 1, a vertical shaft 9 connected to the inside bottom of the ring overflow weir 1, a round-to-square section 10 connected to the bottom of the vertical shaft 9, a stilling well 11 connected to the bottom of the round-to-square section 10, a flow hole formed in the side of the stilling well 11, a pressure slope 12 connected to the side of the stilling well 11 at the flow hole, and a water outlet tunnel 13 connected to the other end of the pressure slope 12. Figure 2 As shown in FIG. 4, the ladder-shaped cofferdam 2 and the ring overflow weir 1 and the vertical shaft 9 form a circular ring structure, and the center of the circular ring structure of the ladder-shaped cofferdam 2 coincides with the center of the circular ring structure of the ring overflow weir 1 and the vertical shaft 9.

[0029] Embodiment 4

[0030] The vertical shaft spillway structure with the ring overflow weir and the ladder-shaped cofferdam provided by the embodiment includes a ring overflow weir 1, a vertical shaft 9 connected to the inside bottom of the ring overflow weir 1, a round-to-square section 10 connected to the bottom of the vertical shaft 9, a stilling well 11 connected to the bottom of the round-to-square section 10, a flow hole formed in the side of the stilling well 11, a pressure slope 12 connected to the side of the stilling well 11 at the flow hole, and a water outlet tunnel 13 connected to the other end of the pressure slope 12. Figure 1 The vertical shaft spillway structure with the ring overflow weir and the ladder-shaped cofferdam provided by the embodiment includes a ring overflow weir 1, a vertical shaft 9 connected to the inside bottom of the ring overflow weir 1, a round-to-square section 10 connected to the bottom of the vertical shaft 9, a stilling well 11 connected to the bottom of the round-to-square section 10, a flow hole formed in the side of the stilling well 11, a pressure slope 12 connected to the side of the stilling well 11 at the flow hole, and a water outlet tunnel 13 connected to the other end of the pressure slope 12. Figure 2 As shown in FIG. 4, the ladder-shaped cofferdam 2 and the ring overflow weir 1 and the vertical shaft 9 form a circular ring structure, and the center of the circular ring structure of the ladder-shaped cofferdam 2 coincides with the center of the circular ring structure of the ring overflow weir 1 and the vertical shaft 9.

[0031] Embodiment 5

[0032] The vertical shaft spillway structure with the ring overflow weir and the ladder-shaped cofferdam provided by the embodiment includes a ring overflow weir 1, a vertical shaft 9 connected to the inside bottom of the ring overflow weir 1, a round-to-square section 10 connected to the bottom of the vertical shaft 9, a stilling well 11 connected to the bottom of the round-to-square section 10, a flow hole formed in the side of the stilling well 11, a pressure slope 12 connected to the side of the stilling well 11 at the flow hole, and a water outlet tunnel 13 connected to the other end of the pressure slope 12. Figure 1As shown, the system includes an annular overflow weir 1, with a vertical shaft 9 connected to the bottom of the inner side of the annular overflow weir 1. A circular-to-square section 10 is connected to the bottom of the vertical shaft 9, and a stilling well 11 is connected to the bottom of the circular-to-square section 10. A discharge hole is provided on the side of the stilling well 11, and a slope 12 is connected to the discharge hole on the side of the stilling well 11. A drainage tunnel 13 is connected to the other end of the slope 12. The system also includes a trapezoidal cofferdam 2, located outside the sidewall of the annular overflow weir 1. The inlet of the annular overflow weir 1 is a funnel-shaped inlet, and the inner diameter of the bottom of the annular overflow weir 1 is the same as the inner diameter of the vertical shaft 9. Figure 2 As shown, the trapezoidal cofferdam 2, together with the annular overflow weir 1 and the vertical shaft 9, forms a circular structure. The center of the trapezoidal cofferdam 2 coincides with the center of the annular overflow weir 1 and the vertical shaft 9. The height ratio of the trapezoidal cofferdam 2 to the height of the annular overflow weir 1 is 1:2-3:4. The trapezoidal cofferdam 2 includes an inner sidewall 6, and the ratio of the distance from the bottom of the inner sidewall 6 to the sidewall of the annular overflow weir 1 to the inner diameter of the vertical shaft 9 is 1:2.5. The trapezoidal cofferdam 2 also includes an outer sidewall 7, and the ratio of the distance from the bottom of the outer sidewall 7 to the sidewall of the annular overflow weir 1 to the inner diameter of the vertical shaft 9 is 1:0.7. Figure 3 As shown, the trapezoidal cofferdam 2 includes a trapezoidal cofferdam base plate 8, the width of which is in the ratio of the inner diameter of the vertical shaft 9 to the width of the trapezoidal cofferdam base plate 8 to the inner diameter of the shaft 9 is 1:2.5; the trapezoidal cofferdam 2 includes a trapezoidal cofferdam crest 14, which is composed of a trapezoidal cofferdam oblique-line crest structure 3, an inner arc-shaped crest structure 4, and an outer arc-shaped crest structure 5. The inner arc-shaped crest structure 4, the trapezoidal cofferdam oblique-line crest structure 3, and the inner sidewall 6 are all tangent to each other, and the slope of the inner sidewall 6 is 1:11-1:7. The outer arc-shaped crest structure 5, the trapezoidal cofferdam oblique-line crest structure 3, and the outer sidewall 7 are all tangent to each other, and the slope of the outer sidewall 7 is 1:12-1:8.

[0033] Example 6

[0034] The annular overflow weir vertical shaft spillway structure with trapezoidal cofferdam proposed in this embodiment, such as... Figure 1 As shown, the system includes an annular overflow weir 1, with a vertical shaft 9 connected to the bottom of the inner side of the annular overflow weir 1. A circular-to-square section 10 is connected to the bottom of the vertical shaft 9, and a stilling well 11 is connected to the bottom of the circular-to-square section 10. A discharge hole is provided on the side of the stilling well 11, and a slope 12 is connected to the discharge hole on the side of the stilling well 11. A drainage tunnel 13 is connected to the other end of the slope 12. The system also includes a trapezoidal cofferdam 2, located outside the sidewall of the annular overflow weir 1. The inlet of the annular overflow weir 1 is a funnel-shaped inlet, and the inner diameter of the bottom of the annular overflow weir 1 is the same as the inner diameter of the vertical shaft 9. Figure 2As shown, the trapezoidal cofferdam 2 and the annular overflow weir 1 and the shaft 9 form a circular ring structure, the center of the trapezoidal cofferdam 2 coincides with the center of the annular overflow weir 1 and the shaft 9; the height ratio of the trapezoidal cofferdam 2 to the annular overflow weir 1 is 1:2-3:4; the trapezoidal cofferdam 2 includes the trapezoidal cofferdam inner side wall 6, the distance from the bottom of the trapezoidal cofferdam inner side wall 6 to the side wall of the annular overflow weir 1 is 1:2.5 times the inner diameter of the shaft 9; the trapezoidal cofferdam 2 includes the trapezoidal cofferdam outer side wall 7, the distance from the bottom of the trapezoidal cofferdam outer side wall 7 to the side wall of the annular overflow weir 1 is 1:0.7 times the inner diameter of the shaft 9. As shown Figure 3 As shown, the trapezoidal cofferdam 2 includes the trapezoidal cofferdam bottom plate 8, the width of the trapezoidal cofferdam bottom plate 8 is 1:2.5 times the inner diameter of the shaft 9; the trapezoidal cofferdam 2 includes the trapezoidal cofferdam crest 14, which is composed of the trapezoidal cofferdam inclined crest structure 3, the trapezoidal cofferdam inner side arc crest structure 4 and the trapezoidal cofferdam outer side arc crest structure 5, the trapezoidal cofferdam inner side arc crest structure 4 is tangent to the trapezoidal cofferdam inclined crest structure 3 and the trapezoidal cofferdam inner side wall 6, the slope of the trapezoidal cofferdam inner side wall 6 is 1:11-1:7, the trapezoidal cofferdam outer side arc crest structure 5 is tangent to the trapezoidal cofferdam inclined crest structure 3 and the trapezoidal cofferdam outer side wall 7, the slope of the trapezoidal cofferdam outer side wall 7 is 1:12-1:8; the trapezoidal cofferdam inclined crest structure 3 is designed as an inner low and outer high structure along the water flow direction, the slope ratio of the trapezoidal cofferdam inclined crest structure 3 is 1:2, the length of the trapezoidal cofferdam inclined crest structure 3 to the width of the trapezoidal cofferdam bottom plate 8 is 1:2.85; the radii of the trapezoidal cofferdam inner side arc crest structure 4 and the trapezoidal cofferdam outer side arc crest structure 5 are the same, the radius of the trapezoidal cofferdam inner side arc crest structure 4, the radius of the trapezoidal cofferdam outer side arc crest structure 5 and the length of the trapezoidal cofferdam inclined crest structure 3 are all 1:3.5.

Claims

1. A structure of a ring spillway shaft spillway with a ladder cofferdam, characterized in that, The utility model provides a kind of circular overflow weir (1), the inside bottom of the circular overflow weir (1) is connected with shaft (9), the bottom of the shaft (9) is connected with round square section (10), the bottom of the round square section (10) is connected with stilling well (11), the side of the stilling well (11) is equipped with flow hole, the side of the stilling well (11) is connected with pressure slope (12) at the flow hole, the other end of the pressure slope (12) is connected with water tunnel (13), further include trapezoidal cofferdam (2), the trapezoidal cofferdam (2) is located in the side wall periphery of the circular overflow weir (1).

2. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 1, wherein, The water inlet of the circular overflow weir (1) is a horn-shaped water inlet, and the inner diameter of the bottom of the circular overflow weir (1) is the same as the inner diameter of the shaft (9).

3. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 2, wherein, The trapezoidal cofferdam (2) and the circular overflow weir (1) and the shaft (9) form a circular ring structure, and the center of the trapezoidal cofferdam (2) coincides with the center of the circular overflow weir (1) and the shaft (9).

4. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 3, wherein, The height ratio of the trapezoidal cofferdam (2) to the circular overflow weir (1) is 1:2-3:

4.

5. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 4, wherein, The trapezoidal cofferdam (2) includes a trapezoidal cofferdam inside side wall (6), and the distance from the bottom of the trapezoidal cofferdam inside side wall (6) to the side wall of the circular overflow weir (1) is 1:2.5 times the inner diameter of the shaft (9).

6. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 5, wherein, The trapezoidal cofferdam (2) includes a trapezoidal cofferdam outside side wall (7), and the distance from the bottom of the trapezoidal cofferdam outside side wall (7) to the side wall of the circular overflow weir (1) is 1:0.7 times the inner diameter of the shaft (9).

7. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 6, wherein, The trapezoidal cofferdam (2) includes a trapezoidal cofferdam bottom plate (8), and the width of the trapezoidal cofferdam bottom plate (8) is 1:2.5 times the inner diameter of the shaft (9).

8. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 7, wherein, The trapezoidal cofferdam (2) includes a trapezoidal cofferdam top (14), which is composed of a trapezoidal cofferdam inclined line type top structure (3), a trapezoidal cofferdam inside circular arc type top structure (4), and a trapezoidal cofferdam outside circular arc type top structure (5). The trapezoidal cofferdam inside circular arc type top structure (4) is tangent to the trapezoidal cofferdam inclined line type top structure (3) and the trapezoidal cofferdam inside side wall (6). The slope of the trapezoidal cofferdam inside side wall (6) is 1:11-1:

7. The trapezoidal cofferdam outside circular arc type top structure (5) is tangent to the trapezoidal cofferdam inclined line type top structure (3) and the trapezoidal cofferdam outside side wall (7). The slope of the trapezoidal cofferdam outside side wall (7) is 1:12-1:

8.

9. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 8, wherein, The trapezoidal cofferdam inclined line type top structure (3) is designed as an inner low and outer high structure along the direction of water flow. The slope ratio of the trapezoidal cofferdam inclined line type top structure (3) is 1:

2. The length of the trapezoidal cofferdam inclined line type top structure (3) is 1:2.85 times the width of the trapezoidal cofferdam bottom plate (8).

10. The ring spillway shaft spillway structure with trapezoidal cofferdams of claim 9, wherein, The trapezoidal cofferdam inside circular arc type top structure (4) and the trapezoidal cofferdam outside circular arc type top structure (5) have the same radius. The radius of the trapezoidal cofferdam inside circular arc type top structure (4) and the radius of the trapezoidal cofferdam outside circular arc type top structure (5) are 1:3.5 times the length of the trapezoidal cofferdam inclined line type top structure (3).

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