A staged water storage structure and staged water storage method for dam water storage in advance

Abstract

The present invention relates to a staged water storage structure and method for pre-filling a dam. The technical solution employed by the present invention is: a staged water storage structure for pre-filling a dam, characterized in that: a spillway is provided on at least one side of the dam body, the upstream end of the spillway being located upstream of the dam body and the bottom plate of the upstream end being lower than the normal water level of the reservoir, and the downstream end of the spillway being located downstream of the dam body; an overflow weir is provided at the upstream end of the spillway, the top of the overflow weir being at the same height as the normal water level of the reservoir, and a notch is reserved in the overflow weir. In this manner, after the dam body construction is completed, the dam can be closed and water can be stored. During the construction of the dam crest, if the water storage on the upstream side of the dam increases and the water level rises, the weir notch can be used to discharge the excess water on the upstream side of the dam through the spillway, thereby preventing the water level on the upstream side from rising to the dam crest and affecting the dam crest construction.

Description

Technical Field

[0001] The present invention relates to a staged water storage structure and a staged water storage method for pre-storing water in a dam, and is applicable to the technical field of dam engineering. Background Art

[0002] The water conservancy and hydropower industries rely on local topographical and geological conditions to construct dams and reservoirs, intercepting natural runoff and collecting it into reservoirs. To meet flood control and flood control needs during operation, reservoirs often require spillways for flood discharge. A spillway is excavated into the geology adjacent to the dam, and an overflow weir is installed at the spillway's entrance. This allows water to flow over the weir and into the spillway when the water level in the reservoir upstream of the dam is high, allowing it to be discharged from the spillway.

[0003] For earth-rockfill dams, the construction period requires that the dam and spillway be fully constructed according to design requirements before the dam can be lowered for water storage. The dam crest, with its complex structure consisting of wave-breaking walls, cable trenches, and road surfaces, faces a tight construction schedule. Often, by the scheduled time for dam closing, the dam crest structure is not complete, hindering the dam's closing and impeding water storage, as well as the overall construction schedule. This directly increases project duration and investment, while also compromising power generation efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: In order to solve the above technical problem, the present invention provides a staged water storage structure and staged water storage method for dam water storage in advance.

[0005] The technical solution adopted by the present invention is: a staged water storage structure for pre-filling a dam, characterized in that: a spillway is provided on at least one side of the dam body, the upstream end of the spillway is located upstream of the dam body and the bottom plate of the upstream end is lower than the normal water level of the reservoir, and the downstream end of the spillway is located downstream of the dam body;

[0006] An overflow weir is provided at the upstream end of the spillway, and the top of the overflow weir is at the same height as the normal water level of the reservoir, and a gap section is reserved on the overflow weir. In this way, after the construction of the dam body is completed, the dam can be closed and water can be stored, so that the dam can be closed and water can be stored before the dam top construction is completed, avoiding affecting the overall project. The dam top construction can still be continued after the established dam closing time node, and the dam top construction will not affect the water storage of the dam. During the dam top construction process, when the water volume on the upstream side of the dam is large, the water stored on the upstream side of the dam will discharge the excess water stored in the upstream section of the dam to the downstream section of the dam under the action of the gap section of the overflow weir, avoiding the water level on the upstream side of the dam rising to the position of the dam top and affecting the dam top construction.

[0007] The bottom elevation of the gap section is the same as the bottom plate of the upstream end of the spillway. This allows water to flow out of the gap in the spillway when the water level in the upstream section of the dam is higher than that in the spillway. This allows the reservoir water level to be lower than the normal storage level during the construction period, thus reducing the construction requirements for the dam at the time of closing the sluice gates and filling the water.

[0008] The overflow surface of the overflow weir is arranged in an arc shape. In this way, when water flows toward the overflow weir, the arc-shaped overflow surface can smooth the water flow and reduce the scouring of the overflow weir.

[0009] The initial planned dam crest elevation, which serves as the upper limit for reservoir water level buildup during construction, was used as the width of the weir gap, based on the maximum discharge required during construction. This ensured that excess water on the upstream side of the dam could be discharged through the weir during maximum discharge during construction, preventing the upstream water level from rising and impacting dam crest construction due to the inability of the weir to discharge excess water.

[0010] A phased water storage method for dam water storage in advance, applied to the above-mentioned phased water storage structure for dam water storage in advance, is characterized by:

[0011] Determine the flood control standards of the dam and the water storage capacity of the reservoir on the upstream side of the dam;

[0012] The top elevation of the initially proposed dam project, based on the top elevation, dam flood control standards and reservoir storage capacity, determines the maximum discharge volume required to be discharged through the overflow weir next to the dam;

[0013] Calculate the width of the overflow weir beside the dam and the width of the overflow weir at the spillway inlet based on the top elevation and the maximum discharge at the overflow weir;

[0014] Determine the top elevation of the dam project and the width of the gap section on the overflow weir;

[0015] During the construction of the dam body, the spillway is constructed on the geology beside the dam body, and the overflow weir is constructed at the spillway entrance according to the determined gap width;

[0016] After the dam body construction is completed, the dam top construction will be carried out;

[0017] After the construction of the dam body, spillway and overflow weir is completed, the sluice gates are lowered and water is stored according to the set closing time node. At this time, the water storage elevation of the dam is the elevation of the gap bottom of the gap section on the overflow weir;

[0018] When the dam crest construction is complete and the overflow weir is completed during the dry season, water can be stored at the dam crest elevation. This allows the dam to be lowered and filled with water once the dam body construction is complete and a gap has been created in the overflow weir on the spillway. At this point, the dam's water storage elevation is the elevation of the gap bottom of the gap in the overflow weir. Water storage on the upstream side of the dam will not affect the construction work at the dam crest. By completing the overflow weir when the dam crest construction is complete and the dry season is underway, water can be stored at the dam crest elevation, thus achieving phased water storage.

[0019] The method for determining the top elevation at which the dam project needs to be completed is as follows: preliminarily plan the top elevation at which the dam project needs to be completed, use the preliminarily planned top elevation as the upper limit elevation for the reservoir water level increase during the construction period, plan the width of the overflow weir gap section based on the maximum discharge demand during the construction period, calculate the reservoir water level increase during the construction period and adjust the width of the overflow weir gap section until the width of the reserved gap in the overflow weir is less than the total width of the overflow weir and the upper limit elevation for the reservoir water level increase during the construction period is lower than the top elevation at which the dam needs to be completed. In this way, the width of the reserved gap section in the overflow weir and the top elevation at which the dam needs to be completed can be finally determined.

[0020] The beneficial effects of the present invention are as follows: during the construction of the dam body, the present invention sets a spillway beside the dam body, sets an overflow weir at the upstream end of the spillway, and sets a gap on the overflow weir to meet the maximum discharge volume during the construction period, so that after the construction of the dam body and the spillway is completed, the dam can be closed and water can be stored, thereby avoiding the slow construction of the entire dam project due to the complicated construction of the dam crest, which will lead to the closing of the sluice gates for water storage and the overall construction period. During the process of completing the dam closing and water storage and carrying out the dam crest construction, when the water storage on the upstream side of the dam increases and the water level rises, the operating water level of the reservoir on the upstream side of the dam is lower than the permanent normal water storage level due to the action of the gap section of the overflow weir, and the excess water storage on the upstream side of the dam can be discharged. Water is discharged through the spillway to prevent the water level on the upstream side of the dam from rising to the dam crest and affecting the dam crest construction; after the dam crest construction is completed, the overflow weir is filled so that the operating water level of the reservoir on the upstream side of the dam can reach the normal water storage level to ensure the operation of the dam. When the dam body is completed and a gap section is made on the overflow weir on the spillway, the dam can be lowered to store water. At this time, the water storage elevation of the dam is the gap bottom elevation of the gap section on the overflow weir, and the water storage on the upstream side of the dam will not affect the dam crest construction project; when the dam crest construction is completed and the overflow weir is filled during the dry season, water can be stored at the dam crest elevation, thereby realizing phased water storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Schematic diagram of the dam crest construction structure in the background technology of the present invention.

[0022] Figure 2 : Schematic diagram of the structure of the dam body, spillway and overflow weir in the present invention.

[0023] Figure 3 : Structural cross-sectional view of the spillway and overflow weir in the present invention.

[0024] Figure 4 : Schematic diagram of a gap reserved when constructing an overflow weir in a spillway according to the present invention.

[0025] In the figure: 1. Reservoir; 2. Dam body; 3. Spillway; 4. Overflow weir; 5. Gap section. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are intended to explain the present invention, but the present invention is not limited to the following examples.

[0027] This embodiment is a staged water storage structure for storing water in advance in a dam. The dam comprises a dam body 2 and a dam top. The dam top is provided with a wave-breaking wall, a cable trench, and a road surface.

[0028] In this embodiment, during dam construction, a spillway 3 is provided on at least one side of the dam body 2. The upstream end of the spillway 3 is located upstream of the dam body 2, and its bottom plate is lower than the normal water level of the reservoir 1. The downstream end of the spillway 3 is located downstream of the dam body 2. The top of the overflow weir 4 of the spillway 3 is at the same height as the normal water level of the reservoir 1. When the reservoir water level is higher than the normal water level, floodwater can be discharged through the spillway 3 by gravity, without the need for gate control. The upstream end of the spillway 3 is provided with an overflow weir 4, and the top of the overflow weir 4 is at the same height as the normal water level of the reservoir 1. The width of the spillway 3 is determined based on the permanent flood control needs during the operation period.

[0029] In this embodiment, a notch section 5 is provided on the overflow weir 4 of the spillway 3 based on the maximum discharge required during the construction period. After the construction of the dam body 2 and spillway 3 is completed, the notch section 5 remains on the overflow weir 4 of the spillway 3. At this point, after the dam is closed and water is stored, the water level on the upstream side of the dam begins to rise. When the water storage on the upstream side of the dam increases, causing the water level to rise upstream, and when the water level reaches the location of the notch section 5 on the spillway 3, the water stored on the upstream side of the dam is discharged to the downstream section of the dam through the spillway 3, preventing the water level in the upstream section from continuing to rise to the dam crest construction location and thus affecting the dam crest construction. Due to the notch section 5 on the overflow weir 4, the operating water level of the reservoir 1 during the construction period is lower than the permanent normal water storage level.

[0030] In this embodiment, the overflow surface of the overflow weir 4 is arranged in an arc shape. In this way, when the water flows toward the overflow weir 4, the arc-shaped overflow surface can smooth the water flow and reduce the scouring of the overflow weir 4.

[0031] In this embodiment, the top elevation of the dam to be completed initially is used as the upper limit elevation of the reservoir water level during the construction period. Based on the maximum discharge requirement during the construction period, the width of the notch section 5 of the overflow weir 4 is determined so that the excess water on the upstream side of the dam can be discharged through the overflow weir 4 during the maximum discharge during the construction period, thereby avoiding the water level on the upstream side of the dam from rising and affecting the dam top construction due to the excess water on the upstream side of the dam being unable to be discharged from the overflow weir 4.

[0032] In this embodiment, the bottom elevation of the notch section 5 of the overflow weir 4 is the same as the bottom plate of the upstream end of the spillway 3. Thus, during dam crest construction, when the water level on the upstream side of the dam is higher than the bottom elevation of the notch section 5 of the overflow weir 4, the excess water on the upstream side of the dam can overflow the notch section 5 of the overflow weir 4 and be discharged from the spillway 3 to the downstream side of the dam.

[0033] In this embodiment, after the dam top construction is completed, the gap section 5 on the overflow weir 4 is filled according to the design requirements during the dry season when the overflow weir 4 is not discharging flood water.

[0034] The staged water storage method for the dam in advance in this embodiment is as follows:

[0035] 1. Determine the flood control standard of the dam based on the project scale and calculate the water storage capacity of Reservoir 1 on the upstream side of the dam at the planned water storage time;

[0036] 2. The top elevation of the dam project that needs to be constructed at the time of initial planned closure and water storage. Based on the top elevation, the dam flood control standards and the water storage capacity of reservoir 1, the maximum discharge volume required to be discharged through the four overflow weirs next to the dam during the construction period is determined;

[0037] 3. Determine the width of the notch section 5 on the overflow weir 4 next to the dam based on the maximum discharge at the overflow weir 4 during the construction period;

[0038] 4. The overflow weir gap section 5 and the completed overflow weir section 4 have different shapes and heads, and the calculation methods and single-width flow rates are also different. The flood discharge capacity needs to be calculated separately. The sum of the discharge volumes of the two sections is the temporary flood discharge capacity of spillway 3 during the construction period.

[0039] 5. If, after the entire width of the overflow weir 4 is reserved according to the gap section 5, the reservoir water level calculated by flood control still exceeds the top elevation of the dam project that needs to be constructed at the initially planned time of closing the gates and filling the water, it is necessary to increase resource investment and increase the top elevation of the dam that needs to be completed, that is, to re-plan the top elevation of the dam project that needs to be constructed at the time of closing the gates and filling the water.

[0040] 6. Repeat steps 2 through 5 above until the calculated reservoir water level for flood control is lower than the required dam top elevation at the initially planned sluice gate closing and water filling time. This finalizes the required dam top elevation for dam 2 and the width of the gap 5 reserved for overflow weir 4 at the time of sluice gate closing and water filling.

[0041] 7. The overflow weir gap section 5 is reserved in full height as a whole. The overflow weir 4 in the gap section is not constructed as a whole, and the other sections are constructed according to the design drawings.

[0042] 8. After the dam crest structure is completed, the overflow weir gap section 5 is constructed according to design requirements during the dry season, when overflow weir 4 is not discharging floodwaters. The gap section 5 is reserved at its full height and can utilize the same formwork and construction techniques. During construction of the gap section 5 reserved for overflow weir 4, the reservoir water level must be controlled to not exceed the gap bottom elevation, and an appropriate reserve must be left to ensure dry-land construction and construction safety.

[0043] 9. Because the gap 5 is reserved and can release floodwater by gravity, the reservoir operating water level during construction is approximately one overflow weir 4 height lower than the permanent normal water level, usually about 6-8 meters. Therefore, the sluice gates can be opened in advance to store water before construction is completed on the 6-8 meter section above the dam 2.

[0044] 10. Before the construction of gap section 5 of overflow weir 4, the operating water level in the lower reservoir cannot reach the originally designed normal water storage level, and the water level is usually at or below the bottom elevation of gap section 5. Only after the construction of gap section 5 is completed can the operating water level of the reservoir reach the originally designed normal water storage level, which is the so-called staged water storage. Staged water storage is the water storage process formed by the gap section 5 reserved in the overflow weir. The main purpose of the gap section 5 reserved in the overflow weir is to open the gates earlier and save construction time.

[0045] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A staged water storage structure for pre-filling a dam, characterized by: A spillway (3) is provided on at least one side of the dam body (2), wherein the upstream end of the spillway (3) is located upstream of the dam body (2) and the bottom plate of the upstream end is lower than the normal water level of the reservoir (1), and the downstream end of the spillway (3) is located downstream of the dam body (2); An overflow weir (4) is provided at the upstream end of the spillway (3), the top of the overflow weir (4) is at the same height as the normal water level of the reservoir (1), and a notch section (5) is reserved on the overflow weir (4); The notch bottom elevation of the notch section (5) is the same as the bottom plate at the upstream end of the spillway (3); Based on the top elevation of the initially planned dam to be completed, the upper limit elevation of the reservoir water level during the construction period is used as the upper limit elevation. Based on the maximum discharge demand during the construction period, the width of the notch section (5) on the overflow weir (4) is determined.

2. The staged water storage structure for dam water storage in advance according to claim 1 is characterized in that: The overflow surface of the overflow weir (4) is arranged in an arc shape.

3. A phased water storage method for dam water storage in advance, applied to the phased water storage structure for dam water storage in advance according to any one of claims 1-2, characterized in that: Determine the flood control standards of the dam and the water storage capacity of the reservoir (1) on the upstream side of the dam; The top elevation of the initially proposed dam project, based on the top elevation, the dam flood control standard and the water storage capacity of the reservoir (1), determines the maximum discharge volume of the water to be discharged through the overflow weir (4) next to the dam; Calculate the width of the overflow weir (4) beside the dam and the width of the overflow weir (4) at the entrance of the spillway (3) based on the top elevation and the maximum discharge at the overflow weir (4); Determine the elevation of the dam top and the width of the gap (5) on the overflow weir (4); During the construction of the dam body (2), a spillway (3) is constructed on the geology beside the dam body (2), and an overflow weir (4) is constructed at the entrance of the spillway (3) according to the determined width of the notch section (5); After the construction of the dam body (2) is completed, the dam top construction will be carried out; After the construction of the dam body (2), spillway (3) and overflow weir (4) is completed, the sluice gate is lowered and water is stored according to the set sluice gate closing time node. At this time, the water storage elevation of the dam is the gap bottom elevation of the gap section (5) on the overflow weir (4); When the dam top construction is completed and the overflow weir (4) is completed during the dry season, water storage at the dam top elevation is achieved.

4. The phased water storage method for dam water storage in advance according to claim 3 is characterized in that: The method for determining the top elevation of the dam project and the width of the gap section (5) on the overflow weir (4) is as follows: based on the top elevation of the dam to be completed initially, take this as the upper limit elevation of the reservoir water level during the construction period, and according to the maximum discharge demand during the construction period, formulate the width of the gap section (5) of the overflow weir (4), calculate the reservoir water level during the construction period and adjust the width of the gap section (5) of the overflow weir (4) until the width of the gap reserved for the overflow weir (4) is less than the total width of the overflow weir (4) and the upper limit elevation of the reservoir water level during the construction period is lower than the top elevation of the dam to be completed. Then, the width of the gap section (5) reserved for the overflow weir (4) and the top elevation of the dam to be completed can be finally determined.

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