Flood control structure arrangement and design method of construction platform of diaphragm wall of temporary weir body
Patent Information
- Application Number
- CN202610966419.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-30
- Publication Date
- 2026-09-15
Smart Images
Figure CN122758505A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of diversion and interception technology in water conservancy and hydropower engineering construction, specifically relating to the layout and design method of a flood protection structure for a temporary weir construction platform. Background Technology
[0002] A cofferdam is a temporary water-retaining structure built on a thick overburden layer, such as loose sedimentary layers of sand, gravel, silt, or soft soil; this is the temporary dam body in this invention. Earth-rock cofferdams are constructed on thick overburden riverbeds. The seepage prevention structure of the cofferdam typically employs methods such as cut-off walls, high-pressure jet grouting, and overburden grouting. Since cofferdams can leak, a deep trench is dug and filled with concrete at the bottom of the cofferdam to create an underground water-blocking wall, completely preventing water seepage at the bottom of the dam. This underground water-blocking wall is the cut-off wall. To create the conditions for constructing the cut-off wall, a construction platform is typically set up on the cofferdam. This platform is used to park drilling rigs, grab buckets, cranes, and to store materials. Workers operate on this platform to construct the cut-off wall. The cut-off wall construction platform is a construction platform set up at a certain elevation along the width of the river channel at the cofferdam, and it is generally built on the top surface of the temporary dam body. To ensure the quality and efficiency of the cutoff wall construction, the construction platform of the cutoff wall is generally constructed using a granular structure. When water flows through, the destructive effects of the water flow are twofold: first, the kinetic energy of the water flowing down the downstream slope of the cutoff wall construction platform continuously increases, scouring the overflow surface; second, the seepage pressure generated by the water seeping into the fill causes the downstream slope of the cutoff wall construction platform to slide along with the fill, leading to the collapse of the dam.
[0003] With the continuous advancement of water conservancy and hydropower projects in Southwest China, many projects involve the construction of cofferdams under deep overburden conditions. Cofferdams typically require completion within a single dry season. However, for cofferdams with deep overburden, the depth of the anti-seepage walls is excessive, sometimes reaching hundreds of meters. Completing riverbed closure, anti-seepage wall construction, and cofferdam filling within a single dry season is extremely difficult. Therefore, for high cofferdams with deep overburden, construction is generally divided into two dry seasons. Typically, most of the anti-seepage wall construction is completed in one dry season, with the remaining construction proceeding in the next, followed by cofferdam filling. Following this construction procedure, after the first dry season, the anti-seepage wall construction platform must be properly protected. Otherwise, if the platform is destroyed during a major flood, the anti-seepage wall will be damaged, affecting the entire project schedule and investment.
[0004] There are currently no engineering precedents for the protection of the seepage barrier construction platform of temporary dams under deep overburden conditions. The scour protection of the overflow surface of the seepage barrier construction platform, the downstream slope foundation of the seepage barrier construction platform, and the joints on both banks are the key points of the water flow protection design of the temporary dam construction platform. It is necessary to conduct in-depth analysis of the water flow hydraulic conditions of the seepage barrier construction platform and propose appropriate temporary dam protection layout and methods to ensure safe flood control and the smooth implementation of the project. Summary of the Invention
[0005] The purpose of this invention is to provide a method for the layout of flood protection structure of a temporary dam construction platform for seepage prevention, and to solve the problems of lack of unified standards for the layout of flood protection structure of temporary dam construction platforms and difficulty in determining the overflow surface protection structure.
[0006] To achieve the above objectives, the technical solution of this invention is as follows: A flood control protection structure for a temporary dam construction platform is disclosed. The construction platform is located on the top surface of the temporary dam and includes an upstream and a downstream construction platform. Both the upstream and downstream construction platforms include a high platform, a low platform, and a sloping section connecting the high and low platforms. The high platform is located upstream of the river channel, and the low platform is located downstream of the river channel. The top surface of the high platform is higher than the top surface of the low platform.
[0007] Furthermore, the end of the ramp connecting to the high platform is at the same height as the high platform, and the end of the ramp connecting to the low platform is at the same height as the low platform.
[0008] A design method for the layout of the flood protection structure of the anti-seepage wall construction platform of the temporary weir, the method comprising: Establish hydraulic calculation formulas for the anti-seepage wall construction platform as shown in (Equation 1) to (Equation 4). Calculate the elevation P1 of the high platform, the elevation P2 of the low platform, and the slope ratio of the high and low platform slopes based on (Equation 1) to (Equation 4). Complete the construction of the anti-seepage wall construction platform based on the elevation P1 of the high platform, the elevation P2 of the low platform, and the slope ratio of the high and low platform slopes. Achieve flood protection through the anti-seepage wall construction platform with elevation differences. (Equation 1) (Equation 2) (Equation 3) (Equation 4) Where Q represents the total flow rate from the upstream; Indicates the upstream controlled water level; Indicates the downstream control water level; A represents the cross-sectional area of the diversion tunnel. denoted by ; B represents the flow coefficient of the diversion tunnel; ; m represents the axial length of the anti-seepage wall construction platform; ; g represents the gravitational acceleration; ; V represents the flow velocity at the top of the anti-seepage wall platform. φ This represents the velocity-head correction factor; four values are obtained through four formulas: the height of the high platform of the cutoff wall platform P1; the height of the low platform of the cutoff wall platform P2; and the flow rate of the diversion tunnel. ; Flow distribution of the anti-seepage wall platform .
[0009] Furthermore, the slope ratio of the high and low platform slopes is (P1-P2) / L, where L represents the horizontal distance between the high and low platforms. The flood control protection structure of the temporary dam construction platform is arranged according to the calculated elevation P1 of the high platform of the anti-seepage wall, the elevation P2 of the low platform of the anti-seepage wall, and the slope ratio of the high and low platform slopes.
[0010] Furthermore, the overflow surface of the anti-seepage wall construction platform adopts a grouting concrete structure. The grouting concrete structure is filled with large stones as a skeleton to form the main protective body. The grout is filled with grout through pressure grouting and bonded into a whole.
[0011] The beneficial effects of this invention are: 1. This invention establishes a hydraulic calculation formula for the construction platform of the anti-seepage wall, scientifically determines the elevation and slope ratio of the high platform, low platform and sloping section, solves the problem of the lack of unified design standards for flood protection of temporary dam platforms in deep overburden layers, realizes the precise design of the layout of the protection structure and the shape of the overflow surface, and significantly improves the safety and reliability of flood control.
[0012] 2. The construction platform structure of the seepage prevention wall adopts a high-low drop type, which can guide the water flow smoothly during the flood season and reduce the risk of scouring. This avoids the destruction of the protective structure due to excessive hydraulic parameters and also prevents the waste of project investment due to overly conservative protective design, thus achieving a dual optimization of safety and economy.
[0013] 3. The overflow surface of the anti-seepage wall platform innovatively adopts a grouting concrete structure, with large stones as the skeleton and pressure grouting to bond it into a whole. It has strong erosion resistance, fast construction speed, and convenient subsequent demolition. At the same time, it is tightly integrated with the upper dam body and does not form a smooth contact surface or weak interlayer, which greatly improves the overall stability of the cofferdam.
[0014] 4. After the flood season, the grouting concrete protective structure can be directly retained and work together with the upper dam body to bear the load. The cofferdam can be heightened and filled without demolition, which significantly shortens the construction period and reduces demolition costs. This solves the problem of the difficulty in demolishing traditional reinforced concrete protective structures and the impact on the continuous construction of the cofferdam.
[0015] 5. This invention is applicable to high cofferdam projects with deep overburden layers that are constructed during the dry season. It can effectively protect the construction platform and structure of the anti-seepage wall, ensure the continuity of cofferdam construction, and avoid delays and increased investment due to damage during the flood season. It has strong engineering applicability and promotion value. Attached Figure Description
[0016] Figure 1 This is a plan view of the flood protection layout of the anti-seepage wall construction platform of the present invention.
[0017] Figure 2 This is a longitudinal section view of the flood protection of the anti-seepage wall construction platform of the present invention.
[0018] Figure 3 This is a traditional reinforced concrete seepage barrier construction platform for flood protection.
[0019] Figure 4 This invention relates to a flood control protection structure for a grouting concrete seepage barrier construction platform.
[0020] Among them: 1-Interception dike; 2-Thick overburden; 3-Bedrock; 4-Upstream erosion control riprap; 5-Downstream erosion control riprap; 6-High platform; 6.1-Large boulders for grouting concrete structure; 6.2-Grouting slurry for grouting concrete structure; 6.3-Reinforced concrete structure; 6.3.1-Longitudinal connecting bars for reinforced concrete structure; 6.3.2-Surface reinforcement bars for reinforced concrete structure; 7-Sloping section; 8-Low platform; 9-Water surface line; 10-Right bank diversion tunnel; 11-Left bank diversion tunnel; 12-Protective structure for anti-seepage wall construction trench; 13-Upper weir body of anti-seepage wall construction platform. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific examples described herein are only some embodiments of this invention, not all embodiments, and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.
[0022] This technical solution is applicable to water conservancy and hydropower projects with construction platforms featuring anti-seepage walls in the construction cofferdam. It proposes a method for the layout and design of flood control protection structures for anti-seepage wall construction platforms.
[0023] This invention establishes hydraulic calculation formulas for the anti-seepage wall construction platform, determines the layout of the protective structure and the overflow surface morphology for the anti-seepage wall construction platform, and innovates the overflow surface protection structure.
[0024] This invention mainly includes establishing hydraulic calculation formulas for the anti-seepage wall construction platform, determining the flood protection layout for the anti-seepage wall construction platform, the overflow surface protection structure, and the construction of cofferdam heightening and filling.
[0025] like Figure 1 As shown, in the geological structure of the natural riverbed, bedrock 3 is the bottom bearing layer, and the thick overburden layer 2, such as gravel, silt, and soft soil, is a loose surface sedimentary layer covering the bedrock 3. In the river channel with the thick overburden layer, the intercepting dike 1 is built on the thick overburden layer 2 of the riverbed. The intercepting dike 1 is a temporary water-retaining structure before the cofferdam construction. On the basis of the intercepting dike, a temporary dam is formed by raising, filling, and installing an anti-seepage body. The anti-seepage wall construction platform serves as the top surface of the temporary dam and is arranged as a whole on the upper part of the temporary dam. Its load is transferred to the thick overburden layer through the temporary dam and the intercepting dike, and is ultimately borne by the bedrock 3.
[0026] This invention simultaneously sets up upstream anti-scour riprap 4 and downstream anti-scour riprap 5. The upstream anti-scour riprap 4 is set on the upstream side of the high platform 6 of the anti-seepage wall construction platform, the water-facing slope toe of the temporary weir, and the upstream riverbed area to resist the scouring of the flood season and protect the upstream slope toe and foundation of the weir. The downstream anti-scour riprap 5 is set on the downstream side of the low platform 8 of the anti-seepage wall construction platform, the back slope toe of the temporary weir, and the downstream riverbed area to reduce the scouring force of the water flow and protect the downstream slope toe and riverbed cover layer of the weir.
[0027] like Figure 1 and Figure 2 As shown, the anti-seepage wall construction platform includes a high platform 6, a low platform 8, and a sloping section 7 connecting the high platform 6 and the low platform 8. The design of its height difference can guide the water flow and reduce scouring during the flood season, thus preventing the anti-seepage wall and the dike from being destroyed by floods.
[0028] High platform 6 is located upstream of the river channel, and low platform 8 is located downstream. The top surface of high platform 6 is higher than that of low platform 8. Sloping section 7 is located between high platform 6 and low platform 8 of the anti-seepage wall. High platform 6 is a grouted concrete structure. Figure 4 As shown, the high platform 6 uses grouting concrete structure large stones 6.1 and grouting concrete structure grout 6.2. The large stones are used as the skeleton to fill and form the main protective structure. Then, pressure grouting is used to fill the gaps between the stones and bond them into a whole. The low platform 8 also uses grouting concrete structure.
[0029] One end of the ramp 7 that connects to the high platform 6 is at the same height as the high platform 6, and the other end of the ramp 7 that connects to the low platform 8 is at the same height as the low platform 8.
[0030] Because the high platform, sloping section, and low platform of the anti-seepage wall construction platform of this invention create a height difference, if a major flood occurs after the first dry season, the anti-seepage wall construction platform with this height difference can more easily guide the water flow through, and the structure with this height difference can facilitate drainage. When the cofferdam construction needs to be completed within two dry seasons, and a major flood occurs after the first dry season, the water level 9 is higher than the top surface of the anti-seepage wall construction platform. Through the height difference of the anti-seepage wall construction platform of this invention, drainage can be more easily achieved, thus achieving flood protection through the anti-seepage wall construction platform with this height difference.
[0031] The upper weir body 13 of the anti-seepage wall construction platform is the main weir body part of the cofferdam that is finally filled and formed. It is set on the high platform 6, low platform 8 and overflow surface protection structure of the anti-seepage wall. After the flood season, it is directly filled on the upper part of the protection structure and works together with the lower protection structure to form a complete cofferdam water-retaining structure.
[0032] The design of the anti-seepage wall construction platform includes the following steps: Step 1: Establish hydraulic calculation formulas for the anti-seepage wall construction platform. Under the condition of combined discharge using a diversion tunnel and an anti-seepage wall construction platform, calculate the elevation P1 of the high platform, the elevation P2 of the low platform, and the slope ratio of the high and low platform sections according to formulas (1)-(4), providing a basis for determining the elevation and layout of the protective platform of the anti-seepage wall construction platform. In this invention, the right bank diversion tunnel 10 and the left bank diversion tunnel 11, built on both sides of the slope, are used for combined discharge with the anti-seepage wall construction platform. The diversion tunnels connect the upstream and downstream river channels. The inlet of the diversion tunnel is connected to the upstream river channel on one side of the temporary dam, and the outlet of the diversion tunnel is connected to the downstream river channel on the other side of the temporary dam. Water upstream of the temporary dam can flow to the downstream river channel through the diversion tunnels.
[0033] (Equation 1) (Equation 2) (Equation 3) (Equation 4) Of the four formulas, the known values include: Q represents the design flood discharge, which is given by the hydrological report; This indicates the upstream control water level, determined by diversion or flood control design. The downstream control water level is determined by the relationship between the downstream water level and flow rate of the project; A represents the cross-sectional area of the diversion tunnel, calculated according to the design dimensions. denoted by , representing the flow coefficient of the diversion tunnel, selected from tables according to the diversion design specifications; denoted by B, representing the axial length of the anti-seepage wall construction platform, adopted according to the engineering layout drawing; denoted by m, representing the flow coefficient of the broad-crested weir, selected from tables according to the hydraulic calculation specifications for broad-crested weirs; denoted by g, representing gravitational acceleration; denoted by V, representing the flow velocity at the top of the anti-seepage wall platform, determined based on the erosion resistance of the grouting concrete protective structure; and represents known control parameters. φ This represents the velocity-head correction factor, which is selected from tables or empirically based on open channel flow specifications.
[0034] Four values are obtained using four formulas: Diversion tunnel flow rate The formula (2) is used to obtain the result; Flow distribution of the anti-seepage wall platform , will get Substitute into formula (1) to obtain the result; The height of the anti-seepage wall platform is P1, which will be obtained Substitute into formula (3) to find the answer; The lower platform height P2 of the anti-seepage wall platform will be obtained. Substitute into formula (4) to obtain the elevation and layout of the protective platform for the construction platform of the seepage prevention wall.
[0035] Step 2: Determine the flood protection layout of the temporary dam construction platform. Based on the calculation results in formulas (1) to (4), and based on the calculated elevations P1 of the high platform of the anti-seepage wall, P2 of the low platform of the anti-seepage wall, and the slope ratio of the high and low platform sections, combined with the hydraulic flow velocity index of each part, determine the flood protection layout of the temporary dam construction platform.
[0036] The slope ratio of the high and low platform sloping section is (P1-P2) / L, where L represents the horizontal distance between the high and low platforms. The horizontal length of the sloping section of the anti-seepage wall construction platform is usually taken as 8-12m, and the horizontal distance L between the high and low platforms is a standard value directly determined by the design.
[0037] The arrangement of the flood protection structure of the anti-seepage wall construction platform of the present invention also includes the arrangement of the overflow surface protection structure of the anti-seepage wall construction platform and the construction of the cofferdam heightening and filling.
[0038] The overflow surface protection structure of the anti-seepage wall construction platform is arranged as follows: The overflow surface of the anti-seepage wall construction platform is formed by the top surface of the high platform of the anti-seepage wall, the slope surface of the high and low platform sections, and the top surface of the low platform of the anti-seepage wall, which is the surface through which water flows. The thickness of the overflow surface protection layer is determined according to the maximum flow velocity obtained from hydraulic calculations of each section of the platform. Grouting concrete is used as the erosion-resistant protection structure to meet the requirements for flood control and erosion prevention. Based on the calculation results obtained from the above four formulas, the overflow surface protection structure of the anti-seepage wall construction platform is determined. In this invention, the overflow surface adopts a grouting concrete structure. The overflow surface protection structure uses grouting concrete large stones and grouting concrete slurry. The large stones are used as the skeleton to fill and form the main body of the protection. Then, pressure grouting is used to fill the gaps between the stones and bond them into a whole. It has strong erosion resistance, fast construction speed, and is easy to break down later. It is also tightly integrated with the upper weir body and does not produce smooth contact surfaces or weak interlayers, which can significantly improve the overall stability of the cofferdam, while greatly reducing project investment and shortening the construction and demolition period. As a comparison, traditional overflow surface protection uses... Figure 3 The reinforced concrete structure 6.3 shown is a traditional overflow protection method. It involves binding the longitudinal connecting bars 6.3.1 of the reinforced concrete structure with the surface layer bars 6.3.2 of the reinforced concrete structure to form a steel skeleton before pouring concrete. It has high rigidity and strong integrity, but it has disadvantages such as many construction procedures, long construction period, high cost, difficulty in later demolition, and easy to form a weak surface by delamination at the contact surface with the upper weir.
[0039] Construction of the cofferdam for heightening and filling: After the flood protection of the anti-seepage wall construction platform is completed, the protective structure of the construction platform directly above the anti-seepage wall is dismantled, and the remaining anti-seepage wall construction continues. The protective structures of the remaining anti-seepage wall construction platforms are not dismantled, and the upper cofferdam filling construction continues. A protective structure 12 for the anti-seepage wall construction trench is set directly above the anti-seepage wall. The protective structure 12 for the anti-seepage wall construction trench is a temporary support measure used to maintain the stability of the trench wall and prevent collapse during the construction of the anti-seepage wall. It is also used to protect the anti-seepage wall trench section from water erosion and siltation during the flood season. Common forms include steel casings and reinforced concrete guide walls. The specific location of the protective structure 12 for the anti-seepage wall construction trench depends on the function of the anti-seepage wall and the project requirements. The setting of the protective structure 12 for the anti-seepage wall construction trench is existing technology and will not be described in detail here. After the flood season is over, the protective structure 12 of the construction trench will be removed so that the remaining anti-seepage wall construction can continue. The protective structure of the remaining area of the anti-seepage wall construction platform will be retained, and the upper weir 13 of the anti-seepage wall construction platform will be directly filled on the upper platform 6, the lower platform 8 of the anti-seepage wall and the upper protective structure. The upper weir 13 and the lower protective structure are closely integrated and work together to form a complete cofferdam water-retaining section.
[0040] Taking a hydropower station on the Jinsha River as an example, the upstream and downstream cofferdams of the hydropower station adopt the flood control protection technology of the anti-seepage wall construction platform of this invention. Simultaneously, the protective structure innovatively adopts a grouting concrete structure. The implementation method includes: ① Using the hydraulic calculation formula of the anti-seepage wall platform, it can be determined that the upstream anti-seepage wall construction platform adopts an 834m high platform and an 830m low platform, and the downstream anti-seepage wall construction platform adopts an 831m high platform and an 826m low platform. The hydraulic model test and the hydraulic indicators calculated by this formula are highly consistent. The flow rate calculated using the formula of this invention is 14500 m³ / h. 3 Under the condition of / s, the calculated maximum flow velocities of the upstream and downstream anti-seepage wall construction platforms are 4.39 m / s and 5.14 m / s, respectively; the hydraulic model test flow rate is 14500 m³ / s. 3 Under the condition of / s, the calculated maximum flow velocities of the upstream and downstream anti-seepage wall construction platforms are 4.23 m / s and 5.32 m / s, respectively, proving the effectiveness of this calculation formula. ② If the downstream anti-seepage wall construction platform of the hydropower station adopts a reinforced concrete protective structure, the volume of reinforced concrete reaches 15,000 m³. 3 The connecting bars and surface reinforcement reached 200 tons, with an investment of approximately 8.7 million yuan and a construction period of 4 months. After adopting a grouting concrete protective structure for the downstream anti-seepage wall construction platform of Wudongde, the amount of reinforced concrete work was reduced, significantly lowering the investment to 3 million yuan and the construction period to 1 month, saving both investment and time. ③ If the upstream and downstream anti-seepage wall construction platforms of Wudongde adopted reinforced concrete protective structures, the demolition period for the reinforced concrete structure would be approximately 1 month after the flood season and before the cofferdam continues to be filled. However, after adopting a grouting concrete protective structure for the downstream anti-seepage wall construction platform of Wudongde, demolition is unnecessary, saving 1 million yuan in demolition investment and 1 month in demolition time.
[0041] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A dike construction platform for a cutoff wall of a temporary weir flood protection structure, the dike construction platform being located on a top surface of the temporary weir flood protection structure, characterised in that: The anti-seepage wall construction platform includes a high platform (6), a low platform (8), and a slope section (7) connecting the high platform (6) and the low platform (8); the high platform (6) is located upstream of the river and the low platform (8) is located downstream of the river, and the top surface of the high platform (6) is higher than the top surface of the low platform (8).
2. The dike construction platform flood protection structure of temporary weir body according to claim 1, characterized in that: The slope section (7) is at the same height as the high platform (6) at one end, and at the same height as the low platform (8) at the other end.
3. The dike construction platform flood protection structure of claim 1, wherein: The overflow surface of the anti-seepage wall construction platform adopts a grouting concrete structure. The grouting concrete structure is filled with large stones as a skeleton to form the main protective body. The grout is filled between the stones and bonded into a whole by pressure grouting.
4. A design method for a flood control protection structure of a construction platform for an anti-seepage wall of a temporary dam as described in claim 1, the method comprising: Establish hydraulic calculation formulas for the anti-seepage wall construction platform as shown in (Equation 1) to (Equation 4). Calculate the elevation P1 of the high platform, the elevation P2 of the low platform, and the slope ratio of the high and low platform slopes based on (Equation 1) to (Equation 4). Complete the construction of the anti-seepage wall construction platform based on the elevation P1 of the high platform, the elevation P2 of the low platform, and the slope ratio of the high and low platform slopes. Achieve flood protection through the anti-seepage wall construction platform with elevation differences. (Equation 1) (Equation 2) (Equation 3) (Equation 4) Where Q represents the total flow rate from the upstream; Indicates the upstream controlled water level; Indicates the downstream control water level; A represents the cross-sectional area of the diversion tunnel. denoted by ; B represents the flow coefficient of the diversion tunnel; ; m represents the axial length of the anti-seepage wall construction platform; ; g represents the gravitational acceleration; ; V represents the flow velocity at the top of the anti-seepage wall platform. φ This represents the velocity-head correction factor; four values are obtained through four formulas: the height of the high platform of the cutoff wall platform P1; the height of the low platform of the cutoff wall platform P2; and the flow rate of the diversion tunnel. ; Flow distribution of the seepage prevention wall platform .
5. The design method for the flood control protection structure of the temporary dam construction platform according to claim 4, characterized in that: The slope ratio of the high and low platform slopes is (P1-P2) / L, where L represents the horizontal distance between the high and low platforms. The flood control protection structure of the temporary dam construction platform is arranged according to the calculated elevation P1 of the high platform of the anti-seepage wall, the elevation P2 of the low platform of the anti-seepage wall, and the slope ratio of the high and low platform slopes.