Construction method for debris flow interception at the intake of a hydropower station

Abstract

This invention relates to the field of water diversion technology in water conservancy and hydropower engineering, specifically to a construction method for a debris barrier at the intake of a hydropower station. The invention includes: A) Fixing the foundations at both ends: Finding suitable foundation fixing points on both the left and right banks, the fixing points must be located on rock, using rock anchor foundations, and grouting with C30 fine aggregate concrete; B) Foundation point pouring; C) Construction of the main debris barrier structure; D) Installation of the debris barrier. This invention addresses the shortcomings of existing technologies by providing a construction method for a debris barrier at the intake of a hydropower station, applicable to the construction of the end structure of the debris barrier under complex conditions, with a short construction period, convenient construction, and low construction cost.

Description

Technical Field

[0001] This invention relates to the field of water diversion technology in water conservancy and hydropower projects, specifically to a construction method for intercepting pollutants at the intake of a hydropower station. Background Technology

[0002] Currently, some hydropower station basins have many trees and concentrated residential areas. Floating branches and debris cover the trash racks in the reservoir area, affecting the flow rate. To solve the problem of excessive flow, trash rack floats are generally installed at the water intake of the hydropower station to effectively intercept floating objects of all sizes and smaller floating objects on and below the water surface.

[0003] Currently, most debris barriers are fixed on both banks, or fixed at one end to the inlet and the other end to the bank. Construction methods for debris barriers are still in the exploratory stage, with no corresponding technical regulations or standards to follow. After excavation at the end of the debris barrier, an independent construction platform needs to be erected and a large amount of concrete backfilled along the slope. This method has high construction costs and concrete pouring costs, and a long construction period. In some projects, the end structure of the debris barrier is designed with a slope to reduce the volume of backfilled concrete. This method places high demands on the design of the hinged structure of the end pontoon of the debris barrier. In engineering applications, the end pontoon of the debris barrier often gets stuck due to excessive resistance, making it impractical. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a construction method for a debris barrier at the intake of a hydropower station. This method is applicable to the construction of the end structure of the debris barrier at the intake under complex conditions, and features a short construction period, convenient construction, and low construction cost.

[0005] The technical solution of this invention is as follows: A construction method for intercepting debris at the intake of a hydropower station, characterized by comprising the following steps:

[0006] A. Foundation fixing at both ends: Find suitable foundation fixing points on the left and right banks. The fixing points must be located on the rocks. Rock anchor foundations are used, and C30 fine stone concrete is used for grouting and pouring.

[0007] B. Foundation point pouring:

[0008] B1. At the pouring point, excavate a pouring pit 800mm long, 800mm wide, and 500mm deep, embedding it into the interior of the mountain.

[0009] B2. Roughen the edges and bottom of the pouring pit, and clean the roughened parts.

[0010] B3. At the bottom of the pouring pit, find 4 points, each 120mm away from the mountain, and drill holes with a diameter of 80mm and a depth of 1000mm. Insert anchor rods with a diameter of d=22mm and a length of 1900mm into each hole. The anchor rods should be 50mm away from the bottom of the hole. The anchor rods should be made of hot-rolled ribbed threaded steel.

[0011] B4. Diagonal reinforcement bars are arranged from the bottom of the casting pit along the four anchor rods, with a spacing of 100mm between the diagonal reinforcement bars, and arranged up to 400mm above the ground. They are then welded firmly to the surrounding anchor rods to form a steel reinforcement cage.

[0012] B5. A ring is made of d=25mm threaded steel at the appropriate location. The ring is connected to the steel cage for later fixing of the wire rope.

[0013] B6. For the above-ground part, formwork is erected 120mm away from the anchor rod, with a formwork height of 500mm. Finally, the entire pouring point is cleaned.

[0014] B7. C30 concrete is used for pouring. Dry materials are transported manually from the left bank highway pouring material storage area to the concrete pouring area. Water is added to the pouring point for mixing and pouring.

[0015] B8. For the right bank pouring, dry materials are mixed manually on the shore and transported to the right bank by boat. Water is then added manually for mixing during pouring.

[0016] C. Construction of the main structure for the pollution interception system:

[0017] C1. Safety verification of the tensile strength of the debris barrier, including calculation of the tensile strength of the debris barrier's own weight and the breaking tensile strength of the wire rope;

[0018] C2. Lay steel wire ropes according to the width of the river surface. The foundation ends on the left and right banks should be 5m away from the river surface. The steel wire rope connection should maintain an arc sag of 12 to 70m.

[0019] C3. The steel wire rope is laid on the left bank of the road, and a pulley is installed at the foundation end on the right bank. The pulley is used to pull the steel wire rope to the foundation end on the right bank, and the steel wire rope is fixed on the rings at the foundation ends on the left and right banks.

[0020] D. Installation of debris barriers:

[0021] D1. Place the modular pontoons on the ship. After the construction workers move along the steel wire rope to the installation position, install the modular pontoons onto the steel wire rope. The installation is stable and the pontoons are evenly distributed on the steel wire rope.

[0022] D2. Install the combined pontoons for the arrangement of the debris net. The debris net is wrapped around the pontoons and fixed with strong self-sealing tape. The lower 8m debris net is placed underwater with counterweights at 1m intervals.

[0023] D3. After assembly, secure the connected steel wire ropes again.

[0024] Step A also includes cleaning the anchor holes before pouring, and using threaded steel with a diameter of d=22mm for the anchor rods.

[0025] Preferably, the debris barrier is composed of a combined pontoon, a debris net, a steel wire rope, a buckle, and a counterweight. The combined pontoon has a diameter of 600mm, a length of 1000mm, a wall thickness of 4mm, and is made of LLDPE material. The debris net is a polyethylene mesh with a mesh size of 150X150mm, and the steel wire rope has a diameter of 28mm.

[0026] One counterweight is installed every 2-3m on the debris-blocking net. The counterweight is made of hollow precast concrete and is suspended from the main steel wire rope by Ø11mm steel wire rope.

[0027] Preferably, in step A, if it is impossible to excavate to the bedrock, the excavation depth needs to be increased according to the actual site conditions; the foundation surface is excavated into a 1:6 reverse slope, with the slope direction opposite to the direction of the main steel wire rope of the debris barrier; both vertical anchor rods and inclined anchor rods are made of φ25mm HRB335 steel bars, the drill hole diameter is 28mm, and a special anchoring agent is used for filling.

[0028] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0029] This invention provides a construction method for a debris barrier at the intake of a hydropower station, applicable to the construction of the end structure of the debris barrier under complex conditions. It features a short construction period, convenient construction, and low construction cost. The invention utilizes rock anchoring as the foundation ends on both banks. A reinforced concrete cage is constructed by excavating and pouring concrete at the bottom of the pit, welding anchor bolts around the perimeter, and finally pouring concrete, ensuring the stability of the foundation structure. Steel wire ropes are placed according to the width of the river surface, with the rope connections maintaining a certain sag. Pulleys are installed on the right bank foundation to pull the steel wire ropes to the right bank foundation, and the ropes are then fixed to the rings on both the left and right bank foundations. The entire construction process is convenient. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the bleaching device of the present invention;

[0032] Figure 2 for Figure 1Schematic diagram of the structure of the central sludge filter;

[0033] Figure 3 for Figure 1 A schematic plan of the foundation end on the left bank;

[0034] Figure 4 for Figure 3 A cross-sectional schematic diagram;

[0035] Figure 5 for Figure 1 A schematic plan of the foundation end on the right bank;

[0036] Figure 6 for Figure 5 A cross-sectional schematic diagram;

[0037] Figure 7 This is a schematic diagram of the site after the pollution interception project was completed.

[0038] In the diagram: 1-Left bank foundation end, 2-Right bank foundation end, 3-Wire rope, 4-Balloon barrier, 41-Combined pontoon, 42-Balloon barrier net. Detailed Implementation Example

[0039] like Figures 1 to 6 As shown, the construction method for intercepting debris at the intake of the hydropower station is characterized by the following steps:

[0040] A. Foundation Fixing at Both Ends: Find suitable fixing points for foundation end 1 on the left bank and foundation end 2 on the right bank. The fixing points must be located on rock, using rock anchor foundations, and grouting with C30 fine aggregate concrete. Clean the anchor holes before pouring. Use threaded steel with a diameter of d=22mm for the anchors. If it is impossible to excavate to bedrock, the excavation depth needs to be increased according to the actual site conditions. The foundation surface should be excavated with a 1:6 reverse slope, opposite to the direction of the main steel wire rope 3 of the debris barrier. Both vertical and inclined anchors should use φ25mm HRB335 steel bars, with a drilled hole diameter of 28mm, and filled with a special anchoring agent.

[0041] B. Foundation point pouring:

[0042] B1. At the pouring point, excavate a pouring pit 800mm long, 800mm wide, and 500mm deep, embedding it into the interior of the mountain.

[0043] B2. Roughen the edges and bottom of the pouring pit, and clean the roughened parts.

[0044] B3. At the bottom of the pouring pit, find 4 points, each 120mm away from the mountain, and drill holes with a diameter of 80mm and a depth of 1000mm. Insert anchor rods with a diameter of d=22mm and a length of 1900mm into each hole. The anchor rods should be 50mm away from the bottom of the hole. The anchor rods should be made of hot-rolled ribbed threaded steel.

[0045] B4. Diagonal reinforcement bars are arranged from the bottom of the casting pit along the four anchor rods, with a spacing of 100mm between the diagonal reinforcement bars, and arranged up to 400mm above the ground. They are then welded firmly to the surrounding anchor rods to form a steel reinforcement cage.

[0046] B5. A ring is made of d=25mm threaded steel at the appropriate location. The ring is connected to the steel cage and used to fix the steel wire rope 3 later.

[0047] B6. For the above-ground part, formwork is erected 120mm away from the anchor rod, with a formwork height of 500mm. Finally, the entire pouring point is cleaned.

[0048] B7. C30 concrete is used for pouring. Dry materials are transported manually from the left bank highway pouring material storage area to the concrete pouring area. Water is added to the pouring point for mixing and pouring.

[0049] B8. The right bank pouring adopts the method of manually mixing dry materials on the shore, transporting them to the right bank by boat, and then manually adding water and mixing them for pouring.

[0050] C. Construction of the main structure for the pollution interception system:

[0051] The debris barrier float 4 consists of a combined pontoon 41, a debris net 42, a steel wire rope 3, buckles, and counterweights. The combined pontoon 41 has a diameter of 600mm, a length of 1000mm, a wall thickness of 4mm, and is made of LLDPE material. The debris net 42 has a mesh size of 150X150mm, and the steel wire rope 3 has a diameter of 28mm.

[0052] C1. Safety verification of the tensile strength of the debris barrier 4, including calculation of the tensile strength of the debris barrier's own weight and the breaking tensile strength of the steel wire rope 3.

[0053] The weight of the debris barrier 4 is 21kg (weight of the pontoon itself) x 320 (number of pontoons) = 6720Kg;

[0054] The self-weight of the wire rope = 2.16 kg (2.16 kg / meter) x 340 m (length of wire rope) = 734.4 kg;

[0055] Calculation of breaking tensile force of wire rope

[0056] The calculation formula is: S = DxDx52

[0057] Breaking strength of wire rope = 28 x 28 x 52 = 40768 kg

[0058] Actual breaking strength safety factor = 40768 (theoretical breaking strength) ÷ 4 (4 times safety factor) = 10192 kg

[0059] 10192kg (breaking force with a safety factor of 4) ≥ 6720 (weight of the debris barrier) + 734.4 (length of the wire rope)

[0060] In summary: the breaking tensile force under extreme conditions is ≥ 4 times the extreme condition, which fully meets the requirements for safe operation;

[0061] C2. Based on the width of the river surface of 280m, place steel wire rope 3. The foundation ends 1 and 2 on the left and right banks are each 5m away from the river surface. The connection of steel wire rope 3 should have a certain sag, and the sag length is 12m.

[0062] C3. The steel wire rope 3 has a d=28mm diameter and a length of 340m. The steel wire rope is laid on the left bank road and a pulley is installed at the right bank foundation end 2. The pulley is used to pull the steel wire rope 3 to the right bank foundation end 2 and fix the steel wire rope 3 on the rings at the left and right bank foundation ends 1 and 2.

[0063] D. Installation of debris barriers:

[0064] D1. Place the combined pontoon 41 on the ship. After the construction personnel move along the steel wire rope 3 to the installation position, the combined pontoon 41 is installed on the steel wire rope 3. The installation is stable and the pontoons are evenly distributed on the steel wire rope.

[0065] D2. Install the pontoons and arrange the debris net. Wrap the debris net around the pontoons and fix it with strong self-sealing tape. Place the 8m debris net below underwater with counterweights spaced 1m apart. Install one counterweight every 2-3m on the debris net. The counterweights are made of hollow precast concrete and are suspended from the main steel wire rope by Ø11mm steel wire rope.

[0066] D3. After assembly, secure the connected steel wire rope 3 again to complete the installation of the debris barrier. The final effect is as follows: Figure 7 As shown.

[0067] The working process of this invention is as follows: This invention provides a construction method for a debris barrier at the intake of a hydropower station, applicable to the construction of the end structure of the debris barrier under complex conditions. It features a short construction period, convenient construction, and low construction cost. This invention uses rock anchoring as the foundation ends on both banks. A reinforced concrete cage is constructed by excavating and pouring concrete at the bottom of the pit, welding anchor bolts firmly around the perimeter, and finally pouring concrete, ensuring structural stability. Steel wire ropes are placed according to the width of the river surface, with the rope connections maintaining a certain sag. Pulleys are installed on the right bank foundation, and the steel wire ropes are pulled to the right bank foundation and fixed to the rings on both the left and right bank foundations. The entire construction process is convenient, quick, and highly efficient.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method for intercepting debris at the intake of a hydropower station, characterized in that, Includes the following steps: A. Selection of foundation anchoring points at both ends: Find suitable foundation anchoring points on both the left and right banks. The anchoring points must be located on the rock and rock anchoring foundations should be used. B. Casting at the foundation end fixing point: B1. At the pouring point, excavate a pouring pit 800mm long, 800mm wide, and 500mm deep, embedding it into the interior of the mountain. B2. Roughen the edges and bottom of the pouring pit, and clean the roughened parts. B3. At the bottom of the pouring pit, find 4 points, each 120mm away from the mountain, and drill holes with a diameter of 80mm and a depth of 1000mm. Insert anchor rods with a diameter of d=22mm and a length of 1900mm into each hole. The anchor rods should be 50mm away from the bottom of the hole. The anchor rods should be made of hot-rolled ribbed threaded steel. B4. Diagonal reinforcement bars are arranged from the bottom of the casting pit along the four anchor rods, with a spacing of 100mm between the diagonal reinforcement bars, and arranged up to 400mm above the ground. They are then welded firmly to the surrounding anchor rods to form a steel reinforcement cage. B5. A ring is made of d=25mm threaded steel at the appropriate location. The ring is connected to the steel cage for later fixing of the wire rope. B6. For the part above ground, set up formwork 120mm away from the anchor rod, with a formwork height of 500mm, and finally clean the entire pouring point. B7. C30 concrete is used for pouring. Dry materials are transported manually from the left bank highway pouring material storage area to the concrete pouring area. Water is added to the concrete and it is then mixed and poured into the pouring point. B8. The right bank pouring adopts the method of manually mixing dry materials on the shore, transporting them to the right bank by boat, and then manually adding water and mixing them for pouring. C. Construction of the main structure for the pollution interception system: C1. Conduct a tensile safety test on the debris barrier, including calculations of the debris barrier's own weight tensile force and the wire rope breaking tensile force; C2. Lay steel wire ropes according to the width of the river surface. The foundation ends on the left and right banks should be 5m away from the river surface. The steel wire rope connection should maintain an arc sag of 12 to 70m. C3. The steel wire rope is laid on the left bank of the road, and a pulley is installed at the foundation end on the right bank. The pulley is used to pull the steel wire rope to the foundation end on the right bank, and the steel wire rope is fixed on the rings at the foundation ends on the left and right banks. D. Installation of debris barriers: D1. Place the modular pontoons on the ship. After the construction workers move along the steel wire rope to the installation position, install the modular pontoons onto the steel wire rope. The installation is stable and the pontoons are evenly distributed on the steel wire rope. D2. Install the combined pontoons for the arrangement of the debris net. The debris net is wrapped around the pontoons and fixed with strong self-sealing tape. The 8m debris net is placed underwater with counterweights. One counterweight is installed on the debris net every 1m. D3. After assembly, secure the connected steel wire ropes again.

2. The construction method for intercepting debris at the intake of a hydropower station according to claim 1, characterized in that: Step B also includes cleaning the anchor holes before pouring, and using threaded steel with a diameter of d=22mm for the anchor rods.

3. The construction method for intercepting debris at the intake of a hydropower station according to claim 1 or 2, characterized in that: The debris barrier consists of a combined pontoon, a debris net, steel wire rope, buckles, and counterweights. The combined pontoon has a diameter of 600mm, a length of 1000mm, a wall thickness of 4mm, and is made of LLDPE material. The debris net is a polyethylene mesh with a mesh size of 150X150mm, and the steel wire rope has a diameter of 28mm.

4. The construction method for intercepting debris at the intake of a hydropower station according to claim 1, characterized in that: The counterweight is made of hollow precast concrete and is suspended from the main steel wire rope by an Ø11mm steel wire rope.

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