GB2614441A

GB2614441A - Anti-cavitation-corrosion device for hydraulic structure, and construction method

Info

Publication number: GB2614441A
Application number: GB2218147.3A
Authority: GB
Inventors: Zhai Yanwei; Yang Zhenggui; Xiong Jianwu; Li Xinming; Yang Xiaohua; Li Jianbo
Original assignee: China Three Gorges Corp; China Gezhouba Group No 1 Engineering Co Ltd
Current assignee: China Three Gorges Corp; China Gezhouba Group No 1 Engineering Co Ltd
Priority date: 2021-06-15
Filing date: 2021-12-06
Publication date: 2023-07-05
Also published as: DE112021002168T5; WO2022135123A1; GB202218147D0

Abstract

Provided are an anti-cavitation-corrosion device for a hydraulic structure, and a construction method. The anti-cavitation-corrosion device comprises a fixed frame pre-buried in concrete, wherein the fixed frame is connected to a bearing layer, and an anti-cavitation-corrosion panel is fixedly connected to the bearing layer. The anti-cavitation-corrosion panel is made of an anti-cavitation-corrosion alloy material, which comprises a stainless steel material or a titanium alloy material. Alternatively, the anti-cavitation-corrosion panel is made of a rubber material. The construction method comprises: sticking a double-sided adhesive tape to a form of a lining trolley, and sticking an anti-cavitation-corrosion panel of an anti-cavitation-corrosion device to the form by means of the double-sided adhesive tape; connecting the lining trolley of the next truss to the lining trolley of the current truss, and repeating the steps; mounting an end form, pouring concrete, and performing concrete vibration to make same compact; and after concrete curing reaches an age, removing the form. An anti-cavitation-corrosion device at a variable cross-section segment is constructed by means of the steps. A special anti-cavitation-corrosion panel is used at an overflowing part where cavitation corrosion damage tends to occur, thereby reducing the possibility of cavitation and reducing the cavitation corrosion damage to the greatest extent when cavitation corrosion occurs.

Description

ANTI-CAVITATION-CORROSION DEVICE FOR

HYDRAULIC STRUCTURE, AND CONSTRUCTION METHOD

FIELD OF THE INVENTION

The present invention relates to the technical field of protection against cavitation erosion for hydraulic tunnels, in particular to an anti-cavitation device for hydraulic buildings and a construction method thereof

BACKGROUND OF THE INVENTION

hi a flowing liquid, when the pressure in the local area due to some reason suddenly drops below the vapor pressure corresponding to the temperature of the liquid in this area, that part of the liquid evaporates and the gas dissolved in the liquid escapes forming a cavitation bubble in the liquid stream is called cavitation. When cavitation bubbles enters the area with higher pressure along with the liquid flow, external conditions suddenly change to enable the cavitation bubbles to collapse, and the liquid moves around the original cavitation bubbles to enable the pressure in the local area to increase suddenly. If the cavitation bubbles that are constantly formed and grows in the liquid flow frequently collapses near a solid wall, the wall will suffer from repeated impacts of huge pressure, as inventor's research, a high-speed jet will be generated inside the material during rupturing of the cavitation bubbles, causing fatigue damage and even surface erosion to the material, so this process is called cavitation erosion. People focus on cavitation and cavitation erosion as one of the key issues in research, design and operation management for the design and operation management of the drainage buildings with high-velocity and large flow. Cavitation erosion becomes one of the most common failure modes in large-scale water conservancy and hydropower projects. In the drainage buildings of a large number of water conservancy and hydropower projects with medium and high flood peak at home and abroad, cavitation damage often occurs in some flow-passing portions. Cavitation damage will directly affect the normal use and service life of the buildings within water conservancy and hydropower projects, and even cause accidents to the entire building, resulting in great risk to life and property safety, so cavitation and cavitation erosion has always been an emphasis and difficulty of research in the field of hydraulic projects. So far, there is no good solution for it. One technical idea is to add some special materials to concrete to improve the anti-erosion effect, such as a technical solution described in the Chinese patent CN100396638C, named a concrete additive and preparation method of same and a concrete applied with the additive. Although this solution can improve resistance to cavitation corrosion, it is still difficult to avoid cavitation damage, and the problem, such as different concrete materials prone to cracking, al so exists, The inventor intended to arrange anti-cavitation panels at a flow-passing position where the problem of cavitation and cavitation erosion is prone to occur, but how to flatten the anti-cavitation panels in an array arrangement still is a difficult problem. Furthermore, uneven anti-cavitation panels will aggravate the problem of cavitation and cavitation erosion.

SUMMARY OF THE INVENTION

One technical problem to be solved by the present invention consists in the cavitation erosion of hydraulic tunnels, therefor we provide an anti-cavitation device for hydraulic buildings, so as to protect against cavitation damage of the inner wall of hydraulic tunnels, and greatly extend the service life of the inner wall of hydraulic tunnels A preferred solution of the present invention also contributes to later maintenance.

Another technical problem to be solved by the present invention consists in the flatness and high construction efficiency of the anti-cavitation panels, therefor we provide a constniction method of an anti-cavitation device for hydraulic buildings.

In order to solve the above technical problem, the technical scheme adopted in the present invention is as follows an anti-cavitation device for hydraulic buildings, comprising a fixed frame, a bearing layer, and an anti-cavitation panel, wherein the fixed frame is embedded in advance in concrete, the fixed frame is connected to the bearing layer, and the anti-cavitation panel is fixedly connected to the bearing layer.

In a preferred solution, the anti-cavitation panel is made from anti-cavitation alloy materials, including a stainless steel material or a titanium alloy material In a preferred solution, the anti-cavitation panel is made from rubber materials.

In a preferred solution, the anti-cavitation panel is connected to the bearing layer by means of a connecting layer, the connecting layer is made from a binder, and the bearing layer is made from elastic polymer materials or an aluminum alloy material In a preferred solution, the bearing layer is connected to the fixed frame by means of a gripping groove, and the fixed frame is connected to a lining reinforcing bar-net by a connecting rib.

In a preferred solution, the gripping groove is a dovetail groove.

In a preferred solution, the anti-cavitation device is arranged at a variable section of the hydraulic tunnel and lies in an array arrangement along the inner wall of the variable section; the downstream of the anti-cavitation panels of the adjacent anti-cavitation device are provided with a lap joint slant, the top of which extends downstream, and the bottom of which extends upstream.

In a preferred solution, the bearing layer of the anti-cavitation device located in the bottom row is connected with the fixed frame by a connection of screws in array, and the bearing layers at other positions are connected with the fixed frame by means of the gripping groove.

A construction method of the anti-cavitation device for hydraulic buildings, comprising the following steps: St. selecting a lining trolley with a single truss for a variable section, and standing a molding plate on the lining trolley in line with a preset profile shape; 52. pasting a double-sided adhesive tape on the molding plate on the lining trolley, and connecting the anti-cavitation panel of the anti-cavitation device with the molding plate by means of the double-sided adhesive tape S3. fixedly connecting the fixed frame of the anti-cavitation device to a two-lining reinforcing bar-net by means of a connecting rib; S4. connecting the lining trolley at the next truss to the lining trolley at the current truss, and repeating steps SI-S3 until completing the arrangement of the anti-cavitation device of the entire variable section; S5. installing a molding plate head, casting concrete, and tamping concrete; and SO. after reaching the maintenance life of concrete, removing molding plates, wherein the above steps enables the anti-cavitation device at the variable section to be constructed.

In a preferred solution, the molding plate on the lining trolley has a multi-segment structure from top to bottom, and the anti-cavitation device is installed from the bottom to the top during its installation; at the time of installing the anti-cavitation device, a steel wire is buried in the double-sided adhesive tape, and the steel wire is arranged in the axis direction of the variable section, in order to cut the double-sided adhesive tape during removing the molding plates.

The anti-cavitation device for hydraulic buildings and the construction method thereof provided by the present invention can be applied to different types of flow-passing portions of drainage buildings, so as to reduce the possibility of cavitation, minimize the cavitation damage at occurrence of cavitation by adopting special anti-cavitation panels on the flow-passing portions that are prone to cavitation damage, and protect the inner wall of hydraulic tunnels, especially the variable section that is prone to cavitation erosion. The present invention adopts an assembled structure with low construction difficulty, high reliability, and convenience for mass processing and production, as well as convenience for transportation and later maintenance.

BRIEF DESCRIPTION OF THE DRAWINGS

Now, we shall describe the present invention in detail in combination with the examples and drawings as follows.

FIG. I is a top view at construction according to the present invention.

FIG. 2 is a front view at construction according to the present invention.

FIG. 3 is a partial elevation view of the hydraulic tunnel at construction according to the present invention.

FIG. 4 is a local cross-sectional view of the anti-cavitation device according to the present invention FIG. 5 is a preferred structure diagram of the fixed frame in the present invention.

FIG 6 is an cavitation image of the control side in the experimental examples of the present invention.

FIG. 7 is a surface image of the cavitation erosion on the control side in Experimental Example 2 of the present invention.

FIG. 8 is a surface image on the study side in Experimental Example 2 of the present invention.

Where:1-variable section, 2-hydraulic tunnel, 3-molding plate head,4-molding plate,5-anti-cavitation device, 501-anti-cavitation panel, 502-lap joint slant,503-connecting layer,504-fixed frame,505-connecting rib,506-bearing layer,507-gripping groove, 508-connecting screw,6-lining trolley.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Example 1:

As shown in FIGs.1, 3 and 4, in the anti-cavitation device for hydraulic buildings, the anti-cavitation device 5 includes a fixed frame 504 embedded in advance in concrete, the fixed frame 504 is connected to the bearing layer 506, and the anti-cavitation panels 501 is fixedly connected with the bearing layer 506. This structure enables the anti-cavitation panels 501 to be reliably fixed on the inner wall of the hydraulic tunnel 2, so as to mitigate cavitation damage at this location.

As a preferred solution shown in FIG.4, the anti-cavitation panel 501 is made from anti-cavitation alloy materials, including a stainless steel material or a titanium alloy material. When the flow-passing velocity is lower than 14m/s, for example, the flow-passing velocity is 8m/s, smooth and flawless anti-cavitation alloy materials are used, and in this example the titanium alloy material is preferred. The bearing layer 5 06 is made from polymer materials th certain elasticity, for example, ultra-high molecular weight polyethylene, polyvinyl chloride, nylon and other materials.

As a preferred solution shown in FIG. 4, the anti-cavitation panel 501 is made from rubber materials with preferred elastic modulus as 50MPa. When the flow-passing velocity is higher than 14m/s, smooth and defect-free rubber materials are used, and the bearing layer 506 is made from polymer materials with certain elasticity, for example, ultra-high molecular weight polyethylene, polyvinyl chloride, nylon and other materials.

As a preferred solution shown in FIG.4, the anti-cavitation panel 501 is connected to the bearing layer 506 by means of the connecting layer 503, wherein the connecting layer 503 is made from a binder, and the bearing layer 506 is made from elastic polymer materials or an aluminum alloy material. The connecting layer 503 is preferably made from a AB glue or a polyethylene glue.

As a preferred solution shown in FIG. 4, the bearing layer 506 is connected to the fixed frame 504 by means of the gripping groove 507, and the fixed frame 504 is connected to the lining reinforcing bar-net by the connecting rib 505. The lining reinforcing bar-net refers to a reinforcing bar-net embedded in advance in the two-lining concrete of hydraulic tunnel 2.

As a preferred solution shown in FIG. 4, the gripping groove 507 is a dovetail groove. This structure contributes to later maintenance. As a preferred solution shown in FIG. 5, the gripping groove 507 consists in intermittent structure, and the length of the gripping groove 507 at disconnection position is greater than its length at connection position, so as to enable the entire bearing layer 506 to be removed in the condition that the bearing layer 506 only needs to slide a small distance along the vertically arranged gripping groove 507, reducing the strength to maintain it.

As a preferred solution shown in FIG. 1, the anti-cavitation device 5 is arranged at variable section 1 of the hydraulic tunnel 2 and lies in an array arrangement along the inner wall of the variable section 1. As researched by us, cavitation occur more violently at the most position where a large section transitions to a small section, thus velocity changes to generate a large number of cavitation structures. Therefore, the anti-cavitation device 5 is arranged in an array on the inner wall of the variable section 1.

As shown in FIGs. 3 and 4, the downstream of the anti-cavitation panels 501 of the adjacent anti-cavitation device 5 are provided with a lap joint slant 502, the top of which extends downstream, and the bottom of which extends upstream. This structure enables a lap joint seam along flow to form between adjacent anti-cavitation panels 501 upstream and downstream, avoiding more ease to generate cavitation due to a straight seam structure.

As a preferred solution shown in FIG. 3, the bearing layer 506 of the anti-cavitation device 5 located in the bottom row is connected with the fixed frame 504 by a connection of screws in array, and the bearing layers 506 at other posi Lions are connected with the fixed frame 504 by means of the gripping groove 507.

This structure enables the anti-cavitation device 5 located in the bottom row first to be removed at maintenance, and the bearing layers 506 of all upper rows next to be detached from the gripping groove 507.

Example 2:

As shown in FIGs.1 and 2, a construction method of the forementioned anti-cavitation device for hydraulic buildings includes the following steps.

Sl. Selecting a lining trolley 6 with a single truss for the variable section 1, and standing a molding plate 4 on the lining trolley 6 in line with the preset profile shape of the inner wall of the hydraulic tunnel 2.

S2. Pasting a double-sided adhesive tape on the molding plate on the lining trolley 6, and connecting the anti-cavitation panel 501 of the anti-cavitation device 5 with the molding plate by means of the double-sided adhesive tape. In the preferred solution, at the time of installing the anti-cavitation device 5, a steel wire is buried in the double-sided adhesive tape, and the steel wire is arranged in the axis direction of the variable section 1, in order to cut the double-sided adhesive tape during removing the mold for convenience of mold removal.

S3. Fixedly connecting the fixed frame 504 of the anti-cavitation device 5 to the two-lining reinforcing bar-net by means of the connecting rib 505, which may be welded together or bound together. Specifically, a plurality of connecting seats are provided on the back of the fixed frame 504, a thread is provided on the connecting seat, and one end of the connecting rib 505 is fixedly mounted on the connecting seat by means of the thread. The other end of the connecting rib 505 is welded or bound with the two-lining reinforcing bar-net, typically the connecting rib 505 positioned in the middle of the fixed frame 504 is in spot welding connection, and the connecting rib 505 positioned at the edge position is in binding connection, for ease of operation.

S4. Connecting the lining trolley 6 at the next truss to the lining trolley 6 at the current truss, and repeating steps S1-S3 until completing the arrangement of the anti-cavitation device 5 of the entire variable section 1. Using the lining trolley 6 at each frame to make a fixation is convenient for the anti-cavitation device 5 and the two-lining reinforcing bar-net to connect with each other. The lining trolley 6 at each frame may be drawn to move by some devices such as an excavator, a winch and an electric hoist.

S5. Installing a molding plate head 3, casting concrete, and tamping concrete. In a preferred solution, the molding plate on the lining trolley 6 has a multi-segment structure from top to bottom, the anti-cavitation device 5 is installed from the bottom to the top during its installation. The anti-cavitation device 5 may be installed layer by layer from top to bottom, and the way of casting concrete from top to bottom under construction and tamping concrete layer by layer can improve the quality of concrete casting.

S6. After reaching the maintenance life of concrete, removing molds. During removal of the molds, the way of pulling the steel wire along the profile of the molding plate and cutting the adhesive tape is convenient for the molding plate 4 to retract.

The above steps enable the anti-cavitation device 5 at the variable section 1 to be constructed.

The present invention has different combinations according to the base material to be protected, the flow-passing characteristics and the types of framework layers and protective layer materials, and makes flexible combinations according to the requirements of the scenes, so as to achieve a better protection effect.

Compared with Reference Document CN 107587968 B, the present invention makes a more firm conjunction with the substrate of concrete, and the material type of the anti-cavitation panel 501 can be selected according to the requirements of the scenes; when the protective layer material is aged or damaged, it isn't necessary to completely replace it, instead only replace the damaged bearing layer 506 and the anti-cavitation panel 501.

Compared with Reference Document CN 202895813 U, the modularized array arrangement structure of the present invention has unstrict requirements to the base material, roughness, etc., and the flow-passing portion does not need pretreatment.

Compared with Reference Document CN 107605874 B, the present invention has more advantages in the principle of protection against cavitation erosion. This Reference Document discloses that microgrooves contain air to form an air film for cavitation erosion. According to the principle of cavitation, the air core contained in the microgrooves will aggravate the cavitation, meanwhile the microgrooves increase unevenness on the surface and also aggravate the cavitation, so this structure provides a very limited anti-cavitation effect on its surface layer. The protective layer in the present invention is smooth and flawless, in principle reduces the possibility to cavitate and has a better anti-cavitation effect.

Experimental Example 1: The anti-cavitation device 5 is arranged in array on the side of the flow-passing section of the variable section 1 with flow-passing velocity of 8m/s, which serves as a study side, the anti-cavitation panel 501 is made from a titanium alloy material, and the bearing layer 506 is made from polymer materials with certain elasticity. The original flow-passing section of concrete with certain roughness arranged on the other side serves as a control side. The initiation and development of cavitation on both sides are monitored by means of a hydrophone and a high-speed camera, respectively, as shown in FIG.6. When cavitation is detected on the control side, no cavitation occurs on the study side.

Experimental Example 2: The anti-cavitation device 5 is arranged in array on the side of the flow-passing section of the variable section I with flow-passing velocity oh' 14m/s, which serves as a study side, the anti-cavitation panel 501 is made from a smooth and flawless anti-cavitation elastic rubber material with thickness of 16mm and elastic modulus of 50MPa, and the bearing layer 506 is made from a aluminum alloy material. Pits or holes are observed on the surface of the control side subject to water impact for a certain period, that is, some obvious cavitation damage characteristics appear, but there is no obvious change on the surface of the study side, and no cavitation damage occurs. As shown in FIGs.7 and 8, the device made of an aluminum alloy material in FI6.7 has a large number of visible cavitation structures on the surface, but the device made of made of a rubber material in FIG.8 has no cavitation on the surface.

Based on the above experimental examples, it is proved that the present invention can be used to prevent cavitation or reduce cavitation damage at different velocity, and enable very effective protection against cavitation erosion, thereby protecting the key flow-passing portions of the hydraulic tunnel 2.

The above embodiments are only preferred technical solutions of the present invention, and should not be regarded as limiting the present invention. The scope of protection of the present invention shall be the technical solutions recorded in the claims, including the equivalent alternatives of the technical features in the technical solutions recorded in the claims. Equivalent substitutions and improvements in the scope are also included in the scope of protection of the present invention

Claims

CLAIMS: I. An anti-cavitation device for hydraulic buildings, comprising a fixed frame (504), a bearing layer (506), and an anti-cavitation panel (501), wherein said fixed frame (504) is embedded in advance in concrete, said fixed frame (504) is connected to said bearing layer (506), and said anti-cavitation panel (501) is fixedly connected to said bearing layer (506).
2. The anti-cavitation device for hydraulic buildings according to claim 1, wherein said anti-cavitation panel (501) is made from anti-cavitation alloy materials, including a stainless steel material or a titanium alloy material.
3. The anti-cavitation device for hydraulic buildings according to claim 1, wherein said anti-cavitation panel (501) is made from rubber materials.
4. The anti-cavitation device for hydraulic buildings according to any one of claims 1-3, wherein said anti-cavitation panel (501) is connected to said bearing layer (506) by means of a connecting layer (503), said connecting layer (503) is made from a binder, and said bearing layer (506) is made from elastic polymer materials or an aluminum alloy material.
5. The anti-cavitation device for hydraulic buildings according to claim 4, wherein said bearing layer (506) is connected to said fixed frame (504) by means of a gripping groove (507), and said fixed frame (504) is connected to a lining reinforcing bar-net by a connecting rib (505).
6. The anti-cavitation device for hydraulic buildings according to claim 5, wherein said gripping groove (507) is a dovetail groove.
7. The anti-cavitation device for hydraulic buildings according to any one of claims 1-3, 5-6, said anti-cavitation device (5) is arranged at a variable section (1) of said hydraulic tunnel (2) and lies in an array arrangement along the inner wall of said variable section (1); the downstream of said anti-cavitation panels (501) of the adjacent anti-cavitation device (5) are provided with a lap joint slant (502), the top of which extends downstream, and the bottom of which extends upstream.
8. The anti-cavitation device for hydraulic buildings according to claim 7, wherein said bearing layer (506) of said anti-cavitation device (5) located in the bottom row is connected with said fixed frame (504) by a connection of screws in array, and said bearing layers (506) at other positions are connected with said fixed frame (504) by means of said gripping groove (507).
9. A construction method of said anti-cavitation device for hydraulic buildings according to any one of claims 1-8, comprising the following steps: Sl. selecting a lining trolley (6) with a single truss for a variable section (1), and standing a molding plate (4) on said lining trolley (6) in line with a preset profile shape; S2. pasting a double-sided adhesive tape on the molding plate on said lining trolley (6), and connecting the anti-cavitation panel (501) of said anti-cavitation device (5) with the molding plate by means of said double-sided adhesive tape; S3. fixedly connecting the fixed frame (504) of said anti-cavitation device (5) to a two-lining reinforcing bar-net by means of a connecting rib (505); 54. connecting said lining trolley (6) at the next truss to said lining trolley (6) at the current truss, and repeating steps Sl-S3 until completing the arrangement of said anti-cavitation device (5) of the entire variable section (1); 55. installing a molding plate head (3), casting concrete, and tamping concrete and S6. after reaching the maintenance life of concrete, removing molding plates, wherein the above steps enables said anti-cavitation device (5) at said variable section (1) to be constructed.
10. The construction method of the anti-cavitation device for hydraulic buildings according to claim 9, wherein the molding plate on said lining trolley (6) has a multi-segment structure from top to bottom, and said anti-cavitation device (5) is installed from the bottom to the top during its installation; at the time of installing said anti-cavitation device (5), a steel wire is buried in said double-sided adhesive tape, and said steel wire is arranged in the axis direction of said variable section (1), in order to cut said double-sided adhesive tape during removing the molding plates.