Steel lining structure of round-square gradual transition section of tail water of pumped storage power station

Abstract

The utility model provides a kind of pumped storage power station tail water round square gradual change section steel lining structure, it is related to the technical field of water conservancy and hydropower engineering, including gradual change section steel pipe, multiple thrust ring is welded in steel pipe outer circle, multiple I-beam is welded in steel pipe outer surface and is arranged with thrust ring interval, multiple mortar anchor rod extends into rock and is welded connection with thrust ring. Multiple openings are provided on the steel pipe, and reinforcing plates are welded outside the openings. The openings are closed after grouting with the grouting plugs. Through the cooperative work of the thrust ring, I-beam, and mortar anchor rod, the external pressure stability of the tail water round square gradual change section steel lining is significantly improved, the instability deformation of the steel lining during construction and operation is effectively prevented, and the safe and stable operation of the power station is ensured.

Description

Technical Field

[0001] This utility model relates to the field of water conservancy and hydropower engineering technology, specifically to a steel lining structure for the tailrace transition section of a pumped storage power station. Background Technology

[0002] Pumped storage power stations are important peak-shaving and frequency-regulating facilities in power systems, and the safe and stable operation of their water conveyance systems is crucial to the normal operation of the power station. In the water conveyance system of a pumped storage power station, the tailrace branch pipe is located at the lowest point of the entire system and is usually constructed with a steel-lined structure. In particular, the tailrace branch pipe near the tailrace emergency gate chamber well seat requires a gradually changing steel-lined structure design with round-to-square and square-to-round transition sections to meet hydraulic requirements and structural transition needs.

[0003] However, due to the unique location of the tailrace branch transition section's steel lining structure, it faces severe challenges in external pressure stability during both construction and operation. During construction, external loads generated during backfilling and grouting may cause instability and deformation of the steel lining structure; during operation, groundwater pressure will also exert continuous external pressure on the steel lining structure. If these external pressures exceed the steel lining structure's resistance to external pressure, buckling deformation and bulging will occur, seriously affecting the safe operation of the power plant.

[0004] Several pumped-storage power stations already built in China have experienced incidents of bulging in the steel lining of the tailrace branch transition section during construction or operation. These incidents are mainly due to insufficient external pressure resistance of the transition section steel lining structure and poor backfill concrete construction quality. Traditional transition section steel lining structure designs often only consider internal water pressure and insufficient external pressure stability; while conventional backfill concrete construction techniques are also difficult to guarantee the compactness of the foundation slab concrete, easily leading to voids between the steel lining and the concrete, further reducing the steel lining's resistance to external pressure.

[0005] To address these issues, existing technologies typically employ measures such as increasing the thickness of the steel lining, adding stiffening rings, or increasing the thickness of the backfill concrete to improve the external pressure resistance of the steel lining in the transition section. However, these measures often have drawbacks such as large material consumption, high construction difficulty, and significantly increased costs, and they cannot fundamentally solve the problems of insufficient backfill concrete density and insufficient connection strength between the steel lining and the surrounding rock. Utility Model Content

[0006] The purpose of this utility model is to provide a steel lining structure for the tailrace transition section of a pumped storage power station. The structure is optimized, the construction is reliable, and the economy is reasonable. It can effectively improve the stability against external pressure, prevent the occurrence of steel lining bulging accidents, and ensure the safe and stable operation of the power station.

[0007] To achieve the above objectives, this utility model employs the following technical solution: A steel lining structure for the tailrace transition section of a pumped storage power station, comprising: Gradient section steel pipe; multiple thrust rings, welded to the outer circumference of the gradient section steel pipe; Multiple I-beams are welded to the outer surface of the transition section steel pipe and are arranged at intervals with the thrust ring, and are evenly distributed in the circumferential direction. Multiple mortar anchors extend into the rock and are welded to the thrust ring; The steel pipe of the transition section is provided with multiple openings, and a reinforcing plate is welded to the outside of the openings. And a grouting plug that mates with the opening, used to seal the opening after grouting and backfilling with concrete.

[0008] Furthermore, the number of openings in the bottom plate of the gradually changing section of the steel pipe is greater than that in other sections.

[0009] Furthermore: the I-beams are I40a I-beams, and are evenly arranged at circumferential intervals of approximately 8°-20°.

[0010] Furthermore, the thrust rings have a spacing of 500-1000mm, a thickness of 18-30mm, and a height of 100-200mm.

[0011] Furthermore: the length of the mortar anchor is 3-6m, the rock penetration depth is 50%-70% of the total length of the mortar anchor, and it is arranged in a quincunx pattern.

[0012] Furthermore: after the grouting plug is welded to the transition section steel pipe, the square protrusion is cut off and ground flat.

[0013] Furthermore, an aluminum washer is provided between the grouting plug and the transition section steel pipe, and the thickness of the aluminum washer is 1-5mm.

[0014] Furthermore, the opening is used for venting during the backfilling of concrete and grouting process.

[0015] Furthermore, the backfill concrete is self-compacting concrete with a strength grade of C20 for concrete aggregate size.

[0016] Furthermore, the transition section steel pipe has a round-to-square or square-to-round structure and is located at the transition section of the tailrace emergency gate chamber of the pumped storage power station.

[0017] Compared with the prior art, the present invention has the following advantages: I. By setting a collaborative working structure of thrust ring, I-beam and mortar anchor rod outside the transition section steel pipe, the external pressure resistance stability of the tailrace transition section steel lining is significantly improved, effectively preventing the instability and deformation (bulging) of the steel lining due to external water pressure during backfilling concrete, grouting construction and power station operation.

[0018] Second, by setting more openings around the steel pipe, especially in the bottom plate area, and using a design of reinforcing plates and grout plugs to seal, the backfill of the bottom plate concrete is ensured to be dense, effectively excluding air and preventing the gap between the steel pipe and the concrete, thereby eliminating potential stability hazards.

[0019] Third, the installation of mortar anchors effectively enhances the connection strength between the steel lining structure and the surrounding rock, forming a more reliable overall load-bearing system, and further improving the stability and safety of the structure.

[0020] Fourth, the uniform circumferential arrangement of the I-beams and the spaced thrust rings not only enhance the local stiffness of the steel lining but also form an overall anti-deformation reinforced structure, which solves the problem of resisting external pressure during the construction and operation periods while meeting the requirements of backfill concrete construction.

[0021] V. Compared with the traditional method of simply increasing the thickness of steel plates or concrete, the structural optimization scheme adopted in this utility model is more economical and reasonable, saves material costs, and improves construction reliability, thus having good engineering application value. Attached Figure Description

[0022] Figure 1 This is a schematic front view of the steel lining structure of the tailrace transition section of the pumped storage power station according to this utility model. Figure 2 for Figure 1 A schematic diagram of the cross-section of section AA. Figure 3 for Figure 1 A schematic diagram of the cross-section of section BB in the middle; Figure 4 for Figure 1 A schematic diagram of the cross-section of section C; Figure 5 This is a schematic diagram of the structure of this utility model in application; Figure 6 for Figure 5 Schematic diagram of the anchor bolt welding process for the interrupted thrust ring; Figure 7 Schematic diagram of the opening in the bottom plate of the transition section of the tailrace branch pipe; Figure 8 Schematic diagram of the reinforcement plate for grouting holes; Figure 9 This is a schematic diagram of the grouting hole details; Figure 10 This is a schematic diagram of the grout plug structure; In the picture: 1. Tailwater transition section with round and square steel lining; 2. Thrust ring; 3. I-beam; 4. Mortar anchor; 5. Opening; 6. Reinforcing plate; 7. Grout plug; 8. Washer. Detailed Implementation

[0023] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0024] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] This invention provides a steel lining structure for the transition section of the tailrace of a pumped storage power station, comprising a transition section steel pipe, a thrust ring 2, an I-beam 3, mortar anchors 4, openings 5, reinforcing plates 6, and grout plugs 7. To improve the external pressure resistance of the transition section steel lining, this invention effectively solves the problem of insufficient external pressure resistance leading to instability and deformation of the steel lining in the transition section of the tailrace branch pipe of a pumped storage power station during construction and operation by rationally designing the structure of these components and their interrelationships.

[0026] The transition section steel pipe is the main part of the structure of this utility model. It is usually a round-to-square or square-to-round structure and is located at the well seat of the tailrace emergency gate chamber of a pumped storage power station. In one specific embodiment, the inner diameter of the tailrace branch pipe is 5.1m, and the thickness of the steel plate of the transition section steel pipe is 30mm. The outer surface of the transition section steel pipe is welded with a thrust ring 2 and an I-beam 3, and multiple openings 5 ​​are provided inside.

[0027] Thrust rings 2 are welded to the outer circumference of the transition section steel pipe to enhance the circumferential stiffness and resistance to external pressure. In a preferred embodiment, the thrust rings 2 have a spacing of 750 mm, a thickness of 24 mm, and a height of 150 mm. These parameters can be selected within a spacing range of 500-1000 mm, a thickness range of 16-30 mm, and a height range of 100-200 mm, depending on the actual engineering requirements. Thrust rings 2 not only enhance the structural strength of the steel pipe but also, in conjunction with mortar anchor bolts 4, connect the steel lining structure to the surrounding rock, forming a unified load-bearing system.

[0028] I-beams 3 are welded to the outer surface of the transition section steel pipe, spaced apart from thrust rings 2, and evenly distributed circumferentially. The function of the I-beams 3 is to enhance the local stiffness of the steel pipe and further improve the resistance of the steel lining to external pressure. In one specific embodiment, I40a I-beams 3 are used, evenly distributed at approximately 15° intervals circumferentially. Depending on actual engineering needs, the circumferential interval can be adjusted within the range of 8°-20°. In a practical application, 17 rings of I-beams 3 are set in each transition section, with 24 I-beams per ring. The arrangement of the I-beams 3 must avoid pipe wall welds, longitudinal water collection angle steel, and grouting holes to ensure structural integrity and construction feasibility.

[0029] The mortar anchor bolt 4 extends into the rock and is welded to the thrust ring 2 to enhance the connection strength between the steel lining structure and the surrounding rock. In a preferred embodiment, the mortar anchor bolt 4 is 4.5m long and has a rock penetration depth of 3.05m, accounting for approximately 67.8% of the total length. Depending on the actual engineering requirements, the length of the mortar anchor bolt 4 can be selected within the range of 3-6m, and the rock penetration depth can be 50%-70% of the total length. The anchor bolts are arranged in a staggered pattern with a spacing of 1m × 1m. The construction sequence of the mortar anchor bolt 4 is as follows: first, the anchor bolt is positioned and driven into the rock; then, after the transition section steel pipe is installed in place, it is welded to the thrust ring 2. The anchor bolt location should avoid pre-embedded pipelines within the concrete to ensure construction safety and structural integrity.

[0030] The transition section of the steel pipe has multiple openings 5, which are mainly used for venting during the backfilling and grouting process to ensure the compaction of the backfill. A key feature of this invention is that the number of openings 5 ​​at the bottom plate of the transition section is greater than in other areas. This is because the bottom plate is the area most prone to incomplete backfilling and voids; increasing the number of openings 5 ​​helps improve the density of the bottom plate concrete, thereby enhancing the overall resistance of the structure to external pressure.

[0031] A reinforcing plate 6 is welded to the outside of the opening 5 to compensate for the reduction in structural strength caused by the opening 5. The reinforcing plate 6 ensures that the opening 5 does not affect the overall structural strength of the steel pipe. A grouting plug 7 is used in conjunction with the opening 5 to seal it after grouting and backfilling with concrete. After the grouting plug 7 is welded to the transition section of the steel pipe, any protruding parts are removed and ground smooth to ensure a smooth inner surface of the steel pipe, reduce water flow resistance, and prevent eddies and cavitation.

[0032] A metal gasket 8 is provided between the grouting plug 7 and the transition section steel pipe. In the preferred embodiment, an aluminum metal gasket 8 with a thickness of 2mm is used. Depending on the actual engineering requirements, the thickness of the metal gasket 8 can be selected within the range of 1-5mm. The metal gasket 8 improves the sealing performance at the connection between the grouting plug 7 and the steel pipe, preventing leakage of grouting material or infiltration of external moisture.

[0033] The backfill concrete is self-compacting concrete with a strength grade of C20 for concrete aggregate size. Self-compacting concrete has good fluidity and density, which can effectively fill the gaps between the steel pipe and the rock, improving the integrity of the structure and its resistance to external pressure.

[0034] In one specific embodiment, the steel-lined structure of the tailrace transition section of this utility model is applied to a pumped storage power station. This power station is equipped with six 300MW vertical-shaft single-stage mixed-flow reversible pump-turbine units, with a total installed capacity of 1800MW. The water conveyance system adopts a "one tunnel, two turbines" layout, constructing three independent water conveyance systems. There are six tailrace branch pipes with an inner diameter of 5.1m. Each tailrace branch pipe has a tailrace emergency steel gate chamber, with its transition sections lined with steel plates 30mm thick.

[0035] During construction, special attention must be paid to the quality of the backfill concrete pouring. When backfilling the bottom of the transition section, the concrete should be poured from one side, vibrated until concrete appears on the other side, and then poured symmetrically to ensure the bottom concrete is dense. After pouring above the steel pipe waistline, both sides can be poured simultaneously for even rising. Venting should be done during the pouring process; the vent holes should be opened during the backfilling construction, and after grout returns, the vent holes should be sealed with grout plugs immediately. Close monitoring is necessary during the backfilling process to prevent instability of the external pressure on the steel pipe.

[0036] Before grouting, check for any voids between the steel pipe and the backfill concrete. During grouting, strictly control the grouting pressure. The backfill grouting pressure should be approximately 0.2 MPa to 0.3 MPa, the contact grouting pressure should not exceed 0.1 MPa, and the consolidation grouting pressure should not exceed 0.98 MPa. The final grouting pressure should be determined based on grouting tests. During grouting, proper venting and close monitoring are also necessary to prevent instability of the steel pipe wall.

[0037] In practical applications, if bulges are found in the steel lining of the transition section, appropriate measures must be taken. First, the exact extent of the bulge should be measured and determined. An opening (5) should be made at the highest point of the bulge for inspection, focusing on the degree of detachment of the lining steel plate, the stiffening ring, the damage to the I-beam (3), and the quality of the backfill concrete. Before proceeding with the repair, internal supports must be installed to ensure the overall structural strength of the transition section before cutting the damaged steel plate. The specific scope of the cutting and repair should be determined jointly by all parties. During the repair process, care should be taken to avoid damaging any pre-embedded pipelines outside the steel lining.

[0038] Through the above structural design and construction measures, the steel lining structure of the tailrace transition section of the pumped storage power station of this utility model can effectively improve the external pressure resistance stability of the transition section steel lining, avoid the steel lining instability and deformation problems that may occur during the construction and operation periods, and ensure the safe and stable operation of the power station.

[0039] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent transformations or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A steel lining structure for the tailrace transition section of a pumped storage power station, characterized in that, include: Gradient section steel pipe; multiple thrust rings, welded to the outer circumference of the gradient section steel pipe; Multiple I-beams are welded to the outer surface of the transition section steel pipe and are arranged at intervals with the thrust ring, and are evenly distributed in the circumferential direction. Multiple mortar anchors extend into the rock and are welded to the thrust ring; The steel pipe of the transition section is provided with multiple openings, and a reinforcing plate is welded to the outside of the openings. And a grouting plug that mates with the opening, used to seal the opening after grouting and backfilling with concrete.

2. The steel lining structure of the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, The number of openings in the bottom plate of the transition section of the steel pipe is greater than in other parts.

3. The steel lining structure of the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, The I-beams are I40a I-beams, evenly arranged at circumferential intervals of approximately 8°-20°.

4. The steel lining structure for the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, The thrust rings have a spacing of 500-1000mm, a thickness of 18-30mm, and a height of 100-200mm.

5. The steel lining structure for the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, The mortar anchor bolts are 3-6m long and have a rock penetration depth of 50%-70% of their total length, arranged in a quincunx pattern.

6. The steel lining structure of the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, After the grouting plug is welded to the transition section steel pipe, the square protruding part is cut off and ground flat.

7. The steel lining structure for the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, An aluminum washer with a thickness of 1-5 mm is provided between the grouting plug and the transition section steel pipe.

8. The steel lining structure for the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, The opening is used to vent air during the backfilling and grouting process.

9. The steel lining structure of the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, The backfill concrete is self-compacting concrete with a strength grade of C20 for concrete aggregate size.

10. The steel lining structure of the tailrace transition section of a pumped storage power station according to claim 1, characterized in that, The transition section steel pipe has a round-to-square or square-to-round structure and is located at the transition section of the tailrace emergency gate chamber well seat of the pumped storage power station.

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