A coupling loading model test device for a belled pile foundation and a use method thereof

Abstract

The application discloses a coupling loading model test device for a pile foundation with an expanded bottom and a use method thereof. The coupling loading model test device for the pile foundation with the expanded bottom transmits a vertical pushing force to a vertical loading bottom plate, and the vertical loading bottom plate provides a vertical pushing force to the pile foundation with the expanded bottom, so that the vertical self weight is simulated. A hydraulic cylinder provides a horizontal pushing force to the pile foundation with the expanded bottom, and the pressure data returned by a tension and compression force sensor and a control system instruction are combined to control the output load size, so that the random wind load effect is simulated. The application has a wide application range, high automation degree, and accurate control, can realize the simulation test of the wind power pile foundation with the expanded bottom under the coupling loading of the random wind load and the vertical self weight, can accurately realize the control of the random wind load and the vertical self weight, and can simulate the pile foundation with the expanded bottom under the random load effect of different wind speeds in different characteristic base soils.

Description

Technical Field

[0001] This invention belongs to the field of experimental devices, specifically relating to a coupled loading model experimental device for expanded-base pile foundations and its usage method. Background Technology

[0002] my country's onshore wind farms are widely distributed in the "Three Norths" region, where the soil is mainly collapsible loess. Expanded pile foundations have advantages such as high bearing capacity and the ability to eliminate collapsibility, making them one of the basic types of wind power projects in loess areas.

[0003] During their normal service life, wind turbine expanded-base pile foundations not only bear the vertical self-weight of the superstructure but also the horizontal wind load. Traditional methods of considering load conditions separately and then analyzing the bearing deformation characteristics of wind turbine expanded-base pile foundations according to the principle of small deformation superposition will lead to safety issues or design waste. Therefore, it is necessary to study the static and dynamic characteristics of wind turbine expanded-base pile foundations by considering the coupled loading conditions of vertical self-weight and horizontal wind load.

[0004] Experimentation is the most direct means of studying the static and dynamic characteristics of pile foundations under complex loads, and the development of a coupled loading device for vertical self-weight and horizontal wind load is a prerequisite for effectively studying the dynamic characteristics of wind turbine expanded-base pile foundations under this condition. While current experimental devices can achieve combined vertical and horizontal static loads, there is a problem of mutual constraint between the vertical and horizontal loading mechanisms; that is, the loading in the two directions often affects each other, leading to errors in the experimental analysis results. More importantly, horizontal wind loads exhibit typical periodicity and pulsation. Existing devices, which simply apply a combination of vertical self-weight and horizontal static load or cyclic load, cannot reflect the long-term coupled loading condition of vertical self-weight and horizontal wind loads on wind turbine expanded-base pile foundations in actual engineering projects, and therefore have significant limitations.

[0005] For the coupled loading conditions borne by the expanded-base pile foundation of wind power, it is necessary to conduct analysis in conjunction with indoor model tests. The key technology is how to simulate the coupled loading effect of vertical self-weight and horizontal wind load. Summary of the Invention

[0006] To address the analysis of the coupled loading conditions of vertical self-weight and horizontal static force or cyclic load on the expanded-base pile foundation of wind power, a coupled loading model test device and its usage method for the expanded-base pile foundation are provided.

[0007] A coupled loading model test device for an enlarged-base pile foundation includes two supports, which are respectively fixed on both sides of the top of the model box. A support beam is placed horizontally between the supports, and the two ends of the support beam are respectively fixed on the two supports.

[0008] A vertical loading top plate is suspended below the support beam. The vertical loading top plate can move up and down relative to the support beam. A vertical loading bottom plate is fixedly suspended below the vertical loading top plate. The bottom surface of the vertical loading bottom plate is in contact with the bullseye pulley, which is located at the top of the wind turbine model tower.

[0009] One end of a flat steel strip is fixed to the side of the support beam. A first fixed pulley is installed on the inside of the flat steel strip. A second fixed pulley is fixed to the outside of the support. One end of a vertical loading device is fixed to the bottom surface of the vertical loading top plate. The vertical loading device passes around the first and second fixed pulleys. The other end of the vertical loading device is placed on the outside of the support.

[0010] A hydraulic cylinder is fixed inside the support. An actuating rod is installed inside the hydraulic cylinder. The other end of the actuating rod is connected to one end of a tension / compression sensor. The other end of the tension / compression sensor is installed with one end of a connecting rod. The other end of the connecting rod is fixed to the axial surface of the wind turbine model tower. The tension / compression sensor is connected to the control system.

[0011] The bottom of the wind turbine model tower is placed inside the model box, and the bottom of the wind turbine model tower is fixedly connected to the foundation platform. The bottom of the foundation platform is fixed with the enlarged base piles.

[0012] The support beam and the vertical loading top plate are connected by several sliding rods. One end of the sliding rod is fixed to the support beam, and the vertical loading top plate can slide on the sliding rod.

[0013] The vertical loading base plate and the vertical loading top plate are fixedly connected by several uprights.

[0014] One end of a steel wire rope is fixed to the bottom surface of the vertically loaded top plate. The steel wire rope passes over the first and second fixed pulleys, and the other end of the steel wire rope is connected to a tray, which is used to hold the weights.

[0015] An adjustable reaction frame is placed horizontally between the two supports, with both ends of the adjustable reaction frame fixed to the two supports respectively.

[0016] The bottom of the first fixed pulley and the top of the second fixed pulley are on the same horizontal line.

[0017] The model box consists of a frame made of angle iron and steel plates. The steel plates fill the bottom and sides of the frame and are welded to the angle iron.

[0018] One end of the connecting rod is clamped to the axial surface of the wind turbine model tower through an arc-shaped loading end. The bottom of the wind turbine model tower is equipped with a disc, and the disc and the foundation platform are connected by screws.

[0019] The base plate of the hydraulic cylinder is fixed to the bracket by clips.

[0020] The method of using the above-mentioned coupled loading model test device for enlarged-base pile foundation includes the following steps:

[0021] Add weights and transfer the vertical thrust to the vertical loading base plate through the vertical loading device. The downward thrust of the vertical loading base plate applies force to the expanded-base pile.

[0022] According to the instructions of the control system, the actuator rod is extended and retracted, and under the horizontal thrust of the hydraulic cylinder, force is applied to the expanded foundation pile. The pressure data transmitted by the tension and compression sensors is combined with the instructions of the control system to control the magnitude of the output load.

[0023] Compared with existing technologies, the advantages of this invention lie in its wide applicability, high degree of automation, and precise control. It enables simulation tests of wind turbine expanded-base pile foundations under coupled loading of random wind loads and vertical self-weight, accurately controlling both. Simulations of expanded-base pile foundations under random loads at different wind speeds can be conducted in soils with varying characteristics. By setting two fixed pulleys to position the vertical loading device outside the support frame, and by adding weights to control the magnitude of the vertical thrust, the device transmits the vertical thrust to the vertical loading base plate, which provides vertical thrust to the expanded-base pile. A hydraulic cylinder provides horizontal thrust to the expanded-base pile. Pressure data from tension and compression sensors, combined with control system commands, controls the output load, thus simulating random wind load effects. The inclusion of tension and compression sensors improves the level of automation, enabling random loading of horizontal wind loads. This overcomes the limitation of existing research on wind turbine expanded-base pile foundations in loess, which only focuses on the periodicity and long-term nature of wind load effects.

[0024] Furthermore, vertical loading is achieved by setting a sliding rod; an adjustable reaction frame is set to increase the stability of the support; and the bottom of the first fixed pulley and the top of the second fixed pulley are on the same horizontal line to ensure the accuracy of vertical loading. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below:

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the combined structure of the slide bar, loading plate, and first fixed pulley in this invention;

[0028] Figure 3 This is a schematic diagram of the combined structure of the vertical loading base plate and the bullseye pulley in this invention;

[0029] Figure 4 This is a schematic diagram of the combined structure of the support frame, hydraulic cylinder, and wind turbine model tower in this invention;

[0030] Figure 5This is a schematic diagram of the combined structure of the wind power model tower, foundation cap, and expanded-base piles in this invention;

[0031] Figure 6 This is a three-dimensional structural diagram of the model box in this invention;

[0032] In the diagram: 1. Model box; 2. Bolt; 3. Bracket; 4. Buckle; 5. Hydraulic cylinder; 6. Base plate; 7. Actuating rod; 8. Tension / compression sensor; 9. Connecting rod; 10. Wind turbine model tower; 11. Bullseye pulley; 12. Vertical loading base plate; 13. Upright; 14. Vertical loading top plate; 15. Sliding rod; 16. Bracket beam; 17. Flat steel strip; 18. First fixed pulley; 19. Steel wire rope; 20. Second fixed pulley; 21. Steel buckle; 22. Pallet; 23. Weight; 24. Adjustable reaction frame; 25. Screw; 26. Foundation platform; 27. Expanded base pile; 28. Steel plate; 29. ​​Angle steel. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings:

[0034] like Figure 1 As shown, a coupled loading model test device for an enlarged-base pile foundation includes a model box 1. Two supports 3 are fixed to the flanges on both sides of the top of the model box 1 with bolts 2. The supports 3 are connected by an adjustable reaction force support 24 and a support beam 16. The two ends of the adjustable reaction force support 24 are fixed to the middle of the two supports 3 with buckles. The two ends of the support beam 16 are welded to the top of the two supports 3.

[0035] A vertical loading top plate 14 is installed below the support beam 16. The support beam 16 and the vertical loading top plate 14 are connected by four sliding rods 15. One end of the sliding rod 15 is fixed to the support beam 16, and the other end is placed in the round hole of the vertical loading top plate 14, allowing the vertical loading top plate 14 to move on the sliding rods 15. A vertical loading bottom plate 12 is installed below the vertical loading top plate 14. The vertical loading bottom plate 12 and the vertical loading top plate 14 are fixedly connected by four uprights 13. The bottom surface of the vertical loading bottom plate 12 and the bullseye joint are connected. The pulley 11 is in contact with the top of the wind turbine model tower 10. The side of the support beam 16 is welded with a flat steel strip 17. The side of the flat steel strip 17 is equipped with a first fixed pulley 18. One end of the wire rope 19 is connected to the pre-reserved connecting ring on the vertical loading top plate 14 through a steel rope buckle. The wire rope 19 passes around the first fixed pulley 18 and the second fixed pulley 20 fixed to the outside of the support 3 with a steel buckle 21. The other end of the wire rope 19 is connected to the tray 22, which can hold the vertical loading weight 23.

[0036] A hydraulic cylinder 5 is fixed on the bracket 3, and the base plate 6 of the hydraulic cylinder 5 is fixed on the bracket 3 with a buckle 4. One end of the actuating rod 7 is set inside the hydraulic cylinder 5, and the other end of the actuating rod 7 is connected to the tension and compression sensor 8. The tension and compression sensor 8 is connected to the control system. The pressure data transmitted by the tension and compression sensor 8 and the control system command are used to control the output load. A connecting rod 9 is installed on the other end of the tension and compression sensor 8. One end of the connecting rod 9 is clamped to the axial surface of the wind turbine model tower 10 through an arc-shaped loading end.

[0037] The bottom of the wind turbine model tower 10 is placed inside the model box 1. The bottom of the wind turbine model tower (10) is provided with a disc with 8 bolt holes. The disc and the foundation platform 26 are connected by screws 25. The bottom of the foundation platform 26 is fixed with an expanded base pile 27.

[0038] The model box 1 includes a frame made of angle steel 29 and a steel plate 28. The steel plate 28 fills the bottom and sides of the frame and is welded to the angle steel 29.

[0039] like Figure 2 As shown, the vertical loading top plate 14 is made of a steel plate with a length of 180mm, a width of 200mm, and a thickness of 8mm, and the flat steel strip 17 is made of a square steel tube with a length of 300mm and a side length of 40mm.

[0040] like Figure 3 As shown, the vertical loading base plate 12 is in contact with the bullseye pulley 11.

[0041] like Figure 4 As shown, one end of the connecting rod 9 is fixed to the wind turbine model tower 10, and the base plate 6 of the hydraulic cylinder 5 is fixed to the bracket 3. The bracket 3 is made of a square steel tube with a length of 1485mm and a side length of 40mm. The base plate 6 is made of a steel plate with a length of 180mm, a width of 200mm, and a thickness of 8mm. The wind turbine model tower 10 is made of a round bar with a length of 1330mm and a diameter of 44mm.

[0042] like Figure 5 As shown, one end of the wind turbine model tower 10 is provided with an M16 bolt hole for connecting the bullseye pulley 11, and the other end of the wind turbine model tower 10 is provided with a disc with a diameter of 124mm and a thickness of 8mm for connecting the foundation platform 26. The bottom of the foundation platform 26 is fixed with an enlarged base pile 27, and each pile of the enlarged base pile 27 is made of an aluminum rod with a length of 415mm.

[0043] See Figure 6 The model box 1 is formed by welding a frame made of angle steel 29 and steel plate 28. The model box is 800mm long, 1000mm wide and 800mm high.

[0044] The method of using a coupled loading model test device for an enlarged-base pile foundation is as follows:

[0045] Step 1: First, fill the model box 1 with test soil. Then, use bolts 2 to install the bracket 3 on the flanges on both sides of the top of the model box 1. Fix the adjustable reaction frame 24 and the bracket beam 16 to the bracket 3. Weld the flat steel strip 17 to the side of the bracket beam 16. Install the sliding rod 15 on the bracket beam 16 with bolts. Install the vertical loading top plate 14 on the sliding rod 15. Install the first fixed pulley 18 on the flat steel strip 17. Fix the second fixed pulley 20 on the outside of the bracket 3 with steel clips 21. Connect the steel wire rope 19 to the vertical loading top plate 14. By bypassing the first fixed pulley 18 and the second fixed pulley 20, the vertical loading base plate 12 is fixedly connected to the vertical loading top plate 14; the wind turbine model tower 10 connected to the bullseye pulley 11 is installed at the lower end of the vertical loading base plate 12, the foundation platform 26 is installed at the lower end of the wind turbine model tower 10, the expanded base pile 27 is installed at the lower end of the foundation platform 26, the hydraulic cylinder 5 is installed on the bracket 3, the actuating rod 7 is installed in the hydraulic cylinder 5, the actuating rod 7 is connected in sequence to the tension and compression sensor 8 and the connecting rod 9, and one end of the connecting rod 9 is clamped to the axial surface of the wind turbine model tower 10.

[0046] Step 2: Add weights 23. According to the designed vertical force, the vertical force is applied to the vertical loading top plate 14 through the steel rope 19, and then transferred to the vertical loading bottom plate 12 through the upright 13. The force is then applied to the bullseye pulley 11 at the top of the wind turbine model tower 10, and finally transferred to the foundation platform 26 and the expanded base piles 27 to apply force to the expanded base piles 27.

[0047] Step 3: Control the extension and retraction of the actuator rod 7 of the hydraulic loading device. According to the instructions of the control system, apply force to the expanded foundation pile under the horizontal thrust of the hydraulic cylinder 5, and control the output load by combining the pressure data transmitted by the tension and compression sensor 8 with the instructions of the control system.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A coupled loading model test device for an enlarged-base pile foundation, characterized in that, It includes two supports (3), which are fixed on the top two sides of the model box (1) respectively. A support beam (16) is placed horizontally between the supports (3), and the two ends of the support beam (16) are fixed on the two supports (3) respectively. A vertical loading top plate (14) is suspended below the support beam (16). The vertical loading top plate (14) can move up and down relative to the support beam (16). A vertical loading bottom plate (12) is fixedly suspended below the vertical loading top plate (14). The bottom surface of the vertical loading bottom plate (12) is in contact with a bullseye pulley (11). The bullseye pulley (11) is at the top of the wind turbine model tower (10). The support beam (16) and the vertical loading top plate (14) are connected by several sliding rods (15). One end of the sliding rod (15) is fixed to the support beam (16). The vertical loading top plate (14) can move up and down relative to the support beam (16). 5) Sliding upwards; one end of a flat steel strip (17) is fixed to the side of the support beam (16), a first fixed pulley (18) is installed on the inside of the flat steel strip (17), and a second fixed pulley (20) is fixed on the outside of the support (3); one end of a steel wire rope (19) is fixed on the bottom surface of the vertical loading top plate (14), the steel wire rope (19) passes around the first fixed pulley (18) and the second fixed pulley (20), and the other end of the steel wire rope (19) is connected to a tray (22), which is used to hold weights (23); the bottom end of the first fixed pulley (18) and the top end of the second fixed pulley (20) are at the same horizontal line; A hydraulic cylinder (5) is fixed inside the bracket (3). An actuating rod (7) is set inside the hydraulic cylinder (5). The other end of the actuating rod (7) is connected to one end of a tension and compression sensor (8). The other end of the tension and compression sensor (8) is installed with one end of a connecting rod (9). The other end of the connecting rod (9) is fixed on the axial surface of the wind turbine model tower (10). The tension and compression sensor (8) is connected to the control system. The bottom of the wind turbine model tower (10) is placed inside the model box (1). The bottom of the wind turbine model tower (10) is fixedly connected to the foundation platform (26). The bottom of the foundation platform (26) is fixed with the expanded base pile (27).

2. The coupled loading model test device for an enlarged-base pile foundation according to claim 1, characterized in that, The vertical loading base plate (12) and the vertical loading top plate (14) are fixedly connected by several uprights (13).

3. The coupled loading model test device for an enlarged-base pile foundation according to claim 1, characterized in that, An adjustable reaction frame (24) is placed horizontally between the two supports (3), and the two ends of the adjustable reaction frame (24) are fixed on the two supports (3) respectively.

4. The coupled loading model test device for an enlarged-base pile foundation according to claim 1, characterized in that, The model box (1) includes a frame made of angle steel (29) and a steel plate (28), which fills the bottom and sides of the frame and is welded to the angle steel (29).

5. The coupled loading model test device for an enlarged-base pile foundation according to claim 1, characterized in that, One end of the connecting rod (9) is clamped to the axial surface of the wind turbine model tower (10) through an arc-shaped loading end. The bottom of the wind turbine model tower (10) is provided with a disc, and the disc and the foundation platform (26) are connected by screws (25).

6. The coupled loading model test device for an enlarged-base pile foundation according to claim 1, characterized in that, The base plate (6) of the hydraulic cylinder (5) is fixed to the bracket (3) by a buckle (4).

7. The method of using the coupled loading model test device for an enlarged-base pile foundation according to any one of claims 1-6, characterized in that, Includes the following steps: Add weights (23) and transfer the vertical thrust to the vertical loading base plate (12) through the steel wire rope (19). The downward thrust of the vertical loading base plate (12) applies force to the expanded base pile (27). According to the instructions of the control system, the actuator (7) is extended and retracted, and the hydraulic cylinder (5) applies force to the expanded foundation pile (27) under the horizontal thrust. The pressure data transmitted by the tension and pressure sensor (8) is combined with the instructions of the control system to control the magnitude of the output load.

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