Model test platform and test method for simulating single pile penetration and loading

Abstract

The invention relates to a model test platform for simulating single pile penetration and loading and a test method. The test platform comprises a test box, a movable frame, a positioning assembly, a first loading assembly and a second loading assembly. According to the experiment platform, the model pile in the test box can be loaded in the vertical direction and the horizontal direction, the stable simulation effect is achieved, meanwhile, the test soil type in the test box is switched, the loading force of the first driving part and the loading force of the second driving part are adjusted, and the test efficiency is improved. The device can simulate the penetration, horizontal static and dynamic loading process of a model pile in soil under different site conditions and different loading conditions (including static and dynamic loading in the horizontal direction, the vertical direction and the force control and displacement control conditions), and can accurately collect and analyze all necessary data at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of marine engineering, and in particular to a model test platform and a test method for simulating single pile penetration and loading. Background Art

[0002] Offshore wind power construction and development is a key area in response to the country's low-carbon green energy development and the group company's new energy transformation. At present, when the nearshore water depth is less than 40m, the single pile foundation is the first choice for wind turbine foundation type. Since it does not require the use of large piling ships and equipment during installation, it has the characteristics of high installation efficiency and low installation cost, and has become the basic type widely used for fixed wind turbines.

[0003] Generally, wind turbine foundations bear not only conventional marine environmental loads (waves, currents, etc.) but also vertical weight loads from upper wind turbines and large cyclic wind loads. Under the combined action of complex loads, the safe operation of wind turbines depends on the stability of the foundation. The coupling mechanism between the foundation and the foundation soil and the stability of the foundation during the in-situ operation of the wind turbine are the most critical issues in the design of wind turbine foundations. For fixed wind power, the diameter of a single offshore wind power pile is up to 10.5m, the depth of entry into the mud is usually less than 70m, the aspect ratio of a single pile is less than 10, the pile-soil interaction and the failure mode of the pile foundation are different from those of the driven pile foundation of the jacket foundation (the aspect ratio is greater than 30), and the conventional API pile foundation interaction analysis method is no longer applicable to large-diameter single piles. Therefore, in order to study the failure mode of large-diameter single piles, the pile-soil interaction mechanism and response prediction, it is of great significance to carry out horizontal loading model tests of large-diameter single pile foundations on the basis of domestic and foreign research, and to conduct in-depth research on the above issues. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a model test platform and test method for simulating the penetration and loading of a single pile, so as to simulate the penetration of the model pile in the soil and the horizontal loading process, so as to carry out simulation research.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A model test platform for simulating single pile penetration and loading, comprising: A test box, wherein the top of the test box is open to be filled with test soil; A movable frame, which is arranged on the top of the test box and is slidably connected to the test box, and a sliding direction is parallel to a length direction of the test box; A positioning component, the positioning component is arranged on the movable frame to limit the movable frame from sliding on the test box; a first loading assembly, the first loading assembly being disposed on the movable frame, the first loading assembly comprising a first driving member and a first linkage member, the first driving member driving the first linkage member to move vertically so as to press the model pile into the test box; and The second loading component is arranged on the side of the movable frame, and the second loading component includes a second driving member and a second linkage member. The second driving member drives the second linkage member to move horizontally to push the model pile in the test box.

[0006] In one possible embodiment, the second loading assembly further includes a movable connecting member, and the movable connecting member includes: A fixing clip, the fixing clip is used to clamp and fix on the model pile; and A shaft body, one end of which is hinged to the fixing clamp, and the other end of which is connected to the second linkage member, and the hinge axis of the shaft body is arranged in the same direction as the axis of the model pile.

[0007] In one possible implementation manner, the first driving member and the second driving member are both servo actuators.

[0008] In one possible implementation: The first driving member is a 50 kN servo actuator, and the second driving member is a 20 kN servo actuator.

[0009] In one possible implementation manner, the first linkage member and the second linkage member are both connecting rods formed by connecting a plurality of extension rods.

[0010] In one possible implementation, the movable frame comprises: Two load-bearing plates are provided and arranged opposite to each other on the top of the test box, and the load-bearing plates are slidably connected to the test box; and A crossbeam is provided to span and connect the two load-bearing plates.

[0011] In one possible implementation manner, one side of the test box is also open and has a baffle detachably connected thereto.

[0012] In one possible implementation manner, a drain port is provided at the bottom of the test box.

[0013] In one possible implementation manner, a water inlet is provided on a side of the test box.

[0014] The present invention also provides a model test method for simulating single pile penetration and loading, comprising the following steps: Complete the assembly of the test chamber and baffle: Fill the test chamber with test soil; Place the model pile at the test point, and adjust the movable frame so that the first linkage member corresponds to the model pile; Starting the first driving member, statically pressing the model pile into the test depth through the first linkage member, and recording the loading stroke of the first driving member and the loading force; After the model pile reaches the test depth, the first driving member is adjusted to be separated from the model pile, and the movable frame is adjusted to make the second driving member and the second linkage member correspond to the model pile, and the movable connecting member is clamped and installed; Start the second driving member, push the model pile horizontally through the second linkage member and the movable connecting member, and record the loading stroke of the second driving member and the loading force; After stopping the second driving member, dismantle the movable connecting member, move the second driving member to separate from the model pile, and slowly pull out the model pile after the test by using the wire rope.

[0015] The present invention adopts the above technical solution, which has the following advantages: When using the experimental platform to conduct a simulation experiment, first fill the test box with test soil, then place the model pile on the test soil, insert the model pile vertically into the test soil, then adjust the movable frame so that the first linkage member of the first loading assembly corresponds to the top of the model pile, and then use the positioning assembly to position and fix the position of the movable frame; After the model pile, the movable frame and the first loading assembly are positioned, the first driving member is started, and the first driving member links the first linkage member to load the model pile until the first driving member presses the model pile to the test depth of the test soil, and then the first driving member is controlled to make the first linkage member disengage from the model pile; Slide and adjust the movable frame again to make the second linkage member correspond to the end of the exposed part of the model pile, and then position and fix the position of the movable price again by the positioning component; Start the second driving member, the second driving frame will move horizontally with the second linkage member to push the model pile. After reaching the required displacement value, the second driving member is controlled to make the second linkage member disengage from the model pile. Then, the model pile after the test is completed is slowly pulled out with a steel wire rope. At this time, the experiment is completed. This experimental platform can load the model piles in the test box vertically and horizontally to achieve a stable simulation effect. At the same time, by switching the test soil type in the test box and adjusting the loading force of the first drive member and the second drive member, it can simulate the penetration, horizontal static and dynamic loading process of the model piles in the soil under different site conditions and different loading conditions (including horizontal and vertical directions, static and dynamic loading under force control and displacement control conditions), and can accurately collect and analyze the necessary data. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the internal structure of a model test platform in one embodiment of the present invention; Figure 2 A top view of a model test platform in one embodiment of the present invention; Figure 3 This is a schematic diagram of the working principle of the second loading component in one embodiment of the present invention; Figure 4 A top view of a second loading assembly in one embodiment of the present invention; Reference numerals: 1. Test chamber; 11. Baffle; 12. Drainage outlet; 2. Movable frame; 21. Load-bearing plate; 211. Screw hole; 22. Crossbeam; 3. Positioning assembly; 31. Positioning bolt; 32. Connecting hole; 4. First loading assembly; 41. First driving member; 42. First linkage member; 5. second loading assembly; 51. second driving member; 52. second linkage member; 53. movable connecting member; 531. fixing clamp; 532. shaft body; 6. Model pile; 7. Pressure sensor; 8. Movable seat; 81. Clamping bolt. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work are within the scope of protection of the present invention.

[0018] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second", "third", "fourth" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0019] The wind turbine foundation is subjected to not only conventional marine environmental loads (waves, currents, etc.) but also vertical weight loads from the upper wind turbine and large cyclic wind loads. Under the combined action of complex loads, the safe operation of the wind turbine depends on the stability of the foundation. The coupling mechanism between the foundation and the foundation soil and the stability of the foundation during the in-situ operation of the wind turbine are the most critical issues in the design of the wind turbine foundation. For fixed wind power, the diameter of a single offshore wind power pile is up to 10.5m, the depth of entry into the mud is usually less than 70m, the aspect ratio of the single pile is less than 10, the pile-soil interaction and the failure mode of the pile foundation are different from the driven pile foundation of the jacket foundation (the aspect ratio is greater than 30), and the conventional API pile foundation interaction analysis method is no longer applicable to large-diameter single piles. Therefore, in order to study the failure mode of large-diameter single piles, the pile-soil interaction mechanism and response prediction, it is of great significance to carry out horizontal loading model tests of large-diameter single pile foundations on the basis of domestic and foreign research, and to conduct in-depth research on the above issues. In view of the above technical problems, the present invention provides a model test platform and test method for simulating the penetration and loading of a single pile, so as to simulate the penetration of the model pile in the soil and the horizontal loading process, so as to carry out simulation research. The technical solution of the present invention is described in detail below in conjunction with specific examples.

[0020] Reference Figure 1 as well as Figure 2 As shown, the present invention relates to a model test platform for simulating single pile penetration and loading, comprising a test box 1, a movable frame 2, a positioning component 3, a first loading component 4 and a second loading component 5.

[0021] The top of the test box 1 is open for filling with test soil. The movable frame 2 is arranged on the top of the test box 1, and the movable frame 2 is slidably connected to the test box 1, and the sliding direction is parallel to the length direction of the test box 1. The positioning component 3 is arranged on the movable frame 2 to limit the movable frame 2 from sliding on the test box 1.

[0022] The first loading assembly 4 is disposed on the movable frame 2 . The first loading assembly 4 includes a first driving member 41 and a first linkage member 42 . The first driving member 41 drives the first linkage member 42 to move vertically so as to press the model pile 6 into the test box 1 .

[0023] The second loading assembly 5 is disposed on the side of the movable frame 2 . The second loading assembly 5 includes a second driving member 51 and a second linkage member 52 . The second driving member 51 drives the second linkage member 52 to move horizontally to push the model pile 6 in the test box 1 .

[0024] For example, when using the experimental platform to conduct a simulation experiment, the test box 1 is first filled with test soil, and then the model pile 6 is placed on the test soil, and the model pile 6 is vertically inserted into the test soil, and then the movable frame 2 is adjusted so that the first linkage member 42 of the first loading assembly 4 corresponds to the top of the model pile 6. At this time, the position of the movable frame 2 is positioned and fixed by the positioning assembly 3; After the model pile 6, the movable frame 2 and the first loading assembly 4 are positioned, the first driving member 41 is started, and the first driving member 41 is linked with the first linkage member 42 to load the model pile 6 until the first driving member 41 presses the model pile 6 into the test depth of the test soil, and then the first driving member 41 is controlled to make the first linkage member 42 disengage from the model pile 6; The movable frame 2 is slid and adjusted again to make the second linkage member 52 correspond to the end of the exposed part of the model pile 6, and then the position of the movable price is positioned and fixed again by the positioning component 3; The second driving member 51 is started, and the second driving frame will link the second linkage member 52 to move horizontally to push the model pile 6. After reaching the required displacement value, the second driving member 51 is controlled to make the second linkage member 52 disengage from the model pile 6, and then the model pile 6 after the test is completed is slowly pulled out using a wire rope, and the experiment is completed at this time.

[0025] This experimental platform can load the model pile 6 in the test box 1 in the vertical and horizontal directions to achieve a stable simulation effect. At the same time, by switching the test soil type in the test box 1 and adjusting the loading force of the first driving member 41 and the second driving member 51, it can simulate the penetration, horizontal static and dynamic loading process of the model pile 6 in the soil under different site conditions and different loading conditions (including horizontal and vertical directions, static and dynamic loading under force control and displacement control conditions), and at the same time, it can accurately collect and analyze various necessary data.

[0026] Reference Figure 3 as well as Figure 4 In order to facilitate the collection of loading forces in the horizontal and vertical directions, pressure sensors 7 are provided on both the first linkage member 42 and the second linkage member 52 .

[0027] Specifically, in this embodiment, the first driving member 41 and the second driving member 51 are both servo actuators. Among them, the first driving member 41 is a 50kN servo actuator, and the second driving member 51 is a 20kN servo actuator. The loading capacity of the 50kN servo actuator is 50kN, the stroke is 200mm, and the maximum linear speed is 100mm / s. The loading capacity of the 20kN servo actuator is 20kN, the stroke is 300mm, and the maximum linear speed is 100mm / s. Both the 50kN servo actuator and the 20kN servo actuator have high-precision displacement sensors with an accuracy of 0.001mm.

[0028] In one embodiment, the overall structure of the movable frame 2 is further refined. The movable frame 2 includes a load-bearing plate 21 and a crossbeam 22, wherein two load-bearing plates 21 are provided and are arranged opposite to each other on the top of the test box 1. The load-bearing plates 21 are slidably connected to the test box 1, and the crossbeam 22 spans and connects the two load-bearing plates 21.

[0029] In one embodiment, both ends of the cross beam 22 are slidably connected to the load-bearing plate 21, and a plurality of screw holes 211 are arranged at intervals on the load-bearing plate 21, while both ends of the cross beam 22 are fixed by installing bolts. During the test, the vertical height can be adjusted by the cooperation of the bolts and the screw holes 211, thereby providing overall test flexibility.

[0030] It should be noted that, in this embodiment, in order to facilitate cleaning of the test soil in the test box 1, one side of the test box 1 is also open and has a baffle 11 detachably connected thereto.

[0031] In this embodiment, the overall structure of the positioning assembly 3 is further refined. The positioning assembly 3 includes positioning bolts 31. A plurality of connection holes 32 are provided at intervals along the length direction at the top of both sides of the test box 1, and the positioning bolts 31 are provided on two load-bearing plates 21.

[0032] When adjusting the movable frame 2, the movable frame 2 is slid as a whole to the desired position, and then the positioning bolts 31 on the two bearing plates 21 are threadedly connected with the currently corresponding connection holes 32, thereby completing the positioning and fixing of the movable frame 2. When the movable frame 2 needs to be adjusted again later, the positioning bolts 31 can be removed.

[0033] In this embodiment, it is more preferable that, in order to enable the first loading assembly 4 to achieve horizontal displacement movement adjustment, a movable seat 8 is movably connected and provided on the crossbeam 22, and the first driving member 41 is fixedly installed on the movable seat 8, and the overall position of the first loading assembly 4 can be slidably adjusted by sliding the movable seat 8. At the same time, a clamping bolt 81 is provided on the movable seat 8 to achieve clamping and fixing between the movable seat 8 and the crossbeam 22. When the first driving member 41 needs to be fixed as a whole, the clamping bolt 81 is tightened to clamp and fix the movable seat 8 on the crossbeam 22. When the movable seat 8 needs to be slidably adjusted, the clamping bolt 81 is loosened.

[0034] In one embodiment, it is more preferred that the second loading assembly 5 further includes a movable connecting member 53, and the movable connecting member 53 includes a fixing clamp 531 and a shaft 532. The fixing clamp 531 is used to clamp and fix on the model pile 6, one end of the shaft 532 is hinged to the fixing clamp 531, and the other end is connected to the second linkage member 52, and the hinge axis of the shaft 532 is arranged in the same direction as the axis of the model pile 6.

[0035] It should be noted that the movable connecting member 53 can realize the movable connection between the second linkage member 52 and the model pile 6, and can optimize the loading stability between the two.

[0036] In this embodiment, specifically, the first linkage member 42 and the second linkage member 52 are both connecting rods formed by connecting a plurality of extension rods. The extension rods are connected by flanges. The extension rods can flexibly increase and decrease the loading distance to match the test position of the model pile 6, further optimizing the operational flexibility of the test platform.

[0037] Specifically, the model piles 6 are all made of 304 seamless steel pipes, with a material yield strength of 205 MPa and an elastic modulus of 210 GPa. The outer diameter of the model piles 6 is 152 mm and the wall thickness is 2.5 mm. The overall length of the model piles 6 is 1850 mm. To avoid the influence of the boundary effect, when the model piles 6 are located at the initial position on the surface of the test soil bed, in the loading direction, the distance between the center of the pile and the boundary of the box is not less than 760 mm.

[0038] In one embodiment, in order to facilitate the adjustment of the humidity of the test soil, a drain port 12 is provided at the bottom of the test box 1 , and a water inlet is provided at the side of the test box 1 .

[0039] The present invention also provides a model test method for simulating single pile penetration and loading, comprising the following steps: Complete the assembly of the test box 1 and the baffle 11, and apply waterproof glue on the connection gap between the baffle 11 and the test box 1: Fill the test box 1 with test soil, and prepare a dry sand bed by layered compaction method, and then add water through the water inlet to prepare a saturated sand bed; Place the model pile 6 at the test point, and adjust the movable frame 2 so that the first linkage member 42 corresponds to the model pile 6; Start the first driving member 41, statically press the model pile 6 into the test depth through the first linkage member 42, and record the loading stroke of the first driving member 41 and the loading force; After the model pile 6 reaches the test depth, the first driving member 41 is adjusted to be separated from the model pile 6, and the movable frame 2 is adjusted to make the second driving member 51 and the second linkage member 52 correspond to the model pile 6, and the movable connecting member 53 is clamped and installed; The second driving member 51 is started to horizontally push the model pile 6 through the second linkage member 52 and the movable connecting member 53; When the second driving member 51 pushes the model pile 6 horizontally, the second driving member 51 is stopped when the following conditions occur: 1. During the static loading test, the horizontal force or horizontal displacement changes abnormally; 2. The force value fed back by the pressure sensor 7 is close to the full scale; 3. The stroke of the second driving member 51 is close to the full range; 4. During dynamic loading, the test soil was significantly damaged, resulting in difficulty in force control; After the second driving member 51 is stopped, the movable connecting member 53 is disassembled, the second driving member 51 is moved to be separated from the model pile 6, and the model pile 6 after the test is completed is slowly pulled out by using a steel wire rope.

[0040] The test method of the experimental platform can load the model pile 6 in the test box 1 in the vertical and horizontal directions to achieve a stable simulation effect. At the same time, by switching the test soil type in the test box 1 and adjusting the loading force of the first driving member 41 and the second driving member 51, it can simulate the penetration, horizontal static and dynamic loading process of the model pile 6 in the soil under different site conditions and different loading conditions (including horizontal and vertical directions, static and dynamic loading under force control and displacement control conditions), and at the same time, it can accurately collect and analyze various necessary data.

[0041] In some specific implementations, before the test soil in the test box 1 is prepared, a gravel cushion layer needs to be laid on the bottom of the box so that water can flow in evenly from the drainage port 12 at the bottom.

[0042] In some specific implementations, the water inlet and the water outlet 12 can also be used simultaneously for water intake and water discharge, so that the soil bed of the test soil is more easily fully saturated.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A model test platform for simulating single pile penetration and loading, characterized in that: include: A test box, wherein the top of the test box is open to be filled with test soil; A movable frame, which is arranged on the top of the test box and is slidably connected to the test box, and a sliding direction is parallel to a length direction of the test box; A positioning component, the positioning component is arranged on the movable frame to limit the movable frame from sliding on the test box; a first loading assembly, the first loading assembly being arranged on the movable frame, the first loading assembly comprising a first driving member and a first linkage member, the first driving member driving the first linkage member to move vertically so as to press the model pile into the test box; as well as The second loading component is arranged on the side of the movable frame, and the second loading component includes a second driving member and a second linkage member. The second driving member drives the second linkage member to move horizontally to push the model pile in the test box.

2. The model test platform according to claim 1, characterized in that: The second loading assembly further includes a movable connecting member, and the movable connecting member includes: A fixing clip, the fixing clip is used to clamp and fix on the model pile; and A shaft body, one end of which is hinged to the fixing clamp, and the other end of which is connected to the second linkage member, and the hinge axis of the shaft body is arranged in the same direction as the axis of the model pile.

3. The model test platform according to claim 1 or 2, characterized in that: The first driving member and the second driving member are both servo actuators.

4. The model test platform according to claim 3, characterized in that: The first driving member is a 50 kN servo actuator, and the second driving member is a 20 kN servo actuator.

5. The model test platform according to claim 1, characterized in that: The first linkage member and the second linkage member are both connecting rods formed by connecting a plurality of extension rods.

6. The model test platform according to claim 1, characterized in that: The movable frame comprises: Two load-bearing plates are provided and arranged opposite to each other on the top of the test box, and the load-bearing plates are slidably connected to the test box; and A crossbeam is provided to span and connect the two load-bearing plates.

7. The model test platform according to claim 1, characterized in that: One side of the test box is also open and is detachably connected with a baffle.

8. The model test platform according to claim 1, characterized in that: A drainage port is provided at the bottom of the test box.

9. The model test platform according to claim 8, characterized in that: A water inlet is provided on the side of the test box.

10. A model test method for simulating single pile penetration and loading, characterized in that: The following steps are involved: Complete the assembly of the test chamber and baffle: Fill the test chamber with test soil; Place the model pile at the test point, and adjust the movable frame so that the first linkage member corresponds to the model pile; Starting the first driving member, statically pressing the model pile into the test depth through the first linkage member, and recording the loading stroke of the first driving member and the loading force; After the model pile reaches the test depth, the first driving member is adjusted to be separated from the model pile, and the movable frame is adjusted to make the second driving member and the second linkage member correspond to the model pile, and the movable connecting member is clamped and installed; Start the second driving member, push the model pile horizontally through the second linkage member and the movable connecting member, and record the loading stroke of the second driving member and the loading force; After stopping the second driving member, dismantle the movable connecting member, move the second driving member to separate from the model pile, and slowly pull out the model pile after the test by using the wire rope.

Images