Eccentric hoop test pile loading tool and loading method

Abstract

The invention discloses an eccentric hoop test pile loading tool and a loading method, and relates to the technical field of steel pile foundation construction.The eccentric hoop test pile loading tool comprises a C-shaped steel pile, an n-shaped steel plate, a vertical steel plate and a horizontal steel plate fixed to the center of the vertical steel plate, and the n-shaped steel plate and the vertical steel plate surround the C-shaped steel pile and are fixed through bolts to hoop the C-shaped steel pile; the vertical steel plate is attached to a web of the C-shaped steel pile, and a loading hole is formed in the eccentric side of the horizontal steel plate. On the basis of the mechanics principle, the bending moment formed between the loading force and the C-shaped steel pile web is counteracted in an eccentric loading mode, torsion instability of the steel pile foundation in the loading process is avoided, the integrity and credibility of test data are improved, the original structure of the section steel is not changed, and the accuracy of the test data is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of steel pile foundation construction, and in particular to an eccentric hoop test pile loading tool and a loading method. Background Art

[0002] For onshore photovoltaic projects, the hammer-pressed steel pile foundation is a widely adopted foundation form, which has the advantages of high strength, good penetration performance, fast pile driving speed, small soil compaction effect, fast construction speed, etc. The main steel section forms are H-shaped steel, C-shaped steel, etc. Compared with H-shaped steel, the cold bending process adopted by C-shaped steel can more easily adjust the steel pile size by bending the steel plate.

[0003] Before actual construction, it is often necessary to conduct a lateral loading test on the steel pile foundation to obtain the soil mechanics parameters required by the modeling analysis software, and input these parameters into common modeling analysis software such as L-Pile to design the steel pile foundation. To verify the accuracy of the modeling analysis, the test load and test conditions (loading height, embedment depth, steel section) are often substituted into the model to observe whether the same results as the field test can be obtained and to reproduce the field test.

[0004] However, in actual lateral loading tests, the foundation mostly uses profiled steel with irregular cross-sections. Among them, C-shaped steel piles have good economy. If central loading is adopted for C-shaped steel piles, since the bending center and shear center of C-shaped steel piles do not coincide, during the actual loading process, a moment will be formed between the shear stress generated by the web and the applied load, which will cause the steel pile foundation to undergo torsional instability, and thus complete failure load test data cannot be obtained.

[0005] At present, the main anti-torsion measures for profiled steel are to weld external plates (stiffeners) inside the profiled steel to enhance the stability of the profiled steel, such as Patent CN219773179U, etc. However, this method will damage the original structure of the profiled steel, reduce the credibility of the obtained test parameters, and the processing process is cumbersome, which is not suitable for large-scale test scenarios. Summary of the Invention

[0006] In order to solve the problems in the background art, the present invention provides an eccentric hoop test pile loading tool and a loading method. Based on the mechanical principle, by adopting the eccentric loading method, the moment formed between the loading force and the web of the C-shaped steel pile is offset, the torsional instability of the steel pile foundation during loading is avoided, the integrity and credibility of the test data are improved, and the original structure of the profiled steel is not changed, enhancing the accuracy of the test data.

[0007] To achieve the above object, the present invention provides an eccentric hoop pile testing loading tool, which includes a C-shaped steel pile, a channel-shaped steel plate, a vertical steel plate, and a horizontal steel plate fixed at the central position of the vertical steel plate. The channel-shaped steel plate and the vertical steel plate surround the C-shaped steel pile and are fixed by bolts to hoop the C-shaped steel pile. The vertical steel plate is attached to the web of the C-shaped steel pile, and a loading hole is provided on the eccentric side of the horizontal steel plate.

[0008] Further, bolt holes are aligned and opened at the connection between the channel-shaped steel plate and the vertical steel plate, and the channel-shaped steel plate and the vertical steel plate are fixed together by bolts.

[0009] Further, the bolt holes are symmetrically arranged with the C-shaped steel pile as the center.

[0010] Further, a first triangular steel plate is welded at the corner of the channel-shaped steel plate.

[0011] Further, first triangular steel plates are welded at the upper, lower, left, and right corners of the channel-shaped steel plate.

[0012] Further, two second triangular steel plates are welded respectively at the upper and lower parts of the vertical steel plate and the horizontal steel plate at the position where the horizontal steel plate is horizontally trisected.

[0013] Further, the loading hole is arranged outside the second triangular steel plate.

[0014] Further, the width of the channel-shaped steel plate is the same as the width of the C-shaped steel pile it surrounds.

[0015] The present invention also provides a loading method, which is carried out by using the above eccentric hoop pile testing loading tool, and includes the following steps: Step 1: Drive the C-shaped steel pile into the soil to a predetermined buried depth position; Step 2: Install the eccentric hoop pile testing loading tool on the C-shaped steel pile; Step 3: The loading device includes a hook, a pulley block, a dynamometer, and a winch. One end of the hook is connected to the eccentric hoop pile testing loading tool through the loading hole, and the other end is successively connected to the pulley block, the dynamometer, and then to the winch. The loading method is as follows: 1. Uniformly load to 25% of the calculated failure load within 240 s, and unload and statically wait for 120 s; 2. Uniformly load to 50% of the calculated failure load within 240 s, and unload and statically wait for 120 s; 3. Uniformly load to 75% of the calculated failure load within 240 s, and unload and statically wait for 120 s; 4. Uniformly load to 100% of the calculated failure load within 240 s, and unload and statically wait for 120 s; 5. Uniformly load to 130% of the calculated failure load within 240 s, and unload and statically wait for 120 s; 6. Uniformly load until the C-shaped steel pile undergoes lateral displacement failure; During the loading process, record the displacement of the C-shaped steel pile at the ground surface with a dial gauge and record the failure load by reading the force gauge.

[0016] The beneficial effects of the present invention are as follows: 1. Through mechanical principles, counteract the bending moment generated by the traditional central loading method, avoid the torsion of the C-shaped steel pile foundation, and improve the integrity and credibility of the test data; 2. This tool does not change the original structure of the steel section, enhancing the accuracy of the test data; 3. This tool is convenient to process. The loading position can be adjusted by adjusting the opening position of the steel plate, and it can be applied to C-shaped steel piles with different cross-sectional sizes; 4. This tool can be reused and is suitable for large-scale test scenarios. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of the eccentric hoop test pile loading tool of the present invention; Figure 2 It is a top view of the eccentric hoop test pile loading tool of the present invention; Figure 3 It is a mechanical analysis of the centroid and shear center of the C-shaped steel pile of the present invention; Figure 4 It is the shear flow of the centroid and shear center of the C-shaped steel pile of the present invention; Figure 5 It is a schematic diagram of the loading test.

[0018] In the figure: C-shaped steel pile 1, C-shaped steel pile web 11, channel-shaped steel plate 2, first triangular steel plate 3, bolt hole 4, vertical steel plate 5, horizontal steel plate 6, second triangular steel plate 7, loading hole 8, eccentric hoop test pile loading tool 9, pulley block 10, force gauge 11, winch 12, dial gauge 13. Detailed Embodiment

[0019] The following further explains the structures involved in the present invention or the technical terms used. These explanations are only examples to illustrate how the present invention is implemented and cannot constitute any limitation to the present invention.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "lateral", "longitudinal", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated positions or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0021] In the description of the present invention, unless otherwise clearly specified and defined, terms such as "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a direct connection or an indirect connection through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] As Figure 1 and Figure 2 shown, this embodiment introduces an eccentric hoop pile loading tool, which includes a C-shaped steel pile 1, a channel-shaped steel plate 2, a vertical steel plate 5, and a horizontal steel plate 6 fixed at the central position of the vertical steel plate 5. The channel-shaped steel plate 2 and the vertical steel plate 5 surround the C-shaped steel pile 1 and are fixed by bolts to hoop the C-shaped steel pile 1. The vertical steel plate 5 is in contact with the web 11 of the C-shaped steel pile, and a loading hole 8 is provided on the eccentric side of the horizontal steel plate 6.

[0023] As an alternative embodiment, as Figure 2 shown, bolt holes 4 are aligned and opened at the connection between the channel-shaped steel plate 2 and the vertical steel plate 5, and the channel-shaped steel plate 2 and the vertical steel plate 5 are fixed together by bolts. Specifically, one bolt hole 4 is opened on each side of the vertical steel plate 5, and the two bolt holes 4 are symmetrically arranged with the C-shaped steel pile 1 as the center.

[0024] As an alternative embodiment, as Figure 1 shown, a first triangular steel plate 3 is welded to the corners of the channel-shaped steel plate 2. Specifically, the first triangular steel plates 3 are welded to the upper, lower, left, and right corners of the channel-shaped steel plate 2 to enhance the stability of the eccentric hoop pile loading tool 9.

[0025] As an alternative embodiment, as Figure 2 shown, two second triangular steel plates 7 are welded respectively above and below at the horizontal three-equal-part position of the horizontal steel plate 6 between the vertical steel plate 5 and the horizontal steel plate 6 to enhance the stability of the eccentric hoop pile loading tool 9.

[0026] As an alternative embodiment, as Figure 2As shown in the figure, the width of the U-shaped steel plate 2 is the same as the width of the C-shaped steel pile 1 it encloses. Considering the installation error, a 2-mm gap is provided between the U-shaped steel plate 2 and the C-shaped steel pile 1 on the left and right. See Figure 2 .

[0027] As an alternative embodiment, as Figure 2 shown, the loading holes 8 are eccentrically arranged on the horizontal plate 6 and are arranged outside the second triangular steel plate 7 to facilitate the installation of the lifting hook. Specifically, the opening position of the loading holes 8 needs to be determined by theoretical calculation, and the opening diameter needs to be determined according to the on-site loading device.

[0028] Performing a mechanical analysis on the C-shaped steel pile 1, as Figure 3 shown, it is found that the shear center (shearing center) of the C-shaped steel pile 1 does not coincide with the centroid. When the horizontal force acts along the centroid, a moment along the shear center will be generated, causing the C-shaped steel pile 1 to twist.

[0029] As Figure 4 shown, the shear center is the point of action of the resultant force of the shear flow of the cross-section and is also the center of torsion. When the lateral load passes through the cross-section shear center, the member only undergoes bending and does not twist; when the lateral load does not pass through the cross-section shear center, the member will undergo flexural-torsional buckling.

[0030] According to the shear stress reciprocity theorem of material mechanics, by calculating the static moment and integrating, it can be known that the shear center is independent of the external load and only related to the structural shape.

[0031] This embodiment also introduces a loading method, which is carried out using the above eccentric hoop test pile loading tool, including the following steps: Step 1: Installation of the pile foundation Perform axis measurement and setting out according to the drawings, move the rammer into position, and operate the rammer according to the operation manual. First, use the rammer to gently strike the C-shaped steel pile 1 with a low hammer, and then perform formal striking to drive the C-shaped steel pile 1 into the soil to the predetermined buried depth position.

[0032] Step 2: Fabrication of the eccentric hoop test pile loading tool The fabrication steps are as follows: 1. According to the calculation results, reserve the position of the loading holes 8, drill holes in the horizontal steel plate 6 to reserve the loading holes 8, and reserve 2 bolt holes 4 in the U-shaped steel plate 2; 2. Weld the four second triangular steel plates 7 to the horizontal steel plate 6 respectively, and weld the four first triangular steel plates 3 to the U-shaped steel plate 2 respectively; 3. Weld the horizontal steel plate 6 and the second triangular steel plate 7 to the vertical steel plate 5; 4. Put the U-shaped steel plate 2 into the C-shaped steel pile 1, and connect and fasten the U-shaped steel plate 2 and the vertical steel plate 5 with bolts.

[0033] Step 3: Loading of the test piece The loading device includes a lifting hook, a pulley block 10, a dynamometer 11, and a winch 12. As Figure 5 shown, one end of the lifting hook is connected to the eccentric hoop pile loading tool 9 through a loading hole 8, and the other end is successively connected to the pulley block 10, the dynamometer 11, and then to the winch 12. The loading method is as follows: 1. Uniformly load to 25% of the calculated failure load within 240 s, and unload and statically rest for 120 s; 2. Uniformly load to 50% of the calculated failure load within 240 s, and unload and statically rest for 120 s; 3. Uniformly load to 75% of the calculated failure load within 240 s, and unload and statically rest for 120 s; 4. Uniformly load to 100% of the calculated failure load within 240 s, and unload and statically rest for 120 s; 5. Uniformly load to 130% of the calculated failure load within 240 s, and unload and statically rest for 120 s; 6. Uniformly load until the C-shaped steel pile 1 undergoes lateral displacement failure.

[0034] During the loading process, the displacement of the C-shaped steel pile 1 at the ground surface is recorded by a micrometer 13, and the failure load is recorded by reading the dynamometer 11.

[0035] Step Four: Removing the Device Remove the lifting hook from the eccentric hoop pile loading tool 9, then remove the connecting bolts of the channel steel plate 2 and the vertical steel plate 5, remove the eccentric hoop pile loading tool 9 from the C-shaped steel pile 1, and finally pull out the C-shaped steel pile 1 from the soil.

[0036] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An eccentric clamp pile test loading tool, characterized in that: It includes a C-shaped steel pile, an I-shaped steel plate, a vertical steel plate and a horizontal steel plate fixed at the center of the vertical steel plate. The I-shaped steel plate and the vertical steel plate surround the C-shaped steel pile and are fixed by bolts to clamp the C-shaped steel pile. The vertical steel plate is in contact with the web of the C-shaped steel pile, and a loading hole is provided on the eccentric side of the horizontal steel plate.

2. The eccentric clamp pile test loading tool according to claim 1 is characterized in that: Bolt holes are aligned at the connection points between the I-shaped steel plate and the vertical steel plate, and the I-shaped steel plate and the vertical steel plate are fixed together by bolts.

3. The eccentric clamp pile test loading tool according to claim 2 is characterized in that: The bolt holes are symmetrically arranged with the C-shaped steel pile as the center.

4. The eccentric clamp pile test loading tool according to claim 1 is characterized in that: The corners of the I-shaped steel plate are welded with a first triangular steel plate.

5. The eccentric clamp pile test loading tool according to claim 4 is characterized in that: First triangular steel plates are welded to the upper and lower sides and left and right side corners of the "X"-shaped steel plate.

6. The eccentric clamp pile test loading tool according to claim 1, characterized in that: Two second triangular steel plates are welded between the vertical steel plate and the horizontal steel plate at the upper and lower positions respectively according to the horizontal trisection of the horizontal steel plate.

7. The eccentric clamp pile test loading tool according to claim 6 is characterized in that: The loading holes are arranged on the outside of the second triangular steel plate.

8. The eccentric clamp pile test loading tool according to claim 1, characterized in that: The width of the I-shaped steel plate is the same as the width of the C-shaped steel pile it surrounds.

9. A loading method, characterized in that: The eccentric clamp pile test loading tool according to any one of claims 1 to 8 is used, comprising the following steps: Step 1: Drive the C-shaped steel pile into the soil at a predetermined depth; Step 2: Install the eccentric clamp pile loading tool on the C-shaped steel pile; Step 3: The loading device includes a hook, a pulley block, a dynamometer, and a winch. One end of the hook is connected to the eccentric clamp pile loading tool through the loading hole, and the other end is connected to the pulley block, the dynamometer, and then the winch. The loading method is:

1. Load evenly to 25% of the calculated failure load within 240 seconds, unload and let stand for 120 seconds; 2. Load evenly to 50% of the calculated failure load within 240 seconds, unload and let stand for 120 seconds; 3. Load evenly to 75% of the calculated failure load within 240 seconds, unload and let stand for 120 seconds; 4. Load evenly to 100% of the calculated failure load within 240 seconds, unload and let stand for 120 seconds; 5. Load evenly to 130% of the calculated failure load within 240 seconds, unload and let stand for 120 seconds; 6. Uniform loading until the C-type steel piles are damaged by lateral displacement; During the loading process, the displacement of the C-shaped steel pile at the ground is recorded by a micrometer, and the failure load is recorded by the dynamometer reading.

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