A high-strain large-scale model test guided drop hammer device

Abstract

A high strain large scale model test guiding drop hammer device, including guide frame (1), base pedestal (2), fixed support frame (3) and heavy hammer (4). Heavy hammer is made of multiple same area rectangular steel plates (5) stacked and fastened by bolt, or made of a rectangular cubic steel block (10) and multiple same area rectangular steel plates (5) stacked and fastened by bolt (8) and nut (9); hook flange (7) is fixedly installed at the center of gravity of the top surface of heavy hammer. The utility model uses guide frame and heavy hammer as guiding drop hammer device, after guide frame positioning sleeve enters pile, based on fixed clamp, guide frame and heavy hammer are pasted and slide, the coaxial state of the central axis of heavy hammer and pile is ensured, the adverse effect of eccentric hammering of heavy hammer on sensor signal of pile is avoided, the weight of heavy hammer is adjusted by increasing or decreasing the number of steel plates, the weight of heavy hammer is always greater than 1.0%~1.5% of the estimated ultimate bearing capacity of single pile, so that the test requirement of different bearing capacity pile foundation is met.

Description

Technical Field

[0001] This utility model relates to the technical field of guide drop hammer devices, specifically a guide drop hammer device for high-strain, large-scale model testing. Background Technology

[0002] Pile foundations are the basic structure of buildings, and the integrity and bearing capacity of the piles have a significant impact on the quality of the building. To ensure that the quality of pile foundations meets the design specifications, static load tests and high-strain tests are commonly used to test the vertical bearing capacity of the pile foundations. Among them, the high-strain method has become an important method for pile foundation testing, with advantages such as short testing time, low cost, high efficiency, and wide sampling range. The high-strain method uses a heavy hammer to impact the top of the pile foundation, causing sufficient relative displacement between the pile and the soil, thereby fully stimulating the pile end bearing force and the soil resistance around the pile. By measuring the force and velocity time history curves at the top of the pile, and based on wave theory analysis, the vertical compressive bearing capacity of a single pile and the integrity of the pile body are determined. The hammer impact device in the existing high-strain test includes a guide frame, a heavy hammer, a release hook, and a suspension system, where the release hook is connected to both the heavy hammer and the suspension system. Through manual operation, the heavy hammer is released from the release hook, causing it to fall freely and strike the pile foundation. The guide frame, as a device in high-strain testing, serves to guide and support the weight of the hammer, ensuring that it strikes the pile core vertically after its vertical fall. The hammer, as a device in high-strain testing, provides a transient impact to the pile top, evaluating the single pile bearing capacity and pile integrity by stimulating the pile-soil dynamic response.

[0003] High-strain tests are frequently affected by various complex on-site environments, with the eccentric impact of the hammer striking the pile top being particularly significant; severe eccentric impact can even lead to test failure. Existing guided drop hammer devices require manual operation to release the hammer during high-strain testing. However, during manual operation, the hammer swings left and right with the release hook and the swinging of the hoisting system. Because there is no limit to the hammer's movement, it can strike the pile top eccentrically, resulting in inaccurate high-strain test results. When using high-strain testing to detect pile bearing capacity, the weight of the hammer should be 1.0% to 1.5% greater than the estimated ultimate bearing capacity of a single pile. Therefore, the weight of the hammer will vary depending on the ultimate bearing capacity of different piles. Existing guided drop hammer devices cannot flexibly change the weight of the hammer; hammers of different weights must be customized according to different bearing capacity test requirements. Traditional customization methods are inefficient and costly. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of low efficiency and high cost in traditional high-strain tests by proposing a guide drop hammer device for high-strain large-scale model tests.

[0005] The technical solution of this utility model is as follows: a high-strain, large-scale model test guide drop hammer device, including a support and a hammer. The support consists of a guide frame, a fixed support frame and a base. The upper part of the guide frame is welded and fixed to the inner frame of the fixed support frame, and the lower part of the guide frame is vertically installed on the base. The hammer drops through the guide frame.

[0006] The hammer is formed by stacking multiple rectangular steel plates of the same area and fastening them together with bolts and nuts; or by stacking a rectangular cubic steel block and multiple rectangular steel plates of the same area and fastening them together with bolts and nuts; a hook flange is installed at the center of gravity of the top surface of the hammer, and fixing clamps are installed on the lower middle part of both sides of the hammer.

[0007] The base is constructed from eight rectangular steel bars welded together to form a U-shape, with the central rectangle extending along its two wide sides to the outer frame of the base and welded in place. The size of the central rectangle is the same as that of the rectangular steel plate. The fixed support frame is constructed from four rectangular steel bars welded together to form a rectangle. The guide frame consists of four main uprights and multiple support rods. The lower ends of the four main uprights are vertically installed and welded to the midpoint of the central rectangular side of the base. Each main upright is supported by two support rods at its lower part. The upper ends of the four main uprights are welded to the midpoint of the corresponding four sides of the inner rectangular frame of the fixed support frame. The space between the four main uprights accommodates a weight falling vertically from top to bottom.

[0008] The rectangular cubic steel block has screw holes at the four corners of its rectangular surface and is equipped with square-headed long bolts. The rectangular steel plate has the same shape and size as the rectangular surface of the rectangular cubic steel block, and has round holes at its four corners. Under the condition that the rectangular surface of the rectangular cubic steel block is flush with the steel plate, the round holes at the four corners of the steel plate are concentric with the screw holes at the four corners of the corresponding rectangular cubic steel block. Two sets of fixing clamps are respectively installed and fixed at the lower middle position of the two sides along the length of the rectangular cubic steel block.

[0009] The fixing clamp is attached to the main upright of the guide frame. The inner wall width of the fixing clamp is slightly wider than the width of the main upright by 1-3cm to ensure that the fixing clamps on both sides of the counterweight can slide freely downwards attached to the main upright.

[0010] The rectangular cubic steel block is fitted with square-headed long bolts through the screw holes at its four corners. After the square-headed long bolts are tightened and fixed, multiple rectangular steel plates are stacked on the rectangular cubic steel block through the long bolts at the four corners, and the rectangular steel plates are pressed and fixed into a whole with nuts. According to the needs of high strain testing, the weight of the hammer can be adjusted by increasing or decreasing the number of rectangular steel plates through the bolt and nut structure to meet the needs of different single pile tests.

[0011] The beneficial effects of this utility model are that by using a guide frame and a hammer as a guiding drop hammer device, after the guide frame is positioned and fitted into the pile, the guide frame and the hammer slide together based on the fixing clamp, which can limit the hammer and ensure that the central axis of the hammer and the pile are in a coaxial state. This avoids adverse effects on the sensor signal of the pile due to the eccentric hammer impact. By increasing or decreasing the number of steel plates, the weight of the hammer can be adjusted so that the weight of the hammer is always greater than 1.0% to 1.5% of the estimated ultimate bearing capacity of a single pile, thereby meeting the testing requirements of pile foundations with different bearing capacities. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the guide hammer device of this utility model;

[0013] Figure 2 This is a schematic diagram of the support structure;

[0014] Figure 3 Left view of the support structure;

[0015] Figure 4 This is a top view of the support structure;

[0016] Figure 5 This is a schematic diagram of the counterweight structure;

[0017] Figure 6 Left view of the counterweight structure;

[0018] Figure 7 This is a top view of the counterweight structure;

[0019] Figure 8 A schematic diagram of a counterweight structure consisting of a rectangular cubic steel plate and multiple rectangular steel plates stacked together;

[0020] In the diagram, 1 is the guide frame; 2 is the foundation base; 3 is the fixed support frame; 4 is the counterweight; 5 is the rectangular steel plate; 6 is the fixing clamp; 7 is the hook flange; 8 is the long bolt; 9 is the nut; and 10 is the rectangular cubic steel block. Detailed Implementation

[0021] The specific embodiments of this utility model are shown in the accompanying drawings.

[0022] like Figure 1 As shown in the figure, this embodiment of a high-strain large-scale model test guide drop hammer device includes a guide frame 1, a base 2, a fixed support frame 3, and a weight 4.

[0023] In this embodiment, the lower part of the guide frame 1 is vertically installed on the rectangular frame of the foundation base 2; the inner frame of the fixed support frame 3 is installed and fixed on the main uprights on the upper part of the guide frame 1, and the four main uprights of the guide frame 1 are welded to the middle of the four sides of the rectangular inner frame of the fixed support frame 3 respectively, and the fixed support frame 3 is in a horizontal position; the hammer 4 is dropped through the four main uprights of the guide frame 1.

[0024] like Figure 2 As shown, the foundation base 2 described in this embodiment is formed by welding eight steel bars with rectangular cross sections into a U-shaped base. The middle part is a rectangular inner frame, and its two wide sides extend to the outer frame of the base and are welded and fixed. The rectangular space in the middle is used to accommodate the pile foundation.

[0025] like Figure 2 and Figure 3 As shown, the fixed support frame 3 in this embodiment is a rectangular frame welded from four steel bars with rectangular cross sections.

[0026] like Figure 2 and Figure 4 As shown, the guide frame 1 in this embodiment consists of four main uprights and multiple support rods. The lower ends of the four main uprights are vertically welded and fixed to the middle of the rectangular side of the foundation base. The lower part of each main upright is supported by two support rods. The upper ends of the four main uprights are welded to the midpoints of the four inner sides of the rectangular inner frame of the fixed support frame 3.

[0027] like Figures 5-7 As shown, the hammer 4 in this embodiment is formed by stacking multiple rectangular steel plates 5 of the same area and fastening them with nuts 9. Round holes are uniformly machined at the four corners of the rectangular steel plates 5, and long bolts are provided. The thickness of a single rectangular steel plate 5 is 1-2 cm. A hook flange 7 is installed at the center of gravity of the rectangular steel plate 5 on the top surface of the hammer 4. Fixing clamps 6 are welded to the lower middle part of both sides of the hammer 4, which is formed by stacking rectangular steel plates 5. The fixing clamps 6 are composed of two identical rectangular steel plates, vertically welded to the sides of the hammer. The two steel plates are symmetrical about the center line of the sides of the hammer 4, and the distance between the two steel plates is slightly wider than the width of the main upright by 1-3 cm, facilitating the free fall of the hammer 4 according to the position limited by the fixing clamps 6.

[0028] As another structural embodiment of the hammer 4, such as Figure 8The diagram shows a structural schematic of a counterweight 4 consisting of a rectangular cubic steel block 10 and multiple rectangular steel plates 5 stacked together. In this embodiment, the counterweight 4 is formed by stacking a rectangular cubic steel block 10 and multiple rectangular steel plates 5 of the same area, and then fastening them together with bolts and nuts. The rectangular cubic steel block 10 has screw holes machined at its four corners and is equipped with square-headed long bolts. The rectangular steel plates 5 have the same shape and size as the rectangular surface of the rectangular cubic steel block 10, and have round holes at their four corners. While ensuring that the rectangular surface of the rectangular cubic steel block 10 is flush with the four sides of the rectangular steel plates 5, the round holes at the four corners of the rectangular steel plates 5 are concentric with the corresponding screw holes at the four corners of the rectangular cubic steel block 10. A hook flange 7 is installed at the center of gravity of the rectangular steel plate 5 on the top surface of the hammer 4. Fixing clamps 6 are welded to the lower middle part of both sides of the rectangular cubic steel block 10. The fixing clamps 6 are composed of two identical rectangular steel plates, which are vertically welded to the side of the rectangular cubic steel block 10. The two steel plates are symmetrical about the center line of the side of the steel block. The distance between the two steel plates is 1-3cm wider than the width of the main upright.

[0029] In this embodiment, the height of the rectangular cubic steel block 10 is 10-30cm, and the thickness of a single rectangular steel plate 5 is 1-2cm; the length × width of the rectangular steel plate 5 is (35-45cm) × (45-55cm); the number of rectangular steel plates 5 is determined according to needs; after the rectangular steel plates 5 are stacked on the bolts 8 on the rectangular cubic steel block 10, the rectangular steel plates 5 and the rectangular cubic steel block 10 are connected as a whole by nuts 9 --- hammer 4.

[0030] In this embodiment, the fixing clamp 6 is in contact with the main upright of the guide frame 1 to prevent the hammer from swinging left and right as it falls along the guide frame 1, thus avoiding eccentric hammering of the pile foundation. In this embodiment, a hook flange 7 is installed in the middle of the top of the hammer, which is used for connecting the hammer 4 to the hook.

[0031] The top four corners of the hammer 4 have long bolts 8 and nuts 9 for mounting rectangular steel plates. The long bolts 8 are used to increase or decrease the number of rectangular steel plates 5 to adjust the weight of the hammer 4.

[0032] The working principle of this embodiment is as follows: A foundation base 2 is installed below the guide frame 1, enabling the guide frame 1 to support the weight of the hammer 4. A fixed support frame 3 is installed on the upper part of the guide frame 1 to fix its position and ensure it remains vertically stable. Fixed clamps 6 are installed on the left and right sides below the hammer 4. The inner wall width of the fixed clamp 6 is slightly larger than the width of the main upright of the guide frame 1, which limits the sliding trajectory of the hammer 4, allowing the hammer 4 to fall freely while tightly attached to the guide frame 1. This prevents the hammer 4 from swinging left and right with the release and hoisting system, ensuring that the hammer 4 falls vertically and is coaxial with the central axis of the pile, preventing the hammer 4 from eccentrically hitting the pile foundation. A hook flange 7 is installed in the middle of the top of the hammer 4. The hook flange 7 is connected to the release hook above the hammer and can be operated mechanically or by a control device to allow the hammer 4 to detach from the release hook and complete the drop test.

[0033] The top four corners of the hammer 4 are equipped with long bolts 8 welded inside the rectangular steel plate 5, which allows the upper rectangular steel plate 5 of the hammer 4 to move flexibly. Nuts 9 are threaded on the outside of the long bolts 8, which can fix the movable rectangular steel plate 5 on the upper part of the hammer 4, so that the weight of the hammer 4 can be adjusted as the rectangular steel plate 5 is added or removed, thereby meeting the testing requirements of pile foundations with different bearing capacities.

Claims

1. A guide drop hammer device for high-strain, large-scale model testing, comprising a support and a weight, characterized in that, The support consists of a guide frame, a fixed support frame, and a base. The upper part of the guide frame is welded and fixed to the inner frame of the fixed support frame, and the lower part of the guide frame is vertically installed on the base. The weight is dropped through the guide frame. The hammer is formed by stacking multiple rectangular steel plates of the same area and fastening them together with bolts and nuts; or by stacking a rectangular cubic steel block and multiple rectangular steel plates of the same area and fastening them together with bolts and nuts; a hook flange is installed at the center of gravity of the top surface of the hammer, and fixing clamps are installed on the lower middle part of both sides of the hammer.

2. The high-strain, large-scale model test guide drop hammer device according to claim 1, characterized in that, The base is constructed from eight rectangular steel bars welded together to form a U-shape, with the central rectangle extending along its two wide sides to the outer frame of the base and welded in place. The size of the central rectangle is identical to that of the rectangular steel plate. The fixed support frame is constructed from four rectangular steel bars welded together to form a rectangle. The guide frame consists of four main uprights and multiple support rods. The lower ends of the four main uprights are vertically welded to the midpoints of the rectangular sides of the base, and each main upright is supported by two support rods at its lower end. The upper ends of the four main uprights are welded to the midpoints of the corresponding four sides of the inner rectangular frame of the fixed support frame. The space between the four main uprights accommodates a weight falling vertically from top to bottom.

3. The high-strain, large-scale model test guide drop hammer device according to claim 1, characterized in that, The rectangular cubic steel block has screw holes at the four corners of its rectangular surface and is equipped with square-headed long bolts. The rectangular steel plate is the same size as the rectangular surface of the rectangular cubic steel block and has round holes at its four corners. Under the condition that the rectangular surface of the rectangular cubic steel block is flush with the rectangular steel plate, the round holes at the four corners of the rectangular steel plate are concentric with the screw holes at the four corners of the corresponding rectangular cubic steel block. Two sets of fixing clamps are respectively installed and fixed at the lower middle position of the two sides along the length of the rectangular cubic steel block.

4. The high-strain, large-scale model test guide drop hammer device according to claim 2, characterized in that, The fixing clamp fits tightly against the main upright of the guide frame, and the inner wall width of the fixing clamp is 1-3cm wider than the width of the main upright; the counterweight falls based on the fixing clamp fitting against the main upright of the guide frame.

5. The high-strain, large-scale model test guide drop hammer device according to claim 3, characterized in that, The rectangular cubic steel block is secured by square-headed long bolts installed at its four corners. Multiple rectangular steel plates are stacked on the rectangular cubic block and then pressed together with nuts to form a whole.

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