Low-strain drop hammer device for pile foundation detection

Abstract

The utility model relates to the field of pile foundation detection, in particular to a low-strain drop hammer device for pile foundation detection. The utility model provides a low strain drop hammer device for pile foundation detection, which comprises a guide cylinder capable of being vertically arranged right above a pile foundation to be detected, and a support strip radially penetrating into the guide cylinder, a drop hammer is supported on the support strip, the support strip is radially drawn out of the guide cylinder, and the drop hammer drops along the guide cylinder to knock the top surface of the pile foundation to be detected. According to the drop hammer device, the to-be-detected pile foundation can be accurately knocked by the drop hammer for multiple times, a detector does not need to hold the drop hammer by hand to gradually knock the to-be-detected pile foundation, and detected data are accurate.

Description

Technical Field

[0001] This utility model relates to the field of pile foundation testing, specifically to a low-strain drop hammer device for pile foundation testing. Background Technology

[0002] Pile foundations have a significant impact on building performance parameters. To ensure building quality, testing personnel need to inspect the pile foundations after they have been formed to obtain performance indicators such as compressive strength and density, thereby determining whether the pile foundation meets the standards. Pile foundation measurement can employ the low-strain dynamic testing method. Testing personnel need to attach sensors to the top surface of the pile foundation beforehand. During testing, they repeatedly strike the top surface of the pile foundation with a small hammer to generate stress waves. The sensors receive these stress waves and output corresponding data. Testing personnel can then calculate this data to analyze the dynamic response of the pile foundation, thereby obtaining information on its integrity. During the testing process, to ensure the accuracy of the stress wave data, the testing personnel must manually ensure that the hammer's height (drop distance), force, and direction are approximately the same each time it strikes the top surface of the pile foundation. Any deviation will affect the accuracy of the test. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a low-strain drop hammer device for pile foundation testing, which allows the drop hammer to accurately strike the pile foundation to be tested multiple times without the need for the testing personnel to hold the drop hammer and strike it one by one, and the measured data is more accurate.

[0004] To address the aforementioned issues, this utility model provides a low-strain drop hammer device for pile foundation testing, comprising a guide cylinder that can be vertically positioned directly above the pile foundation to be tested, and a support bar that is radially inserted into the guide cylinder. The support bar supports the drop hammer, and when the support bar is radially pulled out of the guide cylinder, the drop hammer falls along the guide cylinder to strike the top surface of the pile foundation to be tested.

[0005] Furthermore, the guide cylinder has a vertical through-slot that penetrates the cylinder wall radially. An adjusting ring is movably sleeved on the outside of the guide cylinder. The support bar passes through the adjusting ring and enters the guide cylinder through the vertical through-slot. When the adjusting ring moves up and down along the guide cylinder, it drives the support bar to move up and down along the vertical through-slot. After the adjusting ring moves into place, it can be detachably fixed on the outside of the guide cylinder, so that the support bar supports the drop hammer at the corresponding position.

[0006] Furthermore, a vertical limiting groove is opened on the wall of the guide cylinder, the limiting groove extends upward to the top surface of the guide cylinder, and the adjusting ring extends radially inward to form a limiting block. The limiting block is inserted into the limiting groove, and the adjusting ring can be detachably and movably sleeved on the outside of the guide cylinder, and can move up and down relative to the guide cylinder along the limiting groove.

[0007] Furthermore, the adjusting ring has a radially inward locking through hole, in which a locking screw is screwed. When the locking screw is tightened radially inward to press against the wall of the guide cylinder, the adjusting ring is detachably fixed to the outside of the guide cylinder.

[0008] Furthermore, the outer wall of the guide cylinder is provided with graduations along the vertical through groove.

[0009] Furthermore, including a base, the guide cylinder is vertically placed at the center of the base and extends downwards to the bottom of the base.

[0010] Furthermore, the base is equipped with adjustable feet at all four corners.

[0011] Furthermore, a level is provided on the base.

[0012] Beneficial effects: To implement the low-strain dynamic testing method on pile foundations, the inspector first attaches a sensor to the top surface of the pile to be tested and vertically places the guide tube of this invention directly above the pile. Then, the support strip is radially pulled out of the guide tube. The hammer inside the guide tube is no longer supported by the support strip, and it falls downwards along the guide tube under its own weight, striking the top surface of the pile, thus completing one strike. To strike the top surface of the pile again, the inspector needs to first re-insert the support strip radially into the guide tube, then place the hammer back into the guide tube to be supported by the support strip. The inspector can then again pull the support strip radially out of the guide tube, and the hammer will fall along the guide tube under its own weight, striking the top surface of the pile again. Repeating this process multiple times allows for multiple strikes. Because the support bar is fixed in position inside the guide tube, the height of the drop hammer supported by the support bar from the top surface of the pile foundation being tested is basically the same each time; because the drop hammer is only subject to its own weight when it falls, the force of each strike is also basically the same; under the guidance of the guide tube, the direction of the drop hammer striking the top surface of the pile foundation being tested is also basically the same each time. Therefore, the drop hammer device of this utility model can allow the drop hammer to strike the pile foundation being tested more accurately multiple times, without the need for the testing personnel to hold the drop hammer and strike it one by one, and the measured data is more accurate. Attached Figure Description

[0013] Figure 1 This is a simplified structural diagram of a low-strain drop hammer device used for pile foundation testing.

[0014] Figure 2 This is a simplified top view of a low-strain drop hammer device used for pile foundation testing.

[0015] Figure 3 It is along Figure 2 Simplified sectional view along the AA direction.

[0016] Figure 4 It is along Figure 2 Simplified sectional view along the BB direction.

[0017] Figure 5 This is a simplified schematic diagram of the regulating ring.

[0018] Symbol explanation:

[0019] 1-Base; 11-Level; 12-Foot; 2-Guide cylinder; 21-Limiting slot; 22-Vertical through slot; 23-Scale; 3-Adjusting ring; 31-Limiting block; 32-Through hole; 33-Locking through hole; 34-Locking screw; 4-Supporting strip; 5-Drop hammer. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments.

[0021] Low-strain drop hammer device for pile foundation testing (see...) Figure 1 The system includes a plate-shaped base 1, on which a level 11 is mounted. Each of the four corners of the base 1 is screwed with a foot 12. The foot 12 can be raised or lowered relative to the base 1 by rotating around its own vertical axis. By adjusting the four feet 12 to level the level 11 on the base 1, the base 1 can be placed in a horizontal position.

[0022] A guide cylinder 2 is vertically placed at the center of the base 1, with its lower end extending downwards to the bottom of the base 1 (see...). Figure 3 A vertical limiting groove 21 is formed on the outer wall of the guide cylinder 2, located on the left side of the guide cylinder 2 and extending upwards to the top surface of the guide cylinder 2. A limiting block 31 is formed by a radially inwardly extending portion of the left side of the adjusting ring 3 (in conjunction with...). Figure 5 The shape of the limiting block 31 matches the limiting slot 21, and the limiting block 31 is engaged in the limiting slot 21, so that the adjusting ring 3 is as follows: Figure 1 As shown, it is detachably and movably sleeved on the outside of the guide cylinder 2, and can move up and down relative to the guide cylinder 2 along the limiting groove 21. A vertical through-slot 22, radially penetrating the cylinder wall, is opened at the rear of the guide cylinder 2, extending upwards to the top surface of the guide cylinder 2; a vertical through-slot 22 is also opened at the front of the guide cylinder 2. The front vertical through-slot 22 and the rear vertical through-slot 22 have the same structure and are symmetrical. See Figure 5 The adjusting ring 3 has radially penetrating holes 32 at both the front and rear. The front and rear holes 32 are symmetrical. When the adjusting ring 3 is fitted onto the outside of the guide cylinder 2, the two holes 32 are aligned with the two vertical through slots 22 (see...). Figure 1 ).See Figure 1 and Figure 3 The columnar support strip 4 passes through the rearmost through hole 32, the rearmost vertical through groove 22, the frontmost vertical through groove 22 and the frontmost through hole 32 in sequence from back to front, and is then detachably inserted into the adjusting ring 3 and the guide cylinder 2.

[0023] See Figure 3 The support bar 4 is housed in the middle of the guide cylinder 2, supporting the drop hammer 5 upwards. When the support bar 4 is pulled radially outwards (i.e., forwards or backwards) outside the guide cylinder 2, the drop hammer 5 is no longer supported by the support bar 4 and falls downwards along the guide cylinder 2 under its own weight, directly below the guide cylinder 2. Figure 4 The left side of the adjusting ring 3 has a radially inward locking through hole 33 (combined with...) Figure 5 A locking screw 34 is screwed into the locking through hole 33 (see...). Figure 2 When adjusting the drop height (i.e., drop distance) of the hammer 5, first move the adjusting ring 3 up and down relative to the guide cylinder 2, thereby causing the support strip 4 passing through it and the hammer 5 supported by the support strip 4 to move up and down along the front and rear vertical through grooves 22. After the adjusting ring 3 moves to the appropriate position of the guide cylinder 2, tighten the locking screw 34 radially inward until it is pressed against the wall of the guide cylinder 2. Then the adjusting ring 3 is detachably fixed to the outside of the guide cylinder 2, and the support strip 4 stops at the corresponding position of the guide cylinder 2 to support the hammer 5, thus changing the drop height of the hammer 5. See Figure 1 The outer wall of the guide cylinder 2 is provided with scales 23 along the edges of the front and rear vertical through grooves 22, which makes it convenient for the testing personnel to judge the movement position of the adjusting ring 3 in order to determine the specific drop height of the hammer 5.

[0024] To perform low-strain dynamic testing on pile foundations, the testing personnel first attach sensors to the pile foundation to be tested. Then, they place the low-strain drop hammer device above the pile foundation, aligning the guide tube of the base 1 downwards with the pile foundation. The four feet 12 of the base 1 are adjusted to level the level instrument 11, ensuring the guide tube is vertically positioned directly above the pile foundation. The testing personnel can then loosen the locking screw 34 radially outwards to release the adjusting ring 3 from its fixation on the outside of the guide cylinder 2. The adjusting ring 3 is then moved up and down along the guide cylinder 2, causing the support strip 4 and the drop hammer 5 supported by the support strip 4 to move up and down together. Once the adjusting ring 3 is in position, the testing personnel tighten the locking screw 34 radially inwards to re-fix the adjusting ring 3 to its fixation on the outside of the guide cylinder 2. The support strip 4 then stops at the corresponding position on the guide cylinder 2, supporting the drop hammer 5, thus changing the drop height of the drop hammer 5. To strike the pile foundation under test with the drop hammer 5, the tester pulls the support strip 4 radially outward (i.e. forward or backward) out of the guide cylinder 2. The drop hammer 5 in the guide cylinder 2 is no longer supported by the support strip 4 and falls downward along the guide cylinder 2 under its own weight to the bottom of the guide cylinder 2, striking the top surface of the pile foundation under test, thus completing one strike. If the hammer 5 is to strike the top surface of the pile foundation to be tested again, the tester needs to first pass the support bar 4 through the rearmost through hole 32, the rearmost vertical through groove 22, the frontmost vertical through groove 22, and the frontmost through hole 32 in sequence from back to front, so that the support bar 4 is re-inserted radially into the guide cylinder 2. Then, the hammer 5 is put into the opening of the guide cylinder 2. The hammer 5 falls along the guide cylinder 2 under its own weight until it is supported by the support bar 4, as shown in the figure. In this way, the tester can pull the support bar 4 radially outward (i.e., forward or backward) out of the guide cylinder 2. The hammer 5 is no longer supported by the support bar 4 and falls downward along the guide cylinder 2 under its own weight to directly below the guide cylinder 2, striking the top surface of the pile foundation to be tested again. By repeating the above operation multiple times, the inspector can achieve multiple strikes. The stress wave generated by each strike is received by the sensor attached to the pile foundation under test, which outputs corresponding data. After multiple strikes, the inspector can obtain the integrity information of the pile foundation by calculating and analyzing the corresponding data output by the sensor. Since the position of the support strip 4 inside the guide tube 2 is fixed, the height of the drop hammer 5 supported by the support strip 4 from the top surface of the pile foundation under test is basically the same each time. Since the drop hammer 5 is only affected by its own weight when falling, the force of each strike is also basically the same. Under the guidance of the guide tube 2, the direction of each strike of the drop hammer 5 to the top surface of the pile foundation under test is also basically the same. Therefore, the drop hammer 5 can accurately strike the pile foundation under test multiple times, without the need for the inspector to hold the drop hammer 5 and strike it one by one. The data measured by the sensor is more accurate.

[0025] The above description is merely an embodiment of the present invention and does not limit the scope of patent protection. Any non-substantial changes or substitutions made by those skilled in the art based on the present invention will still fall within the scope of patent protection.

Claims

1. A low-strain drop hammer device for pile foundation testing, characterized in that, It includes a guide tube that can be placed vertically directly above the pile foundation to be tested, and a support strip that is radially inserted into the guide tube. A drop hammer is supported on the support strip. When the support strip is radially pulled out of the guide tube, the drop hammer falls along the guide tube to strike the top surface of the pile foundation to be tested.

2. The low-strain drop hammer device as described in claim 1, characterized in that, The guide cylinder has a vertical through-slot that penetrates the cylinder wall radially. An adjusting ring is movably sleeved on the outside of the guide cylinder. The support bar passes through the adjusting ring and enters the guide cylinder through the vertical through-slot. When the adjusting ring moves up and down along the guide cylinder, it drives the support bar to move up and down along the vertical through-slot. After the adjusting ring moves into place, it can be detachably fixed on the outside of the guide cylinder, so that the support bar supports the drop hammer at the corresponding position.

3. The low-strain drop hammer device as described in claim 2, characterized in that, The guide cylinder wall has a vertical limiting groove that extends upward to the top surface of the guide cylinder. The adjusting ring extends radially inward to form a limiting block. The limiting block is engaged in the limiting groove, and the adjusting ring can be detachably and movably sleeved on the outside of the guide cylinder, allowing it to move up and down relative to the guide cylinder along the limiting groove.

4. The low-strain drop hammer device as described in claim 2, characterized in that, The adjusting ring has a radially inward locking through hole, and a locking screw is screwed into the locking through hole. When the locking screw is tightened radially inward to press against the wall of the guide cylinder, the adjusting ring is detachably fixed to the outside of the guide cylinder.

5. The low-strain drop hammer device as described in claim 2, characterized in that, The outer wall of the guide cylinder is marked with graduations along the vertical through groove.

6. The low-strain drop hammer device according to any one of claims 1 to 5, characterized in that, Includes a base, with the guide cylinder vertically positioned at the center of the base and extending downwards to the bottom of the base.

7. The low-strain drop hammer device as described in claim 6, characterized in that, The base is equipped with adjustable feet at all four corners.

8. The low-strain drop hammer device as described in claim 6, characterized in that, A level is provided on the base.

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