Laser measuring device for measuring displacement of pile top in static load test

Abstract

The application discloses a kind of laser measuring devices of pile top displacement measurement of static load test, including laser transmitter and laser receiving unit, the laser reflector is synchronous with the pile to be examined to lift, the spatial position of the laser receiving unit is fixed and is used to receive the laser that laser transmitter emits, the laser receiving unit includes box, refractor being set to the front of box and reading board being set to the back of box, the refractor is used to refract laser to form light spot on reading board, and the reading board is equipped with back scale. Since laser transmitter and the pile to be examined are synchronous to lift, so the position deviation generated by its lifting can be refracted to the scale on reading board by refractor and form light spot, in its process, the displacement of the pile to be examined can be amplified by refractor and the accurate displacement value of the pile to be examined is obtained by reading board auxiliary measurement.

Description

Technical Field

[0001] This invention relates to the field of engineering testing, and in particular to a laser measuring device for measuring the displacement of the top of a pile in a static load test. Background Technology

[0002] According to Table 4.2.6 of the People's Republic of China industry standard "Technical Specification for Testing of Building Foundation Piles" (JGJ 1016-2014), the distance between the center of the reference pile and the edge of the counterweight platform support should be ≥4D and >2.0m. This distance requirement is to prevent the settlement of the support foundation from disturbing the reference pile, thus making it impossible to measure the pile top displacement. In testing, the specification requires the reference beam length to be >12m. However, in practical applications, the reference beam must meet the following requirements: lightweight (manual handling and disassembly), high rigidity (no deformation under its own weight), and easy transport. This results in the reference beam length being limited to ≤12m, thus contradicting the specification requirement and actual operation. Article 8.2.10 of the "Code for Testing of Building Foundations" (DBJ / T 15-60-2019) stipulates that for large-tonnage static load tests, when the reference beam length reaches 12m, but the distance between the reference pile and the counterweight platform support still does not meet the requirements, the reference beam length can be taken as 12m. In this case, the vertical displacement of the reference pile should be tested. Testing the benchmark piles wastes a lot of manpower and resources. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a laser measuring device for measuring the top displacement of a large-tonnage single pile under vertical compressive static load testing, which meets relevant testing standards, does not require a reference beam, and provides accurate and reliable results.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a laser measuring device for measuring the displacement of the top of a static load test pile, comprising a laser transmitter and a laser receiving unit. The laser transmitter is raised and lowered synchronously with the pile under test. The laser receiving unit is spatially fixed and is used to receive the laser emitted by the laser transmitter. The laser receiving unit includes a housing, a refractor disposed on the front of the housing, and a reading plate disposed on the back of the housing. The refractor is used to refract the laser to form a light spot on the reading plate. The reading plate is provided with a rear scale.

[0005] The beneficial effects of this invention are as follows: The laser measuring device for measuring the displacement of the top of a pile in a static load test employs a laser transmitter 1 and a laser receiving unit to detect the settlement displacement of the pile under test. Since the laser transmitter 1 and the pile under test rise and fall synchronously, the positional deviation generated by its rise and fall is refracted by a refractor onto the corresponding scale of the reading plate, forming a light spot. During this process, the displacement of the pile under test can be amplified by the refractor and measured with the aid of the reading plate to obtain the accurate displacement value of the pile under test. In use, the laser transmitter 1 can be placed directly on the pile under test or a jack, while the laser receiving unit can be placed at a distance according to relevant standards to eliminate disturbances from the settlement of the foundation. There is no mechanical structural connection between the laser receiving unit and the laser transmitter 1, and it does not require a reference beam to support the laser receiving unit or the laser transmitter 1. Compared with existing technologies, this effectively saves a significant amount of manpower and resources, simplifies operation, and improves efficiency.

[0006] Preferably, the refractor is made of transparent material. The front of the refractor is planar, while the back of the refractor has multiple rows of raised strips arranged from top to bottom. The cross-section of each raised strip is an arc-shaped structure protruding from the back of the refractor. These raised strips act like convex lenses, refracting the laser light. Furthermore, this invention uses multiple rows of raised strips instead of a single convex lens structure. The advantage of this is that, given the same refractor height, the focal length of a single convex lens structure would be much greater than the focal length of each raised strip structure in this invention, resulting in a much longer housing than in this invention, which is detrimental to miniaturization.

[0007] Preferably, the height W between each of the convex structures is equal, and each height W is less than 2mm.

[0008] Preferably, the front of the refractor is provided with a front scale for indicating the position of the raised structure, and the spacing between the graduations on the front scale is equal to the height W between the raised structures. The front scale indicates which raised structure the laser is projecting onto, allowing the inspection personnel to accurately calculate the displacement of the inspected pile by combining the readings from the front and rear scales.

[0009] Preferably, the reading plate is further provided with a vernier scale, which is slidably adjusted relative to the rear scale, and the scale interval on the vernier scale is equal to the height W between the convex structures. The inspection operator can move the vernier scale according to the reading on the front scale to correct the reading on the rear scale, thereby further improving the accuracy of the results.

[0010] Preferably, the laser receiving unit further includes a bracket, which includes a base for supporting the housing and legs for supporting the base. Ear plates are provided on both sides of the housing, and each ear plate has through holes. The base and the housing are connected by bolts passing through the through holes in the ear plates. This method facilitates the installation and disassembly of the laser receiving unit; disassembly simply requires loosening the connecting bolts between the base and the housing.

[0011] Preferably, the lower side of the base is also threaded with multiple adjusting screws that press the housing upwards. By turning the adjusting screws, the pressure exerted on the housing can be adjusted, thereby enabling fine-tuning of the housing height.

[0012] Preferably, the horizontal distance between the laser emitter and the laser receiver is 12-15m.

[0013] Preferably, the laser emitter is fixedly connected to the base plate of the jack, and the jack is fixedly installed on the top of the pile under inspection. This method allows for synchronous raising and lowering of the laser emitter and the pile under inspection.

[0014] Preferably, the refractive index is made of glass or resin. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the usage state of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of the laser receiving unit of the present invention.

[0017] Figure 3 for Figure 2 A magnified view of a portion of region A in the middle.

[0018] Figure 4 This is a schematic diagram illustrating the principle of laser refraction using the refractive index of this invention.

[0019] Figure 5 This is a schematic diagram of the front scale of the present invention.

[0020] Figure 6 This is a schematic diagram of the rear scale and vernier scale of the present invention.

[0021] Among them, 1-laser emitter, 2-laser receiving unit, 21-box, 22-refractor, 221-convex structure, 23-reading plate, 231-rear scale, 232-vernier scale, 241-base, 242-support foot, 243-adjusting screw, 3-jack, 4-inspection stake. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] See Figures 1 to 4 As shown, in this embodiment, the laser transmitter is fixedly connected to the base plate of the jack 3, and the jack 3 is fixedly installed on the top of the pile under inspection 4. The laser transmitter 1 and the pile under inspection 4 are raised and lowered synchronously in this manner. The laser receiving unit 2 has a fixed spatial position and is used to receive the laser emitted by the laser transmitter 1. In this embodiment, the horizontal distance between the laser transmitter 1 and the laser receiving unit 2 is 12-15m, which conforms to the industry standard "Technical Specification for Testing Building Foundation Piles" and has the effect of eliminating disturbances caused by foundation settlement.

[0025] In this embodiment, the laser receiving unit 2 includes a housing 21, a bracket for mounting the housing 21, a refractor 22 disposed on the front of the housing 21, and a reading plate 23 disposed on the back of the housing 21.

[0026] The support frame includes a base 241 for supporting the housing 21 and legs 242 for supporting the base 241. Ear plates are provided on both sides of the housing 21, and each ear plate has through holes. The base 241 and the housing 21 are connected by bolts passing through the through holes of the ear plates. Multiple adjusting screws 243 are threadedly connected to the underside of the base 241 to press the housing 21 upwards. By turning the adjusting screws 243, the upward pressure on the housing 21 can be adjusted, thereby allowing for fine-tuning of the height of the housing 21.

[0027] The refractor 22 is used to refract the laser to form a light spot on the reading plate 23. In this embodiment, the refractor 22 is made of a transparent material (such as glass or resin). The front of the refractor 22 is planar, while the back of the refractor 22 has multiple rows of raised strips 221 arranged from top to bottom. The cross-section of each raised strip 221 is an arc-shaped structure protruding from the back of the refractor 22. The height W between each raised strip 221 is equal, and each height W is less than 2mm. In addition, in this embodiment, the front of the refractor 22 is provided with a front scale for indicating the position of the raised strips 221. The spacing between the graduations on the front scale is equal to the height W between the raised strips 221. The front scale can indicate which raised strip 221 the laser is projected onto, allowing the inspection operator to accurately calculate the displacement of the inspected pile 4 by combining the readings of the front scale and the rear scale 231.

[0028] The reading plate 23 is provided with a rear scale 231. In this embodiment, the zero point of the rear scale 231 is aligned with the zero division of the front scale. At the same time, the reading plate 23 is also provided with a vernier scale 232. The vernier scale 232 is slidably adjusted relative to the rear scale 231, and the scale spacing on the vernier scale 232 is equal to the height W between the convex strip structures 221.

[0029] The usage method of this embodiment is as follows:

[0030] Positioning and calibration: After the laser transmitter 1 is fixedly installed on the base plate of the jack 3, the laser receiving unit 2 is installed at a distance of 112~15m from the laser transmitter 1, and the laser transmitter 1 and the laser receiving unit 2 are aligned with each other. Then, the housing 21 is raised and lowered for fine adjustment by turning the adjusting screw 243. When the adjustment is in place, the laser will be projected into the 0 degree scale of the front scale and form a light spot at the zero point of the rear scale 231.

[0031] Measurement method: S1. Read the value 'a' from the front scale, see [reference]. Figure 5 As shown, the value 'a' in the front scale represents the number of intervals between the corresponding convex structure 221 and the initial convex structure 221 on the refractor 22 where the laser is projected. For example, when the value 'a' is 0, it means that the laser is projected into the initial convex structure 221. When the value 'a' is 2 or -2, it means that the number of intervals between the corresponding convex structure 221 and the initial convex structure 221 is two. The positive or negative value of the value 'a' represents the direction of displacement. Since the pile under test 4 will usually settle during the test, the laser emitter 1 will also descend synchronously. Therefore, in order to facilitate reading, the negative value scale of the front scale is located above the 0 degree scale, and the positive value scale is located below the 0 degree scale.

[0032] S2. Then, move the vernier scale 232 according to the value 'a' on the front scale, see [reference]. Figure 6As shown, the scale intervals within the vernier scale 232 are the same as those of the front scale, and both intervals are equal to the height W between the convex structures 221. The 0-degree mark of the vernier scale 232 is located at its center, and like the front scale, negative values ​​on the vernier scale 232 are above the 0-degree mark, while positive values ​​are below it. During adjustment, based on the value 'a' of the front scale, the corresponding mark on the vernier scale 232 is aligned with the light spot on the reading plate 23. For example, if the current scale value 'a' is 2, the mark on the vernier scale 232 is aligned with the light spot.

[0033] S3. Read the value b from the rear scale 231. When reading the value b, the 0-degree mark of the vernier scale 232 should be used as the indicator.

[0034] S4. Calculate the displacement h of the tested pile 4 using the following formula:

[0035] h=b, when a=0;

[0036] h = (|a| - 0.5) × W + b, when a ≠ 0;

[0037] The displacement h of the test pile can be measured using the above method.

[0038] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any person skilled in the art can make more possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, all equivalent changes made based on the concept of the present invention without departing from the scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A laser measuring device for measuring the displacement at the top of a pile during a static compressive load test, characterized in that: The device includes a laser emitter (1) and a laser receiving unit (2). The laser emitter (1) is raised and lowered synchronously with the pile under inspection (4). The laser receiving unit (2) has a fixed spatial position and is used to receive the laser emitted by the laser emitter (1). The laser receiving unit (2) includes a housing (21), a refractor (22) disposed on the front of the housing (21), and a reading plate (23) disposed on the back of the housing (21). The refractor (22) is used to refract the laser to form a light spot on the reading plate (23). The reading plate (23) is provided with a rear scale (231). The refractor (22) is made of transparent material. The front of the refractor (22) is a planar structure, while the back of the refractor (22) has multiple rows of raised strip structures (221) arranged from top to bottom. The cross-section of each of the raised strip structures (221) is an arc surface structure protruding from the back of the refractor (22). The height W of each of the aforementioned convex structures (221) is equal, and each height W is less than 2 mm; The refractor (22) has a front scale on its front side for indicating the position of the convex structure (221), and the distance between each scale in the front scale is equal to the height W between the convex structures (221); The reading plate (23) is also provided with a vernier scale (232), which is slidably adjusted relative to the rear scale (231), and the scale spacing on the vernier scale (232) is equal to the height W between the convex structures (221).

2. The laser measuring device for measuring the displacement at the top of a pile in a static compressive load test according to claim 1, characterized in that: The laser receiving unit (2) also includes a bracket, which includes a base (241) for supporting the housing (21) and a support leg (242) for supporting the base (241). The housing (21) is provided with ear plates on both sides, and the ear plates have through holes. The base (241) and the housing (21) are connected by bolts that pass through the through holes of the ear plates.

3. The laser measuring device for measuring the displacement at the top of a pile in a static load test according to claim 2, characterized in that: The base (241) is also threaded with multiple adjusting screws (243) that press the housing (21) upward.

4. The laser measuring device for measuring the displacement at the top of a pile under static compressive load as described in claim 1, characterized in that: The horizontal distance between the laser transmitter (1) and the laser receiver (2) is 12-15m.

5. The laser measuring device for measuring the displacement at the top of a pile in a static compressive load test according to claim 1, characterized in that: The laser emitter (1) is fixedly connected to the base plate of the jack (3), and the jack (3) is fixedly installed on the top of the pile under inspection (4).

6. The laser measuring device for measuring the displacement at the top of a pile in a static compressive load test according to claim 1, characterized in that: The refractive index (22) is made of glass or resin.

Images