Method for detecting hole-forming quality of large-angle inclined cast-in-place pile

Abstract

The invention provides a large-angle inclined cast-in-place pile pore-forming quality detection method, and is suitable for the technical field of pile foundation construction. The method comprises the steps of detection preparation, detection equipment installation, initial calibration, laser scanning detection, data processing and analysis and pore-forming quality judgment, the equipment is calibrated through a Zhang Zhengyou calibration method and a coplanar target device, and the measurement accuracy is ensured; the method comprises the following steps of: ensuring that a light plane is horizontal through a height-adjustable bracket and a circular level, scanning a hole wall by utilizing a linear structured light laser, capturing a projection image through a monocular camera, acquiring pixel coordinates of points on the hole wall, converting the pixel coordinates into world coordinates by combining calibrated internal and external parameters, and performing ellipse fitting to obtain the hole wall. And then the hole diameter, the inclination angle and the depth of the pile hole are deduced, so that the hole forming quality of the large-angle inclined cast-in-place pile is rapidly and comprehensively evaluated, and the problem that the hole diameter of the large-angle inclined cast-in-place pile cannot be detected through a traditional manual inspection method is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation construction, and particularly relates to a method for detecting the hole forming quality of cast-in-place piles with large-angle inclination. Background Art

[0002] With the increasingly mature technology of infrastructure construction, cast-in-place piles, as an important foundation project, are widely used in important projects such as bridges, high-rise buildings, and large-scale buildings. The construction quality of cast-in-place piles directly affects the stability and safety of buildings. Therefore, hole forming quality detection has also become a key link in the construction process of cast-in-place piles. Some projects are limited by on-site construction conditions and can only construct cast-in-place piles with large-angle inclination. However, the traditional method for detecting the hole forming quality of cast-in-place piles that relies on manual inspection and simple measuring tools cannot judge the hole forming quality of cast-in-place piles with large-angle inclination.

[0003] In recent years, with the rapid development of computer vision technology and laser scanning technology, automated and high-precision hole forming quality detection methods have gradually emerged. In the prior art, the scheme of using laser ranging combined with data processing for detection can greatly improve the detection accuracy and efficiency, but there are still certain deficiencies. For example, the existing laser scanning method lacks a comprehensive scan of different positions of the pile hole, and the point scanning method will amplify the influence of small-size abnormal points on the hole forming quality, increasing the misjudgment rate.

[0004] In contrast, the method for detecting the hole forming quality of cast-in-place piles with large-angle inclination proposed in this paper combines the synchronous operation of a monocular camera and a line-structured light laser. Through precise light plane control and laser scanning, it can obtain high-precision data of the hole wall in real time and perform effective data processing and analysis. This method can not only quickly and comprehensively evaluate key quality parameters such as hole depth, hole diameter, and pile hole inclination angle, but also effectively improve the accuracy and reliability of hole forming quality evaluation. Compared with the prior art, this method can achieve more automated and refined quality evaluation and has high practical application value. Summary of the Invention

[0005] The purpose of the present invention is to propose a method for detecting the hole forming quality of cast-in-place piles with large-angle inclination in view of the problem that the traditional manual detection technology cannot judge the hole forming quality of cast-in-place piles with large-angle inclination and the laser ranging method has misjudgment of hole forming quality, so as to make the hole forming quality detection of cast-in-place piles more automated and refined, improve the accuracy and reliability of hole forming quality evaluation, and can be widely applied to the technical field of pile foundation construction.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A method for detecting the hole forming quality of cast-in-place piles with large-angle inclination specifically includes the following steps:

[0008] S1. Detection preparation, including obtaining the design drawings of the cast-in-place pile, the content of the design drawings including the position of the cast-in-place pile, the pile diameter requirement, the hole forming depth, and the hole inclination angle of the pile hole; determining the number and positions of the holes to be detected, conducting a preliminary inspection on the completed holes, cleaning the environment around the hole opening, preliminarily confirming the risk status of water accumulation in the hole and hole wall collapse, and proceeding to the next step after confirming that there are no obstacles affecting the safety and accuracy of the detection equipment;

[0009] S2. Installing the detection equipment, including after completing the calibration of the monocular camera and the structured light calibration, setting up the bracket around the hole opening, making the central axis of the bracket coincide with the central axis of the pile hole opening, with a structured light laser on the central axis of the bracket, emitting structured light in two opposite directions respectively. Stipulating the two directions as the left and right directions, then monocular cameras are arranged on both the front and back sides of the structured light laser. The front monocular camera captures the structured light projection emitted to the left / right, and the rear monocular camera correspondingly captures the structured light projection emitted to the right / left; adjusting the height of each bracket to keep the light plane of the structured light horizontal;

[0010] S3. Initial calibration, including turning on the structured light laser, emitting the structured light projection onto the top hole wall of the pile hole, forming a structured light strip on the hole wall, recording the initial height of the structured light laser, and recording the distance h0 between the current structured light strip and the top of the pile hole;

[0011] S4. Laser scanning detection, including gradually lowering the structured light laser along the central axis of the pile hole from the hole opening to the hole bottom at a preset speed v1 smoothly, scanning the hole wall, continuously capturing the structured light strip on the hole wall by the monocular camera synchronized with the structured light laser until it is lowered to trigger the stop device to contact the hole bottom, recording the total lowering duration T, rotating the structured light laser and the synchronized monocular camera by 90° around the central axis of the pile hole, smoothly lifting at a preset speed v1, scanning the hole wall, and continuously capturing the structured light strip on the hole wall by the monocular camera synchronized with the structured light laser;

[0012] S5. Data processing and analysis, including preprocessing the images collected by the monocular camera, extracting the center points of the structured light strips, and fitting the ellipse of the pile hole at the corresponding height of the image data according to the center points of the structured light strips, obtaining the center coordinates, the lengths of the major and minor axes, and the rotation angle of the ellipse. Denote the length of the major axis as a and the length of the minor axis as b, then the pile hole diameter at this height is b, and the pile hole inclination angle is arcsin(b / a); the hole depth H is

[0013] H = h0 + v1T + l (2)

[0014] In the formula, l - the distance from the bottom of the trigger stop device to the light plane along the central axis of the pile hole;

[0015] S6. Judgment of hole formation quality, including that the hole depth H and the hole diameter are not less than the designed value, and the verticality i meets the specification requirements.

[0016] As a preferred technical solution of the present invention, the monocular camera calibration adopts the Zhang Zhengyou calibration method.

[0017] As a preferred technical solution of the present invention, the line structured light calibration uses a coplanar target device to calibrate the light plane equation of the line structured light.

[0018] As a preferred technical solution of the present invention, a platform is provided at the center of the bracket, and a circular spirit level is on the platform. The light plane of the line structured light is kept horizontal by calibration with the circular spirit level.

[0019] As a preferred technical solution of the present invention, the light planes of the line structured light in the left - right direction are on the same plane.

[0020] As a preferred technical solution of the present invention, the fitting of the ellipse is performed by the least - squares method.

[0021] The beneficial effects of the present invention are as follows: The equipment is calibrated by the Zhang Zhengyou calibration method and the coplanar target device to ensure the accuracy of measurement; The light plane is ensured to be horizontal by the bracket with adjustable height and the circular spirit level. The hole wall is scanned by the line structured light laser, and the projection image is captured by the monocular camera to obtain the depth information of the hole wall relative to the reference plane in real time, which is further converted into pixel coordinates. Combining the calibrated internal and external parameters, the pixel coordinates are converted into world coordinates, and the ellipse is fitted according to the world coordinates. Then, the pile hole diameter, the pile hole inclination angle, and the pile hole depth are inferred, so as to quickly and comprehensively evaluate the hole formation quality of the large - angle inclined cast - in - place pile, and solve the problem that the traditional manual inspection method cannot detect the hole diameter of the large - angle inclined cast - in - place pile; In addition, the least - squares method is used for ellipse fitting, which avoids the amplification of the influence of small - size abnormal points on the hole formation quality, improves the accuracy and reliability of the hole formation quality evaluation, and ensures the scientific evaluation of the pile hole quality during the construction process. Description of the Drawings

[0022] Figure 1 It is the flow chart of the hole formation quality detection method for the large - angle inclined cast - in - place pile of the present invention;

[0023] Figure 2 It is the installation schematic diagram of the hole formation quality detection of the cast - in - place pile of the present invention;

[0024] Reference numerals in the drawings: 1 - bracket, 2 - platform, 3 - line structured light laser, 4 - trigger stop device, 5 - light plane, 6 - pile hole. Detailed Embodiment

[0025] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments given here are only used to illustrate and explain the present invention and cannot be used to limit the present invention. It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may have other embodiments and variations, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0026] Embodiment 1. The method for detecting the hole-forming quality of a cast-in-place pile with a large-angle inclination is as follows:

[0027] S1. Obtain the design drawings of the cast-in-place pile. The content of the design drawings includes the position of the cast-in-place pile, the requirements for the pile diameter, the hole-forming depth, and the inclination angle of the pile hole; determine the number and positions of the holes to be detected, conduct a preliminary inspection on the completed holes, clean the environment around the hole opening, and preliminarily confirm the risk status of water accumulation in the hole and hole wall collapse. After confirming that there are no obstacles affecting the safety and accuracy of the detection equipment, proceed to the next step;

[0028] S2. Complete the calibration of the monocular camera. The imaging position of point Q in the world coordinate system (X W , Y W , Z W ) T on the pixel plane is Q p = (u, v) T . The coordinate transformation relationships in the camera imaging process, including world coordinate - camera coordinate, camera coordinate - image coordinate, theoretical image coordinate - actual image coordinate, and actual image coordinate - pixel coordinate, and the corresponding coordinate transformation equations are respectively

[0029]

[0030] In the formula, R - coordinate system rotation, T - coordinate system translation, k1, k2, p1, p2 - distortion coefficients, α, β, γ, u0, v0 - elements of the camera internal parameter matrix; use the Zhang-Zhengyou calibration method to calibrate the internal and external parameters of the monocular camera imaging model;

[0031] Complete the calibration of the line structured light. In the camera coordinate system, use the coplanar target device to calibrate the equation of the light plane 5 of the line structured light. Place the coplanar target at a position where both the emission of the line structured light laser 3 and the camera shooting are appropriate, and use the calibrated camera to shoot the coplanar target image; detect the pixel coordinates of the checkerboard corner point image and obtain the camera coordinates of the checkerboard corners using the checkerboard size. Use the camera coordinates of the checkerboard corners to obtain the coplanar target equation G1 through plane fitting; then, along the length direction of the line structured light stripe image, use the Steger algorithm to detect the pixel coordinates of the key points of the light stripe image width at 5 different positions; use the pixel coordinates of the key points of the light stripe image and the camera internal parameters to obtain the equation G of the line connecting the key points of the detected line structured light stripe image and the camera optical center. i (i = 1, 2,..., 5); Simultaneously solve equations G1 and G i , and solve for the camera coordinates (x ci , y ci , z ci ) (i = 1, 2,..., 5) of the midpoint of the light stripe on the black surface of the checkerboard. Keep the positions of the camera and the line structured light laser 3 unchanged, change the position of the coplanar target and then shoot the image again, repeat the above content, and obtain the camera coordinates of the key points of the line structured light stripe. Since the position of the coplanar target changes, the camera coordinates of the midpoint of the light stripe also change. At the same time, the camera coordinates of the midpoint of the light stripe obtained at different positions of the coplanar target are all located on the light plane. Obtain the equation of the light plane 5 by fitting the plane.

[0032] Ax c + By c + Cz c + 1 = 0 (6)

[0033] In the formula, A, B, C - the three mutually perpendicular direction components of the light plane normal; According to the angle relationship between the light plane 5 equation and the horizontal plane, adjust the attitude of the line structured light laser 4 so that the light plane remains horizontal in the initial state.

[0034] Install the support 1 around the orifice so that the central axis of the support 1 coincides with the central axis of the pile hole 6 orifice. A line structured light laser 4 is provided on the central axis of the support 1, and line structured light is emitted in two opposite directions. It is stipulated that the two directions are the left and right directions. Then, monocular cameras are arranged on both the front and back sides of the line structured light laser. The front monocular camera shoots the projection of the line structured light emitted to the left / right, and the rear monocular camera correspondingly shoots the projection of the line structured light emitted to the right / left; Adjust the height of each support 1 to keep the light plane 5 of the line structured light horizontal; A platform 2 is provided at the center of the support 1, and there is a circular spirit level on the platform. Calibrate through the circular spirit level to keep the light plane 5 of the line structured light horizontal; The light planes of the line structured light in the left and right directions are on the same plane.

[0035] S3. Turn on the line structured light laser 3, emit line structured light and project it onto the top hole wall of the pile hole 6 to form a line structured light strip on the hole wall. Record the initial height of the line structured light laser and the distance h0 between the current line structured light strip and the top of the pile hole.

[0036] S4. Gradually lower the line structured light laser 3 from the hole opening to the hole bottom at a preset speed v1 smoothly. Scan the entire hole wall, and use a monocular camera synchronized with the line structured light laser 3 to intermittently capture the line structured light strip on the hole wall at a period t until it is lowered to trigger the stop device 4 to contact the hole bottom. Record the total lowering duration T. Rotate the line structured light laser 3 and the synchronized monocular camera 90° around the central axis of the pile hole, and smoothly lift it at a preset speed v1 to scan the hole wall, and use a monocular camera synchronized with the line structured light laser 3 to intermittently capture the line structured light strip on the hole wall at a period t.

[0037] S5. Preprocess the images collected by the monocular camera, extract the center points of the line structured light strips, and fit the ellipse of the pile hole 6 at the corresponding height according to the world coordinates of the center points of the line structured light strips. Based on the least squares principle, use the existing ellipse fitting function in the open cv library to perform ellipse fitting on the input world coordinates to obtain the center coordinates, major and minor axis lengths, and rotation angle of the ellipse. Denote the major axis length as a and the minor axis length as b. Then the aperture of the pile hole 6 at this height is b, and the inclination angle of the pile hole is arcsin(b / a). The hole depth H is

[0038] H = h0 + v1T + l (7)

[0039] In the formula, l is the distance from the bottom of the trigger stop device 4 to the light plane.

[0040] S6. Determine the hole formation quality, including that the hole depth H and the aperture are not less than the design values, and the verticality i meets the requirements of the "Code for Acceptance of Construction Quality of Building Foundation Engineering" GB 50202 - 2018.

[0041] In summary, the method for detecting the hole formation quality of large - angle inclined cast - in - place piles of the present invention has the characteristics of high efficiency, accuracy, and high degree of automation in the field of pile foundation construction technology.

[0042] It should be understood that the above - mentioned embodiments are one or more embodiments of the present invention. Based on the present invention, there are many other embodiments and their deformations. When ordinary technicians in this industry do not make pioneering innovations, the deformations and modifications made through the present invention all fall within the protection scope of the present invention.

Claims

1. A method for detecting the quality of bored piles with large inclination angles, characterized in that: The specific steps include: S1. Preparation for testing, including obtaining the design drawings of the bored piles, which include the location of the bored piles, pile diameter requirements, hole depth, and pile hole inclination angle; determining the number and location of holes to be tested, conducting a preliminary inspection of the completed holes, cleaning the environment around the hole openings, preliminarily confirming the risk of water accumulation in the holes and hole wall collapse, and proceeding to the next step after confirming that there are no obstacles that affect the safety and accuracy of the testing equipment; S2. Install the detection equipment, including completing the calibration of the monocular camera and the calibration of the line structure light, erecting the bracket around the hole mouth so that the central axis of the bracket coincides with the central axis of the pile hole hole mouth, and a line structure light laser is arranged on the central axis of the bracket to emit line structure light in two opposite directions respectively, and the two directions are specified as left and right directions, then monocular cameras are arranged on the front and rear sides of the line structure light laser, the front monocular camera shoots the line structure light projection emitted from the left / right, and the rear monocular camera correspondingly shoots the line structure light projection emitted from the right / left; adjust the height of each bracket to keep the light plane of the line structure light horizontal; S3, initial calibration, including turning on the line structured light laser, emitting line structured light to project to the hole wall at the top of the pile hole, forming a line structured light strip on the hole wall, recording the initial height of the line structured light laser, and recording the distance h0 between the current line structured light strip and the top of the pile hole; S4, laser scanning detection, including gradually lowering the line structured light laser from the hole mouth to the bottom of the hole along the central axis of the pile hole, steadily lowering it at a preset speed v1, scanning the hole wall, and continuously capturing the line structured light strips on the hole wall using a monocular camera synchronized with the line structured light laser, until it is lowered to a trigger stop device to contact the bottom of the hole, and recording the total lowering time T, the line structured light laser and the synchronized monocular camera rotate 90° around the central axis of the pile hole, and steadily lift it at a preset speed v1, scanning the hole wall, and continuously capturing the line structured light strips on the hole wall using a monocular camera synchronized with the line structured light laser; S5, data processing and analysis, including image preprocessing of the image captured by the monocular camera, extracting the center point of the line structured light strip, and fitting the ellipse of the pile hole at the corresponding height of the image data according to the center point of the line structured light strip, obtaining the center coordinates, major and minor axis lengths and rotation angle of the ellipse, denoting the major axis length as a and the minor axis length as b, then the pile hole diameter at this height is b, and the pile hole inclination angle is arcsin(b / a); the hole depth H is H=h0+v1T+l (2) Where, l is the distance from the bottom of the trigger stop device to the light plane along the center axis of the pile hole; S6. Determination of hole quality, including hole depth H, hole diameter not less than the design value, and verticality i meeting the specification requirements.

2. The method for detecting the quality of bored piles with large inclination angles according to claim 1 is characterized in that: The monocular camera calibration adopts Zhang Zhengyou calibration method.

3. The method for detecting the quality of bored piles with large inclination angles according to claim 1 is characterized in that: The line structured light calibration utilizes a coplanar target device to calibrate the light plane equation of the line structured light.

4. The method for detecting the quality of bored piles with large inclination angles according to claim 1 is characterized in that: A platform is provided at the center of the bracket, and a circular level is provided on the platform. The circular level is used to calibrate the light plane of the line structured light so as to keep it horizontal.

5. The method for detecting the quality of bored piles with large inclination angles according to claim 1 is characterized in that: The light planes of the line structured lights in the left and right directions are on the same plane.

6. The method for testing the quality of bored piles with large inclination angles according to claim 1 is characterized in that: The fitting ellipse is fitted by the least square method.

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