A method and system for monitoring dynamic compaction construction

Abstract

This invention relates to the fields of construction management and engineering construction surveying technology, specifically providing a method and system for monitoring dynamic compaction construction. The monitoring system includes a processing module and a positioning module, an acquisition module, and a display module connected to the processing module. The monitoring method includes: acquiring an image sequence of the displacement of a characteristic target on a wire rope; based on the image sequence of the displacement of the characteristic target on the wire rope, using an image processing algorithm to measure the relative displacement of the characteristic target in two adjacent images, and then combining this with the actual number of compaction blows to obtain the total compaction settlement; by comparing the actual number of compaction blows and the total compaction settlement with preset standard values ​​for the number of compaction blows and the standard values ​​for the compaction settlement, determining whether the operation at the compaction point is qualified. This invention utilizes the change in the acceleration of the hammer during operation to monitor the number of compaction blows, eliminating the need for monitoring while the hammer is in high-speed motion, and features high efficiency, high reliability, high convenience, and strong applicability.

Description

Technical Field

[0001] This invention relates to the fields of construction management and engineering construction surveying technology, specifically to a dynamic compaction construction monitoring method and monitoring system. Background Technology

[0002] Dynamic compaction machines are widely used engineering machinery in foundation treatment. They utilize lifting equipment to raise the hammer to a certain height, then release it to fall freely. The powerful impact of the falling hammer compacts the soil, thereby increasing the bearing capacity of the foundation. Dynamic compaction machines are classified into two types based on the hammer's descent method: detachable and non-detachable. The detachable type uses a detachment device to separate the hammer from the hook, allowing for free fall, but requires manual assistance to reattach it. The non-detachable type, however, maintains a constant connection between the hammer and the wire rope during both lifting and lowering. A traction device enables high-speed, loaded hammer drop, eliminating the need for manual intervention, resulting in higher efficiency and reduced construction costs.

[0003] In engineering practice, the quality control indicators for dynamic compaction operations mainly include settlement, number of blows, and compaction point location. The compaction point location is determined by construction layout surveying and generally has no deviation. However, settlement and number of blows are often measured on-site and recorded using random sampling records, which has significant drawbacks, including: ① Real-time monitoring of dynamic compaction operations cannot be achieved during construction, resulting in low timeliness of compaction operation verification results; ② Human inspection leads to high labor costs and is easily influenced by subjective factors. In the absence of effective supervision, the personnel's own qualifications can cause a series of chain reactions; ③ The complex environment at dynamic compaction construction sites increases the risk factor for surveyors.

[0004] Regarding the issue of detecting the number of blows and the amount of settlement during dynamic compaction operations, some research has been conducted in the existing technologies (such as CN106149670B, CN114277765A, CN217980279U, CN218148264U). However, these methods require modification or upgrading of the dynamic compaction equipment, or the addition of various sensors to achieve automatic monitoring. In addition, the current methods only provide effective solutions for individual problems in the dynamic compaction operation, such as measuring the number of blows and determining the amount of settlement, which cannot meet the needs of actual construction.

[0005] In summary, there is an urgent need for a highly efficient and widely applicable method and system for full monitoring of roadbed dynamic compaction to solve the problems existing in the current technology. Summary of the Invention

[0006] The purpose of this invention is to provide a method for full monitoring of dynamic compaction of roadbeds. This method relies on the rapid development of technologies such as machine vision and image processing, employing image measurement technology based on a monocular camera. It requires no modification or alteration of mechanical equipment, and through simple equipment installation, effectively reduces labor costs during dynamic compaction operations, improves the safety of surveyors, enhances the efficiency of construction process management, increases the reliability of test data, and reduces problems such as under-compaction or over-compaction caused by human factors. It achieves fully automated monitoring of the operation process, solving problems such as high labor costs, lax supervision, untimely information transmission, and low safety levels for operators in current dynamic compaction inspection of roadbeds. The specific technical solution is as follows: A method for monitoring dynamic compaction construction includes the following steps: Step 1: Obtain an image sequence of the displacement of the feature targets on the wire rope, specifically including: Step 1.1: Use a steel wire rope to suspend the ram to its highest point and collect accelerometer data in real time. ; Step 1.2: Transfer accelerometer data With acceleration threshold Perform real-time comparison; if If so, return to step 1.1; if Then proceed to the next step; Step 1.3: The number of tamping blows is automatically incremented by 1, and at the same time, the high-definition camera is triggered to capture images of the characteristic targets on the steel wire rope and add the images of the characteristic targets on the steel wire rope to the target image set. Step 1.4: Determine if the required number of tamping blows has been completed. If completed, an image sequence of the displacement of the characteristic target on the wire rope is obtained based on the target image set; if not completed, return to step 1.1. Step 2: Based on the image sequence of the displacement of the feature target on the wire rope obtained in Step 1, use image processing algorithms to measure the relative displacement of the feature target in two adjacent images. Then, combined with the actual number of tamping blows Obtain the total settlement ,in: ; Step 3: Based on the actual number of tamping blows Total tamping volume With the preset number of tamping blows Standard values ​​and compaction volume The standard value is compared to determine whether the compaction point operation is qualified.

[0007] This invention monitors the number of tamping blows by utilizing the change in acceleration of the tamping hammer during operation. The image sequence is acquired by using an accelerometer to determine the critical state of the tamping hammer from rest to motion and capturing images, ensuring the stability of image acquisition. Monitoring is not required when the tamping hammer is in high-speed motion, meaning that high-performance products such as high-speed cameras can be used to automatically detect the number of tamping blows and the degree of tamping during the tamping operation.

[0008] Preferably, in step one, the accelerometer is bound to the tamping hammer, and the number of tamping blows is automatically measured by analyzing the numerical changes of the accelerometer during a single tamping operation, as follows: ① With the vertically upward axis as the sensitive axis of the accelerometer, when the steel wire rope suspends the ram at its highest point, it is in a static equilibrium state, that is, the net force is 0. At this time, the accelerometer outputs... Where: g is the acceleration due to gravity; ② When the steel wire rope is loosened and the hammer falls, the accelerometer outputs... When the hammer undergoes free fall with an acceleration of g, the accelerometer outputs... ; ③ After the tamping hammer completes its impact, the wire rope needs to lift the hammer back up. During this uniform lifting process, the accelerometer outputs... When accelerating the lifting process, the accelerometer outputs... .

[0009] Preferably, step two specifically involves: Step 2.1: Calibrate the camera and determine its intrinsic and extrinsic parameters; Step 2.2: Adjust the camera angle to ensure the target feature on the steel cable remains in the image, and measure the distance from the camera's main optical axis to the plane of the traction steel cable. ; Step 2.3: Capture the initial image of the moment the steel wire rope lifts the ram, obtain the image after distortion correction, and extract the region of interest (ROI); Step 2.4: Extract feature points from the region of interest (ROI); Step 2.5: Use a feature detection algorithm to detect the feature region boundaries of the feature targets on the wire rope in the region of interest (ROI), and select feature points at the center of the feature regions. ; Step 2.6: Analyze the changes in the angles of feature points relative to the camera's optical axis point O on the two time-series images. That is, to obtain the distance of the feature point on the image. ;in: From a vertical perspective, Image height; Step 2.7: Obtain the actual distance the feature points on the wire rope have moved based on the distances between the feature points in the image. That is, the amount of compaction is obtained. ;in The focal length of the camera; Step 2.8: By processing all time-series images during the dynamic compaction operation, the total settlement at the completion of the hammer operation is obtained. .

[0010] The present invention also provides a dynamic compaction construction monitoring system, including a processing module and a positioning module, a data acquisition module and a display module connected to the processing module; The positioning module is used to locate the position of the dynamic compaction operation point; The acquisition module includes an accelerometer that is attached to the hammer and a camera placed on the top of the cab of the dynamic compaction machine. The accelerometer collects acceleration data during the compaction operation, and the camera captures a sequence of images of the movement of characteristic targets on the steel wire rope of the dynamic compaction machine. The processing module is used to execute the steps for implementing the above-described dynamic compaction construction monitoring method; The display module is used to show the location of the dynamic compaction work point and the status of the work.

[0011] Preferably, the positioning module is used to locate the position of the dynamic compaction work point; the acquisition module collects the values ​​output by the accelerometer in real time and remotely transmits them back to the server in the processing module. By comparing them with the acceleration threshold, the number of hammer blows is automatically recorded. At the same time, a high-definition camera is triggered to capture an image sequence of the movement of the feature target on the steel wire rope of the dynamic compaction machine and transmit it back to the server. The image processing algorithm in the server measures the displacement change of the feature target in the time sequence image and converts it into the calculation of the compaction settlement. By detecting the degree of consistency between the number of blows, the compaction settlement and the values ​​specified in the project, the monitoring status of the work point is automatically displayed in the display module, realizing full-process, fully automatic monitoring.

[0012] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0013] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is an architecture diagram of the dynamic compaction construction monitoring system in a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the overall principle of automatic measurement of compaction amount based on image processing in a preferred embodiment of the present invention; Figure 3This is a schematic diagram of the automatic measurement principle of compaction amount based on image processing in a preferred embodiment of the present invention. Detailed Implementation

[0014] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0015] Example: A method for monitoring dynamic compaction construction involves using a dynamic compaction construction monitoring system (see details). Figure 1 It includes a processing module and a positioning module, a data acquisition module, and a display module connected to the processing module; The positioning module is used to locate the position of the dynamic compaction operation point; The acquisition module includes an accelerometer that is attached to the hammer and a camera placed on the top of the cab of the dynamic compaction machine. The accelerometer collects acceleration data during the compaction operation, and the camera captures a sequence of images of the movement of characteristic targets on the steel wire rope of the dynamic compaction machine. The processing module is used to execute the steps of the dynamic compaction construction monitoring method; The display module is used to show the location of the dynamic compaction work point and the status of the work.

[0016] The principle of the dynamic compaction construction monitoring system in this embodiment is as follows: the positioning module is used to locate the position of the dynamic compaction operation point; the acquisition module collects the values ​​output by the accelerometer in real time and remotely transmits them back to the server in the processing module. By comparing them with the acceleration threshold, the number of hammer blows is automatically recorded. At the same time, a high-definition camera is triggered to capture an image sequence of the movement of the feature target on the steel wire rope of the dynamic compaction machine and transmit it back to the server. The image processing algorithm in the server measures the displacement change of the feature target in the time sequence image and converts it into the calculation of the compaction settlement. By detecting the degree of consistency between the number of blows, the compaction settlement and the values ​​specified in the project, the monitoring status of the operation point is automatically displayed in the display module, realizing full-process, fully automatic monitoring.

[0017] The dynamic compaction construction monitoring method in this embodiment specifically includes the following steps: Step 1: Obtain an image sequence of the displacement of the feature targets on the wire rope, specifically including: Step 1.1: Use a steel wire rope to suspend the ram to its highest point and collect accelerometer data in real time. ; Step 1.2: Transfer accelerometer data With acceleration threshold Perform real-time comparison; if If so, return to step 1.1; if Then proceed to the next step; Step 1.3: The number of tamping blows is automatically incremented by 1, and at the same time, the high-definition camera is triggered to capture images of the characteristic targets on the steel wire rope and add the images of the characteristic targets on the steel wire rope to the target image set. Step 1.4: Determine if the required number of tamping blows has been completed. If completed, an image sequence of the displacement of the characteristic target on the wire rope is obtained based on the target image set; if not completed, return to step 1.1.

[0018] An accelerometer is attached to a tamping hammer. By analyzing the changes in the accelerometer readings during a single tamping operation, the number of tamping blows is automatically measured, as follows: ① With the vertically upward axis as the sensitive axis of the accelerometer, when the steel wire rope suspends the ram at its highest point, it is in a static equilibrium state, that is, the net force is 0. At this time, the accelerometer outputs... Where: g is the acceleration due to gravity; ② When the steel wire rope is loosened and the hammer falls, the accelerometer outputs... When the hammer undergoes free fall with an acceleration of g, the accelerometer outputs... ; ③ After the tamping hammer completes its impact, the wire rope needs to lift the hammer back up. During this uniform lifting process, the accelerometer outputs... When accelerating the lifting process, the accelerometer outputs... .

[0019] From the initial moment, by detecting the changing pattern of the acceleration count waveform, the tamping process can be identified, and the number of tamping blows can be automatically measured. In actual operation, the tamping hammer cannot maintain a strictly uniform lifting speed, so when the tamping hammer is lifted by the wire rope, the accelerometer output... To prevent data errors caused by sensor jitter, an acceleration threshold is selected and set. Output via accelerometer With threshold Real-time comparison, when This indicates that one tamping operation has been completed, and at the same time... This serves as a trigger condition for executing step 1.3. At the moment the rammer is lifted with the wire rope, the wire rope will be taut. The additional length of the wire rope lowered corresponds to the depth to which the rammer compacts the roadbed, i.e., the compaction depth. As a criterion, the wire rope is in a taut state, which can filter out measurement errors when the wire rope is slack.

[0020] Step 2: Based on the image sequence of the displacement of the feature target on the wire rope obtained in Step 1, use image processing algorithms to measure the relative displacement of the feature target in two adjacent images. Then, combined with the actual number of tamping blows Obtain the total settlement ,in: .

[0021] In fulfilling step one After the conditions are met, the high-definition camera is automatically triggered to capture images. The server receives the time-series images captured for each tamping impact. By measuring the relative displacement of the feature targets in two adjacent time-series images, the settlement amount of each tamping impact can be automatically measured. The relative displacement between the initial and final images is the final settlement amount. The number of tamping impacts can also be accumulated by counting the time-series images. The implementation principle is as follows: Figure 2 and Figure 3 As shown.

[0022] To obtain a stable image acquisition position, the camera is typically placed on top of the driver's cab of the dynamic compaction machine. This facilitates installation and provides a wide field of view, ensuring excellent stability during operation. Furthermore, when capturing high-definition images, the wire rope remains relatively stationary as it lifts the hammer from the compaction position, maintaining a constant relative distance between the wire rope and the camera. The wire rope plane is perpendicular to the camera's optical axis, significantly reducing measurement errors caused by variations in shooting angle and distance, as well as camera distortion. Moreover, when the hammer is lifted by the wire rope, gravity restricts its movement to vertical. Theoretically, the target in the image sequence moves only in one direction, unlike measurements of target displacement changes under multi-directional motion. This method reduces image processing complexity and offers extremely high accuracy and stability. Regarding the selection of target objects during dynamic compaction operations, since the target is lifted by the wire rope, artificial markers or existing markers with high color differentiation can be used. Considering the relatively uniform color of the various components of the dynamic compaction machine, a certain length of the wire rope is cut and painted red as a target marker, facilitating both practical application and image recognition.

[0023] After the server acquires the image sequence, it automatically measures the relative displacement of the feature targets on the wire rope in the image sequence. The specific steps are as follows: Step 2.1: Calibrate the camera and determine its intrinsic and extrinsic parameters; Step 2.2: Adjust the camera angle to ensure the target feature on the steel cable remains in the image, and measure the distance from the camera's main optical axis to the plane of the traction steel cable. ; Step 2.3: Capture the initial image of the moment the steel wire rope lifts the ram, obtain the image after distortion correction, and extract the region of interest (ROI); Step 2.4: Extract feature points from the region of interest (ROI); Step 2.5: Use a feature detection algorithm to detect the feature region boundaries of the feature targets on the wire rope in the region of interest (ROI), and select feature points at the center of the feature regions. ; Step 2.6: Analyze the changes in the angles of feature points relative to the camera's optical axis point O on the two time-series images. That is, to obtain the distance of the feature point on the image. ;in: From a vertical perspective, Image height; Step 2.7: Obtain the actual distance the feature points on the wire rope have moved based on the distances between the feature points in the image. That is, the amount of compaction is obtained. ;in The focal length of the camera; Step 2.8: By processing all time-series images during the dynamic compaction operation, the total settlement at the completion of the hammer operation is obtained. .

[0024] Step 3: Based on the actual number of tamping blows Total tamping volume With the preset number of tamping blows Standard values ​​and compaction volume The standard value is compared to determine whether the compaction point operation is qualified.

[0025] Criteria for successful compaction point operation: A test compaction area is selected within the dynamic compaction construction area. Soil samples from the test compaction area are identical to those from the construction area. A point-by-point compaction test is conducted on the undisturbed soil samples within the test compaction area to obtain the number of blows at m compaction points that meet the relevant engineering specifications. With tamping volume The arithmetic mean of the number of blows and the settlement at each compaction point is taken as the standard value for the number of blows and the settlement of the compaction area, as follows: ; .

[0026] Different tonnage dynamic compaction machines were tested separately to obtain the standard values ​​of the number of blows and the amount of settlement for the corresponding machine models.

[0027] During dynamic compaction construction, the number of blows of this machine is used to measure the impact rate. With tamping volume Automatic monitoring, and the number of impacts Standard values ​​and compaction volume By comparing the standard value, it can be automatically determined whether the impact point meets the standard requirements.

[0028] The technical solution of this embodiment uses acceleration to determine the movement process of the tamping hammer and counts the impacts. Then, by using the critical point from the tamping hammer's rest to its movement during the movement, the impact depth is identified and determined through the image from the camera. The advantages of this invention are: 1. In terms of hardware, only an accelerometer and a conventional camera are needed, without the need to capture high-speed moving objects, thus reducing the performance requirements of the camera; 2. In terms of software, there is no need to train the image model through a server or computer. The impact depth of the tamping hammer can be measured through two time-series images from a monocular camera.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for monitoring dynamic compaction construction, characterized in that, Includes the following steps: Step 1: Obtain an image sequence of the displacement of the feature targets on the wire rope, specifically including: Step 1.1: Use a steel wire rope to suspend the ram to its highest point and collect accelerometer data in real time. ; Step 1.2: Transfer accelerometer data With acceleration threshold Perform real-time comparison; if If so, return to step 1.1; if Then proceed to the next step; Step 1.3: The number of tamping blows is automatically incremented by 1, and at the same time, the high-definition camera is triggered to capture images of the characteristic targets on the steel wire rope and add the images of the characteristic targets on the steel wire rope to the target image set. Step 1.4: Determine if the required number of tamping blows has been completed. If completed, an image sequence of the displacement of the characteristic target on the wire rope is obtained based on the target image set; if not completed, return to step 1.

1. Step 2: Based on the image sequence of the displacement of the feature target on the wire rope obtained in Step 1, use image processing algorithms to measure the relative displacement of the feature target in two adjacent images. Then, combined with the actual number of tamping blows Obtain the total settlement ,in: ; Step 3: Based on the actual number of tamping blows Total tamping volume With the preset number of tamping blows Standard values ​​and compaction volume The standard value is compared to determine whether the compaction point operation is qualified.

2. The method for monitoring dynamic compaction construction according to claim 1, characterized in that, In step one, the accelerometer is attached to the tamping hammer. The number of tamping blows is automatically measured by analyzing the changes in the accelerometer's value during a single tamping operation, as follows: ① With the vertically upward axis as the sensitive axis of the accelerometer, when the steel wire rope suspends the ram at its highest point, it is in a static equilibrium state, that is, the net force is 0. At this time, the accelerometer outputs... Where: g is the acceleration due to gravity; ② When the steel wire rope is loosened and the hammer falls, the accelerometer outputs... When the hammer undergoes free fall with an acceleration of g, the accelerometer outputs... ; ③ After the tamping hammer completes its impact, the wire rope needs to lift the hammer back up. During this uniform lifting process, the accelerometer outputs... When accelerating the lifting process, the accelerometer outputs... .

3. The method for monitoring dynamic compaction construction according to claim 2, characterized in that, Step two specifically involves: Step 2.1: Calibrate the camera and determine its intrinsic and extrinsic parameters; Step 2.2: Adjust the camera angle to ensure the target feature on the steel cable remains in the image, and measure the distance from the camera's main optical axis to the plane of the traction steel cable. ; Step 2.3: Capture the initial image of the moment the steel wire rope lifts the ram, obtain the image after distortion correction, and extract the region of interest (ROI); Step 2.4: Extract feature points from the region of interest (ROI); Step 2.5: Use a feature detection algorithm to detect the feature region boundaries of the feature targets on the wire rope in the region of interest (ROI), and select feature points at the center of the feature regions. ; Step 2.6: Analyze the changes in the angles of feature points relative to the camera's optical axis point O on the two time-series images. That is, to obtain the distance of the feature point on the image. ;in: From a vertical perspective, Image height; Step 2.7: Obtain the actual distance the feature points on the wire rope have moved based on the distances between the feature points in the image. That is, the amount of compaction is obtained. ;in The focal length of the camera; Step 2.8: By processing all time-series images during the dynamic compaction operation, the total settlement at the completion of the hammer operation is obtained. .

4. A dynamic compaction construction monitoring system, characterized in that, It includes a processing module, as well as a positioning module, a data acquisition module, and a display module connected to the processing module; The positioning module is used to locate the position of the dynamic compaction operation point; The acquisition module includes an accelerometer that is attached to the hammer and a camera placed on the top of the cab of the dynamic compaction machine. The accelerometer collects acceleration data during the compaction operation, and the camera captures a sequence of images of the movement of characteristic targets on the steel wire rope of the dynamic compaction machine. The processing module is used to execute the steps of implementing the dynamic compaction construction monitoring method according to any one of claims 1 to 3; The display module is used to show the location of the dynamic compaction work point and the status of the work.

5. The dynamic compaction construction monitoring system according to claim 4, characterized in that, The positioning module is used to locate the position of the dynamic compaction work point; the acquisition module collects the values ​​output by the accelerometer in real time and remotely transmits them back to the server in the processing module. By comparing them with the acceleration threshold, the number of hammer blows is automatically recorded. At the same time, a high-definition camera is triggered to capture an image sequence of the movement of the feature target on the steel wire rope of the dynamic compaction machine and transmit it back to the server. The image processing algorithm in the server measures the displacement change of the feature target in the time sequence image and converts it into the calculation of the settlement. By detecting the degree of conformity between the number of blows, the settlement and the values ​​specified in the project, the monitoring status of the work point is automatically displayed in the display module, realizing full-process, fully automatic monitoring.

Images