Pile foundation depth accurate measurement system and method based on laser sensing

Abstract

The invention relates to a laser sensing-based pile foundation depth accurate measurement system and method.The laser sensing-based pile foundation depth accurate measurement system comprises a depth acquisition module, a cloud processing module, a terminal display module and a communication module, the depth acquisition module is integrated with an acquisition module, and the acquisition module is fixed to the top of a hammer head of a pile driver through a supporting assembly; the overall displacement of the hammer head along with the sinking of the pile body and the distance dynamic waveform data corresponding to the hammering reciprocating motion are collected in real time; the cloud processing module is used for receiving the distance dynamic waveform data through the communication module and executing depth value real-time calibration and pile foundation depth state judgment in combination with buffer piece deformation and pile body springback compensation parameters; and the terminal display module is used for displaying the pile foundation number, the real-time depth value, the waveform curve and the state identifier in real time. According to the invention, full data tracing from construction to acceptance can be realized, and by combining a two-dimensional dynamic error compensation algorithm, the measurement precision is obviously improved, the error influence is greatly reduced, and non-contact accurate distance measurement is realized.

Description

Technical Field

[0001] This invention relates to the field of building pile foundation construction technology, specifically to a precise pile foundation depth measurement system and method based on laser sensing. Background Technology

[0002] Pile foundations are a common type of foundation in civil engineering, used to bear the loads of buildings or other structures and transfer the loads to deeper soil or rock layers. Pile foundations are typically columnar structures made of materials such as concrete, reinforced concrete, or steel, and are increased in bearing capacity and stability by being pre-embedded or driven into the ground. Hammer-driven pile driving falls under the category of reinforced concrete precast pile construction technology. It uses the impact force generated by the falling hammer to overcome the soil resistance and drive the pile into the soil layer. Simultaneously, the sinking process creates a lateral compaction effect on the surrounding soil, increasing the density of the foundation.

[0003] The depth of the pile foundation is a core indicator that determines the bearing capacity and structural safety of the foundation. In the existing technology for measuring the depth of pile foundation holes, most of the time, after the pile driving is completed, a sensor probe with a distance measuring function and a traction rope connected to it are lowered into the pile foundation hole. When the sensor touches the bottom, it sends a feedback signal to measure the hole depth.

[0004] However, the measurement equipment is susceptible to interference from factors such as pile hole inclination, visual errors, and construction dust. Furthermore, the torsion of the traction rope during release can cause overall rotational shifts in the measuring equipment, leading to unstable data readings from the sensors. Measurement depth deviations typically exceed 5cm, failing to meet the precision requirements of high-standard projects and resulting in significant measurement errors. In addition, existing measurement data requires manual recording and entry into the management system, with a lag time generally exceeding 10 minutes. This makes it impossible to immediately determine whether the depth meets the standard, easily leading to "over-drilling" (wasting materials) or "under-drilling" (insufficient load-bearing capacity).

[0005] Therefore, it is necessary to study a precise measurement system and method for pile foundation depth based on laser sensing. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a laser-sensing-based system and method for accurately measuring the depth of pile foundations, in order to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the technical solution adopted by this invention is: a laser-sensor-based precise pile foundation depth measurement system, comprising a depth acquisition module, a cloud processing module, a terminal display module, and a communication module for data transmission between the modules. The depth acquisition module integrates an acquisition module, which is fixed to the top of the pile driver hammer head by a support component. This acquisition module follows the hammer head's reciprocating motion during impact, acquiring in real-time dynamic waveform data of the overall displacement of the hammer head as the pile sinks and the distance corresponding to the reciprocating motion. The cloud processing module receives the dynamic waveform data through the communication module and, in conjunction with parameters such as buffer deformation and pile rebound compensation, performs real-time depth value calibration and pile foundation depth status judgment. The terminal display module displays the pile foundation number, real-time depth value, waveform curve, and status indicator in real-time.

[0008] Furthermore, the acquisition module includes a laser ranging sensor, an edge computing unit, and a power supply unit disposed within the housing. A receiving end is provided at the bottom of the fixed crossbeam of the pile driver. The output end of the laser ranging sensor faces vertically upward toward the receiving end, and is used to acquire dynamic data of the straight-line distance between itself and the receiving end in real time. The edge computing unit is used to preprocess the sensor data, including timestamp marking and abnormal data filtering, and outputs dynamic distance data with timestamps, depth values, and abnormal tags. The power supply unit is used to supply power to the acquisition module.

[0009] Furthermore, the support assembly includes a mounting base, a support frame, and elastic connectors. The mounting base has a hollow inner cavity, and the support frame is located in the mounting base and has a stepped structure. A recessed cavity is provided in the middle of the support frame, and the acquisition module is fixed in the recessed cavity. A disc spring assembly is provided between the bottom of the support frame and the bottom of the inner cavity of the mounting base to buffer the vertical impact load generated by the hammering. The elastic connectors are inclinedly arranged on the left and right sides of the support base, and the two ends of the elastic connectors are respectively hinged to the side walls of the support frame and the mounting base to buffer the lateral vibration generated during the hammering process.

[0010] Furthermore, a buffer pad is provided between the hammer head and the pile cap, and a displacement sensor for measuring its axial compression deformation is pre-embedded in the buffer pad; the displacement sensor is communicatively connected to the edge computing unit to provide compensation parameters for borehole depth calibration.

[0011] Furthermore, the receiving end is a high-reflectivity reflective target, and the reflective surface of the reflective target is perpendicularly aligned with the output optical path of the laser rangefinder.

[0012] Furthermore, the cloud processing module incorporates a dynamic calibration algorithm to compensate for the distance dynamic data based on the real-time compression deformation of the buffer pad, the pile rebound coefficient, and the distance dynamic waveform characteristic data within the hammering cycle, thereby eliminating the distance measurement error caused by buffer pad compression and pile rebound.

[0013] Furthermore, the formula for calculating the real-time calibration depth value at time t during the execution of the dynamic calibration algorithm is as follows: H(t)=(L(t)-L0)-(△h1'-△h1)-K•(L(t)-L0) Wherein, H(t) is the real-time calibration depth value at time t, L(t) is the straight-line distance between the laser rangefinder and the receiver at time t, L0 is the initial straight-line distance between the laser rangefinder and the receiver in the initial state of pile driving, Δh1' is the real-time compression of the buffer pad at time t, Δh1 is the initial compression of the buffer pad when the hammer first contacts the pile body in the initial state of pile driving, and K is the pile body rebound coefficient, which takes a value of 0.01-0.08.

[0014] Furthermore, the cloud processing module is also used to calculate the assembly hole depth, using the following formula: .

[0015] Furthermore, the cloud processing module presets a depth threshold to compare the calibrated assembly hole depth with the design depth value, triggering and pushing status signals to the terminal display module: when the depth reaches 90% of the design depth, a warning state is triggered; when the depth reaches the design depth, a completion state is triggered; when the depth exceeds 5% of the design depth, an over-limit state is triggered, and each status signal is pushed to the terminal display module simultaneously.

[0016] This invention also provides a method for accurate measurement of pile foundation depth based on laser sensing, comprising the following steps: Step 1: Calibrate the initial straight-line distance L0 between the laser rangefinder and the receiver when the hammer head is at its initial high position in the initial state of pile driving; at the same time, record the initial compression amount Δh1 of the buffer pad when it first contacts the pile body, and determine the self-rebound coefficient K of the pile body through a test pile test; Step 2: The depth acquisition module reciprocates with the hammer's impact, acquiring real-time dynamic data of the straight-line distance between the laser range sensor and the receiver, and simultaneously acquiring real-time compression data of the buffer pad, which is then displayed on the terminal display module as a distance-time dynamic waveform. Step 3: Extract the lowest distance value Li in each hammering cycle from the above dynamic waveform image, calculate the real-time net settlement height of the hammer head relative to the initial reference plane after eliminating the error of buffer pad compression and pile rebound, and thus calculate the single effective penetration depth △Hi corresponding to each cycle. Step 4: Accumulate ΔHi for all hammering cycles and calculate the assembly hole depth.

[0017] The beneficial effects of the above technical solution are as follows: The laser sensing-based pile foundation depth precision measurement system and method provided by the present invention abandons the traditional contact measurement method inside the pile hole, uses the fixed crossbeam of the pile driver as the reference, avoids the interference of soil layer obstruction, soil falling, hole shrinkage, etc. when directly measuring the pile displacement, and instead uses the reciprocating motion waveform of the hammer head to extract the effective soil entry signal to achieve non-contact precision distance measurement.

[0018] This invention constructs a full-process monitoring system for pile driving, replacing the traditional manual recording and delayed input mode. It realizes high-frequency sampling, low transmission delay, and second-level status judgment and early warning of pile foundation depth data. It solves the problems of lagging traditional measurement data and the inability to judge whether the depth meets the standard in real time, which easily leads to under-drilling or over-drilling. At the same time, it stores the depth data with timestamps and waveform characteristics throughout the process, realizing the traceability of pile foundation construction process data and meeting the requirements of data integrity for project acceptance.

[0019] The acquisition module of this invention is based on a support component fixed to the top of the hammer. Through the design of a multi-level shock absorption and buffer structure, the vibration displacement of the laser sensor can be controlled within ±0.5mm and the optical path offset ≤0.1°, ensuring the stability of sensor data under high-frequency hammering conditions. Combined with a dual-dimensional dynamic error compensation algorithm for buffer pad deformation and pile rebound, the virtual displacement error during the hammering process is accurately eliminated, improving the accuracy of pile foundation depth measurement from the traditional deviation >5cm to ±2cm, meeting the high precision requirements of construction standards. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the connection principle of the measurement system of the present invention; Figure 2 This is a schematic diagram of the implementation structure of the acquisition module of the present invention; Figure 3 This is a schematic diagram of the structure of the support component of the present invention; Figure 4 This is a schematic diagram of the internal structure of the acquisition module of the present invention; Figure 5 This is a schematic diagram showing the state of the hammer head during hammering operation according to the present invention.

[0021] Reference numerals: 1-Mounting base, 2-Elastic connector, 3-Disc spring, 4-Support frame, 5-Acquisition module, 6-Receiver end, 7-Pile driver, 8-Hammer, 9-Crossbeam, 10-Guide frame, 11-Pile body. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Example 1: This example aims to provide a precise pile foundation depth measurement system based on laser sensing. Addressing the problems of low accuracy, poor real-time performance, and low reusability in existing pile foundation depth measurement methods, this invention's measurement system collects drilling process data using a laser rangefinder, processes it through an edge computing unit, and then wirelessly transmits it to a cloud server. This allows for real-time acquisition of dynamic drilling depth data and status assessment, thereby dynamically displaying depth curves and progress indicators to improve the automation and accuracy of pile foundation depth measurement.

[0023] like Figure 1-5 As shown, a laser-sensing-based system for precise measurement of pile foundation depth includes a depth acquisition module, a cloud processing module, a terminal display module, and a communication module for data transmission between the modules. The depth acquisition module integrates an acquisition module 5, which includes a laser ranging sensor, an edge computing unit, and a power supply unit housed within a casing. Figure 4 As shown, in this embodiment, the measurement accuracy of the laser rangefinder is ±2cm, and the measurement range is 1-20m. A receiving end 6 is provided at the bottom of the fixed crossbeam 9 of the pile driver 7. The receiving end 6 is a high reflectivity reflective target. The reflective surface of the reflective target is vertically aligned with the output optical path of the laser rangefinder sensor, which is used to collect dynamic data of the straight-line distance between the target and the receiving end 6 in real time, thereby obtaining the pile foundation drilling depth data in real time.

[0024] The edge computing unit is used to preprocess sensor data, including filtering and calibration (eliminating ambient light interference), and outputting timestamped depth values ​​and anomaly tags. In this specific implementation, the edge computing unit uses an STM32H743 microcontroller (480MHz), integrating an RS485 communication interface and a 4G full-network module (Quectel EC20). It incorporates core preprocessing algorithms, including timestamp marking to bind a 1ms precision timestamp to each set of ranging data, ensuring the timeliness of the process data; anomaly filtering, using a sliding window filtering algorithm to take the average of five consecutive sampling points as valid data, eliminating pulse interference with single jumps >10cm, such as sensor occlusion or data jumps; and receiving real-time compression data of the buffer pad from an LVDT displacement sensor embedded in the buffer pad, enabling fusion processing with multi-source data such as laser ranging sensors. This embodiment reduces the cloud computing load and improves data processing efficiency through edge computing unit preprocessing, effectively solving the problems of large errors and lack of process timeliness information in traditional single-source measurements.

[0025] The power supply unit uses a 12V / 8Ah lithium polymer battery, supports fast charging (fully charged in 2 hours), and has a working time of ≥8 hours on a single charge. When the remaining power is <20%, the hardware indicator light flashes red and uploads a low power alarm signal to the cloud.

[0026] like Figure 2 and 3 As shown, the acquisition module 5 of the present invention is fixed to the top of the hammer head 8 of the pile driver 7 by a support component, and is used to follow the hammer head 8 in the reciprocating motion of hammering, so as to collect the overall displacement of the hammer head 8 as it sinks with the pile body 11 and the distance dynamic waveform data corresponding to the reciprocating motion of hammering in real time.

[0027] Specifically, in this embodiment, the support assembly includes a mounting base 1, a support frame 4, and an elastic connector 2. The mounting base 1 is fixed to the top of the hammer head 8 by bolts. The mounting base 1 has a hollow inner cavity. The support frame 4 is located in the mounting base 1 with a stepped structure. A recessed cavity is provided in the middle of the support frame 4, and the acquisition module 5 is fixed in the recessed cavity. A set of disc springs 3 is provided between the bottom of the support frame 4 and the bottom of the inner cavity of the mounting base 1. There are three sets in this embodiment. In actual application, the three sets of disc springs can be evenly distributed along the ring to buffer the vertical impact load generated by the hammer. The elastic connector 2 is inclined on the left and right sides of the support base. The two ends of the elastic connector 2 are respectively hinged to the side walls of the support frame 4 and the mounting base 1. The elastic connector 2 includes a telescopic rod and a spring. The spring is sleeved on the telescopic rod. The two ends of the telescopic rod are respectively hinged to the support frame 4 and the mounting base 1. The elastic connector 2 has an angle of 45° with the vertical direction, which can buffer the lateral vibration generated by the hammer to maintain the verticality of the laser rangefinder sensor optical path.

[0028] In this embodiment, the communication module is used for data transmission between modules, adapting to the complex network environment of on-site construction. It adopts TCP / IP connection + MQTT 3.1.1 protocol, with the deep acquisition module acting as the MQTT client and the cloud processing module as the server, using a "publish-subscribe" mode to reduce data transmission latency (measured ≤500ms) and ensure connection stability. Data transmission includes regular transmission, abnormal trigger transmission, and network outage caching. In regular transmission mode, a set of data including timestamp, laser ranging value L(t), buffer pad compression Δh1', and sensor status is uploaded every 1 second. When abnormalities such as data jumps, low battery, or optical path obstruction are detected, abnormal data is uploaded immediately without waiting for a period. It supports 4G full network compatibility and is compatible with common mobile, Unicom, and Telecom signals on construction sites. When there is no 4G signal, data is automatically cached locally with a cache capacity of ≥1000 sets, and automatic retransmission is performed after the signal is restored. This module adapts to the simultaneous operation of multiple devices through a lightweight wireless transmission strategy, and network outage caching avoids data loss, solving the problems of complex wiring, poor compatibility with multiple devices, and easy data loss associated with traditional wired transmission.

[0029] It is important to note that when the pile driver is working, such as Figure 5As shown, the hammer's movement is not a continuous downward motion with the pile body, but rather a reciprocating impact motion along the guide frame 10 of the pile driver. First, the hammer is raised to a set height (initial lifting position), then released, allowing it to fall freely along the guide groove to impact the pile cap on top of the pile, completing one hammering cycle. After the impact, the hammer rebounds upwards, then strikes downwards again, and rebounds again, repeating this process. In practical applications, a buffer pad is installed between the hammer and the pile cap. At the moment of impact, the enormous impact force causes the buffer pad between the hammer and the pile cap to compress instantaneously. At this time, the laser sensor moves downwards with the hammer a certain distance, but this distance does not cause the pile body to sink; it is merely the elastic deformation of the buffer pad. If this deformation is not deducted, the measurement result will be directly inflated beyond the actual pile advance. Therefore, error compensation is performed using a pre-embedded displacement sensor.

[0030] Therefore, in this embodiment, a miniature LVDT displacement sensor (its size is adapted to the thickness of the buffer pad) is pre-embedded in the buffer pad to measure its axial compression deformation. Its output end is connected to the edge computing unit to provide compensation parameters for depth calibration. Furthermore, in this embodiment, the two ends of the displacement sensor are respectively fixed to the upper and lower surfaces of the buffer pad (not shown in the figure). When the hammering operation is performed, the buffer pad is compressed, and the electrical signal output by the sensor corresponds to the change in thickness, so the real-time compression amount can be directly obtained, that is, compression amount = initial thickness - real-time thickness.

[0031] The cloud processing module is the core of data calibration and analysis. This embodiment uses an Alibaba Cloud ECS server (4 cores, 8GB memory, 100GB SSD storage), which supports elastic expansion and can adapt to the data processing needs of pile foundation construction of different scales. It has built-in dynamic calibration algorithm and depth status judgment logic, which can accurately measure the depth of the pile foundation. Before construction, parameter calibration is required. For the initial distance L0, when the hammer is in the initial high position before hammering, 10 static distance measurement values ​​from the laser sensor and receiver are collected and averaged to eliminate random errors in static distance measurement. The initial compression amount Δh1 is obtained by controlling the pile driver to slowly lower the hammer to a state of lightly touching the pile body (no impact), and continuously collecting the compression amount of the buffer pad 5 times and averaging it.

[0032] The pile rebound coefficient K needs to be determined through pile test (when the pile is hammered, it overcomes the soil resistance and penetrates downwards. After the hammering force disappears, the elasticity of the soil will cause the pile to rebound slightly upwards. For example, if the pile penetrates 5cm after hammering and rebounds 1cm, the actual effective penetration is 4cm, so error compensation is required). Select test piles with the same soil layer and pile type as the engineering piles, record the hammer drop distance for each hammering and the actual penetration depth of the pile measured accurately by a total station, and then calculate it using the formula K=(hammer drop distance - actual penetration depth) / hammer drop distance. In cohesive soil conditions, K is 0.03-0.08, and in sandy soil conditions, it is 0.01-0.03. This series of multiple sampling and averaging calibration methods effectively eliminates static errors, and the K value calibrated by the test piles can be adapted to different soil conditions, solving the problem of lack of adaptability of traditional error compensation.

[0033] Furthermore, the accurate calculation of the depth value is achieved by deducting the two types of dynamic errors: buffer pad deformation and pile rebound. This includes: real-time calibration of the depth value H(t) to reflect the instantaneous penetration depth of the pile foundation at time t. The calculation formula is as follows: H(t)=(L(t)-L0)-(△h1'-△h1)-K·(L(t)-L0) Where H(t) is the real-time calibration depth value at time t, L(t) is the straight-line distance between the laser ranging sensor and the receiving end at time t, L0 is the initial straight-line distance between the laser ranging sensor and the receiving end in the initial state of pile driving, Δh1' is the real-time compression amount of the buffer pad at time t, Δh1 is the initial compression amount of the buffer pad when the hammer first contacts the pile body in the initial state of pile driving, and K is the pile body rebound coefficient; (L(t)-L0) is the falling distance of the hammer relative to the initial high position; (△h1'-△h1) is the difference between the real-time compression of the buffer pad and the initial compression, deducting the virtual displacement caused by the elastic deformation of the buffer pad; K·(L(t)-L0) is the rebound amount of the pile body, deducting the upward rebound error of the pile body caused by the elasticity of the soil layer.

[0034] The final hole depth is obtained by accumulating the effective penetration depth of each hammer blow. Specifically, the lowest distance value Li (corresponding to the lowest point of the hammer head falling to the top of the pile) for each hammer blow is extracted from the laser ranging dynamic waveform using a peak detection algorithm. Then, the effective penetration depth for a single blow is calculated. Finally, the effective penetration depths of all hammer cycles are summed to obtain the final hole depth H. The calculation formula is as follows: It should be noted that the L(t) captured by the laser sensor is a waveform structure. Overall, the center line of the waveform rises slowly and monotonically, corresponding to the overall sinking of the hammer / pile and the increase in hole depth. In the short term, there are sawtooth waves superimposed on the waveform, corresponding to the cycle of a single hammer lifting, falling, impacting, and rebounding. The maximum and minimum values ​​of each hammering cycle can be extracted through the waveform structure.

[0035] In this embodiment, the cloud processing module reduces the measurement error under dynamic working conditions from >5cm to ±2cm through dual-dimensional error compensation. The waveform feature extraction accurately identifies valid soil-entry data, solving the core problem that traditional measurement does not consider the deformation of the buffer pad and the rebound of the pile body.

[0036] Furthermore, after calculating the depth of the assembly hole, the corresponding status signal can be triggered and pushed to the terminal display module by comparing it with the preset depth. When the depth reaches 90% of the design depth, an early warning state is triggered to remind the construction personnel that the standard is about to be met; when the depth reaches the design depth, a completion state is triggered, and a pop-up window reminds the construction personnel to stop hammering; when the depth exceeds 5% of the design depth, an over-limit state is triggered, and an audible and visual alarm is triggered at the construction site.

[0037] In this invention, the terminal display module is used to realize data visualization and interaction, supporting web and WeChat mini-programs, with a refresh rate of 1Hz. The web interface layout is as follows: Left side: Pile foundation distribution map (marked according to the coordinates of the construction drawings, with different colors indicating the status); Middle: Real-time data area (displaying the selected pile foundation number, current depth, target depth, and progress percentage); Right side: Depth-time curve (data for the past 5 minutes, with time on the horizontal axis and depth on the vertical axis, and the target depth line marked); Bottom: Anomaly alert area (scrolling display of unprocessed anomaly information, including pile foundation number, anomaly type, and occurrence time); Interactive function: Clicking the pile foundation icon will display a pop-up window showing the complete record (start time, time to reach the target, maximum depth, number of anomalies). This full-dimensional visualization allows construction personnel to intuitively grasp the pile foundation depth status, and historical data can be exported to adapt to engineering acceptance specifications, solving the problems of traditional measurement lacking visualization and data traceability.

[0038] The laser-sensor-based precise pile foundation depth measurement system provided in this embodiment achieves full data traceability from construction to acceptance by collecting dynamic waveform data of the entire hammering process. At the same time, the multi-level shock absorption structure of the acquisition module is adapted to the high-frequency impact conditions of hammering to ensure the stability of the sensor. Combined with a two-dimensional dynamic error compensation algorithm, the measurement accuracy is significantly improved, the influence of errors is greatly reduced, and the effective soil penetration data is accurately extracted, thereby achieving non-contact precise distance measurement.

[0039] Example 2, based on Example 1, provides a method for accurate measurement of pile foundation depth based on laser sensing, specifically including the following steps: Step 1: Install the laser rangefinder sensor on the top of the hammer head using the support assembly, aligning the laser sensor's vertical optical path with the receiving end at the bottom of the crossbeam. Embed the LVDT displacement sensor in the buffer pad between the hammer head and the pile cap, and connect it to the edge computing unit. Then, start the laser sensor calibration to determine the initial straight-line distance L0 between the laser rangefinder sensor and the receiving end when the hammer head is at its initial high position in the initial pile driving state. Simultaneously, record the initial compression amount Δh1 of the buffer pad when it first contacts the pile body, and determine the pile body's own rebound coefficient K through a pile test. Step 2: After the pile body is assembled, the pile driver depth acquisition module is started. The hammer head reciprocates with the hammer, and the hammer head moves along the guide frame in a reciprocating motion of lifting-falling-hammering-rebounding. The dynamic data of the straight-line distance between the laser range sensor and the receiving end is collected in real time, and the real-time compression data of the buffer pad is collected simultaneously. The distance-time dynamic waveform is generated on the terminal display module. The edge computing unit timestamps the data and filters anomalies, and uploads it to the cloud through the communication module. Step 3: Extract the lowest distance value Li in each hammering cycle from the above dynamic waveform image, calculate the real-time net settlement height of the hammer head relative to the initial reference plane after eliminating the error of buffer pad compression and pile rebound, and thus calculate the single effective penetration depth △Hi corresponding to each cycle. Step 4: Accumulate △Hi for all hammering cycles to calculate the total hole depth; at the same time, the cloud processing module compares the calculated hole depth with the design depth in real time, triggering warning / completion / over-limit status; at the same time, the terminal display module displays the pile foundation status, depth data, depth-time curve, and push notifications for abnormal statuses in real time.

[0040] The embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. The basic concept of the present invention is not to directly measure the displacement of the pile, but to install a laser rangefinder sensor on the hammer head to measure the dynamic distance from the hammer head to the top fixed crossbeam. During repeated hammering, the hammer head will move up and down relative to the crossbeam, generating a dynamic waveform. The laser sensor captures this distance change, and by analyzing the waveform data, the actual drilling depth of the pile foundation, that is, the hole depth, can be accurately calculated. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A precise pile foundation depth measurement system based on laser sensing, characterized in that: It includes a depth acquisition module, a cloud processing module, a terminal display module, and a communication module for data transmission between the modules. The depth acquisition module integrates an acquisition module, which is fixed to the top of the pile driver hammer head by a support component. It is used to follow the hammer head's reciprocating motion to acquire the overall displacement of the hammer head as the pile sinks and the dynamic waveform data of the distance corresponding to the reciprocating motion in real time. The cloud processing module is used to receive the distance dynamic waveform data through the communication module, and combine the buffer deformation and pile rebound compensation parameters to perform real-time depth value calibration and pile foundation depth status judgment. The terminal display module is used to display the pile foundation number, real-time depth value, waveform curve and status indicator in real time.

2. The laser-sensing-based precise pile foundation depth measurement system according to claim 1, characterized in that: The acquisition module includes a laser ranging sensor, an edge computing unit, and a power supply unit installed in the housing. The bottom of the fixed crossbeam of the pile driver is equipped with a receiving end. The output end of the laser ranging sensor faces the receiving end vertically upwards and is used to acquire dynamic data of the straight-line distance between the sensor and the receiving end in real time. The edge computing unit is used to preprocess the sensor data, including timestamp marking and abnormal data filtering, and outputs dynamic distance data with timestamps, depth values, and abnormal tags. The power supply unit is used to supply power to the acquisition module.

3. The laser-sensing-based precise pile foundation depth measurement system according to claim 2, characterized in that: The support assembly includes a mounting base, a support frame, and elastic connectors. The mounting base has a hollow inner cavity. The support frame is located in the mounting base and has a stepped structure. A recessed cavity is provided in the middle of the support frame, and the acquisition module is fixed in the recessed cavity. A disc spring assembly is provided between the bottom of the support frame and the bottom of the inner cavity of the mounting base to buffer the vertical impact load generated by hammering. The elastic connectors are inclinedly arranged on the left and right sides of the support base. The two ends of the elastic connectors are respectively hinged to the side walls of the support frame and the mounting base to buffer the lateral vibration generated during the hammering process.

4. The laser-sensing-based precise pile foundation depth measurement system according to claim 2 or 3, characterized in that: A buffer pad is provided between the hammer and the pile cap, and a displacement sensor for measuring its axial compression deformation is pre-embedded in the buffer pad; the displacement sensor is communicatively connected to the edge computing unit to provide compensation parameters for borehole depth calibration.

5. The laser-sensing-based precise pile foundation depth measurement system according to claim 2, characterized in that: The receiving end is a high-reflectivity reflective target, and the reflective surface of the reflective target is perpendicularly aligned with the output optical path of the laser rangefinder.

6. The laser-sensing-based precise pile foundation depth measurement system according to claim 1, characterized in that: The cloud processing module has a built-in dynamic calibration algorithm, which is used to compensate for the distance dynamic data based on the real-time compression deformation of the buffer pad, the pile rebound coefficient, and the distance dynamic waveform characteristic data within the hammering cycle, thereby eliminating the distance measurement error caused by the compression of the buffer pad and the rebound of the pile.

7. The laser-sensing-based precise pile foundation depth measurement system according to claim 6, characterized in that: The formula for calculating the real-time calibration depth value at time t during the execution of the dynamic calibration algorithm is as follows: H(t)=(L(t)-L0)-(△h1'-△h1)-K·(L(t)-L0) Where H(t) is the real-time calibration depth value at time t, L(t) is the straight-line distance between the laser rangefinder and the receiver at time t, and L0 is the initial straight-line distance between the laser rangefinder and the receiver in the initial state of pile driving. △h1' is the real-time compression of the buffer pad at time t, △h1 is the initial compression of the buffer pad when the hammer first contacts the pile body in the initial state of pile driving, and K is the pile body rebound coefficient, which takes a value of 0.01-0.

08.

8. The laser-sensing-based precise pile foundation depth measurement system according to claim 6, characterized in that: The cloud processing module is also used to calculate the assembly hole depth, using the following formula: 。 9. The laser-sensing-based precise pile foundation depth measurement system according to claim 8, characterized in that: The cloud processing module presets a depth threshold to compare the calibrated assembly hole depth with the design depth value, triggering and pushing a status signal to the terminal display module: when the depth reaches 90% of the design depth, an early warning state is triggered; When the depth reaches the designed depth, the completion state is triggered; When the depth exceeds 5% of the design depth, an over-limit status is triggered, and all status signals are simultaneously pushed to the terminal display module.

10. A method for accurately measuring the depth of pile foundations based on laser sensing, using the accurate pile foundation depth measurement system based on laser sensing as described in any one of claims 1-9, characterized in that: Includes the following steps: Step 1: Calibrate the initial straight-line distance L0 between the laser rangefinder and the receiver when the hammer head is at its initial high position in the initial state of pile driving; at the same time, record the initial compression amount Δh1 of the buffer pad when it first contacts the pile body, and determine the self-rebound coefficient K of the pile body through a test pile test; Step 2: The depth acquisition module reciprocates with the hammer's impact, acquiring real-time dynamic data of the straight-line distance between the laser range sensor and the receiver, and simultaneously acquiring real-time compression data of the buffer pad, which is then displayed on the terminal display module as a distance-time dynamic waveform. Step 3: Extract the lowest distance value Li in each hammering cycle from the above dynamic waveform image, calculate the real-time net settlement height of the hammer head relative to the initial reference plane after eliminating the error of buffer pad compression and pile rebound, and thus calculate the single effective penetration depth △Hi corresponding to each cycle. Step 4: Accumulate ΔHi for all hammering cycles and calculate the assembly hole depth.

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