Pile concrete monitoring system based on sounding pipe and method thereof

Abstract

This invention discloses a pile foundation concrete monitoring system and method based on sonic logging tubes, comprising: multiple sonic logging tubes vertically embedded in the pile foundation, spaced apart along the circumferential direction of the pile foundation; each sonic logging tube having two closed ends and filled with an incompressible thermally and pressure-transmitting fluid medium; temperature sensors installed inside the sonic logging tubes, with multiple temperature sensors arranged vertically inside the tubes; pressure sensors installed inside the sonic logging tubes, with multiple pressure sensors arranged vertically inside the tubes; a monitoring platform including an acquisition module, a modeling module, a calculation module, and an evaluation module; the acquisition module being connected to the temperature and pressure sensors, the modeling module being connected to the acquisition module, the calculation module being connected to the modeling module, and the evaluation module being connected to the calculation module; and an interactive terminal connected to the evaluation module. This invention solves the problem that existing pile foundation concrete hydration heat and lateral pressure monitoring technologies cannot achieve coupled analysis of hydration heat and lateral pressure.

Description

Technical Field

[0001] This invention relates to the field of pile foundation monitoring technology, and specifically to a pile foundation concrete monitoring system and method based on sonic logging tubes. Background Technology

[0002] In pile foundation engineering, the hydration process of concrete after pouring directly determines the strength formation, durability, and overall construction quality of the pile structure. The cement hydration process releases a large amount of heat, causing a sharp rise in the internal temperature of the pile concrete, creating a significant temperature gradient with the external environment, and consequently generating temperature stress and volumetric deformation. Simultaneously, the volumetric deformation and hardening during concrete hydration directly alter the lateral pressure exerted by the pile on the surrounding soil and rock. The evolution of this lateral pressure is closely related to the pile-soil interface, pile structural stress, and pile quality. Therefore, full-cycle, high-precision monitoring of the hydration heat and lateral pressure of pile foundation concrete is a core means of assessing the concrete hydration process, preventing early cracking risks, and ensuring pile quality.

[0003] Currently, monitoring of the heat of hydration in pile foundation concrete mostly employs the method of pre-embedded temperature sensors and temperature measuring cables, directly binding the sensing element to the reinforcing cage, which is then lowered into the pile hole along with the cage. This method has significant drawbacks: First, the sensor is in direct contact with the concrete, and is easily damaged by the impact and compression of the aggregate during the concrete pouring process, resulting in a low survival rate. Secondly, the sensor positioning is prone to deviation, making it impossible to guarantee the accuracy of the monitoring points; Third, the sensors cannot be recycled after being embedded, resulting in high monitoring costs, and they can only monitor a single temperature parameter, making them functionally limited.

[0004] Some existing technologies have begun to use acoustic logging tubes as temperature measurement channels, placing temperature measurement cables inside the acoustic logging tubes to complete hydration heat monitoring. This avoids direct contact between the sensor and the concrete, improving the sensor survival rate. However, this type of technology can only achieve temperature monitoring and cannot simultaneously complete lateral pressure monitoring, thus failing to achieve coupled analysis of hydration heat and lateral pressure.

[0005] For monitoring lateral pressure on pile foundations, current technology mainly uses pre-embedded earth pressure cells, which are fixed to the outside of the reinforcing cage and lowered into the pile hole along with the cage. This method has significant shortcomings: First, the earth pressure cell is directly subjected to the impact and compression of concrete pouring, making it prone to displacement and damage, and the measurement accuracy is difficult to guarantee. Secondly, the poor coupling between the pressure cell and the concrete and surrounding soil and rock makes it easy for measurement distortion to occur due to poor contact. Third, additional monitoring lines and fixing devices are required, which increases the complexity of construction and may affect the integrity of the pile foundation structure. Fourth, it is impossible to collect data at the same location and simultaneously with hydration heat monitoring, making it difficult to establish a correlation between the two and to accurately assess the evolution of structural mechanical behavior during the concrete hydration process.

[0006] Meanwhile, existing monitoring technologies generally suffer from low levels of intelligence, often only capable of data collection and simple display. They lack the ability to couple and analyze multiple parameters such as hydration heat and lateral pressure, making it impossible to establish an evolutionary correlation model between the two. This makes it difficult to accurately quantify and assess the early hydration process of concrete, structural safety status, and pile quality. Furthermore, they lack a comprehensive hierarchical early warning and dynamic control mechanism, which fails to provide real-time and scientific decision support for the construction and maintenance process.

[0007] Furthermore, as a standard component for ultrasonic cross-hole integrity testing in pile foundation engineering, the sonic logging tube is idle for a long time during the concrete pouring and curing stages, and is only used for integrity testing after the pile is completed. Its life cycle utilization rate is extremely low, resulting in significant resource waste.

[0008] In summary, existing technologies for monitoring the hydration heat and lateral pressure of pile foundation concrete suffer from several problems, including easily damaged sensors, high construction complexity, asynchronous monitoring parameters, inability to perform multi-parameter coupled analysis, low utilization rate of sonic logging tubes, and insufficient intelligent control capabilities. These issues make it difficult to meet the control requirements of high-quality, refined, and intelligent construction in modern pile foundation engineering. Summary of the Invention

[0009] To overcome the shortcomings of existing technologies, a pile foundation concrete monitoring system and method based on sonic logging tubes are provided to solve the problem that pile foundation concrete hydration heat and lateral pressure monitoring technologies cannot achieve coupled analysis of hydration heat and lateral pressure.

[0010] To achieve the above objectives, a pile foundation concrete monitoring system based on sonic logging tubes is provided, comprising: Multiple sonic logging tubes are vertically embedded in the pile foundation. The multiple sonic logging tubes are spaced apart along the circumferential direction of the pile foundation. Each sonic logging tube has two closed ends and is filled with an incompressible thermally conductive and pressure-transmitting fluid medium. A temperature sensor for collecting concrete hydration heat and temperature data is installed inside the acoustic logging tube, and multiple temperature sensors are arranged vertically inside the acoustic logging tube. A pressure sensor for collecting lateral pressure data of concrete is installed inside the acoustic logging tube, and multiple pressure sensors are arranged vertically inside the acoustic logging tube. The monitoring platform includes an acquisition module for acquiring concrete hydration heat temperature data and concrete lateral pressure data; a modeling module for constructing a hydration heat-lateral pressure coupled evolution model based on the concrete hydration heat temperature data and concrete lateral pressure data; a calculation module for calculating the temperature stress and structural safety factor at each monitoring point of the pile body based on the hydration heat-lateral pressure coupled evolution model; and an evaluation module for calculating the safety assessment result based on a preset safety threshold and the temperature stress and structural safety factor at each monitoring point of the pile body. The acquisition module is connected to the temperature sensor and the pressure sensor, the modeling module is connected to the acquisition module, the calculation module is connected to the modeling module, and the evaluation module is connected to the calculation module. The interactive terminal is connected to the evaluation module.

[0011] Furthermore, the thermally conductive and pressure-transmitting fluid medium is deionized water or thermally conductive silicone oil.

[0012] Furthermore, the monitoring platform also includes a preprocessing module for performing outlier removal, filtering and noise reduction, temperature compensation and linear calibration on the concrete hydration heat temperature data and the concrete lateral pressure data. The acquisition module is connected to the modeling module through the preprocessing module.

[0013] Furthermore, the modeling module includes: A first feature extraction unit, connected to the preprocessing module, is used to extract temperature feature values ​​of each stage of the concrete hydration reaction based on the concrete hydration heat and temperature data. The stages of the concrete hydration reaction include the initial hydration period, the heating period, the cooling period, and the stabilization period. A second feature extraction unit, connected to the preprocessing module, is used to extract the lateral pressure feature values ​​of each stage based on the concrete lateral pressure data. A construction unit, connected to the first feature extraction unit and the second feature extraction unit, is used to quantify the driving mechanism of the hydration heat temperature field on the evolution of concrete volume deformation and lateral pressure based on the temperature feature value and the lateral pressure feature value, combined with the concrete hydration kinetics theory and elastoplastic constitutive model, in order to construct a coupled correlation equation of hydration heat and lateral pressure.

[0014] Furthermore, the monitoring points of the pile body are set at the bottom, middle and top of the pile foundation.

[0015] This invention provides a monitoring method for a pile foundation concrete monitoring system based on sonic logging tubes, comprising the following steps: Multiple sonic logging tubes are vertically buried in the pile foundation. The multiple sonic logging tubes are spaced apart along the circumferential direction of the pile foundation. Each sonic logging tube has two closed ends and is filled with an incompressible thermally conductive and pressure-transmitting fluid medium. Temperature sensors collect temperature data on the heat of hydration of concrete; Pressure sensors collect lateral pressure data of concrete; The acquisition module of the monitoring platform acquires the concrete hydration heat temperature data and the concrete lateral pressure data; The modeling module of the monitoring platform is used to construct a coupled evolution model of hydration heat and lateral pressure based on the concrete hydration heat temperature data and the concrete lateral pressure data. The calculation module of the monitoring platform calculates the temperature stress and structural safety factor at each monitoring point of the pile body based on the hydration heat-lateral pressure coupled evolution model. The evaluation module of the monitoring platform calculates and sends out safety evaluation results based on preset safety thresholds and temperature stress and structural safety factor at each monitoring point of the pile. The security assessment results are obtained from the interactive terminal.

[0016] The beneficial effects of the present invention are that the pile foundation concrete monitoring system based on sonic logging tubes of the present invention reuses the sonic logging tubes that are standard equipment in pile foundation engineering as monitoring carriers, without the need for additional pre-embedded monitoring pipelines and fixing devices, without changing the original structural design and construction procedures of the pile foundation, without damaging the structural integrity of the pile foundation, greatly simplifying the monitoring construction process, reducing monitoring costs, and realizing the efficient utilization of sonic logging tubes throughout their entire life cycle, avoiding resource idleness and waste.

[0017] The pile foundation concrete monitoring system based on sonic logging tubes of this invention adopts a design with an integrated sensing unit built into the sonic logging tube. The sensing unit is kept in a protective environment inside the sonic logging tube throughout the process, without direct contact with the concrete. This completely avoids damage to the sensor caused by aggregate impact and compression during concrete pouring, significantly improving the sensor survival rate and the stability of monitoring work. At the same time, the standardized fixing method ensures the accuracy of the monitoring points, solving the problems of sensor displacement and inaccurate positioning in traditional pre-embedded methods.

[0018] The pile foundation concrete monitoring system based on sonic logging tubes of this invention realizes the same-point, synchronous, and full-cycle continuous monitoring of the hydration heat temperature and lateral pressure of pile foundation concrete. It eliminates the errors caused by inconsistent monitoring points and asynchronous acquisition of the two types of parameters in traditional monitoring technologies, and provides an accurate and reliable data foundation for the coupled analysis of the two. It can truly reflect the correlation and evolution law of thermodynamic behavior and mechanical behavior in the concrete hydration process.

[0019] The pile foundation concrete monitoring system based on sonic logging tubes of this invention constructs a coupled evolution model of hydration heat and lateral pressure, which breaks through the analytical limitations of traditional single-parameter monitoring. It can quantify the driving mechanism of the hydration heat temperature field on the evolution of concrete volume deformation and lateral pressure, accurately calculate the pile body temperature stress and structural safety factor, and realize the quantitative identification and assessment of early cracking risk, hydration abnormality and pile body density defects, providing a more comprehensive and scientific basis for pile quality evaluation. Attached Figure Description

[0020] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the pile foundation concrete monitoring system based on sonic logging tubes according to an embodiment of the present invention. Detailed Implementation

[0021] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] Reference Figure 1 As shown, the present invention provides a pile foundation concrete monitoring system based on a sonic logging tube, including: a sonic logging tube, a temperature sensor 1, a pressure sensor 2, a monitoring platform 3, and an interactive terminal 4.

[0024] The system consists of multiple sonic logging tubes, which are vertically embedded in the pile foundation. These tubes are spaced apart along the circumferential direction of the pile foundation. Each tube has two closed ends and is filled with an incompressible, thermally and pressure-transmitting fluid medium.

[0025] When installing sonic logging tubes in pile foundations, the standardized installation of sonic logging tubes and the calibration and assembly of the built-in sensing and monitoring units are completed based on the design parameters of the pile foundations to be monitored. At the same time, the debugging and parameter configuration of the intelligent monitoring system are also completed.

[0026] The design parameters of the pile foundation to be monitored include pile diameter, pile length, concrete grade, number and specifications of sonic logging tubes, and design parameters of the reinforcing cage. The sonic logging tubes are seamless steel pipes, standard equipment for ultrasonic cross-hole testing of pile foundations. Multiple sonic logging tubes are evenly spaced along the inner circumference of the reinforcing cage and tied to the longitudinal main reinforcement bars of the reinforcing cage. No additional monitoring pipelines are required, and the original structural design and construction procedures of the pile foundation are not changed.

[0027] As a preferred implementation, the heat-conducting and pressure-transferring fluid medium is deionized water or thermally conductive silicone oil.

[0028] Temperature sensor 1 is installed inside the acoustic logging tube, and multiple temperature sensors 1 are arranged vertically inside the acoustic logging tube. Temperature sensor 1 is used to collect the temperature data of concrete hydration heat.

[0029] Pressure sensor 2 is installed inside the sonic logging tube. Multiple pressure sensors 2 are installed vertically inside the sonic logging tube. Pressure sensor 2 is used to collect lateral pressure data of concrete.

[0030] Monitoring points are set at the bottom, middle and top of the pile foundation.

[0031] Temperature sensor 1 and pressure sensor 2 inside multiple sonic logging tubes at the same elevation of the same cross section of the pile body form a distributed monitoring array of the cross section, realizing full cross-sectional monitoring coverage of the pile body.

[0032] After the temperature sensor 1 and pressure sensor 2 are installed, the sonic logging tube is filled with a non-corrosive, heat-conducting, and pressure-transmitting fluid medium. Then, waterproof sealing caps are used to seal the upper and lower ends of the sonic logging tube to prevent the intrusion of external mud, concrete, and impurities.

[0033] The heat-conducting and pressure-transmitting fluid medium is deionized water or thermally conductive silicone oil, which ensures efficient conduction of temperature and pressure, avoids corrosion inside the sonic logging tube, and does not affect the ultrasonic integrity testing function of the sonic logging tube after pile construction.

[0034] For cases where the stiffness of the sonic logging pipe (i.e., steel pipe) is much greater than that of concrete, the following mechanism ensures the accurate transmission of lateral pressure: The lateral pressure of the concrete is a uniformly distributed surface load. When it acts on the outer wall of the sonic logging tube, the rigidity of the steel tube causes only slight elastic deformation. This slight elastic deformation is directly transmitted to the lateral pressure sensing module, which is tightly fitted to the inner wall. Simultaneously, the thermally conductive and pressure-transmitting fluid medium filling the tube is incompressible, which uniformly transmits the pressure from the inner wall of the steel tube to the entire sensing surface of the pressure sensor. This avoids measurement errors caused by uneven local pressure and prevents pressure loss due to the high rigidity of the steel tube, ensuring that the monitoring data accurately reflects the actual lateral pressure of the concrete.

[0035] The temperature or pressure sensor comprises a rigid protective housing, a temperature sensing module (or a lateral pressure sensing module), a signal conditioning module, a positioning module, and a power supply module. The rigid protective housing is made of thermally conductive and pressure-resistant metal, with its outer wall tightly fitted and fixed to the inner wall of the acoustic tube. Both the temperature and lateral pressure sensing modules utilize high-sensitivity, high-stability sensing chips, and their sensing surfaces are tightly fitted to the inner wall of the rigid protective housing to ensure efficient temperature and pressure transmission. The signal conditioning module amplifies, filters, and performs analog-to-digital conversion on the raw signals acquired by the sensing modules. The positioning module acquires the precise elevation and position information of the sensing monitoring unit. The power supply module employs a dual-mode system, combining a built-in lithium battery and an external power supply, to meet the power requirements of full-cycle monitoring.

[0036] The monitoring platform 3 includes an acquisition module 31, a modeling module 33, a calculation module 34, and an evaluation module 35. The acquisition module 31 is connected to the temperature sensor 1 and the pressure sensor 2. The modeling module 33 is connected to the acquisition module 31. The calculation module 34 is connected to the modeling module 33. The evaluation module 35 is connected to the calculation module 34.

[0037] The acquisition module 31 is used to acquire concrete hydration heat temperature data and concrete lateral pressure data. The acquisition module is connected to the pressure sensor and temperature sensor via the transmission module.

[0038] The data transmission between the acquisition module and the pressure and temperature sensors adopts a dual redundancy mode of wireless low-power transmission and wired transmission. The wireless transmission uses any one or more combinations of LoRa, 5G or NB-IoT to ensure the stability and continuity of data transmission in complex construction site environments.

[0039] Modeling module 33 is used to construct a coupled evolution model of hydration heat and lateral pressure based on concrete hydration heat temperature data and concrete lateral pressure data.

[0040] The calculation module 34 is used to calculate the temperature stress and structural safety factor of each monitoring point of the pile body based on the hydration heat-lateral pressure coupled evolution model.

[0041] The evaluation module 35 is used to calculate the safety evaluation results based on the preset safety threshold and the temperature stress and structural safety factor at each monitoring point of the pile.

[0042] The monitoring platform 3 also includes a preprocessing module 32. The acquisition module 31 is connected to the modeling module 33 through the preprocessing module 32. The preprocessing module 32 is used to perform outlier removal, filtering and noise reduction, temperature compensation and linear calibration on the concrete hydration heat temperature data and concrete lateral pressure data, thereby eliminating environmental interference and system errors and improving the accuracy and reliability of the monitoring data.

[0043] Interactive terminal 4 is connected to evaluation module 35. The interactive terminal is used to enable real-time viewing of monitoring data, receiving of early warning information, parameter configuration adjustment, and remote control.

[0044] The modeling module 33 includes a first feature extraction unit, a second feature extraction unit, and a construction unit. The second feature extraction unit is connected to the preprocessing module 32. The construction unit is connected to the first feature extraction unit and the second feature extraction unit.

[0045] The first feature extraction unit is connected to the preprocessing module 32. The first feature extraction unit is used to extract temperature feature values ​​for each stage of the concrete hydration reaction based on the concrete hydration heat and temperature data. The stages of the concrete hydration reaction include the initial hydration period, the heating period, the cooling period, and the stabilization period.

[0046] The second feature extraction unit is used to extract lateral pressure feature values ​​at each stage based on concrete lateral pressure data.

[0047] The building blocks are used to quantify the driving mechanism of the hydration heat temperature field on the evolution of concrete volume deformation and lateral pressure based on temperature characteristic values ​​and lateral pressure characteristic values, combined with the theory of concrete hydration kinetics and the elastoplastic constitutive model, so as to construct the coupled correlation equation of hydration heat and lateral pressure.

[0048] In this embodiment, the monitoring platform also includes a data sharing interface module, which is used to connect with the pile foundation construction management system, BIM model system, and engineering quality supervision system to realize the integrated management of monitoring data and engineering construction data.

[0049] The monitoring platform includes a data storage module. This module receives and stores monitoring data and pile foundation information throughout the entire monitoring cycle.

[0050] This invention provides a monitoring method for a pile foundation concrete monitoring system based on sonic logging tubes, comprising the following steps: S1. Multiple sonic logging tubes are vertically buried in the pile foundation. The multiple sonic logging tubes are spaced apart along the circumferential direction of the pile foundation. The sonic logging tubes have two closed ends and are filled with an incompressible heat-conducting and pressure-transmitting fluid medium.

[0051] S2, Temperature sensor 1 collects concrete hydration heat and temperature data.

[0052] S3, pressure sensor 2 collects lateral pressure data of concrete.

[0053] S4, the acquisition module 31 of the monitoring platform 3 acquires concrete hydration heat temperature data and concrete lateral pressure data.

[0054] S5, the modeling module 33 of the monitoring platform 3 is used to construct a coupled evolution model of hydration heat and lateral pressure based on concrete hydration heat temperature data and concrete lateral pressure data.

[0055] S51. Based on the time-series data of hydration heat and temperature, the concrete hydration reaction is divided into four stages: initial hydration period, heating period, cooling period, and stabilization period. The first feature extraction unit extracts the temperature feature values ​​for each stage. The temperature feature values ​​include heating rate, peak temperature, peak occurrence time, and cooling rate.

[0056] S52. The second feature extraction unit simultaneously extracts the lateral pressure feature values ​​for the corresponding stage. The lateral pressure feature values ​​include the pressure rise rate, peak pressure, pressure relaxation rate, and steady-state pressure value, and establishes a temporal correspondence between the temperature feature values ​​and the pressure feature values.

[0057] S53. Combining the theory of concrete hydration dynamics with the elastoplastic constitutive model, the driving mechanism of the hydration heat temperature field on the evolution of concrete volume deformation and lateral pressure is quantified, and the coupling correlation equation between the two is constructed to form a hydration heat-lateral pressure coupled evolution model.

[0058] S6, the calculation module 34 of the monitoring platform 3 calculates the temperature stress and structural safety factor of each monitoring point of the pile body based on the hydration heat-lateral pressure coupled evolution model.

[0059] Based on the coupled evolution model, the calculation module calculates the temperature stress and structural safety factor at each monitoring point of the pile body.

[0060] S7, the evaluation module 35 of the monitoring platform 3 calculates the safety assessment results based on the preset safety threshold and the temperature stress and structural safety factor of each monitoring point of the pile body, and sends them out.

[0061] Based on the temperature stress and structural safety factor at each monitoring point of the pile, the correlation characteristics between the concrete hydration process and lateral pressure are analyzed, and the quantitative identification and assessment of early cracking risk, abnormal hydration, and pile density defects are completed.

[0062] Based on preset safety thresholds and safety assessment results, abnormal working conditions are classified and warned, and corresponding construction and maintenance optimization strategies are output to achieve dynamic control of the entire pile foundation construction process.

[0063] The tiered early warning system includes three levels: Level 1, Level 2, and Level 3.

[0064] Level 1, Level 2, and Level 3 warnings correspond to alert, warning, and emergency levels, respectively. Specifically, Level 1 warnings indicate parameters deviating from the normal range but not exceeding the safety threshold; Level 2 warnings indicate parameters exceeding the safety threshold and posing a potential safety risk; and Level 3 warnings indicate parameters severely exceeding limits and posing an immediate structural safety risk.

[0065] S8 and Interactive Terminal 4 obtain security assessment results and early warning information.

[0066] For different warning levels, corresponding warning information is pushed to the relevant person in charge (interaction terminal 4), and differentiated maintenance optimization strategies are output, including maintenance temperature control, adjustment of moisturizing measures, and optimization of maintenance cycle.

[0067] The sonic logging tube-based pile foundation concrete monitoring system of the present invention reuses the sonic logging tubes that are standard equipment in pile foundation engineering as monitoring carriers. It does not require additional pre-embedded monitoring pipelines and fixing devices, does not change the original structural design and construction procedures of the pile foundation, and does not damage the structural integrity of the pile foundation. It greatly simplifies the monitoring and construction process, reduces monitoring costs, and realizes efficient utilization of the sonic logging tubes throughout their entire life cycle, avoiding resource idleness and waste.

[0068] The pile foundation concrete monitoring system based on sonic logging tubes of this invention adopts a design with an integrated sensing unit built into the sonic logging tube. The sensing unit is kept in a protective environment inside the sonic logging tube throughout the process, without direct contact with the concrete. This completely avoids damage to the sensor caused by aggregate impact and compression during concrete pouring, significantly improving the sensor survival rate and the stability of monitoring work. At the same time, the standardized fixing method ensures the accuracy of the monitoring points, solving the problems of sensor displacement and inaccurate positioning in traditional pre-embedded methods.

[0069] The pile foundation concrete monitoring system based on sonic logging tubes of this invention realizes the same-point, synchronous, and full-cycle continuous monitoring of the hydration heat temperature and lateral pressure of pile foundation concrete. It eliminates the errors caused by inconsistent monitoring points and asynchronous acquisition of the two types of parameters in traditional monitoring technologies, and provides an accurate and reliable data foundation for the coupled analysis of the two. It can truly reflect the correlation and evolution law of thermodynamic behavior and mechanical behavior in the concrete hydration process.

[0070] The pile foundation concrete monitoring system based on sonic logging tubes of this invention constructs a coupled evolution model of hydration heat and lateral pressure, which breaks through the analytical limitations of traditional single-parameter monitoring. It can quantify the driving mechanism of the hydration heat temperature field on the evolution of concrete volume deformation and lateral pressure, accurately calculate the pile body temperature stress and structural safety factor, and realize the quantitative identification and assessment of early cracking risk, hydration abnormality and pile body density defects, providing a more comprehensive and scientific basis for pile quality evaluation.

[0071] The pile foundation concrete monitoring system based on sonic logging tubes of this invention integrates data acquisition, transmission, intelligent analysis, hierarchical early warning, visual management, and dynamic control into a closed-loop intelligent monitoring system. It has a complete hierarchical early warning mechanism and the ability to output construction and maintenance strategies, enabling intelligent and refined control of the entire pile foundation construction process. It provides real-time decision support for on-site construction and maintenance, effectively improving the construction quality and safety management level of pile foundation projects.

[0072] The sensing and monitoring unit (pressure sensor and temperature sensor) of this invention can be removed before ultrasonic integrity testing after pile construction. After calibration, it can be reused, which greatly reduces the monitoring cost. At the same time, the internal structure and function of the acoustic tube are not affected, and subsequent ultrasonic cross-hole integrity testing can be completed normally, realizing "one tube for multiple uses" and possessing extremely high economic efficiency and engineering practicality.

[0073] To further illustrate the pile foundation concrete monitoring system and method based on sonic logging tubes of the present invention, the following embodiments are provided for explanation. Example

[0074] The present invention provides a pile foundation concrete monitoring method based on sonic logging tubes, comprising the following steps: a. Pre-monitoring preparations.

[0075] First, obtain the design parameters of the pile foundation to be monitored, including pile diameter, pile length, concrete grade, number and specifications of sonic logging tubes, and design parameters of the reinforcing cage.

[0076] The sonic logging tubes are seamless steel pipes, φ57mm×3mm in size, standard for ultrasonic cross-hole testing of pile foundations. Three tubes are evenly spaced along the inner circumference of the reinforcing cage. The sonic logging tubes are welded and fixed to the longitudinal main reinforcement bars of the reinforcing cage with binding straps. They are lowered into the pile hole simultaneously with the reinforcing cage, without the need for additional monitoring pipelines and without changing the original pile foundation construction procedures.

[0077] Subsequently, based on the pile foundation design parameters and monitoring requirements, the planning of monitoring points was completed: Along the longitudinal direction of the pile, monitoring points are set at five key sections: the bottom of the pile, 1 / 4 of the pile, 1 / 2 of the pile, 3 / 4 of the pile, and the top of the pile. The sensing and monitoring units in the three sonic logging tubes of the same section are all set at the same elevation, forming a distributed monitoring array of the section, so as to achieve full-section monitoring coverage of the pile.

[0078] Then, complete the laboratory calibration and assembly of the integrated sensing and monitoring unit: The temperature and lateral pressure sensing modules were calibrated for range, accuracy, and linearity to eliminate system errors. The sensing modules, signal conditioning modules, positioning modules, and power supply modules were integrated, assembled, and powered on to ensure proper functioning. Simultaneously, the overall intelligent monitoring system was debugged and its parameters configured, including preset parameters for sampling frequency, transmission cycle, safety thresholds, and early warning levels.

[0079] b. Installation and sealing of pressure and temperature sensors.

[0080] The calibrated pressure and temperature sensors are lowered to the preset monitoring points along the inside of the sonic logging tube using a dedicated pusher rod, ensuring tight contact and fixation with the inner wall of the tube. The positioning module confirms that the elevation and position of the pressure and temperature sensors meet design requirements, ensuring that sensors at the same cross-section are at the same horizontal elevation. The reinforcing cage is then lowered into the pile hole. After all the sensing and monitoring units are deployed, the sonic logging tube is filled with deionized water to ensure no air bubbles remain, guaranteeing efficient and uniform transmission of temperature and pressure.

[0081] The actual transmission path of lateral pressure is: When the lateral pressure of the concrete acts on the outer wall of the sonic logging tube, the steel tube undergoes micro-elastic radial deformation. Because the sensor is in close contact with the inner wall of the sonic logging tube, the deformation of the steel tube directly transmits the pressure to the lateral pressure sensor. At the same time, the deionized water filling the tube, as an incompressible fluid, evenly transmits the pressure from the inner wall of the steel tube to the entire sensing surface of the sensor, avoiding measurement errors caused by uneven local pressure. The rigidity of the steel tube ensures that the deformation is minimal and does not change the magnitude of the pressure, thus ensuring the accuracy of the lateral pressure monitoring.

[0082] The pressure sensor uses a high-sensitivity vibrating wire pressure sensor with a resolution of up to 0.025%FS, which can accurately capture minute pressure changes.

[0083] Subsequently, waterproof sealing end caps were used to seal the upper and lower ends of the sonic logging pipe to prevent the intrusion of external mud, concrete and impurities, avoid contamination and loss of the medium inside the pipe, and prevent cement slurry from entering the sonic logging pipe and causing blockage during subsequent concrete pouring.

[0084] c. Full-cycle synchronous data acquisition.

[0085] Throughout the entire cycle from the start of concrete pouring to the end of the curing period, the built-in sensors synchronously collect concrete hydration heat temperature data and lateral pressure data at each monitoring point according to the preset sampling frequency.

[0086] During the concrete pouring and hydration heating stages, the sampling frequency is set to once every 10 minutes; during the cooling and stabilization stages, the sampling frequency is set to once every hour. The sampling frequency can be dynamically adjusted according to the actual hydration process.

[0087] The acquired raw signals are amplified, filtered, and converted from analog to digital by the signal conditioning module, and then sent to the preprocessing module of the monitoring platform through the transmission module.

[0088] The preprocessing module preprocesses the raw data, including outlier removal, sliding filter denoising, temperature compensation, and linear calibration, to eliminate environmental interference and system errors and improve data accuracy.

[0089] The preprocessed data is temporarily stored locally.

[0090] d. Multi-parameter coupling analysis and state assessment.

[0091] After receiving the monitoring data, the monitoring platform processes and analyzes the time-series data of hydration heat temperature and lateral pressure through the modeling module, and constructs a coupled evolution model of hydration heat and lateral pressure. The specific process is as follows: First, based on the time series data of hydration heat and temperature, the concrete hydration reaction is divided into four stages: initial hydration period, heating period, cooling period and stabilization period. The first feature extraction unit extracts the temperature feature values ​​of each stage, including key parameters such as heating rate, peak temperature, peak occurrence time, cooling rate and temperature gradient.

[0092] Secondly, the second feature extraction unit simultaneously extracts lateral pressure feature values ​​within the corresponding time period, including parameters such as pressure rise rate, peak pressure, peak occurrence time, pressure relaxation rate, and steady-state pressure value, establishes the temporal correspondence between temperature feature values ​​and pressure feature values, and analyzes the synchronicity and correlation of their evolution.

[0093] Subsequently, the building unit combines the theory of concrete hydration dynamics with the elastoplastic constitutive model to quantify the driving effect of changes in the hydration heat temperature field on the volume expansion and shrinkage deformation of concrete, as well as the influence mechanism of volume deformation on the evolution of lateral pressure of the pile body. Coupled correlation equations of temperature characteristic values ​​and pressure characteristic values ​​are established to form a coupled evolution model of hydration heat-lateral pressure.

[0094] Finally, based on the constructed coupled evolution model, the calculation module calculates the temperature stress, volumetric deformation, and structural safety factor at each monitoring point of the pile body, and the evaluation module completes the quantitative assessment of the risk of early cracking of concrete. At the same time, by identifying the parameter differences at different monitoring points of the same cross section, it identifies quality problems such as abnormal concrete hydration and pile body compaction defects, and realizes early prediction of pile quality.

[0095] e. Tiered early warning and dynamic control.

[0096] Based on preset safety thresholds and status assessment results, the safety assessment and early warning module provides graded early warnings for abnormal operating conditions. In this embodiment, three early warning levels are set: Level 1 Warning (Alert Level): When the monitored parameter deviates from the normal range but does not exceed the safety threshold, or when the parameter change rate is abnormal, the system will push an alert message to the on-site technicians to remind them to pay attention to the parameter change trend. Level 2 Warning (Alert Level): When the monitored parameters exceed the safety threshold, there is a potential structural safety risk or quality defect risk. At this time, the system pushes warning information to the technical person in charge of the construction unit and the supervision unit, and outputs preliminary maintenance optimization suggestions, including adjusting the maintenance temperature and strengthening moisturizing maintenance. Level 3 Warning (Emergency Level): When the monitored parameters seriously exceed the safety threshold, there is an immediate risk of structural cracking or serious quality abnormalities. At this time, the system will simultaneously push emergency warning information to the project manager, construction unit, supervision unit, and construction unit, and activate the emergency response process to output a special handling plan, including suspending subsequent processes, taking special temperature control measures, and carrying out special testing and investigation.

[0097] Simultaneously, the system updates full-cycle monitoring data, analysis results, and maintenance strategies to the visualization management module, allowing relevant personnel to view them in real time via an interactive interface, achieving dynamic control and intelligent management of the entire pile foundation construction and maintenance process. After the concrete curing period ends and monitoring is completed, the sensors inside the sonic logging tube can be removed, calibrated, and reused for subsequent pile foundation monitoring, significantly reducing monitoring costs. The sonic logging tube after sensor removal can then be used normally for subsequent ultrasonic cross-hole integrity testing of pile foundations, achieving "one tube, multiple uses."

[0098] The pile foundation concrete monitoring system based on sonic logging tubes of the present invention reuses the standard sonic logging tubes of pile foundations as monitoring carriers, eliminating the need for additional pre-embedded monitoring pipelines. It achieves simultaneous, full-cycle monitoring of hydration heat and lateral pressure at the same location. At the same time, it constructs a multi-parameter coupled analysis and intelligent control system, solving the problems of easy sensor damage, complex construction, asynchronous parameter monitoring, low level of intelligence, and low resource utilization in traditional monitoring technologies.

[0099] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A pile foundation concrete monitoring system based on sonic logging tubes, characterized in that, include: Multiple sonic logging tubes are vertically embedded in the pile foundation. The multiple sonic logging tubes are spaced apart along the circumferential direction of the pile foundation. Each sonic logging tube has two closed ends and is filled with an incompressible thermally conductive and pressure-transmitting fluid medium. A temperature sensor for collecting concrete hydration heat and temperature data is installed inside the acoustic logging tube, and multiple temperature sensors are arranged vertically inside the acoustic logging tube. A pressure sensor for collecting lateral pressure data of concrete is installed inside the acoustic logging tube, and multiple pressure sensors are arranged vertically inside the acoustic logging tube. The monitoring platform includes an acquisition module for acquiring concrete hydration heat temperature data and concrete lateral pressure data; a modeling module for constructing a hydration heat-lateral pressure coupled evolution model based on the concrete hydration heat temperature data and concrete lateral pressure data; a calculation module for calculating the temperature stress and structural safety factor at each monitoring point of the pile body based on the hydration heat-lateral pressure coupled evolution model; and an evaluation module for calculating the safety assessment result based on a preset safety threshold and the temperature stress and structural safety factor at each monitoring point of the pile body. The acquisition module is connected to the temperature sensor and the pressure sensor, the modeling module is connected to the acquisition module, the calculation module is connected to the modeling module, and the evaluation module is connected to the calculation module. The interactive terminal is connected to the evaluation module.

2. The pile foundation concrete monitoring system based on sonic logging tubes according to claim 1, characterized in that, The thermally conductive and pressure-transmitting fluid medium is deionized water or thermally conductive silicone oil.

3. The pile foundation concrete monitoring system based on sonic logging tubes according to claim 1, characterized in that, The monitoring platform also includes a preprocessing module for outlier removal, filtering and noise reduction, temperature compensation and linear calibration of the concrete hydration heat temperature data and the concrete lateral pressure data. The acquisition module is connected to the modeling module through the preprocessing module.

4. The pile foundation concrete monitoring system based on sonic logging tubes according to claim 3, characterized in that, The modeling module includes: A first feature extraction unit, connected to the preprocessing module, is used to extract temperature feature values ​​of each stage of the concrete hydration reaction based on the concrete hydration heat and temperature data. The stages of the concrete hydration reaction include the initial hydration period, the heating period, the cooling period, and the stabilization period. A second feature extraction unit, connected to the preprocessing module, is used to extract the lateral pressure feature values ​​of each stage based on the concrete lateral pressure data. A construction unit, connected to the first feature extraction unit and the second feature extraction unit, is used to quantify the driving mechanism of the hydration heat temperature field on the evolution of concrete volume deformation and lateral pressure based on the temperature feature value and the lateral pressure feature value, combined with the concrete hydration kinetics theory and elastoplastic constitutive model, in order to construct a coupled correlation equation of hydration heat and lateral pressure.

5. The pile foundation concrete monitoring system based on sonic logging tubes according to claim 1, characterized in that, The monitoring points of the pile body are set at the bottom, middle and top of the pile foundation.

6. A monitoring method for a pile foundation concrete monitoring system based on sonic logging tubes as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Multiple sonic logging tubes are vertically buried in the pile foundation. The multiple sonic logging tubes are spaced apart along the circumferential direction of the pile foundation. Each sonic logging tube has two closed ends and is filled with an incompressible thermally conductive and pressure-transmitting fluid medium. Temperature sensors collect temperature data on the heat of hydration of concrete; Pressure sensors collect lateral pressure data of concrete; The acquisition module of the monitoring platform acquires the concrete hydration heat temperature data and the concrete lateral pressure data; The modeling module of the monitoring platform is used to construct a coupled evolution model of hydration heat and lateral pressure based on the concrete hydration heat temperature data and the concrete lateral pressure data. The calculation module of the monitoring platform calculates the temperature stress and structural safety factor at each monitoring point of the pile body based on the hydration heat-lateral pressure coupled evolution model. The evaluation module of the monitoring platform calculates and sends out safety evaluation results based on preset safety thresholds and temperature stress and structural safety factor at each monitoring point of the pile. The security assessment results are obtained from the interactive terminal.

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