Method for reinforcing defective pile body based on MICP principle

Abstract

The invention discloses a method for reinforcing a defective pile body based on an MICP principle, and the method comprises the steps: carrying out the excitation of a defective pile through a low-strain reflected wave method, collecting a first vibration response signal of a pile top, and analyzing the phase and wave velocity abnormality of a time-domain reflected wave to determine the defect information of the pile body; slurry parameters and grouting parameters are generated based on the pile body defect information, MICP slurry is configured, and a grouting pipe network system is arranged in the circumferential direction of a pile body; grout is injected into the defect area through a grouting pump, feedback signals are synchronously collected, and the opening degree of the valve set is dynamically adjusted through a PID algorithm to optimize the grouting process; and after grouting is completed, a second vibration response signal of the pile top is detected regularly through a low-strain reflected wave method, and grouting effect evaluation information is generated through comparative analysis. According to the method, through accurate defect positioning, intelligent grouting parameter regulation and control and real-time feedback correction, efficient filling of the calcium carbonate crystals to the pile body defects is achieved, the overall strength and bearing performance of the pile foundation are improved, the repairing pertinence is high, the automation degree is high, and the environment compatibility is good.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation treatment, and particularly relates to a method for reinforcing defective pile bodies based on the MICP principle. Background Art

[0002] Under the influence of factors such as hydrology, geology, and construction level, the defect problems generated during the construction of pile foundations are serious, directly affecting the stability and safety of the upper structure. To solve this problem, it is necessary to reinforce the defective pile foundations. Usually, the chemical grouting method is used for reinforcement. The chemical grouting method has strict requirements for the construction process and is not easy to implement. And the chemical grouting materials are usually synthetic polymer materials, such as epoxy resin, polyurethane, etc. The production processes of these materials are complex and the raw material costs are high, which leads to a relatively high overall grouting cost. Chemical slurries usually contain certain toxicity and will pollute the surrounding soil and groundwater after grouting, threatening the lives and health of the surrounding people. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to propose a method for reinforcing defective pile bodies based on the MICP principle, so as to solve the problems of the existing pile foundation reinforcement technology being time-consuming, labor-consuming, highly polluting, and having high raw material prices.

[0004] In order to achieve the above technical purpose, the technical solution adopted by the present application is: A method for reinforcing defective pile bodies based on the MICP principle, applicable to defective piles. The defective piles include pile bodies and pile tops. The method includes:

[0005] Exciting the defective pile using the low-strain reflected wave method and collecting the first vibration response signal of the pile top;

[0006] Performing time-domain reflected wave phase change and wave velocity anomaly analysis on the first vibration response signal to generate pile body defect information. The pile body defect information includes the defect type, defect position, and defect size of the defect area in the defective pile;

[0007] Generating slurry parameters and grouting parameters according to the pile body defect information. The slurry parameters include the mixing ratio information of the slurry, and the grouting parameters include the grouting volume, grouting position, and the layout information of the grouting pipeline;

[0008] Preparing the MICP slurry according to the slurry parameter ratio, and arranging a grouting pipeline network system on the circumference of the pile body according to the grouting parameters. The grouting pipeline network system includes a grouting pipeline, a grouting pump, and a regulating valve group;

[0009] Controlling the grouting pump to pump the MICP slurry into the grouting pipeline so that the MICP slurry enters the defect area of the pile body from the grouting pipeline, and synchronously obtaining a feedback signal;

[0010] Input the feedback signal into the PID control algorithm to obtain the feedback adjustment parameter, and control the opening degree of the regulating valve group according to the feedback adjustment parameter until the grouting in the defective area is completed;

[0011] After the grouting is completed, perform low-strain reflected wave method detection on the pile body at a preset frequency, and collect the second vibration response signal at the pile top;

[0012] Generate grouting effect evaluation information according to the second vibration response signal.

[0013] In some embodiments, exciting a defective pile using the low-strain reflected wave method and collecting the first vibration response signal at the pile top includes:

[0014] Arrange a plurality of sensors on the surface of the pile top, and the sensors are evenly distributed in a ring shape;

[0015] Taking the center of the pile top as the excitation point, use a force hammer to apply transient impact excitation to the excitation point, and control the impact strength and duration;

[0016] Record the impact trigger moment of the force hammer, and synchronously trigger the acceleration sensor to collect the vibration response signal at the pile top;

[0017] Record the time-domain signal collected by the acceleration sensor according to the preset sampling frequency;

[0018] Align the time-domain signal with the impact trigger moment as the reference;

[0019] Calculate the wave velocity value according to the distance from the acceleration sensor to the excitation point and the arrival time of the direct wave;

[0020] Perform consistency verification on the wave velocity value. When the wave velocity dispersion does not exceed the preset wave velocity threshold, determine that the time-domain signal is valid and record it as the first vibration response signal.

[0021] In some embodiments, performing time-domain reflected wave phase change and wave velocity anomaly analysis on the first vibration response signal to generate pile body defect information includes:

[0022] Preprocess the first vibration response signal to obtain the first processed signal;

[0023] Align the first processed signal in the time domain and calculate the time difference information of the same stress wave in multiple first processed signals;

[0024] Construct a defect position equation according to the time difference information and solve it to obtain the defect position in the defective area;

[0025] And extract the incident wave signal and the reflected wave signal from the first processed signal;

[0026] Convert the incident wave signal and the reflected wave signal to obtain the reflected wave characteristic parameters, which include the arrival time of the reflected wave, the amplitude ratio of the reflected wave, and the phase difference of the reflected wave;

[0027] Convert the defect size and defect type according to the reflected wave characteristic parameters;

[0028] Generate pile body defect information based on the defect position, defect size, and defect type.

[0029] In some embodiments, generating the slurry parameters according to the pile body defect information includes:

[0030] Construct a mapping relationship between the pile body defect information and the slurry parameters, which is represented by formula (1), and formula (1) is as follows:

[0031]

[0032] In formula (1), Z0 is the wave impedance of the complete pile body, Z d is the wave impedance of the defect area, ΔZ is the wave impedance change amount, k is the microbial mineralization rate, C b is the bacterial solution concentration, S v is the effective reaction specific surface area;

[0033] Construct an expression for the total amount of slurry and the defect volume in the defect area, which is represented by formula (2), and formula (2) is as follows:

[0034]

[0035] In formula (2), Q is the total amount of slurry, V d is the defect volume, and α is the slurry diffusion compensation coefficient;

[0036] Construct an environmental parameter adjustment equation, which is represented by formula (3), and formula (3) is as follows:

[0037]

[0038] In formula (3), R u is the urea hydrolysis rate, β is the hydrolysis reaction constant, E a is the reaction activation energy, k ′ is the microbial mineralization rate under the influence of temperature.

[0039] Construct an optimization function for the slurry parameters, which is represented by formula (4), and formula (4) is as follows:

[0040]

[0041] In formula (4), ΔZ actual is the actual impedance change amount, ΔZ targetis the target compensation amount, ΔZ target = ΔZ; T opt is the optimal reaction temperature, and λ is the weight coefficient ||ΔZ actual -ΔZ target || represents the mineralization effect, and ||T - T opt || represents the temperature control;

[0042] Obtain the optimized slurry parameters.

[0043] In some embodiments, the MICP slurry obtained according to the slurry parameter ratio includes:

[0044] Place the bacterial solution of Bacillus pasteurii in a constant temperature environment for activation, and the activation temperature range is 20°C - 35°C;

[0045] Configure the concentration of the cementing liquid components, which is represented by formula (5), and formula (5) is as follows:

[0046]

[0047] In formula (5), C urea is the urea concentration, is the calcium ion concentration, ξ1 is the first proportionality coefficient, ξ2 is the second proportionality coefficient, and t r is the expected reaction time,

[0048] Configure the nutrient solution containing yeast extract and peptone, and the configured concentration of the nutrient solution is represented by formula (6), and formula (6) is as follows:

[0049] C nutr = ξ3·C b ·S v ;

[0050] In formula (6), C nutr is the configured concentration of the nutrient solution, and ξ3 is the third proportionality coefficient;

[0051] Mix and prepare the activated bacterial solution, cementing liquid, and nutrient solution according to the slurry parameters to obtain the MICP slurry.

[0052] In some embodiments, the grouting parameters generated according to the pile body defect information include:

[0053] Construct the spatial mapping relationship between the pile body defect information and the grouting pipeline network system, and generate the functional relationship between the grouting pressure and the pile body defect information;

[0054] Generate the layout information of the grouting pipeline and the grouting position according to the spatial mapping relationship, and the layout information includes the number of grouting pipelines and the position of a single grouting pipeline;

[0055] Generate the grouting flow rate of a single grouting pipeline and the grouting pressure of a single grouting pipeline according to the functional relationship between the grouting pressure and the pile body defect information;

[0056] Generate grouting parameters according to the layout information, grouting position, grouting flow rate of a single grouting pipeline, and grouting pressure of a single grouting pipeline.

[0057] In some embodiments, the feedback signal includes a real-time flow signal and a real-time pressure signal;

[0058] Input the feedback signal into the PID control algorithm to obtain feedback adjustment parameters including:

[0059] Calculate the first deviation value between the real-time flow signal and the preset flow signal, and calculate the second deviation value between the real-time pressure signal and the preset pressure signal;

[0060] Match the preset PID control mode according to the defect type, denoted as the first control mode;

[0061] Obtain the viscosity change rate of the MICP slurry, and generate the adjustment frequency of the first control mode according to the viscosity change rate;

[0062] Generate feedback adjustment parameters according to the first deviation value and the second deviation value. The feedback adjustment parameters include at least one of the offset weight, integral time, and differential time;

[0063] Adjust the first control mode according to the adjustment frequency.

[0064] In some embodiments, generating grouting effect evaluation information according to the second vibration response signal includes:

[0065] Compare the time-domain waveforms of the second vibration response signal and the first vibration response signal to obtain a comparison result, and the comparison result includes the change amount of the reflected wave amplitude and the change amount of the reflected wave phase;

[0066] And, recalculate the wave velocity of the pile body according to the second vibration response signal, denoted as the detected pile body wave velocity;

[0067] And, calculate the impedance value of the defect area according to the second vibration response signal, denoted as the detected impedance value;

[0068] Generate grouting effect evaluation information from the comparison result, the detected pile body wave velocity, and the detected impedance value.

[0069] Adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are:

[0070] The above technical solution uses the low-strain reflected wave method to excite defective piles and collect the first vibration response signal at the pile top, analyzes the phase and wave velocity anomalies of the time-domain reflected wave to determine the pile body defect information; generates slurry parameters and grouting parameters based on the pile body defect information, configures MICP slurry, and arranges a grouting network system including grouting pipelines, grouting pumps, and regulating valve groups circumferentially around the pile body; injects the slurry into the defective area through the grouting pump, synchronously collects feedback signals, and dynamically adjusts the opening of the regulating valve group using the PID algorithm to optimize the grouting process; after grouting, regularly uses the low-strain reflected wave method to detect the second vibration response signal at the pile top, and compares and analyzes to generate grouting effect evaluation information. This method realizes the efficient filling of pile body defects by calcium carbonate crystals through accurate defect positioning, intelligent regulation of grouting parameters, and real-time feedback correction, improves the overall strength and bearing performance of the pile foundation, and has strong pertinence, high automation, and good environmental compatibility. Description of the Drawings

[0071] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0072] Figure 1 It is a schematic diagram of the steps from step S101 to step S108 of the method for strengthening defective pile bodies based on the MICP principle described in the specific implementation manner;

[0073] Figure 2 It is a schematic diagram of the first longitudinal section of the grouting device described in the specific implementation manner;

[0074] Figure 3 It is a schematic diagram of the second longitudinal section of the grouting device described in the specific implementation manner;

[0075] Figure 4 It is a schematic diagram of the third longitudinal section of the grouting device described in the specific implementation manner;

[0076] Figure 5 It is a top view of the grouting network system described in the specific implementation manner;

[0077] Figure 6 It is a structural diagram of the grouting pipeline described in the specific implementation manner;

[0078] Figure 7 It is a structural diagram of the nut described in the specific implementation manner;

[0079] Figure 8 It is a technical flow chart of the method for strengthening defective pile bodies based on the MICP principle described in the specific implementation manner;

[0080] The description of the drawings is as follows:

[0081] 1. Pile body;

[0082] 2. Grouting pipeline network system;

[0083] 21. Grouting pipeline;

[0084] 211. Grouting hole;

[0085] 212. Grouting leg;

[0086] 213. Nut;

[0087] 214. Nut with 75mm hole opening;

[0088] 215. Nut with 50mm hole opening;

[0089] 22. Grouting pump;

[0090] 23. Control valve group;

[0091] 3. Grouting bucket;

[0092] 31. Temperature controller. Specific implementation manners

[0093] The present invention will be further described in detail below with reference to the drawings and embodiments. It should be specifically noted that the following embodiments are only used to illustrate the present invention, but do not limit the scope of the present invention. Similarly, the following embodiments are only partial embodiments of the present invention rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0094] Please refer to Figures 1 to 7 , this embodiment provides a method for strengthening defective pile bodies based on the MICP principle, which is applicable to defective piles. The defective piles include pile bodies and pile tops. The method includes:

[0095] S101. Excite the defective pile using the low-strain reflected wave method and collect the first vibration response signal of the pile top;

[0096] S102. Analyze the phase change and wave velocity anomaly of the first vibration response signal in the time domain to generate pile body defect information. The pile body defect information includes the defect type, defect position, and defect size of the defect area in the defective pile;

[0097] S103. Generate slurry parameters and grouting parameters according to the pile body defect information. The slurry parameters include the mixing ratio information of the slurry, and the grouting parameters include the grouting volume, grouting position, and layout information of the grouting pipeline;

[0098] S104. Obtain the MICP slurry according to the slurry parameter ratio, and arrange a grouting pipe network system circumferentially on the pile body according to the grouting parameters. The grouting pipe network system includes a grouting pipeline, a grouting pump, and a regulating valve group;

[0099] S105. Control the grouting pump to pump the MICP slurry into the grouting pipeline so that the MICP slurry enters the defective area of the pile body from the grouting pipeline, and synchronously obtain a feedback signal;

[0100] S106. Input the feedback signal into the PID control algorithm to obtain a feedback adjustment parameter, and control the opening degree of the regulating valve group according to the feedback adjustment parameter until the grouting of the defective area is completed;

[0101] S107. After the grouting is completed, perform low-strain reflected wave method detection on the pile body at a preset frequency, and collect the second vibration response signal at the pile top;

[0102] S108. Generate grouting effect evaluation information according to the second vibration response signal.

[0103] In step S101, the low-strain reflected wave method is a technique for testing the integrity of pile body 1 (such as pile shaft defects like necking, bulging, broken pile, segregation, etc.) based on the characteristics of the elastic response signal, wave velocity, acceleration process, initial velocity value of admittance curve, amplitude spectrum, power spectrum, base spectrum, elastic deformation, penetration degree, etc. measured at the pile top when the pile body 1, the soil around the pile, and the soil at the pile bottom are excited to vibrate. The first vibration response signal is the acceleration or velocity response signal at the pile top.

[0104] In step S102, preferably, the first wave, pile bottom reflection, and abnormal reflections (such as necking, bulging, fracture, etc.) of the reflected wave signal can be observed through time-domain analysis, supplemented by frequency-domain analysis to analyze the spectral characteristics through Fourier transform, identify the resonant frequency, and comprehensively determine the defect type, defect location, and defect size through the phase change of the time-domain reflected wave, combined with wave velocity anomaly analysis and multiple reflections.

[0105] In step S103, the grouting liquid is preferably a microbial liquid and a cementing liquid mixed according to the volume ratio of urea to calcium salt of 1:1. After adding nutrients, a chemical reaction occurs to generate calcium carbonate crystals, continuously filling the defective part, thereby enhancing the integrity and strength of the pile foundation, and also improving the bearing capacity and impermeability of the pile foundation.

[0106] The selection ranges of the slurry parameters and the grouting parameters can refer to the following table:

[0107]

[0108] It should be noted that the above parameters are for reference only, and in actual applications, they need to be optimized and adjusted according to specific engineering situations, geological conditions, material properties, etc.

[0109] In step S104, refer to Figure 2 , the defect of the defective pile in the figure is necking; refer to Figure 3 , the defect of the defective pile in the figure is segregation and mud inclusion; refer to Figure 4 , the defect of the defective pile in the figure is broken pile. A grouting device is arranged in the pile foundation defect area to be reinforced. The grouting device includes a grouting pipeline network system 2 and a grouting bucket 3, and pressure grouting is carried out through the grouting device. The microbial bacterial liquid and the cementing liquid used for grouting are respectively placed in bucket A and bucket B, and the microbial bacterial liquid and the cementing liquid are input into the grouting bucket 3 containing nutrients through pipelines and stirred for one hour until the microorganisms and the nutrients are fully mixed. The grouting bucket 3 is connected to the grouting pump 22 of the grouting pipeline network system 2 through a pipeline, and pressure grouting is carried out through the grouting pump 22 connected to the grouting bucket 3. A temperature controller 31 is attached to the outside of the grouting bucket 3, and the ambient temperature in the grouting bucket 3 is adjusted by heating and refrigeration methods so that the ambient temperature in the grouting bucket 3 is maintained within 20°C to 35°C.

[0110] The grouting pipeline network system 2 includes a grouting pipeline 21, a grouting pump 22 and a regulating valve group 23. A through hole passing through the pile body 1 is provided in the pile foundation defect area to be reinforced, and the grouting pipeline 21 is directly attached to the pile body 1 in the pile foundation defect area to be reinforced. The grouting pipeline 21 includes a grouting hole 211, a grouting leg 212 and a nut 213, and the grouting pipeline 21 is preferably a PE pipe. The bottom of the grouting pipeline 21 is a conical grouting leg 212, and the grouting pipeline 21 is inserted into the soil through the grouting leg 212. A number of grouting holes 211 are evenly arranged on the grouting pipeline 21. The grouting holes 211 can be closed by the nut 213 to ensure that the slurry does not flow out during grouting, and the redundant grouting holes 211 can be closed according to the detected position of the pile foundation defect. The nut 213 also includes a nut 214 with an opening of 75 mm and a nut 215 with an opening of 50 mm. The accuracy of grouting is adjusted by adding nuts 213 with different apertures. The grouting pipeline 21 is inserted into the through hole passing through the pile body 1, and the grouting holes 211 on the grouting pipeline 21 are closely attached to the position of the pile foundation defect, ensuring that the bacterial liquid and the cementing liquid can accurately flow to the area to be reinforced, ensuring that when grouting, the slurry can be injected into these specific defect areas, and can be closed with nuts 213 with different apertures, effectively controlling the diffusion range of the slurry, ensuring accurate reinforcement of the defective part of the pile foundation, and avoiding problems such as slurry leakage and gushing due to excessive slurry flow.

[0111] The grouting pipe network system 2 includes a plurality of grouting pipelines 21, and the plurality of grouting pipelines 21 are inserted into the soil in a circular distribution along the area to be reinforced for the pile foundation defects. A number of grouting holes 211 are evenly formed on each grouting pipeline 21. The number of grouting holes 211 is closed by nuts 213 for reinforcing the position of the pile foundation defect. Adjacent two grouting pipelines 21 are connected by grouting pipe connectors to form the grouting pipe network system 2 with a ring structure. The diameters of all the grouting holes 211 on each grouting pipeline 21 are the same, and all the grouting holes 211 are evenly distributed at a certain distance interval.

[0112] The regulating valve group 23 is used to adjust the slurry flow rate. The regulating valve group 23 includes a plurality of regulating valves. The plurality of regulating valves are respectively arranged on the connecting pipelines between the grouting pump 22 and the grouting pipe network system 2 and on each grouting pipeline 21. The valve plate is rotated according to the depth and severity of the defect position to adjust the slurry flow rate for precise grouting. The equal percentage or linear flow characteristics of the regulating valve determine the non-linear relationship between the opening and the flow rate, and the type selection needs to be combined with the characteristics of the regulating valve. Preferably, the regulating valve is a butterfly throttle valve for controlling the slurry flow rate. The size of the flow rate regulated by the butterfly throttle valve is controlled by changing the rotation angle of the valve plate to adjust the cross-sectional area of the flow channel. The material of the regulating valve is preferably wear-resistant materials such as rubber-lined, fluorine-lined butterfly valves or hard alloy coatings to avoid slurry abrasion.

[0113] In steps S105 to S106, preferably, an electric / pneumatic actuator (supporting 4-20 mA signal or PID feedback) receives the feedback signal and automatically adjusts the opening of the regulating valve group 23 to further adjust the flow rate. The opening of the regulating valve group 23 is 0°-90°, and usually the adjustment accuracy is relatively high in the opening range of 30°-70°. It should be noted that when the opening is <20%, it is easy to cause high-speed slurry to erode the edge of the valve plate, and the throttle orifice plate can be combined for step-down pressure. Preferably, an electromagnetic flowmeter or an ultrasonic flowmeter is installed behind the regulating valve to provide real-time feedback for adjustment.

[0114] Preferably, the feedback adjustment parameters include real-time flow data and valve state feedback. The real-time flow data can directly measure the slurry flow rate (unit: m 3 / h or L / min) through an electromagnetic / ultrasonic flowmeter; the valve state feedback includes the opening signal, the actuator state and the pressure difference. The opening signal feeds back the valve plate position through a potentiometer or an encoder; the actuator state such as torque alarm and fault signal; the pressure difference is detected by pressure sensors before and after the valve, reflecting the change of the flow resistance. By comparing the flow rate set value with the measured value and calculating the correction amount using the PID algorithm, it is possible to dynamically adjust the flow rate according to the ratio, maintain a constant flow rate for pipeline transportation, and prevent settlement.

[0115] In this embodiment, the low-strain reflected wave method is used to accurately analyze the phase change of the time-domain reflected wave and the wave velocity anomaly. Combining the time-frequency domain signal characteristics, the defect type, defect location, and defect size of the pile body 1 are comprehensively determined, providing a reliable basis for formulating grouting parameters. Based on the defect information, the ratios of microbial bacterial liquid, cementing liquid, and grouting volume are dynamically matched, and multi-path precise grouting is realized through the annularly arranged grouting pipeline network system 2. The grouting pipeline 21 adopts a PE pipe structure with a conical grouting leg 212, and the grouting hole 211 is closed with a nut 213 with an adjustable aperture, which can not only deliver the slurry to the defect area in a targeted manner but also control the diffusion range, effectively avoiding slurry leakage and gushing. The PID control algorithm is used to collect the feedback signals of flow rate, valve state, and pressure difference in real time, and the opening of the butterfly throttle valve is dynamically adjusted to maintain a constant grouting flow rate. Combining hierarchical decompression and wear-resistant valve body materials ensures the stability and controllability of the grouting process. The crystals generated by the microbial-induced calcium carbonate precipitation reaction are used to fill the defect voids, and the reinforcement effect is evaluated by periodic reflected wave detection. Finally, the precise positioning, intelligent control, and traceability of the pile body defect repair are realized, significantly improving the overall strength and bearing performance of the pile foundation.

[0116] In some embodiments, the defective pile is excited using the low-strain reflected wave method, and the first vibration response signal at the pile top is collected, including:

[0117] A plurality of sensors are arranged on the surface of the pile top, and the sensors are evenly distributed in a ring shape;

[0118] Taking the center of the pile top as the excitation point, a force hammer is used to apply a transient impact excitation to the excitation point, controlling the impact force and duration;

[0119] The impact trigger moment of the force hammer is recorded, and the acceleration sensor is synchronously triggered to collect the vibration response signal at the pile top;

[0120] The time-domain signal collected by the acceleration sensor is recorded according to the preset sampling frequency;

[0121] Taking the impact trigger moment as the reference, the time-domain signal is time-aligned;

[0122] According to the distance from the acceleration sensor to the excitation point and the arrival time of the direct wave, the wave velocity value is calculated;

[0123] The wave velocity value is subjected to consistency verification. When the wave velocity dispersion does not exceed the preset wave velocity threshold, the time-domain signal is determined to be valid and is recorded as the first vibration response signal.

[0124] In this embodiment, a plurality of sensors are arranged at the center of the pile top or at a distance of 2 / 3 of the radius from the center. A coupling agent such as vaseline or gypsum, or a magnetic base can be used to tightly couple the sensor and the pile body. Ensure that the sensor axis is parallel to the pile axis to avoid tilting.

[0125] Implement transient impact excitation by vertically hitting the excitation point on the pile top with a force hammer, and avoid continuous hitting or trailing. Preferably, the excitation point is close to the sensor installation position, with a distance of about 5 - 10 cm.

[0126] Collect the acceleration or velocity response signal (i.e., vibration response signal) of the pile top, and the sampling frequency needs to satisfy the Nyquist theorem (usually ≥10 kHz).

[0127] Repeat the excitation multiple times (preferably 3 - 5 times), eliminate abnormal signals, and ensure data consistency.

[0128] In this embodiment, the pile top surface is covered by multiple sensors evenly distributed in a ring, combined with the transient impact excitation of the central excitation point, to ensure the comprehensiveness and symmetry of vibration signal acquisition; use a force hammer to vertically hit and precisely control the impact force and trigger moment, synchronously trigger the acceleration sensor to collect signals, effectively suppress the interference of continuous hitting or trailing, and improve the time-domain alignment accuracy of the excitation and response signals; record the time-domain signal through the preset sampling frequency to ensure signal integrity and resolution; perform time-domain alignment based on the impact trigger moment, calculate the wave velocity value by combining the distance from the sensor to the excitation point and the arrival time of the direct wave, and screen out the effective signals with the wave velocity dispersion meeting the preset threshold through consistency verification to improve the reliability of defect analysis; use repeated excitation multiple times and eliminate abnormal data, and fix the axial direction of the sensor parallel to the pile body with a coupling agent to reduce signal distortion caused by installation tilt or poor contact, and ensure the repeatability and consistency of the first vibration response signal, providing a high-precision data basis for subsequent defect location and parameter inversion.

[0129] In some embodiments, perform time-domain reflected wave phase change and wave velocity anomaly analysis on the first vibration response signal to generate pile body defect information including:

[0130] Preprocess the first vibration response signal to obtain the first processed signal;

[0131] Perform time-domain alignment on the first processed signal and calculate the time difference information of the same stress wave in multiple first processed signals;

[0132] Construct a defect position equation based on the time difference information and solve it to obtain the defect position in the defect area;

[0133] In addition, extract the incident wave signal and reflected wave signal from the first processed signal;

[0134] Convert the incident wave signal and reflected wave signal to obtain the reflected wave characteristic parameters, and the reflected wave characteristic parameters include the arrival time of the reflected wave, the amplitude ratio of the reflected wave, and the phase difference of the reflected wave;

[0135] Convert the defect size and defect type according to the reflected wave characteristic parameters;

[0136] Generate pile body defect information based on the defect location, defect size, and defect type.

[0137] In this embodiment, by preprocessing the first vibration response signal, environmental noise and baseline drift interference are eliminated, the signal-to-noise ratio is improved, and a high-fidelity first processed signal is obtained; based on the time-domain alignment technology, multiple first processed signals are calibrated in time reference, the time difference information of the same stress wave propagating in the pile body is accurately calculated, the error caused by the excitation trigger deviation is reduced, and a reliable time reference is provided for subsequent defect location; according to the time difference information, a defect location equation is constructed and solved, combined with the relationship between the stress wave propagation path and wave velocity, the quantitative inversion of the spatial position of the defect area is realized, and the defect location accuracy is improved; by extracting the characteristics of the incident wave signal and the reflected wave signal, the direct wave, defect reflected wave, and pile bottom reflected wave are accurately separated, and combined with characteristic parameters such as the arrival time, amplitude ratio, and phase difference of the reflected wave, a mapping relationship between the reflected wave characteristics and the physical properties of the defect is established, and the defect size and defect type are quantitatively converted; finally, multi-dimensional pile body defect information is generated by integrating the defect location, size, and type, forming a full-process closed loop from signal acquisition, feature analysis to defect analysis, significantly improving the accuracy and comprehensiveness of pile foundation defect detection, and providing high-precision data support for the formulation of subsequent grouting reinforcement parameters.

[0138] In some embodiments, generating the slurry parameters according to the pile body defect information includes:

[0139] Construct a mapping relationship between the pile body defect information and the slurry parameters, which is represented by formula (1). Formula (1) is as follows:

[0140]

[0141] In formula (1), Z0 is the wave impedance of the complete pile body, Z d is the wave impedance of the defect area, ΔZ is the wave impedance change amount, k is the microbial mineralization rate, C b is the bacterial solution concentration, S v is the effective reaction specific surface area;

[0142] Construct an expression for the total slurry volume and the defect volume in the defect area, which is represented by formula (2). Formula (2) is as follows:

[0143]

[0144] In formula (2), Q is the total slurry volume, V d is the defect volume, and α is the slurry diffusion compensation coefficient;

[0145] Construct an environmental parameter adjustment equation, which is represented by formula (3). Formula (3) is as follows:

[0146]

[0147] In formula (3), R u is the urea hydrolysis rate, β is the hydrolysis reaction constant, and E a is the activation energy of the reaction, and k ′ is the microbial mineralization rate under the influence of temperature.

[0148] Construct a slurry parameter optimization function, which is expressed by formula (4). Formula (4) is as follows:

[0149]

[0150] In formula (4), ΔZ actual is the actual impedance change, ΔZ target is the target compensation amount, and ΔZ target = ΔZ; T opt is the optimal reaction temperature, λ is the weight coefficient, ||ΔZ actual -ΔZ target || represents the mineralization effect, and ||T - T opt || represents the temperature control;

[0151] Obtain the optimized slurry parameters.

[0152] In this embodiment, first establish a quantization model for the defect impedance change ΔZ. In the formula, Z0 = ρ0C0, where ρ0 is the density and C0 is the wave velocity; then construct a microbial mineralization rate equation to find In the formula, r is the defect pore radius, is the porosity.

[0153] Express the total slurry amount and the defect volume expression in the defect area through formula (2) to calculate the slurry dosage.

[0154] Express the environmental parameter adjustment equation through formula (3) to perform environmental parameter coupling adjustment. In the formula, [OH - = 10 pH -14 is the hydroxide ion concentration.

[0155] Express the slurry parameter optimization function through formula (4) and solve to obtain the optimal slurry parameter combination. In the formula, ΔZ target directly inherits the wave impedance change ΔZ from formula (1) and is calculated through formula (1) and formula (2); T opt is determined by the extreme value condition of formula (3) determined.

[0156] In this embodiment, by constructing a quantitative mapping relationship between the pile body defect information and the slurry parameters, establishing a dynamic equation of the change in wave impedance with the microbial mineralization rate, the concentration of the bacterial solution, and the effective reaction specific surface area, accurately correlating the defect impedance characteristics with the microbial reaction process; combining the defect volume and the diffusion compensation coefficient to quantify the distribution requirements of the total slurry amount, avoiding insufficient or excessive slurry perfusion; regulating the urea hydrolysis rate and the mineralization rate by coupling environmental parameters to optimize the microbial activity and reaction efficiency; constructing a multi-objective optimization function to synchronously balance the deviation between the actual impedance compensation amount and the target and the deviation between the temperature and the optimal temperature, and solving the optimal combination of the bacterial solution concentration and temperature parameters through the extreme value condition to achieve the adaptive matching of the slurry parameters; finally, forming a full-chain model from defect impedance quantification, slurry dosage calculation, environmental parameter adjustment to multi-objective optimization, significantly improving the scientificity of the slurry ratio and the reliability of the repair effect, and providing an accurate decision-making basis for microbial-induced mineralization reinforcement.

[0157] In some embodiments, the MICP slurry obtained according to the slurry parameter ratio includes:

[0158] Placing the bacterial solution of Bacillus pasteurii in a constant temperature environment for activation, and the activation temperature range is 20°C - 35°C;

[0159] Configuring the concentration of the cementing liquid components, which is represented by formula (5), and formula (5) is as follows:

[0160]

[0161] In formula (5), C urea is the urea concentration, is the calcium ion concentration, ξ1 is the first proportionality coefficient, ξ2 is the second proportionality coefficient, t r is the expected reaction time,

[0162] Configuring a nutrient solution containing yeast extract and peptone, and the configured concentration of the nutrient solution is represented by formula (6), and formula (6) is as follows:

[0163] C nutr = ξ3·C b ·S v ;

[0164] In formula (6), C nutr is the configured concentration of the nutrient solution, and ξ3 is the third proportionality coefficient;

[0165] Mixing and preparing the activated bacterial solution, the cementing liquid, and the nutrient solution according to the slurry parameters to obtain the MICP slurry.

[0166] In this embodiment, placing the Bacillus pasteurii bacterial solution in a constant temperature environment for activation, and the activation temperature T satisfies T min ≤T≤T max , where Tmin and T max are determined according to the temperature control range in the slurry parameters respectively.

[0167] Determine the concentration of the cementing liquid components according to formula (5), and prepare the nutrient solution containing yeast extract and peptone through formula (6).

[0168] Mix the activated bacterial liquid, the cementing liquid and the nutrient medium according to the volume ratio in the slurry parameters, and control the temperature T of the mixed liquid mix to satisfy:

[0169]

[0170] wherein, δ is the reaction heat release coefficient, η is the heat dissipation coefficient, and T env is the ambient temperature.

[0171] In this embodiment, by setting the activation temperature range of the Bacillus pasteurii bacterial liquid and combining with the temperature control requirements in the slurry parameters, the activity of the bacterial strain is ensured to be adapted to the requirements of the mineralization reaction; a quantitative relationship between the components of the cementing liquid and the expected reaction time, the change in wave impedance and the defect volume is established, improving the scientificity and pertinence of the cementing liquid ratio; by dynamically associating the nutrient solution concentration with the bacterial liquid concentration and the effective reaction specific surface area, the coordinated optimization of the microbial metabolism efficiency and the mineralization reaction process is ensured; the reaction heat release and heat dissipation balance is adjusted in real time by using the mixed liquid temperature control equation, maintaining the stability of the mixed liquid temperature, and avoiding overheating or low temperature from inhibiting the mineralization reaction; finally, through the parametric ratio and dynamic temperature control of the activated bacterial liquid, the cementing liquid and the nutrient solution, the efficient preparation of the MICP slurry is realized, ensuring the reliability of the microbial-induced mineralization process and the uniformity of the repair effect.

[0172] In some embodiments, generating the grouting parameters according to the pile body defect information includes:

[0173] Construct the spatial mapping relationship between the pile body defect information and the grouting pipe network system, and generate the functional relationship between the grouting pressure and the pile body defect information;

[0174] Generate the layout information of the grouting pipeline and the grouting position according to the spatial mapping relationship, and the layout information includes the number of grouting pipelines and the position of a single grouting pipeline;

[0175] Generate the grouting flow rate of a single grouting pipeline and the grouting pressure of a single grouting pipeline according to the functional relationship between the grouting pressure and the pile body defect information;

[0176] Generate the grouting parameters according to the layout information, the grouting position, the grouting flow rate of a single grouting pipeline and the grouting pressure of a single grouting pipeline.

[0177] In this embodiment, constructing the spatial mapping relationship between the pile body defect information and the grouting pipe network system is represented by formula (7) as follows:

[0178]

[0179] Among them, (x d , y d , z d ) is the defect center coordinate, Δt ij is the time difference between the reflected waves of sensors i and j, C0 is the wave velocity of the pile body, and τ is the time delay of the reflected wave.

[0180] The functional relationship between the grouting pressure P and the pile body defect information is expressed by formula (8) as follows:

[0181]

[0182] Among them, P0 is the initial pressure, γ is the rheological coefficient of the grout, μ is the viscosity of the grout, K is the defect permeability, and t r is the expected filling time.

[0183] The layout information parameters of the designed grouting pipeline are expressed by formula (9) as follows:

[0184]

[0185] Among them, n is the number of grouting pipes, L d is the longitudinal length of the defect, r ′ is the effective diffusion radius, Q i is the grouting flow rate of a single grouting pipeline, and ΔZ i is the local impedance change.

[0186] Furthermore, a grouting process feedback regulation equation is established to generate dynamic regulation parameters. The grouting process feedback regulation equation is expressed by formula (10) as follows:

[0187]

[0188] Among them, k p , k i are the regulation coefficients, P target is the target pressure value, and P actual is the real-time monitored pressure.

[0189] Finally, a grouting parameter set including the following elements is generated: the spatial coordinates of the grouting pipeline network (x i , y i , z i ), the graded grouting pressure sequence [P1, P2,..., P n , the dynamic flow rate regulation function Q(t), and the grouting termination condition F(V d , P, ΔZ).

[0190] Based on the time difference of reflected waves and wave velocity, this embodiment constructs a spatial mapping relationship of the coordinates of the defect center to accurately locate the layout position of the grouting pipeline network; through the coupling relationship among the defect volume, slurry viscosity and permeability, an adaptive function model of grouting pressure is established to ensure the matching of pressure and defect characteristics; combined with the longitudinal length of the defect and the diffusion radius, the number and flow rate of the grouting pipelines 21 are dynamically allocated to optimize the distribution of grouting resources; the feedback adjustment equation is used to correct the flow deviation in real time to maintain pressure stability; finally, a parameter set including spatial coordinates, hierarchical pressure, dynamic flow function and termination conditions is generated to realize the precision and adaptive control of the grouting process.

[0191] In some embodiments, the feedback signal includes a real-time flow signal and a real-time pressure signal;

[0192] The feedback signal is input into the PID control algorithm, and the obtained feedback adjustment parameters include:

[0193] Calculate the first deviation value between the real-time flow signal and the preset flow signal, and calculate the second deviation value between the real-time pressure signal and the preset pressure signal;

[0194] Match the preset PID control mode according to the defect type, denoted as the first control mode;

[0195] Obtain the viscosity change rate of the MICP slurry, and generate the adjustment frequency of the first control mode according to the viscosity change rate;

[0196] Generate feedback adjustment parameters according to the first deviation value and the second deviation value, and the feedback adjustment parameters include at least one of offset weight, integral time and differential time;

[0197] Adjust the first control mode according to the adjustment frequency.

[0198] In this embodiment, the feedback adjustment parameters include a real-time flow signal and a real-time pressure signal. The real-time flow signal can directly measure the slurry flow velocity through an electromagnetic / ultrasonic flowmeter (unit: m 3 / h or L / min); the real-time pressure signal is detected by a pressure sensor to reflect the change of flow resistance. By comparing the real-time flow signal with the preset flow signal, the correction amount is calculated using the PID algorithm.

[0199] When the second deviation value exceeds the limit, the opening degree is restricted (such as preventing water hammer). Select the opening degree with the smallest second deviation value under the condition of meeting the flow rate, such as using a variable frequency pump for coordination adjustment.

[0200] Generate the adjustment frequency of the first control mode according to the viscosity change rate, and reduce the flow velocity when the slurry concentration is too high to reduce wear.

[0201] In this embodiment, by synchronously collecting real-time flow signals and pressure signals and calculating deviations, the dynamic changes of slurry transportation are accurately identified; based on the defect type, a preset PID control mode is matched and the viscosity change rate is associated to generate the adjustment frequency, realizing the adaptive coupling of control parameters and slurry rheological characteristics; through the dynamic adjustment of bias weight, integral time, and differential time, the response speed and stability of the PID algorithm are optimized; combined with the variable-frequency pump adjustment and opening limit mechanism, under the condition of meeting the preset flow rate, the control strategy with the smallest pressure deviation is preferentially selected to effectively suppress the water hammer phenomenon; according to the change of slurry concentration, the flow rate is actively adjusted to reduce the risk of pipeline wear, ensuring the efficiency of the grouting process and the durability of the equipment, and finally realizing the refined closed-loop control of MICP slurry transportation.

[0202] In some embodiments, generating the grouting effect evaluation information according to the second vibration response signal includes:

[0203] Comparing the time-domain waveforms of the second vibration response signal and the first vibration response signal to obtain a comparison result, where the comparison result includes the change amount of the reflected wave amplitude and the change amount of the reflected wave phase;

[0204] And, recalculating the wave velocity of the pile body according to the second vibration response signal, denoted as the detected pile body wave velocity;

[0205] And, calculating the impedance value of the defect area according to the second vibration response signal, denoted as the detected impedance value;

[0206] Generating the grouting effect evaluation information from the comparison result, the detected pile body wave velocity, and the detected impedance value.

[0207] In this embodiment, by comparing the differences in the time-domain waveforms of the vibration response signals before and after grouting, the change amount of the reflected wave amplitude and the change amount of the phase are extracted to accurately capture the change in the structural interface characteristics caused by grouting and intuitively reflect the grouting filling effect; based on the second vibration response signal, the detected pile body wave velocity is recalculated, and the degree of recovery of the overall density of the pile body is quantitatively evaluated through the change in wave velocity to verify the repair effect of grouting on the integrity of the pile body; combined with the dynamic calculation of the detected impedance value in the defect area, a direct correlation between the change in impedance value and the grouting density is established to comprehensively characterize the improvement effect of the physical characteristics of the defect area; finally, by fusing three key parameters: the comparison result, the detected pile body wave velocity, and the detected impedance value, a multi-dimensional grouting effect evaluation information is constructed to realize the all-round quantitative evaluation from local defect filling to the restoration of the overall performance of the pile body, overcome the limitations of single-index analysis, and provide high-precision and multi-level criterion support for grouting quality acceptance and subsequent reinforcement decision-making.

[0208] Please refer to Figure 8 , further, the following examples can be developed in combination with the above technical solutions:

[0209] The process of the method for strengthening defective piles based on the MICP principle can be understood as follows:

[0210] Use the low-strain pile testing technology to measure the approximate location of the pile foundation defect;

[0211] Transport the microbial liquid and the cementing liquid to the stirring bucket (i.e., the grouting bucket 3) containing nutrients, and stir the biological reinforcement liquid for 1 hour to fully mix the microbial liquid, the cementing liquid and the nutrients;

[0212] Connect the grouting bucket 3 filled with the microbial slurry to the top of the grouting pipeline 21, and control the slurry flow rate through the grouting pump 22 and the butterfly valve (i.e., the regulating valve group 23) for integrated grouting;

[0213] Set the area to be strengthened at the defect position of the pile foundation and arrange through holes passing through the defect of the single-pile foundation. Moreover, a number of grouting holes 211 are evenly opened on the grouting pipeline 21, and the grouting holes 211 not at the defect position of the pile foundation and the nuts 213 with different apertures are closed by nuts 213 to adjust the grouting pressure for precise grouting;

[0214] Insert the grouting pipeline 21 into the through hole, and connect adjacent two grouting pipelines 21 through grouting pipe connectors to form a ring-shaped grouting pipe network system 2;

[0215] Start the grouting operation. The biological grouting reinforcement liquid is used for grouting, and then through pressure grouting, the slurry is injected into the grouting pipeline 21, and the slurry enters the grouting pipeline 21 and flows along the grouting holes 211 to the defect position of the pile foundation;

[0216] After the microbial slurry completely reacts with the pile foundation, use the low-strain pile testing technology to inspect the integrity of the foundation.

[0217] Adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0218] The present invention accurately analyzes the phase change of the time-domain reflected wave and the wave velocity anomaly through the low-strain reflected wave method, comprehensively determines the type, location and size of the pile body defect by combining the time-frequency domain signal characteristics, and provides a reliable basis for formulating grouting parameters; based on the defect information, it dynamically matches the ratio of microbial bacterial liquid, cementing liquid and the grouting volume, and realizes multi-path precise grouting through the annularly arranged grouting pipe network system. The grouting pipeline adopts a PE pipe structure with a conical grouting leg, and cooperates with a nut with an adjustable aperture to seal the grouting hole, which can not only deliver the slurry to the defect area directionally, but also control the diffusion range, effectively avoiding slurry leakage and gushing; through the PID control algorithm, it real-time collects the feedback signals of flow rate, valve state and pressure difference, dynamically adjusts the opening of the butterfly throttle valve to maintain a constant grouting flow rate, and combines hierarchical decompression and wear-resistant valve body materials to ensure the stability and controllability of the grouting process; it uses the crystals generated by the microbial-induced calcium carbonate precipitation reaction to fill the defect voids, combines periodic reflected wave detection to evaluate the reinforcement effect, and finally realizes the precise positioning, intelligent control and effect traceability of pile body defect repair, significantly improving the overall strength and bearing performance of the pile foundation. The present invention reduces slurry waste by matching the grouting hole layout according to the defect location, and at the same time enhances the integrity and impermeability of the pile body, overcoming the defects of traditional grouting technology such as rough positioning and large pollution.

[0219] In addition, in each embodiment of the present invention, each functional unit can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0220] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that makes a contribution to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods in each embodiment of the present invention. The aforementioned storage medium includes: USB flash drive, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and other various media that can store program codes.

[0221] The above are only partial embodiments of the present invention, and thus do not limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for strengthening defective pile bodies based on the MICP principle, characterized in that, Applicable to defective piles, the defective piles including pile bodies and pile tops, the method comprising: Vibrating the defective piles using the low-strain reflected wave method and collecting first vibration response signals of the pile tops; Performing time-domain reflected wave phase change and wave velocity anomaly analysis on the first vibration response signals to generate pile body defect information, the pile body defect information including the defect type, defect location and defect size of the defect area in the defective piles; Generating slurry parameters and grouting parameters according to the pile body defect information, the slurry parameters including the mixing ratio information of the slurry, and the grouting parameters including the grouting volume, grouting location and layout information of the grouting pipeline; Preparing MICP slurry according to the slurry parameter ratio, and arranging a grouting pipeline network system on the circumference of the pile body according to the grouting parameters, the grouting pipeline network system including a grouting pipeline, a grouting pump and a regulating valve group; Controlling the grouting pump to pump the MICP slurry into the grouting pipeline so that the MICP slurry enters the defect area of the pile body from the grouting pipeline, and synchronously obtaining feedback signals; Inputting the feedback signals into a PID control algorithm to obtain feedback adjustment parameters, and controlling the opening degree of the regulating valve group according to the feedback adjustment parameters until the grouting of the defect area is completed; After the grouting is completed, detecting the pile body using the low-strain reflected wave method at a preset frequency and collecting second vibration response signals of the pile tops; Generating grouting effect evaluation information according to the second vibration response signals.

2. The method for strengthening defective pile bodies based on the MICP principle according to claim 1, characterized in that, Vibrating the defective piles using the low-strain reflected wave method and collecting first vibration response signals of the pile tops includes: Arranging a plurality of sensors on the surface of the pile top, the sensors being evenly distributed in a ring shape; Taking the center of the pile top as the excitation point, using a force hammer to perform transient impact excitation on the excitation point, and controlling the impact strength and duration; Recording the impact trigger moment of the force hammer, and synchronously triggering the acceleration sensor to collect the vibration response signals of the pile top; Recording the time-domain signals collected by the acceleration sensor according to a preset sampling frequency; Performing time-domain alignment on the time-domain signals with the impact trigger moment as the reference; Calculating the wave velocity value according to the distance from the acceleration sensor to the excitation point and the arrival time of the direct wave; Performing consistency verification on the wave velocity value, and when the wave velocity dispersion does not exceed a preset wave velocity threshold, determining that the time-domain signals are valid and recording them as first vibration response signals.

3. The method for strengthening defective pile bodies based on the MICP principle according to claim 1, wherein Performing time-domain reflected wave phase change and wave velocity anomaly analysis on the first vibration response signals to generate pile body defect information includes: Performing preprocessing on the first vibration response signals to obtain first processed signals; Performing time-domain alignment on the first processed signals and calculating the time difference information of the same stress wave in multiple first processed signals; Constructing and solving a defect location equation according to the time difference information to obtain the defect location of the defect area; And, extracting incident wave signals and reflected wave signals from the first processed signals; Converting the incident wave signals and reflected wave signals to obtain reflected wave characteristic parameters, the reflected wave characteristic parameters including the arrival time of the reflected wave, the amplitude ratio of the reflected wave, and the phase difference of the reflected wave; The defect size and defect type are calculated based on the reflection wave characteristic parameters; The pile body defect information is generated based on the defect position, defect size, and defect type.

4. The method for strengthening defective pile bodies based on the MICP principle according to claim 1, characterized in that, The slurry parameters generated based on the pile body defect information include: A mapping relationship between the pile body defect information and the slurry parameters is constructed, represented by formula (1), and the formula (1) is as follows: In formula (1), Z0 is the wave impedance of the complete pile body, and Z d is the wave impedance of the defect area, ΔZ is the change in wave impedance, k is the microbial mineralization rate, and C b is the concentration of the bacterial solution, and S v is the effective reaction specific surface area; An expression for the total volume of the slurry and the defect volume in the defect area is constructed, represented by formula (2), and the formula (2) is as follows: In formula (2), Q is the total amount of the slurry, V d is the volume of the defect, and α is the slurry diffusion compensation coefficient; An environmental parameter adjustment equation is constructed, represented by formula (3), and the formula (3) is as follows: In formula (3), R u is the urea hydrolysis rate, β is the hydrolysis reaction constant, E a is the reaction activation energy, k ′ is the microbial mineralization rate under the influence of temperature; A slurry parameter optimization function is constructed, represented by formula (4), and the formula (4) is as follows: In formula (4), ΔZ actual is the actual impedance change, ΔZ target is the target compensation amount, ΔZ target = ΔZ; T opt is the optimal reaction temperature, λ is the weight coefficient, ||ΔZ actual - ΔZ target || represents the mineralization effect, ||T - T opt || represents the temperature control; The optimized slurry parameters are obtained.

5. The method for strengthening defective pile bodies based on the MICP principle according to claim 4, characterized in that, The MICP slurry is obtained according to the ratio of the slurry parameters, including: The bacterial solution of Bacillus pasteurii is placed in a constant temperature environment for activation, and the activation temperature range is 20°C - 35°C; The concentration of the cementing liquid component is configured, represented by formula (5), and the formula (5) is as follows: In formula (5), C urea is the urea concentration, is the calcium ion concentration, ξ1 is the first proportionality coefficient, ξ2 is the second proportionality coefficient, and t r is the expected reaction time. A nutrient solution containing yeast extract and peptone is configured, and the configured concentration of the nutrient solution is represented by formula (6), and the formula (6) is as follows: C nutr = ξ3·C b ·S v ; In formula (6), C nutr is the configured concentration of the nutrient solution, and ξ3 is the third proportionality coefficient; The activated bacterial solution, cementing liquid, and nutrient solution are mixed and prepared according to the slurry parameters to obtain the MICP slurry.

6. The method for strengthening defective pile bodies based on the MICP principle according to claim 1, characterized in that The grouting parameters generated based on the pile body defect information include: A spatial mapping relationship between the pile body defect information and the grouting pipeline network system is constructed, and a functional relationship between the grouting pressure and the pile body defect information is generated; The layout information of the grouting pipeline and the grouting position are generated according to the spatial mapping relationship, and the layout information includes the number of grouting pipelines and the position of a single grouting pipeline; The grouting flow rate of a single grouting pipeline and the grouting pressure of a single grouting pipeline are generated according to the functional relationship between the grouting pressure and the pile body defect information; The grouting parameters are generated according to the layout information, grouting position, grouting flow rate of a single grouting pipeline, and grouting pressure of a single grouting pipeline.

7. The method for strengthening defective pile bodies based on the MICP principle according to claim 1, characterized in that, The feedback signal includes a real-time flow signal and a real-time pressure signal; The feedback signal is input into the PID control algorithm to obtain feedback adjustment parameters, including: The first deviation value between the real-time flow signal and the preset flow signal is calculated, and the second deviation value between the real-time pressure signal and the preset pressure signal is calculated; A preset PID control mode is matched according to the defect type, denoted as the first control mode; The viscosity change rate of the MICP slurry is obtained, and the adjustment frequency of the first control mode is generated according to the viscosity change rate; The feedback adjustment parameters are generated according to the first deviation value and the second deviation value, and the feedback adjustment parameters include at least one of the offset weight, integral time, and differential time; The first control mode is adjusted according to the adjustment frequency.

8. The method for strengthening defective pile bodies based on the MICP principle according to claim 1, characterized in that, The grouting effect evaluation information generated according to the second vibration response signal includes: The second vibration response signal is compared with the first vibration response signal in the time domain waveform to obtain a comparison result, and the comparison result includes the change amount of the reflection wave amplitude and the change amount of the reflection wave phase; And, the wave velocity of the pile body is recalculated according to the second vibration response signal, denoted as the detected pile body wave velocity; Further, calculate the impedance value of the defective area based on the second vibration response signal, denoted as the detected impedance value; Generate the grouting effect evaluation information based on the comparison result, the detected pile wave velocity, and the detected impedance value.

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