A method for assessing and repairing the degree of pulverization of ballastless track concrete.

Abstract

This invention discloses a rapid assessment and precise repair method for the degree of pulverization in ballastless track bed concrete. By preparing concrete reference specimens of different strength grades, a correlation curve between pull-out strength and overall strength is established. Combined with probe diameter selection, surface grinding, and adhesive bonding techniques, a non-destructive and rapid detection of the pulverized layer is achieved. Specifically, the method includes: a preliminary preparation stage where specimens are prepared and a pull-out strength-strength model is established; an evaluation stage where layer-by-layer pull-out testing combined with precise hollow drilling quantitatively determines the depth and extent of pulverization; and a repair stage where the pulverized layer is replaced with a high-toughness material and a drainage slope is installed. This invention solves the problems of low efficiency, significant damage, and inaccurate repair associated with existing methods. Through parametric design and a modular system, it significantly improves detection accuracy and repair effectiveness. It is applicable to the maintenance of concrete structures such as high-speed railway track base plates, meets industry standards, and has the advantages of simple operation, low cost, and strong adaptability.

Description

Technical Field

[0001] This invention relates to a repair method, and more particularly to a method for assessing and repairing the degree of pulverization of ballastless track concrete. Background Technology

[0002] As the service life of some high-speed railway lines has increased, some sections of the ballastless track base slab / support layer have shown signs of pulverization. Specifically, this manifests as lower shallow concrete strength, loosening, cracking, pulverization, erosion, spalling, exposed aggregate, cracking, and exposed and corroded reinforcing steel. The main cause of this defect is the damage caused by inherently defective, non-dense concrete due to freeze-thaw cycles, water erosion, and fatigue loads from the train. This gradually leads to the spalling, exposed aggregate, and loosening of the shallow concrete. As the service life increases, the protective properties of the damaged shallow concrete gradually weaken, and the loose surface is more prone to moisture accumulation. This concrete is more susceptible to water erosion or freeze-thaw damage from water freezing. The erosion gradually progresses from the surface to the interior concrete, creating a vicious cycle and exacerbating the problem, leading to more severe spalling and erosion. At the same time, the internal steel reinforcement of the base plate, lacking the protection of the concrete layer, is prone to corrosion. Accompanied by multiple times chemical volume expansion, this further accelerates the cracking, spalling, and deterioration of the concrete, ultimately failing to meet the minimum load-bearing strength requirements of the base plate structure and affecting train safety.

[0003] Existing repair techniques for concrete pulverization in the base slab / support layer of high-speed railway ballastless track mainly involve cleaning the damaged area, filling it with new materials, and strengthening the area. However, current repair strategies rely on relatively crude methods to determine the depth of the repair layer to be removed, making it difficult to accurately measure the actual depth of the pulverized layer. This limits the precision of the repair results to some extent.

[0004] The main methods for detecting and assessing concrete pulverization include visual inspection, impact testing, ultrasonic testing, and sampling analysis. Visual impact testing assesses the degree of concrete damage through visual observation or the use of simple tools; however, it is highly subjective and difficult to quantify. Ultrasonic testing utilizes the propagation characteristics of ultrasound waves in concrete, measuring parameters such as propagation speed and attenuation to determine the degree of pulverization; however, it is easily affected by various factors. Sampling analysis involves drilling concrete core samples or analyzing the chemical composition of concrete to determine the degree of pulverization; however, this method causes significant damage to the concrete, is complex to operate, and is time-consuming.

[0005] Existing testing methods are not only complex and time-consuming, but also unsuitable for rapidly evaluating the degree of concrete pulverization. Secondly, these methods cause significant damage to the track structure, and the test specimens are whole, resulting in inaccurate assessments of pulverization depth. Currently, there is no accurate and rapid method to assess the degree of pulverization in ballastless track concrete and to develop personalized repair plans based on the assessment results. Therefore, a new assessment and repair method is urgently needed to address this problem.

[0006] Currently, there are many shortcomings in the methods for assessing the degree of pulverization of ballastless track concrete:

[0007] (1) The degree of concrete pulverization is judged by manual observation and tapping test. This method mainly relies on the experience and subjective judgment of maintenance personnel. Its accuracy and reliability are often affected by human factors and it is difficult to analyze quantitatively.

[0008] (2) Core sampling and testing directly observes the internal structure of the core sample to determine the degree of concrete pulverization. However, this method causes significant damage to the track structure, has limited sampling locations, makes it difficult to fully reflect the pulverization of the concrete, and is labor-intensive and time-consuming, failing to meet the needs of rapid evaluation.

[0009] (3) Ultrasonic and radar wave detection methods indirectly determine the degree of pulverization by measuring changes in parameters such as wave velocity and amplitude inside the concrete. Although this method is non-destructive, it is greatly affected by factors such as internal defects in the concrete and aggregate distribution, and its detection accuracy is limited. Therefore, it has certain limitations in practical applications.

[0010] (4) Chemical analysis method: The degree of concrete pulverization is determined by analyzing the chemical composition of the concrete through sampling. However, this method is complicated, time-consuming, and requires professional chemical analysis equipment and personnel, which is not conducive to rapid assessment and repair.

[0011] Due to the unevenness of concrete surfaces and exposed aggregates, traditional rebound strength testing methods cannot be effectively applied to powdery concrete surfaces, limiting the accuracy of evaluation results. Existing repair methods often adopt a one-size-fits-all approach, failing to develop personalized repair plans based on the degree of concrete powdering, resulting in unsatisfactory repair outcomes. Summary of the Invention

[0012] To address the shortcomings of existing technologies, this invention aims to provide a method for accurately and rapidly assessing the range and depth of pulverization in ballastless track concrete, and for developing personalized repair plans based on the assessment results, thereby optimizing the repair effect. Through the implementation of this invention, the performance and durability of ballastless track concrete can be significantly improved, maintenance costs reduced, and the safety and stability of high-speed rail operations ensured. The technical solution is as follows:

[0013] A method for rapid assessment and precise repair of the degree of pulverization in ballastless track concrete, comprising:

[0014] Preliminary preparation stage:

[0015] Step (1) Prepare multiple sets of concrete reference specimens with different strength grades and prepare circular probes with different diameters. Attach circular probes with different diameters to concrete reference specimens of the same strength and perform pull-out tests respectively.

[0016] Step (2) According to the method of step (1), at least 20 pull-out tests are conducted on concrete of different strengths for probes of different diameters. The pull-out strength value corresponding to each probe is recorded. The variation range and distribution law of the test strength value of concrete of the same strength for the same probe are analyzed and compared. The average value and difference range of the test strength are determined. The average value and difference range of the test strength of different diameter probes for concrete of different strengths are determined in turn. The corresponding relationship curve between pull-out strength and concrete strength is established. Through curve analysis, the optimal diameter range of the circular probe is determined.

[0017] 1. Adhesion mechanical model and theoretical derivation

[0018] When bonding probes to the surface of concrete structures, the relationship between the pull-out strength τ and the surface strength of the concrete can be established using an interfacial bond mechanics model. According to fracture mechanics theory, the failure of the bond interface between the probe and the concrete is mainly controlled by the tensile strength, with the following relationship: τ = F / A = 4F / πd 2

[0019] in:

[0020] τ is the actual tensile strength of the concrete surface layer (positively correlated with the concrete strength grade, determined by testing);

[0021] A represents the probe bonding area;

[0022] d is the probe diameter.

[0023] Pull-out strength was tested using concrete reference specimens of different strength grades (e.g., C10 to C50) with probes of different diameters (10mm, 20mm, 30mm, 40mm). Nonlinear curves were established. By comparing the pull-out strength and the range of difference between concrete of different strengths, probe curves with irregular average differences in pull-out strength and significant overlap in the range of difference between adjacent concrete strengths were eliminated. The probe curve with the most regular average difference in pull-out strength and the least or no overlap in the range of difference between adjacent concrete strengths was selected. This probe diameter was chosen as the optimal probe diameter for testing the pull-out strength of concrete in the field, and the pull-out strength-concrete strength curve was chosen as the optimal curve for evaluating concrete in the field.

[0024] Theoretical basis: Concrete surface pulverization will lead to a decrease in pull-out strength τ. By selecting a probe to test the pull-out strength of concrete on site, the strength of concrete on site can be determined according to the corresponding curve, and then the degree of concrete pulverization can be determined.

[0025] 2. The necessity and innovative aspects of establishing the curve

[0026] Compared to the traditional rebound method (which relies on surface hardness), this method is directly related to mechanical property parameters, avoiding interference from exposed aggregates and uneven surfaces.

[0027] Ultrasonic testing is significantly affected by the surface condition of concrete; the loose structure of the pulverized layer can lead to signal attenuation or hardness distortion. Pull-out tests, on the other hand, directly reflect the surface mechanical properties through interfacial bond failure.

[0028] Core drilling damages the concrete structure and requires further on-site testing and evaluation, necessitating laboratory sample preparation, testing, and evaluation. This prevents real-time on-site construction guidance, and the height requirements of compressive strength test specimens limit the ability to perform shallow-level quantitative analysis. In contrast, pull-out testing addresses very minor surface damage to existing concrete structures (diameter and depth less than 10mm), allows for rapid and direct on-site assessment of concrete pulverization, provides real-time on-site construction guidance, and allows for precise layer-by-layer (minimum 10mm per layer) assessment of concrete condition, avoiding unnecessary work on deeply intact concrete.

[0029] The determination of the side of the present invention ensures the accuracy of concrete pull-out strength testing, and the corresponding curve of pull-out strength and concrete strength ensures the accuracy of concrete pulverization assessment. The pull-out test method can quickly and accurately complete the assessment of concrete pulverization without affecting the concrete surface condition or damaging the existing structure, realizing the transition from "qualitative observation, assessment and remediation in stages" to "quantitative detection, detection and remediation integration".

[0030] The core innovation of this invention lies in establishing a quantitative model of pull-out strength versus concrete strength. For pulverized concrete, the surface layer τ gradually recovers to the design strength as the pulverization depth increases. Therefore, by conducting layer-by-layer pull-out tests (removing 5-10mm each time and testing the new surface), the boundary of the pulverized layer can be accurately located. Compared with traditional methods, this technology solves the problems of strong subjectivity, high destructiveness, and insufficient accuracy of existing detection methods through three core means: mechanical model quantification, layered detection and positioning, and parameterized probe adaptation. This enables rapid and accurate assessment and repair of the degree of pulverization.

[0031] Step (3) Identify the ballastless track section where the degree of pulverization needs to be assessed, and grind the concrete surface of the section, mainly grinding away the obviously loose concrete particles on the concrete surface.

[0032] Powdering degree assessment stage:

[0033] Step (1): Apply fast-hardening high-adhesion adhesive to the polished concrete surface and attach the probe of the selected diameter;

[0034] Step (2): Use the concentric circle method to mark the inner circle whose inner diameter is at least 4 mm larger than the probe diameter, and the outer circle whose distance from the outer diameter to the inner diameter is the wall thickness of the hollow drill bit, so as to provide accurate positions for subsequent drilling operations.

[0035] Step (3): Using a hollow drill, drill through the excess adhesive by referring to the inner and outer circles marked on the probe; after the bonding material of the probe reaches the preset strength, perform a pull-out strength test and record the test results;

[0036] Step (4): Set up three probes within the same location range (0.1㎡) of the concrete and test them in sequence according to step (3). The difference between the three test results should not be greater than 0.05MPa. Take the average value and compare it with the established corresponding relationship curve to judge the strength of the test surface. Based on the strength value, evaluate the degree of pulverization of the concrete.

[0037] Step (5): When the measured strength of the test surface does not meet the structural safety service requirements or the preset threshold, continue to chisel and grind down to a new test surface, repeat the test steps (3)-(4) of the pulverization degree assessment stage until the strength of the test surface meets the requirements.

[0038] Step (6): By conducting layer-by-layer tests at different locations, the repair range of the entire powdery layer is determined.

[0039] Precise repair phase:

[0040] Step (1): Based on the measured distance and range from the test surface that meets the strength requirements to the surface of the pulverized structure, accurately determine the depth and range of the concrete that needs to be removed and replaced;

[0041] Step (2): After removing the powdery layer that needs to be repaired, replace and repair it with a high-adhesion, high-toughness repair material;

[0042] Beneficial effects

[0043] ① Based on the correlation curve between pull-out strength and strength: By testing the correlation between pull-out strength and strength obtained by different probes, a curve model is established, which can accurately and quickly assess the degree of pulverization of concrete.

[0044] ② Use of small probes: Using small-diameter circular probes for testing can reduce damage to the track structure and improve the accuracy and reliability of the test.

[0045] ③ Development of precise repair plans: Based on the assessment results, personalized repair plans are developed to ensure optimal repair results and improve the performance and durability of ballastless track concrete.

[0046] ④ Simple operation and low cost: The method of the present invention is simple to operate and low in cost, and has high practical value and promotion prospects. Attached Figure Description

[0047] Figure 1 : Schematic diagram of probe diameter and pull-out strength test, where (a) is a φ30mm probe, (b) is a φ20mm probe, and (c) is a φ10mm probe;

[0048] Figure 2 Schematic diagram showing the relationship between the pull-out strength of the probe diameter and the concrete strength grade;

[0049] Figure 3 : Diagram showing adhesive overflow during probe bonding;

[0050] Figure 4 : Schematic diagram of probe bonding range calibration;

[0051] Figure 5 : Schematic diagram of pull-out strength test layer by layer, where (a) is the failure condition of the first pull-out, and (b) is the failure interface of the next pull-out after cutting and grinding;

[0052] Figure 6 : Schematic diagram of the removal of the powdery layer;

[0053] Figure 7 : Schematic diagram of repair after removal of the powdery layer.

[0054] 1-Concrete test block; 2-Probe; 3-Pull-out instrument; 4-Adhesive material; 5-Hollow drill; 6-Powdered layer; 7-Repair layer. Detailed Implementation

[0055] As service time increases, some sections of the ballastless track base slabs / support layers on high-speed railway lines have experienced pulverization. This manifests as decreased shallow concrete strength, loosening, pulverization, erosion, spalling, exposed aggregate, cracking, and exposed and corroded reinforcing steel. Replacement and repair are necessary. However, indiscriminate repair can lead to over-repair or inadequate repair, causing recurrence of problems. Therefore, it is crucial to accurately and quickly assess the extent and depth of pulverization in the ballastless track base slab / support layer and develop personalized repair plans to optimize the repair effect. Details are as follows:

[0056] The assessment and repair methods for the degree of pulverization of ballastless track concrete mainly include the following steps:

[0057] Preliminary preparation stage:

[0058] Step (1) Prepare concrete reference specimens with a wide range of strength grades and prepare circular probes of different diameters.

[0059] Concrete reference specimens with molding strength grades of 5MPa, 10MPa, 15MPa, 20MPa, 25MPa, 30MPa, 35MPa, 40MPa, 45MPa, and 50MPa were used to ensure sufficient accuracy and applicability in establishing the correlation between pull-out strength and overall strength. Circular probes with diameters of 10mm, 20mm, 30mm, and 40mm were also prepared. Different probe diameters were used to evaluate concrete of different strength grades to select the optimal probe diameter and improve testing accuracy.

[0060] Step (2) Test and record the pull-out strength value corresponding to each probe, and establish the curve of the relationship between pull-out strength and concrete strength: Regarding the relationship between concrete of different strengths and pull-out strength, the pull-out strength corresponding to concrete of different strengths is different. Furthermore, for probes of different diameters that measure concrete of different strengths, after comparative analysis, the probe size with more obvious pull-out strength measurement value of concrete of different strengths is selected for use in the later on-site concrete strength evaluation standard.

[0061] Curve analysis revealed that different probes yielded different readings for concrete of the same strength, and the readings for different strengths of concrete varied significantly, with adjacent readings showing different differences. First, a large number of measurements (at least 20 times) were performed on the same probe for the same strength of concrete. The overlap between adjacent readings was compared; if significant overlap was found, the probe was excluded. Second, the difference in strength readings between adjacent concrete strengths was considered; probes with larger differences were selected to more clearly distinguish the pull-out strength of concrete of different strengths. The optimal diameter range for the circular probe was determined: for each strength grade of concrete, probes ranging from 10-40 mm were used for testing. Through extensive testing, the correlation between the pull-out strength (±5 MPa) within the strength grade range and the actual concrete strength was established. The probe size with higher discriminative power and stronger comparative ability was selected as the probe diameter for that strength grade of concrete. In field applications, the corresponding probe diameter was selected based on the design strength value of the tested concrete.

[0062] A correlation curve was established by attaching each probe to concrete reference specimens of different strength grades and testing and recording the pull-out strength values ​​corresponding to each probe (at least 20 data points were collected for each group). Based on the test results, a correlation curve between pull-out strength and concrete strength was established. Through curve analysis, the optimal diameter range of the circular probe corresponding to each strength grade of concrete was determined to ensure the accuracy of subsequent tests.

[0063] Step (3) Identify the ballastless track section where the degree of pulverization needs to be assessed, and grind the concrete surface of the section, mainly grinding away the obviously loose concrete particles on the concrete surface.

[0064] Assess the pulverized sections, identify the ballastless track sections where the degree of pulverization needs to be evaluated, and grind the concrete surface of these sections to remove the more obvious loose layer, ensuring a smooth surface and a grinding area of ​​no less than 3 times the probe diameter, in order to reduce the impact of surface unevenness on the test results.

[0065] Powdering degree assessment stage:

[0066] Step (1): Apply fast-hardening high-adhesion adhesive to the polished concrete surface and attach the probe of the selected diameter:

[0067] Step (2): Use the concentric circle method to mark the inner circle whose inner diameter is at least 4 mm larger than the probe diameter, and the outer circle whose distance from the outer diameter to the inner diameter is the wall thickness of the hollow drill bit, so as to provide accurate positions for subsequent drilling operations.

[0068] Step (3): Using a hollow drill, drill through the adhesive overflow by referring to the inner and outer circles of the markings, ensuring that the depth of the test surface does not exceed 1mm, so as to protect the original concrete structure from damage; after the bonding material of the probe reaches the preset strength (such as bonding strength above 3MPa), perform a pull-out strength test and record the test results.

[0069] Step (4): Set up three probes within the same location area (0.1㎡) of the concrete and test them sequentially according to step (3). The difference between the three test results should not exceed 0.05MPa. Take the average value and compare the pull-out strength test results with the established correlation curve to determine the strength of the test surface. Based on the strength value, assess the degree of concrete pulverization.

[0070] Step (5): When the measured strength of the test surface does not meet the structural safety service requirements or the preset threshold, continue grinding downwards to a new test surface, and repeat the test steps (3)-(4) of the powdering degree assessment stage until the strength of the test surface meets the requirements. By testing layer by layer; by performing the above tests at different locations, the repair range of the entire powdered layer is determined.

[0071] Precise repair phase:

[0072] Step (1): Based on the measured distance and range from the test surface that meets the strength requirements to the surface of the pulverized structure, accurately determine the depth and range of the concrete that needs to be removed and replaced;

[0073] Step (2): After removing the powdery layer that needs to be repaired, replace and repair it with a high-adhesion, high-toughness repair material;

[0074] In accordance with drainage requirements, drainage slopes are set up in the repair area to ensure that water does not accumulate, thereby preventing further erosion and damage caused by moisture buildup, improving the repair effect and extending the service life.

[0075] Example 1:

[0076] Concrete reference specimens with strength grades ranging from 5 MPa to 50 MPa were prepared according to standard methods. A circular probe with a diameter of 20 mm was selected for testing. (See attached...) Figure 1 The probe was attached to concrete reference specimens of various strength grades, and the pull-out strength values ​​were tested and recorded. A curve showing the relationship between pull-out strength and overall strength was established, as shown in the attached figure. Figure 2 The section of the ballastless track base slab on a certain high-speed railway line was selected as the evaluation section. The concrete surface was ground, and a fast-hardening high-adhesion adhesive was applied to the ground surface before attaching the probe (e.g., ...). Figure 3 ), and use the concentric circle method to mark the inner and outer circles, and use a hollow drill to remove the adhesive overflow, ensuring that the test surface is not damaged to a depth exceeding 1mm. Figure 4After the bonding strength of the bonding material of the test head reaches 3MPa or higher, a pull-out strength test is performed. The test results are compared with the corresponding relationship curve to determine whether the strength of the test surface meets the requirements. If it does not meet the requirements, the process continues to chisel and grind down to a new test surface, testing and determining the repair area layer by layer. This testing process is repeated until the strength of the test surface meets the requirements, and the repair area is determined. Figure 5 ).

[0077] After removing the powdery layer that needs repair ( Figure 6 The repair is performed using a high-adhesion, high-toughness repair material, which consists of polymer, cement, sand, aggregate, admixtures, and additives. The polymer includes polymer powder and emulsion; the cement includes ordinary Portland cement and sulfoaluminate cement; and the admixtures include mineral powder and silica fume. It can cure in 20-60 minutes, with a compressive strength of 20-40 MPa, an elastic modulus of 15-20 GPa, a bond strength with the old concrete of 2.5-3 MPa, and a 28-day shrinkage rate ≤0.1%.

[0078] A drainage slope should be installed in the repair area to ensure that water does not accumulate. Figure 7 Through the technical solutions and embodiments of the present invention, the degree of pulverization of ballastless track concrete can be accurately and quickly assessed, and personalized repair plans can be formulated based on the assessment results to achieve optimal repair results.

[0079] Example 2: By preparing concrete reference specimens of multiple strength grades and testing their pull-out strength, a curve showing the correlation between pull-out strength and concrete strength was established. A section of ballastless track exhibiting pulverization on a high-speed railway line was selected as the test object, and the degree of pulverization was evaluated according to the above technical scheme.

[0080] In this section, comparative tests were conducted using the rebound hammer method, ultrasonic testing, infrared thermal imaging, ground-penetrating radar (GPR), and core sampling. The results showed that: the rebound hammer method relies on surface integrity and only reflects the surface condition of the concrete; ultrasonic testing requires a coupling agent, and loose surfaces cannot guarantee good contact, leading to decreased data reliability. Furthermore, its signal propagation is easily interfered with by factors such as aggregate distribution, porosity, and moisture content within the concrete, especially at the interface between the shallow pulverized layer and the dense concrete interior, where signal attenuation or abnormal reflection can occur, resulting in a systematic bias in determining the pulverization depth; infrared thermal imaging is greatly affected by ambient temperature and humidity, making early pulverization difficult to identify and prone to missed detections; GPR is sensitive to metal objects such as reinforcing bars within the concrete, easily generating interference signals, and surface pulverization has little impact on the radar signal, making it difficult to directly identify the pulverized layer; while core sampling allows for direct observation of the pulverization degree through core samples, the sampling process causes irreversible damage to the track structure, and single-point sampling cannot cover a large area, failing to meet the needs of efficient maintenance for high-speed railway lines. In contrast, this method uses a quantitative model of pull-out strength and concrete strength to achieve accurate layer-by-layer determination of the depth of the pulverized layer, while avoiding the subjectivity, structural damage, and blind spots of traditional methods.

[0081] According to the above technical solution, the concrete surface of the test section was ground, a probe was attached and marked with inner and outer circles, and the adhesive overflow was drilled out to test the pull-out strength. Based on the test results, the concrete was chipped away layer by layer and ground down to the test surface that met the strength requirements, thus determining the repair range of the entire powdery layer.

[0082] Unlike traditional "one-size-fits-all" repair methods, this method dynamically adjusts the removal depth based on layer-by-layer strength test results, achieving precise control over the repair area. This avoids unnecessary damage to structural integrity while ensuring the complete removal of the powdery layer. Furthermore, the repair area determination in this method is based on multi-point test data, significantly reducing the risk of local misjudgment.

[0083] This invention employs highly adhesive and tough repair materials for replacement and repair, and incorporates a drainage slope. After repair, the repaired area underwent quality inspection and acceptance to ensure it meets the safety requirements for high-speed rail operation.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for rapid assessment and precise repair of the degree of pulverization in ballastless track concrete, characterized in that, Includes the following steps: Preliminary preparation stage: (1) Prepare multiple concrete reference specimens with different strength grades and prepare circular probes with different diameters; (2) Test and record the pull-out strength values ​​corresponding to each probe, and establish the curve of the relationship between pull-out strength and concrete strength; (3) Identify the ballastless track sections where the degree of pulverization needs to be assessed, and grind the concrete surface to ensure that the grinding range is not less than 3 times the diameter of the probe. Powdering degree assessment stage: (4) Apply fast-hardening high-adhesion adhesive to the polished concrete surface and attach the probe of the selected diameter; (5) Mark the inner and outer circles, and use a hollow drill to drill through the adhesive overflow; (6) After the bonding material reaches the preset strength, test the pull-out strength and judge the strength of the test surface according to the corresponding relationship curve; (7) Remove the powdery layer by layer and repeat the test to determine the repair depth and range of the powdery layer; Precise repair phase: (8) Remove the powdery layer and replace and repair it with a high-adhesion, high-toughness repair material; (9) Set up a drainage slope in the repair area.

2. The method according to claim 1, characterized in that, The diameter of the circular probe in step (1) is 10mm, 20mm, 30mm or 40mm, and in step (2) a nonlinear correlation curve between pull-out strength and concrete strength is established through regression analysis.

3. The method according to claim 1, characterized in that, In step (3), the grinding range is 3-5 times the diameter of the probe, and the surface roughness Ra after grinding is ≤0.5mm.

4. The method according to claim 1, characterized in that, The fast-hardening high-adhesion adhesive in step (4) has a curing strength of ≥2MPa within 30 minutes and a bonding strength with concrete of ≥3MPa.

5. The method according to claim 1, characterized in that, In step (5), the inner diameter is 4-6 mm larger than the probe diameter, and the distance between the outer and inner circles is equal to the wall thickness of the hollow drill bit.

6. The method according to claim 1, characterized in that, The high-toughness repair material in step (8) is composed of polymer, cement, sand, admixture and additives; it is cured in 0.5-1h, with a compressive strength of 20-40MPa, an elastic modulus of 15-20GPa, and exceeds the bond strength of old concrete by 2.5-3MPa.

7. A system for repairing the powdering of ballastless track bed concrete, characterized in that, include: The evaluation module is used to perform all the steps in the pulverization degree evaluation stage of the rapid evaluation and accurate repair method for pulverization degree of ballastless track concrete as described in any one of claims 1-6. The repair module is used to automatically control the removal of the powdery layer and the filling of repair material based on the assessment results; The drainage design module is used to generate a 3D model of the drainage slope in the remediation area and guide construction.

8. The application of the rapid assessment and precise repair method for the degree of pulverization of ballastless track bed concrete according to any one of claims 1-6 in the maintenance of the base slab or supporting layer concrete of high-speed railway ballastless track, characterized in that, The repaired area meets the requirements for concrete strength and drainage performance in the "Rules for Maintenance of Ballastless Track Lines of High-Speed ​​Railways".

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