Method for evaluating grouting reinforcement effect of cement concrete pavement

Abstract

The evaluation method for the grouting reinforcement effect of the cement concrete pavement of the present application comprises: before grouting: S1.1, setting multiple test points in the evaluation section; S1.2, collecting deflection basin data of each test point by using a falling weight deflectometer; S1.3, calculating the comprehensive equivalent resilient modulus E of the test points before grouting Fi ; S1.4, correcting the comprehensive equivalent resilient modulus E Fi , to obtain a corrected value E F . After grouting: S2.1, collecting deflection basin data of each test point by using a falling weight deflectometer; S2.2, calculating the comprehensive equivalent resilient modulus E of the test points after grouting Bi ; S2.3, correcting the comprehensive equivalent resilient modulus E Bi , to obtain a corrected value E B . Evaluation: S3, outputting the evaluation result of the grouting reinforcement effect according to the corrected values E F and E B . The evaluation method of the present application can effectively improve the accuracy of the evaluation result.

Description

Technical Field

[0001] This invention relates to the field of road grouting reinforcement technology, and specifically to a method for evaluating the grouting reinforcement effect of cement concrete pavement. Background Technology

[0002] Grouting reinforcement technology is widely used in road engineering for foundation reinforcement, compaction, and seepage prevention. After grouting reinforcement, the effectiveness needs to be evaluated to determine if it meets expectations. Currently, commonly used methods for evaluating the effectiveness of grouting reinforcement include core drilling, ground-penetrating radar detection, and borehole inspection. However, these methods are all qualitative evaluations and suffer from inaccurate and subjective results.

[0003] Currently, all methods for evaluating grouting effectiveness using non-destructive testing have their limitations, failing to provide accurate and effective objective assessments. Furthermore, the market offers various road grouting methods such as cement grouting, modified polymer grouting, and polymer grouting, with inconsistent and often substandard practices from different companies. Some companies hold the misconception that "grout fluidity is unimportant, as long as it can be injected; the higher the grouting pressure and the greater the grout volume, the better." In reality, thicker grout, higher grouting pressure, and larger grout volume are more likely to damage the overall road structure, making the road's structural layers more porous and reducing its load-bearing capacity compared to before grouting.

[0004] For pavement structures, the base course has always been the main load-bearing layer. Various studies show that for existing roads with cement-stabilized crushed stone as the base course, the rate of weakening of the subbase strength is significantly greater than that of the upper base course, and the decline in road load-bearing capacity usually begins with fatigue failure of the subbase. Grouting, utilizing the penetration, compaction, and splitting effects of grout, can effectively fill and improve the density of the subgrade and base course. Grouting not only increases the elastic modulus of the subgrade but also has a very significant reinforcement effect on the junctions of the base course, base course, and subgrade.

[0005] Existing evaluation methods mostly use the resilient modulus of the subgrade or the entire pavement as evaluation parameters to assess the effectiveness of grouting reinforcement. However, in practical applications, this approach has the following shortcomings:

[0006] 1. Grouting slurry also has a certain reinforcing effect on the base layer, especially at the junction of the subbase and the subgrade, including the reinforcement of cracks in the subbase and base layer. This area is the "weak" area of ​​the road and is precisely the "key" area for grouting. The effect of grouting reinforcement is particularly obvious. In addition, the grout in the grouting hole "anchors" the base layer and the subgrade, forming a "pile foundation" similar to that in building construction, which can greatly improve the overall bearing capacity of the base layer. Obviously, it is inaccurate to judge the grouting effect by simply calculating the change in the dynamic modulus of the subgrade before and after grouting.

[0007] 2. Most roads reinforced with grouting already have surface damage. For cement concrete pavements, the comprehensive equivalent resilient modulus reflects the overall load-bearing capacity of the road. Due to existing defects such as cracks in the concrete slabs, the increase in the equivalent resilient modulus below the base layer caused by grouting reinforcement does not significantly change the overall load-bearing capacity. However, the actual reinforcement below the base layer is insufficient to be reflected in the comprehensive equivalent resilient modulus of the existing road surface. Clearly, calculating the comprehensive equivalent resilient modulus of existing roads by ignoring the impact of pavement damage is inaccurate. Summary of the Invention

[0008] The technical problem this invention aims to solve is the low accuracy of existing evaluation methods. To address this, this invention provides an evaluation method for the grouting reinforcement effect of cement concrete pavements, which can effectively improve the accuracy of the evaluation results.

[0009] The technical solution adopted by this invention to solve its technical problem is: a method for evaluating the grouting reinforcement effect of cement concrete pavement, comprising:

[0010] Before grouting:

[0011] S1.1 Set up multiple test points within the evaluation section;

[0012] S1.2. Use a falling weight bending tester to collect bending basin data at each test point;

[0013] S1.3 Calculate the comprehensive equivalent resilient modulus of the test points before grouting. ;

[0014] S1.4, Regarding the comprehensive equivalent resilient modulus Make corrections to obtain the corrected value. ;

[0015] After grouting:

[0016] S2.1. Use a falling weight bending tester to collect bending basin data at each test point;

[0017] S2.2 Calculate the comprehensive equivalent resilient modulus of the test points after grouting. ;

[0018] S2.3, Regarding the comprehensive equivalent resilient modulus Make corrections to obtain the corrected value. ;

[0019] evaluate:

[0020] S3, based on the correction value and The evaluation results of the grouting reinforcement effect are output.

[0021] Furthermore, the comprehensive equivalent resilient modulus at the test points before grouting. The calculation formula is:

[0022]

[0023] in, This indicates the overall resilient modulus of the base course and subgrade before grouting. This indicates the resilient modulus of the entire cement concrete pavement before grouting. Indicates the structural layer allocation coefficient. , This represents the load diffusion coefficient of the pavement structure before grouting. This indicates the deflection value at the load center of the drop weight bending tester before grouting. This indicates the test load of the falling weight bending tester. This indicates the radius of the bearing plate of the falling weight bending tester.

[0024] Furthermore, the load diffusion coefficient of the pavement structure before grouting The calculation formula is:

[0025]

[0026] in, , , These represent the deflection values ​​at distances of 300mm, 600mm, and 900mm from the load center before grouting.

[0027] Furthermore, the correction value The calculation formula is:

[0028]

[0029] in, This represents the average value of the comprehensive equivalent resilient modulus at all test points within the evaluated road section before grouting. This represents the guarantee rate coefficient. This represents the standard deviation of the comprehensive equivalent resilient modulus at all test points within the evaluated road section before grouting. This represents the correction factor for changes in the density and modulus of the structural layers caused by factors related to traffic opening. The value range is 1 to 1.05.

[0030] Furthermore, the comprehensive equivalent resilient modulus at the test points after grouting... The calculation formula is:

[0031]

[0032] in, This indicates the overall resilience modulus of the base course and subgrade after grouting. This indicates the resilient modulus of the entire cement concrete pavement after grouting. This represents the load diffusion coefficient of the pavement structure after grouting. This indicates the deflection value at the load center of the drop weight bending tester after grouting.

[0033] Furthermore, the load diffusion coefficient of the grouting pavement structure The calculation formula is:

[0034]

[0035] in, , , These represent the deflection values ​​at distances of 300mm, 600mm, and 900mm from the load center after grouting.

[0036] Furthermore, the correction value The calculation formula is:

[0037]

[0038] in, This represents the average value of the comprehensive equivalent resilient modulus at all test points within the evaluated road section after grouting. This represents the standard deviation of the comprehensive equivalent resilient modulus at all test points within the evaluated road section after grouting. This represents the support effect caused by the hardened grout in the grouting holes, as well as the correction coefficients for changes in the density and modulus of the structural layer due to grouting or traffic conditions. The value range is 1.05 to 1.15.

[0039] Furthermore, the evaluation indicators for the evaluation results include: the rate of improvement in the comprehensive equivalent resilient modulus. The comprehensive equivalent resilient modulus values ​​for different traffic levels.

[0040] Furthermore, the rate of increase in the overall equivalent resilient modulus The calculation formula is: ,when When the grouting rate is not less than 10%, the grouting reinforcement effect is considered to be qualified.

[0041] Furthermore, the comprehensive equivalent resilient modulus values ​​for different traffic levels include:

[0042] When the traffic level is extra heavy, the comprehensive equivalent resilient modulus value should not be less than 120MPa;

[0043] When the traffic level is heavy, the comprehensive equivalent resilient modulus value should not be less than 100MPa;

[0044] When the traffic level is medium or light, the comprehensive equivalent resilient modulus should not be less than 80 MPa.

[0045] The beneficial effects of this invention are:

[0046] The evaluation method for the grouting reinforcement effect of cement concrete pavement of the present invention uses the equivalent resilient modulus of "base course + road base course" and "surface course + base course + road base course" before and after grouting as evaluation parameters, which is more in line with the actual situation of the pavement and can improve the accuracy and objectivity of the test results.

[0047] Furthermore, this invention introduces a structural layer allocation coefficient. This helps improve the universality of the evaluation method; for different situations, only modifications are needed. The numerical value is sufficient; no modification to the testing method is required, and the efficiency of on-site testing can be greatly improved.

[0048] This invention also introduces a correction factor. This can further improve the accuracy of the test results. The evaluation method of the present invention provides more accurate and objective test results. Attached Figure Description

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0050] Figure 1 This is a flowchart of the evaluation method for the grouting reinforcement effect of cement concrete pavement according to the present invention.

[0051] Figure 2 This is a schematic diagram of the structural layers of the cement concrete pavement of the present invention. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0054] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] like Figures 1 to 2 As shown, the evaluation method for the grouting reinforcement effect of cement concrete pavement of the present invention includes: before grouting: S1.1, setting up multiple test points in the evaluation section; S1.2, collecting deflection basin data of each test point using a falling weight bending tester; S1.3, calculating the comprehensive equivalent resilient modulus of the test points before grouting. S1.4, Regarding the comprehensive equivalent resilient modulus Make corrections to obtain the corrected value. .

[0056] After grouting: S2.1, use a falling weight bending tester to collect deflection basin data for each test point; S2.2, calculate the comprehensive equivalent resilient modulus of the test points after grouting. S2.3, Regarding the comprehensive equivalent resilient modulus Make corrections to obtain the corrected value. .

[0057] Evaluation: S3, based on correction value and The evaluation results of the grouting reinforcement effect are output.

[0058] It should be noted that the structural layers of a cement concrete pavement, from top to bottom, are the surface layer, the base layer, and the subgrade. During grouting, the grouting holes pass through the surface layer and the base layer sequentially into the subgrade from top to bottom. Grout is then injected into the grouting holes, and after the grout hardens, it provides reinforcement. As shown in the attached diagram, grouting has a reinforcing effect on the base layer and the interface between the base layer and the subgrade. Therefore, the subgrade should not be considered alone when calculating the resilient modulus.

[0059] In this invention, the comprehensive equivalent resilient modulus at the test points before grouting is... The calculation formula is:

[0060]

[0061] in, This represents the overall resilient modulus (MPa) of the base course and subgrade before grouting. It represents the resilient modulus (MPa) of the entire cement concrete pavement (surface layer + base layer + subgrade) before grouting. Indicates the structural layer allocation coefficient. , This represents the load diffusion coefficient of the pavement structure before grouting. This indicates the deflection value (μm) at the load center of the drop weight bending tester before grouting. This indicates the test load (kPa) of the falling weight bending tester. This represents the radius (mm) of the bearing plate of the falling weight bending tester, typically taken as 150mm. The load diffusion coefficient of the pavement structure before grouting. The calculation formula is: ,in, , , These represent the deflection values ​​(μm) at distances of 300mm, 600mm, and 900mm from the load center before grouting.

[0062] In other words, the comprehensive equivalent resilient modulus of this invention is not simply based on the subgrade or pavement, but rather considers the resilient modulus of the "base course + subgrade" as a whole. Furthermore, this invention also introduces a structural layer distribution coefficient. , Let i = 1, 2, 3, ..., n, where n represents the total number of test points. Structural layer allocation coefficients. The value of determines the resilient modulus of "base course + road base course" and "surface course + base course + road base course" in the calculation of the comprehensive equivalent resilient modulus. The proportion of. The value can be set and adjusted according to the actual road conditions of the evaluated road section. When the accuracy rate of calculating the resilient modulus of only the "base course + subgrade" is higher than that of calculating only the pavement, =1. When the accuracy of evaluating a road segment by calculating only the resilient modulus of the pavement is higher than that by calculating only the resilient modulus of the "base course + subgrade", =0. When the cement concrete pavement has been repaired (new concrete has been laid on top of the surface layer), The value of is between 0 and 1. It is understandable that this is achieved by introducing a structural layer allocation coefficient. This makes the formula for calculating the comprehensive equivalent resilient modulus more universal and applicable. The evaluation of grouting reinforcement effects is generally conducted directly on-site, and a more universal calculation formula also helps improve the efficiency of on-site monitoring and evaluation.

[0063] The comprehensive equivalent resilient modulus of this invention is based on the overall resilient modulus of the base course and subgrade, the resilient modulus of the pavement (surface layer + base course + subgrade), and the structural layer distribution coefficient. On the one hand, it considers more comprehensive factors, which not only improves the accuracy of test results but also enables quantitative evaluation, providing a basis for subsequent rectification. On the other hand, it also improves the versatility of the evaluation method; for different situations, only modifications are needed. The numerical value is sufficient; no modification to the testing method is required, and the efficiency of on-site testing can be greatly improved.

[0064] Considering the supporting "anchoring" effect formed by the grouting holes and the hardened grout inside after grouting, as well as the changes in density and modulus caused by traffic factors, this invention also calculates the comprehensive equivalent resilient modulus. Make corrections to further improve the overall equivalent resilient modulus. Accuracy. Correction value. The calculation formula is: ,in, This represents the average value (MPa) of the comprehensive equivalent resilient modulus of all test points within the evaluated section before grouting. This represents the guarantee rate coefficient (1.645 for expressways and highways, and 1.5 for secondary highways and below). It represents the standard deviation (MPa) of the comprehensive equivalent resilient modulus of all test points in the evaluated section before grouting. This represents a correction factor for changes in the density and modulus of the structural layers caused by factors such as the opening of roads. The value range is 1 to 1.05 (excluding 1.05). Among them, , By introducing a correction factor This can further improve the accuracy of the comprehensive equivalent resilient modulus, which is conducive to improving the accuracy of the evaluation results.

[0065] Similarly, the comprehensive equivalent resilient modulus at the test points after grouting. The calculation formula is:

[0066]

[0067] in, This represents the overall resilient modulus (MPa) of the base course and subgrade after grouting. It represents the resilient modulus (MPa) of the entire cement concrete pavement after grouting. This represents the load diffusion coefficient of the pavement structure after grouting. This represents the deflection value (μm) at the load center of the drop weight bending test after grouting. It also represents the load diffusion coefficient of the pavement structure after grouting. The calculation formula is: ,in, , , These represent the deflection values ​​(μm) at distances of 300mm, 600mm, and 900mm from the load center after grouting. Correction values ​​after grouting. The calculation formula is: ,in, This represents the average value (MPa) of the comprehensive equivalent resilient modulus of all test points within the evaluated road section after grouting. It represents the standard deviation (MPa) of the comprehensive equivalent resilient modulus of all test points in the evaluated section after grouting. This represents the support effect formed by the hardened grout in the grouting hole after grouting, as well as the correction coefficient for changes in the density and modulus of the structural layer caused by grouting or traffic conditions. The value range is 1.05 to 1.15 (inclusive of the two endpoints). The correction factor is used due to the anchoring effect caused by the hardening of the grout after grouting. The value is larger than before grouting.

[0068] For example, the evaluation indicators for the evaluation results include: the rate of improvement in the comprehensive equivalent resilient modulus. Comprehensive equivalent resilient modulus values ​​for different traffic levels. Rate of increase in comprehensive equivalent resilient modulus. The calculation formula is: ,when When the grouting effect is not less than 10%, the grouting reinforcement is considered to be qualified. The comprehensive equivalent resilient modulus values ​​for different traffic levels are as follows: when the traffic level is extra heavy, the comprehensive equivalent resilient modulus value should not be less than 120 MPa; when the traffic level is heavy, the comprehensive equivalent resilient modulus value should not be less than 100 MPa; when the traffic level is medium and light, the comprehensive equivalent resilient modulus value should not be less than 80 MPa.

[0069] In practical applications, only the improvement rate can be used. As an evaluation indicator, traffic level can be used alone, or the improvement rate can be considered. Both traffic level and traffic grade are used as evaluation indicators.

[0070] In summary, the evaluation method for the grouting reinforcement effect of cement concrete pavement of the present invention uses the equivalent resilient modulus of the "base course + subbase course" and the equivalent resilient modulus of the "surface course + base course + subbase course" before and after grouting as evaluation parameters, which better reflects the actual situation of the pavement and can improve the accuracy and objectivity of the test results. Furthermore, the present invention introduces a structural layer distribution coefficient. This helps improve the universality of the evaluation method; for different situations, only modifications are needed. The numerical value is sufficient, requiring no modification to the detection method, and significantly improving the efficiency of on-site detection. This invention also introduces a correction coefficient. This can further improve the accuracy of the test results. The evaluation method of the present invention provides more accurate and objective test results.

[0071] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. A method for evaluating the grouting reinforcement effect of cement concrete pavement, characterized in that, include: Before grouting: S1.1 Set up multiple test points within the evaluation section; S1.

2. Use a falling weight bending tester to collect bending basin data at each test point; S1.3 Calculate the comprehensive equivalent resilient modulus of the test points before grouting. ; Comprehensive equivalent resilient modulus of test points before grouting The calculation formula is: in, This indicates the overall resilient modulus of the base course and subgrade before grouting. This indicates the resilient modulus of the entire cement concrete pavement before grouting. Indicates the structural layer allocation coefficient. , This represents the load diffusion coefficient of the pavement structure before grouting. This indicates the deflection value at the load center of the drop weight bending tester before grouting. This indicates the test load of the falling weight bending tester. Indicates the radius of the bearing plate of the falling weight bending tester; S1.4, Regarding the comprehensive equivalent resilient modulus Make corrections to obtain the corrected value. ; The correction value The calculation formula is: in, This represents the average value of the comprehensive equivalent resilient modulus at all test points within the evaluated road section before grouting. This represents the guarantee rate coefficient. This represents the standard deviation of the comprehensive equivalent resilient modulus at all test points within the evaluated road section before grouting. This represents the correction factor for changes in the density and modulus of the structural layers caused by factors related to traffic opening. The value range is 1 to 1.05; After grouting: S2.

1. Use a falling weight bending tester to collect bending basin data at each test point; S2.2 Calculate the comprehensive equivalent resilient modulus of the test points after grouting. ; The comprehensive equivalent resilient modulus of the test points after grouting The calculation formula is: in, This indicates the overall resilience modulus of the base course and subgrade after grouting. This indicates the resilient modulus of the entire cement concrete pavement after grouting. This represents the load diffusion coefficient of the pavement structure after grouting. This indicates the deflection value at the load center of the drop weight bending test after grouting. S2.3, Regarding the comprehensive equivalent resilient modulus Make corrections to obtain the corrected value. ; The correction value The calculation formula is: in, This represents the average value of the comprehensive equivalent resilient modulus at all test points within the evaluated road section after grouting. This represents the standard deviation of the comprehensive equivalent resilient modulus at all test points within the evaluated road section after grouting. This represents the support effect formed by the hardened grout in the grouting hole after grouting, as well as the correction coefficient for changes in the density and modulus of the structural layer caused by grouting or traffic conditions. The value range is 1.05 to 1.15; evaluate: S3, based on the correction value and The evaluation results of the grouting reinforcement effect are output.

2. The method for evaluating the grouting reinforcement effect of cement concrete pavement as described in claim 1, characterized in that, Load diffusion coefficient of the pavement structure before grouting The calculation formula is: in, , , These represent the deflection values ​​at distances of 300mm, 600mm, and 900mm from the load center before grouting.

3. The method for evaluating the grouting reinforcement effect of cement concrete pavement as described in claim 1, characterized in that, Load diffusion coefficient of grouting pavement structure The calculation formula is: in, , , These represent the deflection values ​​at distances of 300mm, 600mm, and 900mm from the load center after grouting.

4. The method for evaluating the grouting reinforcement effect of cement concrete pavement as described in claim 1, characterized in that, The evaluation indicators for the evaluation results include: the rate of improvement in the comprehensive equivalent resilient modulus. The comprehensive equivalent resilient modulus values ​​for different traffic levels.

5. The method for evaluating the grouting reinforcement effect of cement concrete pavement as described in claim 4, characterized in that, Improvement rate of overall equivalent resilient modulus The calculation formula is: ,when When the grouting rate is not less than 10%, the grouting reinforcement effect is considered to be qualified.

6. The method for evaluating the grouting reinforcement effect of cement concrete pavement as described in claim 4, characterized in that, The comprehensive equivalent resilient modulus values ​​for different traffic levels include: When the traffic level is extra heavy, the comprehensive equivalent resilient modulus value should not be less than 120MPa; When the traffic level is heavy, the comprehensive equivalent resilient modulus value should not be less than 100MPa; When the traffic level is medium or light, the comprehensive equivalent resilient modulus should not be less than 80 MPa.

Images