Resonant frequency-based rapid compaction construction process for rock-filled subgrade

Abstract

The application discloses a kind of filling rock roadbed rapid compaction construction technology based on resonant frequency, comprising the following steps: (1) in the filling rock roadbed to be compacted, select a section of roadbed as test object, the test object is monitored by on-site sweep frequency test to vibration wheel vibration, determine the sensitive frequency interval of roadbed.(2) in sensitive frequency interval take several frequency values, arrange from small to large.Then the roadbed is rolled under these frequency values, after each frequency rolling is finished, porosity detection is carried out, record each frequency and its corresponding roadbed porosity, record as reference group.(3) in the filling rock roadbed to be compacted, select another section of roadbed as test object, carry out first pass rolling to it, after finishing, detect porosity and dynamic deformation modulus detection, and record A1, B1.By analogy, until the porosity of roadbed reaches or is better than the required value.The application realizes the rapid construction of filling rock roadbed, while ensuring good construction quality, significantly improves construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of roadbed construction technology, and in particular to a rapid compaction construction process for rockfill roadbeds based on resonant frequency. Background Technology

[0002] Rockfill subgrades are constructed by blasting and quarrying stones or other waste rock. This not only yields a high-strength and stable subgrade but also allows for the local sourcing and reuse of stone, resulting in both social and economic benefits. However, 22-ton rollers are commonly used for compaction of rockfill subgrades. These rollers suffer from drawbacks: their small tonnage, low vibration force, the need for layered compaction, and relatively low efficiency. Furthermore, current methods for controlling subgrade compaction quality during construction often involve testing porosity and differential settlement. While porosity is frequently measured using the water-filling method, this method is difficult to implement, time-consuming, labor-intensive, and limited in its application to large-scale testing. Although differential settlement allows for relatively quick monitoring of compaction quality, the results are significantly affected by factors such as personnel and equipment conditions, leading to large data dispersion and making it difficult to accurately assess subgrade compaction quality. Summary of the Invention

[0003] In view of this, the present invention provides a rapid compaction construction process for rock-filled roadbeds based on resonant frequency. This invention utilizes the sensitivity of the rock fill material in the rock-filled roadbed to the excitation frequency to achieve rapid construction of the rock-filled roadbed, significantly improving construction efficiency while ensuring good construction quality. To achieve the above objectives, the present invention discloses the following technical solution.

[0004] A rapid compaction construction process for rockfill subgrade based on resonant frequency includes the following steps: (1) Select a section of the roadbed in the rockfill roadbed to be compacted as the test object, and conduct vibration monitoring of the test object by the vibration wheel through on-site frequency sweep test to determine the sensitive frequency range of the roadbed.

[0005] (2) Take several frequency values ​​in the sensitive frequency range and arrange them from smallest to largest. Then compact the roadbed at these frequency values. After each frequency is compacted once, perform porosity testing and record each frequency and its corresponding roadbed porosity as the reference group.

[0006] (3) Select another section of the rockfill subgrade to be compacted as the test object, and perform the first compaction on it. After the first compaction, test the porosity and dynamic deformation modulus, and record them as A1 and B1. Then find the frequency that is closest to the reference group of A1, and continue to compact the subgrade at that frequency value. After the compaction is completed, test the porosity and dynamic deformation modulus, and record them as A2 and B2. Continue in this manner until the porosity of the subgrade reaches or exceeds the required value.

[0007] (4) Fit the porosity and dynamic deformation modulus recorded in step (3) to obtain the correlation equation. Calculate the dynamic deformation modulus corresponding to each porosity in the benchmark group of step (2) according to the correlation equation, and form a construction process reference benchmark together with the benchmark group. Then, after compacting the remaining rockfill subgrade, directly test the dynamic deformation modulus, and obtain the corresponding porosity through the construction process reference benchmark to determine whether the target has been achieved. If the target has not been achieved, the rockfill subgrade can be compacted again at a frequency that can achieve the target through the construction process reference benchmark, and so on until the target is achieved.

[0008] Further, in step (1), the sensitive frequency range is determined based on the roadbed settlement displacement. Optionally, the roadbed settlement displacement is determined by detecting the elevation of the same point before and after compaction using a total station.

[0009] Further, in step (1), the starting point of the sensitive frequency interval is: when the deformation amplitude of the roadbed settlement position at a certain test frequency A increases by more than 4% of the deformation amplitude of the roadbed settlement position at the previous test frequency, frequency A is the starting point of the sensitive frequency interval. The ending point of the sensitive frequency interval is: when the deformation amplitude of the roadbed settlement position at a certain test frequency decreases by more than 4% of the deformation amplitude of the roadbed settlement position at the previous test frequency B, frequency B is the starting point of the sensitive frequency interval. It should be noted that the above "4%" is an illustrative example, and this value can also be adjusted according to actual needs. The sensitive frequency interval is usually an interval where the maximum value of the deformation amplitude of the roadbed settlement position is located, which means that the roadbed is more easily compacted at this frequency, the porosity decreases faster, and thus the roadbed settlement displacement changes more greatly.

[0010] Further, in step (2), the frequency value is an integer value that includes the minimum and maximum values ​​of the sensitive frequency range. Preferably, the frequency value also includes frequencies less than the minimum value and frequencies greater than the maximum value, so that the frequency range formed by the frequency values ​​completely covers the sensitive frequency range.

[0011] Further, in step (2), the porosity value of each subgrade in the reference group is expanded into a range. Preferably, the maximum value of the range is the same as the minimum value of the previous range, and the minimum value of the range is the same as the maximum value of the next range, so as to more quickly determine the range to which a specific porosity belongs, and thus quickly find the corresponding compaction frequency.

[0012] Furthermore, in step (3), the porosity is detected by the pit-digging and water-filling method.

[0013] Furthermore, in step (3), after the porosity of the roadbed reaches or exceeds the required value, the roadbed is statically compacted to finish the process, so as to flatten and eliminate the imprints formed by vibration compaction.

[0014] Furthermore, in step (4), after the target is achieved, the roadbed is statically compacted to flatten and eliminate the imprints formed by vibration compaction.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) The process of the present invention adopts the method of first determining the sensitive frequency range of the subgrade, and all subsequent vibration compaction processes are carried out at frequencies within this sensitive frequency range. This sensitive frequency range is closer to the resonant frequency of the subgrade being tested, so that the porosity of the subgrade can be reduced more quickly during vibration compaction. Tests show that the construction efficiency can be increased by more than 2 times, which greatly improves the construction efficiency, saves the construction period, and reduces the construction cost (the average compaction cost per cubic meter can be reduced by more than 20%), making it easier for the road to be opened to traffic quickly.

[0016] (2) The process of this invention, through close coordination between each step, obtains a construction process reference benchmark after preliminary testing. After compacting the remaining subgrade, the dynamic deformation modulus is directly tested instead of the porosity. Instead, the porosity is found in the aforementioned construction process reference benchmark based on the measured dynamic deformation modulus value, and it is determined whether the required porosity target has been achieved. If the target is not achieved, the rockfill subgrade is compacted again using the compaction test frequency corresponding to the current porosity, selected based on the aforementioned construction process reference benchmark. This process continues until the target is achieved. Compared to testing the porosity after compacting the rockfill subgrade to determine if the target has been achieved, testing the dynamic deformation modulus is faster and can significantly improve construction efficiency. Simultaneously, the obtained dynamic deformation modulus can also be used to test the mechanical properties of the subgrade. Furthermore, using the dynamic deformation modulus as a detection index allows for non-destructive testing, eliminating the need to dig pits and damage the subgrade surface. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 The following are curves showing the relationship between roadbed settlement displacement and vibration frequency in the embodiments below.

[0019] Figure 2 The following are porosity test diagrams corresponding to different frequencies of rolling in the embodiments.

[0020] Figure 3The following is a linear fit diagram of porosity and dynamic deformation modulus in the examples below. Detailed Implementation

[0021] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Furthermore, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art.

[0022] The reagents and raw materials used in this invention can all be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in this invention shall be used in accordance with conventional methods in the art or according to the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The preferred embodiments and materials described in this invention are for illustrative purposes only.

[0023] The rapid compaction construction process of the rock-filled roadbed based on resonant frequency of the present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Example

[0024] A rapid compaction construction process for rockfill subgrade based on resonant frequency is presented in this embodiment, taking a soft rockfill subgrade of an embankment as an example. The uniaxial saturated compressive strength of the rock was measured to be 10.3 MPa, and the maximum dry density was 2.68 g / cm³. 3 The porosity requirement is ≤22%, and the loose thickness of the rock-fill subgrade is 75cm. A 36-ton continuously variable frequency (CVF) roller (model YZ362) is selected for compaction of the rock-fill subgrade. This roller has a maximum excitation force of 800kN. The specific steps include: (1) A section of the rockfill subgrade to be compacted was selected as the test object. Vibration monitoring of the test object was conducted using a vibratory roller during a field frequency sweep test. The vibration monitor was placed on the vibratory roller to detect vibration acceleration. The vibration acceleration data was then converted into amplitude and frequency data using a data processing system. Simultaneously, the elevation of the same point before and after compaction was measured using a total station to test the subgrade settlement displacement under each vibration acceleration / frequency. Finally, the subgrade settlement displacement and its corresponding vibration frequency were plotted as a curve. The results are shown below. Figure 1As shown. The sensitive frequency range is determined as follows: The starting point of the sensitive frequency range is defined as follows: when the deformation amplitude of the roadbed settlement point at a certain test frequency A increases by more than 4% of the deformation amplitude of the roadbed settlement point at the previous test frequency, frequency A is the starting point of the sensitive frequency range. The ending point of the sensitive frequency range is defined as follows: when the deformation amplitude of the roadbed settlement point at a certain test frequency decreases by more than 4% of the deformation amplitude of the roadbed settlement point at the previous test frequency B, frequency B is the starting point of the sensitive frequency range. Based on the above method, the sensitive frequency range is obtained as 18~24Hz, that is, frequency A = 18 Hz and frequency B = 24Hz.

[0025] (2) The frequency range of 15~25Hz, which can completely cover the sensitive frequency range, is selected as the value range, and 15Hz, 16Hz, 17Hz, 18Hz, 19Hz, 20Hz, 21Hz, 22Hz, 23Hz, 24Hz, and 25Hz are selected as the test frequencies. Then, the subgrade is compacted at each of the test frequencies. After compaction at each test frequency, porosity is measured, and the porosity of each frequency and its corresponding subgrade is recorded as the reference group, such as... Figure 2 As shown. Then, the porosity value of each subgrade in the reference group is expanded into a range. Preferably, the maximum value of the range is the same as the minimum value of the previous range, and the minimum value of the range is the same as the maximum value of the next range, as shown in Table 1 below, wherein: the upper limit value of each porosity interval in the table does not include the number itself, and the lower limit value includes the number itself.

[0026] Table 1 Crushing test frequency / Hz 15 16 17 18 19 20 Porosity / % ≥28 26~28 25~26 24~25 23~24 22.5~23 Crushing test frequency / Hz 21 22 23 24 25 Porosity / % 22~22.5 21.5~22 21~21.5 20.5~21 20~20.5 (3) Another section of the rockfill subgrade to be compacted was selected as the test object. It was statically compacted once, and then the porosity of the subgrade was tested by water injection. The test value was 29.1%. According to Table 1 above, the compaction test frequency corresponding to this porosity value range is 15Hz, and the dynamic deformation modulus is 29.6MPa. Then, the subgrade was vibrated and compacted for the second time at a frequency of 15Hz, and the porosity was measured to be 25.4%, and the dynamic deformation modulus was 45.3MPa. By analogy, the third vibratory compaction was carried out at 17Hz... until the fifth vibratory compaction. The porosity of the subgrade was measured to meet the technical requirement of ≤22%, and the results are shown in Table 2 below. Finally, static compaction was performed to eliminate the ruts left by the vibratory compaction.

[0027] Table 2 Number of rolling passes 1 2 3 4 5 Porosity / % 29.1 25.4 24.0 22.5 21.4 Dynamic deformation modulus / MPa 29.6 45.3 47.0 55.8 67.9 Crushing frequency / Hz 0 (static pressure) 15 17 20 23 (4) Perform line fitting on each porosity and its corresponding dynamic deformation modulus in Table 2 above (e.g. Figure 3As shown in the figure, the linear equation is obtained as y = 161.00 - 4.57x. Based on the linear equation, the dynamic deformation modulus corresponding to each porosity in Table 1 is calculated, and together with the benchmark group, forms a construction process reference benchmark. The results are shown in Table 2 below.

[0028] Table 3 Crushing test frequency / Hz 15 16 17 18 19 20 Porosity / % ≥28 26~28 25~26 24~25 23~24 22.5~23 Dynamic deformation modulus / MPa ≤33 33~42 42~47 47~51 51~56 56~58 Crushing test frequency / Hz 21 22 23 24 25 Porosity / % 22~22.5 21.5~22 21~21.5 20.5~21 20~20.5 Dynamic deformation modulus / MPa 58~60 60~63 63~65 65~67 67~70 (5) Compact the remaining rockfill subgrade to be compacted. After compaction, directly test the dynamic deformation modulus instead of the porosity. Instead, find the corresponding porosity in Table 3 above based on the measured dynamic deformation modulus value and determine whether it has reached the target of ≤22%. If the target is not reached, select the compaction test frequency corresponding to the current porosity from Table 3 above and compact the rockfill subgrade again. After compaction, directly test the dynamic deformation modulus and find the corresponding porosity in Table 3 above based on the obtained test value to determine whether it has reached the target of ≤22%. Continue in this manner until the target is reached. Compared to testing the porosity after compacting the rockfill subgrade to determine whether the target has been reached, testing the dynamic deformation modulus is faster and can significantly improve construction efficiency. This is because: when using the water injection method to test porosity, two points need to be tested every 200 meters, which usually takes more than 3 hours to complete the test. When using dynamic deformation modulus as a measure of subgrade quality, according to high-speed railway testing standards, 12 testing points are required for every 200 meters of subgrade, taking only about 12 minutes, improving testing efficiency by approximately 15 times. Furthermore, the obtained dynamic deformation modulus can also be used to test the subgrade's mechanical properties. In addition, using dynamic deformation modulus as a testing indicator allows for non-destructive testing, eliminating the need to excavate and damage the subgrade surface.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rapid compaction construction process for rock-filled roadbeds based on resonant frequency, characterized in that, Includes the following steps: (1) Select a section of the roadbed in the rockfill roadbed to be compacted as the test object, and conduct vibration monitoring of the test object by vibrating wheel through on-site frequency sweep test, and determine the sensitive frequency range of the roadbed; the sensitive frequency range is the range in which the deformation amplitude of the roadbed settlement position is located. The starting point of the sensitive frequency interval is: when the deformation amplitude of the roadbed settlement position at a certain test frequency A increases by more than 4% of the deformation amplitude of the roadbed settlement position at the previous test frequency, frequency A is the starting point of the sensitive frequency interval; the ending point of the sensitive frequency interval is: when the deformation amplitude of the roadbed settlement position at a certain test frequency decreases by more than 4% of the deformation amplitude of the roadbed settlement position at the previous test frequency B, frequency B is the ending point of the sensitive frequency interval. (2) Take several frequency values ​​in the sensitive frequency range and arrange them from small to large; then compact the roadbed at these frequency values. After each frequency is compacted once, perform porosity testing, record each frequency and its corresponding roadbed porosity, and record it as the reference group. (3) Select another section of the roadbed in the rockfill roadbed to be compacted as the test object, and perform the first pass of static compaction on it. After the first pass, detect the porosity and dynamic deformation modulus and record them as A1 and B1. Then find the frequency that is closest to the porosity in the reference group for A1. Then continue to perform the first pass of compaction on the roadbed at the frequency value. After the compaction is completed, detect the porosity and dynamic deformation modulus and record them as A2 and B2. Continue in this way until the porosity of the roadbed reaches or exceeds the required value. (4) Fit the porosity and dynamic deformation modulus recorded in step (3) to obtain the correlation equation; calculate the dynamic deformation modulus corresponding to each porosity in the benchmark group in step (2) according to the correlation equation, and form a construction process reference benchmark together with the benchmark group; then directly test the dynamic deformation modulus of the remaining stone-filled roadbeds to be compacted after rolling, and obtain the corresponding porosity through the construction process reference benchmark to determine whether the target has been achieved.

2. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to claim 1, characterized in that, In step (1), the sensitive frequency range is determined based on the roadbed settlement displacement.

3. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to claim 2, characterized in that, The subgrade settlement displacement was determined by measuring the elevation of the same point before and after compaction using a total station.

4. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to claim 1, characterized in that, In step (2), the frequency value is an integer value that includes the minimum and maximum values ​​of the sensitive frequency range.

5. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to claim 1, characterized in that, The frequency value also includes frequencies less than the minimum value and frequencies greater than the maximum value.

6. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to claim 1, characterized in that, In step (2), the porosity value of each roadbed in the reference group is expanded to a range.

7. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to claim 6, characterized in that, The maximum value of the range is the same as the minimum value of the previous range, and the minimum value of the range is the same as the maximum value of the next range.

8. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to claim 1, characterized in that, In step (3), the porosity is detected by the pit-digging and water-filling method.

9. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to any one of claims 1-8, characterized in that, In step (3), after the porosity of the roadbed reaches or exceeds the required value, the roadbed is statically compacted to finish.

10. The rapid compaction construction process for rock-filled roadbed based on resonant frequency according to any one of claims 1-8, characterized in that, In step (4), after the target is achieved, the roadbed is statically compacted to finish.

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