A construction method for fragile filler roadbed

Abstract

The present invention provides a construction method for a fragile filler roadbed. The method comprises the following steps: step S10, respectively performing multiple indoor compaction tests on multiple samples with different moisture contents to determine the optimal moisture content of the fragile filler, wherein the multiple indoor compaction tests corresponding to the samples with each moisture content are performed in sequence; step S20, sequentially performing multiple indoor compaction tests on the fragile filler with the optimal moisture content to obtain the indoor crushing degree index of the fragile filler with the optimal moisture content; step S30, sequentially laying multiple layers of fragile filler with a preset thickness on the construction site based on the optimal moisture content, and performing rolling operations with a roller to obtain a fragile filler roadbed formed by sequentially stacking multiple layers of sub-roadbeds. The construction method for fragile filler provided by the present invention has the advantages of good compaction quality and good stability of the fragile filler roadbed.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a construction method for a fragile filler roadbed. Background Art

[0002] The fragile fillers have the characteristics of low strength and easy to break, which makes the roadbed constructed with fragile fillers less durable than general roadbeds. Fragile fillers may gradually break during long-term service, causing the roadbed to lose strength, and deform or be damaged by traffic loads and environmental influences, requiring frequent maintenance. The existing specifications have made the following provisions for fragile fillers (bad fillers): "When the nearby fillers do not meet the requirements of the fillers in the corresponding parts of the roadbed structure, or meet the requirements of the fillers in the corresponding parts of the roadbed structure but fail to meet the corresponding compaction standards, after a comprehensive comparison of technical and economic indicators, it should be determined to take improvement measures for the fillers." However, this provision has not been specified, such as specific construction requirements, the proposal of filler control indicators, and testing methods.

[0003] In recent years, the application of friable fillers in highway engineering has gradually increased. Studies have shown that friable fillers can meet the requirements of road engineering materials under certain conditions. However, the existing technology is not adaptable enough to friable fillers, and it is difficult to accurately evaluate their compaction state, leading to potential safety hazards. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for fragile fillers in view of the characteristics of low strength and easy breakage of fragile fillers, which has the advantages of good compaction quality and good stability of the fragile filler roadbed.

[0005] To achieve the above object, the present invention provides a construction method for a friable filler roadbed, comprising the following steps:

[0006] Step S10, performing multiple indoor compaction tests on multiple samples with different moisture contents to determine the optimal moisture content of the fragile filler, wherein multiple indoor compaction tests corresponding to samples with each moisture content are performed sequentially.

[0007] Step S20, performing multiple indoor compaction tests on the fragile filler with the optimal moisture content in sequence to obtain an indoor crushing degree index of the fragile filler with the optimal moisture content, the indoor crushing degree index including the maximum particle size, the range of the maximum particle size group and the percentage of the maximum particle size group in the total filler.

[0008] Step S30: based on the optimal moisture content, multiple layers of fragile filler with preset thickness are laid in sequence on the construction site, and a fragile filler roadbed formed by multiple layers of sub-roadbeds stacked in sequence is obtained by rolling with a roller, wherein the on-site crushing degree index of each layer of sub-roadbed in the fragile filler roadbed meets the indoor crushing degree index and the compaction degree is greater than or equal to the compaction degree standard value.

[0009] The construction steps of each sub-roadbed include:

[0010] A friable fill of preset thickness is laid on the construction site, and the moisture content of the friable fill is adjusted to the optimal moisture content.

[0011] The fragile filler is compacted by a target roller according to a predetermined rolling principle to obtain a fragile filler transition layer. The method for determining the target roller and the predetermined rolling principle includes:

[0012] Step S310: laying a layer of fragile filler with a preset thickness on the test site based on the optimal moisture content, where the test site includes multiple test areas.

[0013] Step S320: Use multiple different types of rollers to conduct on-site compaction tests on different test areas, determine the optimal number of rolling passes corresponding to each type of roller, and obtain the compaction degree and relative crushing rate corresponding to the optimal number of rolling passes for each type of roller.

[0014] Step S330: Based on the compaction degrees and relative crushing rates corresponding to the optimal number of rolling passes of all types of rollers, determine the target roller and the optimal number of rolling passes corresponding to the target roller, and the compaction degree and relative crushing rate corresponding to the optimal number of rolling passes of the target roller are the largest.

[0015] Step S340: Determine a predetermined rolling principle based on the optimal number of rolling passes.

[0016] Obtain the on-site crushing degree index and compaction degree of the fragile filler transition layer. When the on-site crushing degree index does not meet the indoor crushing degree index and / or the compaction degree of the fragile filler transition layer is less than the compaction standard value, add at least one strong vibration treatment to the fragile filler transition layer until the on-site crushing degree index of the fragile filler transition layer meets the indoor crushing degree index and the compaction degree of the fragile filler transition layer is greater than or equal to the compaction standard value, and a layer of sub-roadbed is obtained; when the on-site crushing degree index meets the indoor crushing degree index and the compaction degree of the fragile filler transition layer is greater than or equal to the compaction standard value, the sub-roadbed construction is completed.

[0017] In a specific implementation, the predetermined compaction principle includes: first performing basic compaction, and then performing multiple strong vibrations according to the optimal number of rolling times, wherein the basic compaction is specifically: first performing static compaction once, then performing two weak vibrations, and then performing two strong vibrations.

[0018] In a specific implementation, step S10 includes:

[0019] Step S110, respectively perform the current indoor compaction test on multiple samples with different moisture contents to obtain multiple dry densities corresponding to the current indoor compaction test, wherein the multiple dry densities correspond one-to-one to the multiple samples, wherein the multiple samples are samples that have completed the previous compaction test.

[0020] Step S120, performing Gaussian fitting on multiple dry densities corresponding to the current indoor compaction test of multiple samples to obtain a fitting curve of the current indoor compaction test, where the abscissa of the fitting curve is the moisture content and the ordinate is the dry density;

[0021] Step S130: Based on the fitting curve of the current indoor compaction test, obtain the maximum dry density and the optimal moisture content corresponding to the current indoor compaction test.

[0022] Step S140, obtain the difference in maximum dry density and the difference in optimal moisture content corresponding to the current indoor compaction test and the previous indoor compaction test, and when the absolute value of the difference in maximum dry density is less than or equal to the preset difference in dry density and the absolute value of the difference in optimal moisture content is less than or equal to the preset difference in moisture content, execute step S150; when the absolute value of the difference in maximum dry density is greater than the preset difference in dry density and / or the absolute value of the difference in optimal moisture content is greater than the preset difference in moisture content, repeatedly iterate and execute steps S110 to S130.

[0023] Step S150: taking the optimal moisture content determined by the fitting curve of the current indoor compaction test as the optimal moisture content of the fragile filler.

[0024] In a specific implementation, step S20 includes:

[0025] Step S210: Screen the weighed test filler step by step to obtain the filler weight of each sieve layer, and obtain the initial grading curve of the filler by accumulating the weight percentage of each grade.

[0026] Step S220, conduct the current indoor compaction test on the test filler with the optimal moisture content, and dry the filler that has completed the current indoor compaction test and then screen it step by step to obtain the filler weight of each sieve layer, and obtain the particle size grading curve corresponding to the current indoor compaction test through the cumulative weight percentage of each grade, wherein the filler with the optimal moisture content is the test filler that has completed the previous compaction test.

[0027] Step S230: Calculate the relative crushing rate corresponding to the current indoor compaction test based on the particle size gradation curve corresponding to the current indoor compaction test and the initial gradation curve of the filler.

[0028] Step S240, obtain the first difference in relative crushing rates corresponding to the current indoor compaction test and the previous indoor compaction test. When the first difference in relative crushing rates is greater than the preset difference in relative crushing rates, repeatedly iterate and execute steps S220 and S230; when the difference in relative crushing rates is less than or equal to the preset difference in relative crushing rates, execute step S250.

[0029] Step S250, taking the particle size gradation curve corresponding to the current indoor compaction test as the standard gradation curve, and based on the standard gradation curve, obtaining the indoor crushing degree index of the fragile filler with the optimal moisture content, the indoor crushing degree index includes the maximum particle size, the range of the maximum particle size group and the percentage of the maximum particle size group in the total filler.

[0030] In a specific implementation, in step S320, the method for determining the optimal number of rolling passes corresponding to each type of roller includes:

[0031] Step S321: Use a roller to perform basic rolling on the fragile filler on the test area.

[0032] Step S322: Continue to perform rolling operations on the fragile filler according to the strong vibration to compact the test area, and perform a sand filling method test on the fragile filler that has completed the current strong vibration to obtain the compaction degree corresponding to the current strong vibration.

[0033] Step S323, the fillers used in the sand filling method test are dried and screened step by step to obtain the filler weight of each screen layer, and the particle size distribution curve corresponding to the current strong vibration is obtained by accumulating the weight percentage of each classification.

[0034] Step S324: Based on the particle size gradation curve corresponding to the current strong vibration and the initial gradation curve of the fragile filler in the test area, the relative crushing rate and the maximum particle size corresponding to the current strong vibration are obtained.

[0035] Step S325, obtaining a second difference in relative crushing rate and a difference in compaction degree between the current strong vibration and the previous strong vibration.

[0036] Step S326: based on the second difference of the relative crushing rate, the difference of the compaction degree, and the compaction degree and the maximum particle size corresponding to the current strong vibration, determine whether the preset conditions are met. If the preset conditions are not met, the number of strong vibrations is increased by 1, and steps S322 to S325 are iteratively executed; if the preset conditions are met, terminate the test and execute step S327;

[0037] Step S327, taking the number of strong vibrations corresponding to the current strong vibration as the optimal number of rolling passes.

[0038] In a specific embodiment, the preset conditions include: the absolute value of the second difference in relative crushing rate is less than or equal to the preset difference in relative crushing rate, the absolute value of the difference in compaction degree is less than or equal to the preset difference in compaction degree, the compaction degree corresponding to the current strong vibration is greater than or equal to the preset compaction degree, and the maximum particle size corresponding to the current strong vibration is less than or equal to the maximum particle size in the indoor crushing degree index.

[0039] In a specific embodiment, the multiple different types of rollers include 18 tons, 20 tons, 22 tons, and 26 tons, the target roller is a 22-ton roller, and the optimal number of rolling passes of the target roller is 5 passes.

[0040] In a specific implementation, the strong vibration parameters of the target roller include: an exciting force of 280 kN, and a vibration frequency of 35 Hz; the weak vibration parameters of the target roller include: an exciting force of 390 kN, and a vibration frequency of 29 Hz.

[0041] In a specific embodiment, the friable filler is a red sandstone friable filler, and the optimal moisture content is 7.6%.

[0042] In a specific implementation, the preset thickness is 30-40 cm.

[0043] The beneficial effects of the present invention include at least:

[0044] The present invention provides a construction method for a friable filler roadbed, which comprises the following steps: step S10, respectively performing multiple indoor compaction tests on multiple samples with different moisture contents to determine the optimal moisture content of the friable filler; step S20, sequentially performing multiple indoor compaction tests on the friable filler with the optimal moisture content to obtain an indoor crushing degree index of the friable filler with the optimal moisture content; step S30, sequentially laying multiple layers of friable filler with a preset thickness on a construction site based on the optimal moisture content, and performing a roller rolling operation to obtain a friable filler composed of multiple layers. A fragile filler roadbed is formed by stacking layers of sub-roadbeds in sequence, wherein the on-site crushing degree index of each layer of sub-roadbed in the fragile filler roadbed meets the indoor crushing degree index and the compaction degree is greater than or equal to the compaction standard value, wherein the construction steps of each layer of sub-roadbed include: laying a fragile filler of a preset thickness on the construction site, and adjusting the moisture content of the fragile filler to the optimal moisture content; using a target roller to compact the fragile filler according to a predetermined rolling principle to obtain a fragile filler transition layer; obtaining the on-site crushing degree index and compaction degree of the fragile filler transition layer, and crushing it on site When the degree index does not meet the indoor crushing degree index and / or the compaction degree of the fragile filler transition layer is less than the compaction standard value, at least one strong vibration treatment is added to the fragile filler transition layer until the on-site crushing degree index of the fragile filler transition layer meets the indoor crushing degree index and the compaction degree of the fragile filler transition layer is greater than or equal to the preset compaction degree, so as to obtain a layer of sub-roadbed; in terms of compaction quality evaluation, the construction method provided by the present invention first determines the optimal moisture content of the fragile filler through multiple indoor compaction tests, then obtains the indoor crushing degree index corresponding to the fragile filler with the optimal moisture content, and uses the index as the on-site construction compaction quality index; in terms of on-site construction, the fragile filler is adjusted to the optimal moisture content before construction, and then the target roller and the optimal number of rolling times determined by the rolling test are used for construction. After the construction is completed, the compaction quality is tested, and then the roadbed is judged whether it meets the compaction quality requirements based on the indoor crushing degree index and the compaction standard value. In this way, the compaction quality of the fragile filler roadbed meets the standard, which can overcome the shortcomings of poor durability and easy breakage during service of the existing fragile filler roadbed, and has the advantages of good stability and long service life.

[0045] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A flowchart of the steps of a construction method of a friable filler roadbed provided in one embodiment of the present invention;

[0047] Figure 2 A flow chart of sub-steps of step S10 of a method for constructing a friable filler roadbed provided in one embodiment of the present invention;

[0048] Figure 3 A graph of fitting curves corresponding to four indoor compaction tests obtained in step S10 of the present invention;

[0049] Figure 4 A flow chart of sub-steps of step S20 of a method for constructing a friable filler roadbed provided in one embodiment of the present invention;

[0050] Figure 5 The particle size gradation curve corresponding to the multiple chamber compaction tests and the initial gradation curve of the filler obtained in step S20 of the present invention;

[0051] Figure 6 A flowchart of a method for determining a target roller and a predetermined rolling principle in step S30 of a method for constructing a friable filler roadbed according to an embodiment of the present invention;

[0052] Figure 7 A flowchart of the steps of a method for determining the optimal number of rolling passes corresponding to each type of roller in step S30 of the construction method of a friable filler roadbed provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0054] See also Figures 1 to 7 The present invention provides a construction method for a roadbed with fragile fillers. The construction method uses the best model of roller and the best number of rolling passes determined by a rolling test in a test area as the construction roller and construction parameters, and uses the indoor crushing degree index of the fragile filler (with the highest moisture content) determined by an indoor compaction test as the judgment standard for the crushing degree quality of on-site construction, and uses the compaction standard value specified in the standard as the compaction judgment standard. In this way, the compaction quality of the roadbed with fragile fillers meets the standards, which can overcome the shortcomings of poor durability and easy breakage during service of the existing roadbed with fragile fillers, and has the advantages of good stability and long service life.

[0055] The construction method of the fragile filler roadbed provided by the present invention comprises the following steps:

[0056] Step S10, performing multiple indoor compaction tests on multiple samples with different moisture contents to determine the optimal moisture content of the fragile filler, wherein multiple indoor compaction tests corresponding to samples with each moisture content are performed sequentially.

[0057] Please refer to Figure 2 , step S10 comprises:

[0058] Step S110, respectively perform the current indoor compaction test on multiple samples with different moisture contents to obtain multiple dry densities corresponding to the current indoor compaction test, wherein the multiple dry densities correspond one-to-one to the multiple samples, wherein the multiple samples are samples that have completed the previous compaction test.

[0059] In this embodiment, the moisture contents of the plurality of samples are 2%, 4%, 6%, 8%, 10%, 12% and 14%, respectively.

[0060] It is understandable that in the present invention, the preset moisture content values ​​are 7, and accordingly, the number of samples is also 7.

[0061] In the present invention, the moisture content of multiple samples can be determined based on experience or experiments, and the optimal moisture content cannot be the set maximum moisture content, that is, the fitting curve obtained based on the compaction test must have an inflection point. If no inflection point appears, it is necessary to expand the moisture content range of the sample and continue the compaction test.

[0062] It should be noted that, when the current compaction test is the first compaction test, the multiple samples correspond to the original samples, and the samples that completed the last compaction test refer to the samples that completed 0 compaction tests, that is, the samples that did not undergo compaction tests; when the current compaction test is a compaction test other than the first compaction test, the multiple samples are compaction tests that have completed the other number of times minus 1. For example, if the current time is the second time, the second compaction test is for the samples that have completed the first compaction test; if the current time is the third time, the third compaction test is for the samples that have completed the second compaction test, and so on. They are not listed here one by one.

[0063] In the present invention, the specific steps of the first compaction test include:

[0064] Step (1) Sample preparation

[0065] Collect sufficient amount of fragile filler samples from the test site, dry the samples in a drying oven to constant weight, and record the weights before and after drying.

[0066] Use a sample divider to divide the dried sample into 7 equal parts, and try to ensure the uniformity of each sample to ensure the accuracy of the test results.

[0067] According to the pre-set moisture content values, the seven samples had moisture contents of 2%, 4%, 6%, 8%, 10%, 12% and 14% respectively. During the moisture content adjustment process, a measuring cylinder was used to accurately measure and control the moisture content of the samples.

[0068] After stirring evenly, 7 samples with different moisture contents were sealed and stored for 24 hours to ensure uniform distribution of moisture.

[0069] Step (2): Compaction test

[0070] In the present invention, a compaction test is performed according to the Highway Geotechnical Test Code (JTG 3430-2020). Before the test, the test mold is cleaned and assembled, and the sample with adjusted moisture content is loaded into the mold in three layers, and each layer is evenly spread. The height and weight of the sample after compaction are recorded.

[0071] In the present invention, four compaction tests were carried out on samples with seven moisture contents. The results of the four compaction tests on the seven samples are shown in Table 1.

[0072]

[0073] Step S120, perform Gaussian fitting on multiple dry densities corresponding to the current indoor compaction test of multiple samples to obtain a fitting curve of the current indoor compaction test, where the abscissa of the fitting curve is the moisture content and the ordinate is the dry density.

[0074] In the present invention, the model used for Gaussian fitting is GaussAmp.

[0075] In the present invention, four indoor compaction tests were carried out. The fitting curves of the four indoor compaction tests are shown in Figure 3 .

[0076] Step S130: Based on the fitting curve of the current indoor compaction test, obtain the maximum dry density and the optimal moisture content corresponding to the current indoor compaction test.

[0077] The maximum dry density corresponding to the current compaction test refers to the ordinate corresponding to the vertex of the fitting curve, and the optimal moisture content refers to the abscissa corresponding to the vertex of the fitting curve.

[0078] Step S140, obtain the difference in maximum dry density and the difference in optimal moisture content corresponding to the current indoor compaction test and the previous indoor compaction test, and when the absolute value of the difference in maximum dry density is less than or equal to the preset difference in dry density and the absolute value of the difference in optimal moisture content is less than or equal to the preset difference in moisture content, execute step S150; when the absolute value of the difference in maximum dry density is greater than the preset difference in dry density and / or the absolute value of the difference in optimal moisture content is greater than the preset difference in moisture content, repeatedly iterate and execute steps S110 to S130.

[0079] In this embodiment, the preset difference in dry density is 0.015 g / cm³, and the preset difference in moisture content is 0.5%, that is, the first preset condition is specifically: the absolute value of the difference in maximum dry density is less than 0.015 g / cm³, and the absolute value of the difference in optimal moisture content is less than 0.5%.

[0080] In other embodiments, the absolute value of the difference in maximum dry density can also be smaller than other preset values, such as 0.025 g / cm³, 0.02 g / cm³, etc., and the absolute value of the difference in optimal moisture content can also be smaller than 0.3%, 0.6%, etc.

[0081] In the present invention, when the difference in maximum dry density is less than the preset difference in dry density and the difference in optimal moisture content is less than the preset difference in moisture content, it can be understood that the fitting curves corresponding to the two compaction tests are basically consistent, and the degree of particle crushing obtained under the compaction test tends to be stable.

[0082] When the current compaction test is the first compaction test, the maximum dry density and the optimal moisture content corresponding to the previous compaction test can be considered to be 0, and the maximum dry density difference and the optimal moisture content difference do not meet the first preset condition; continue to carry out the second compaction test, and then calculate the difference between the dry density and the optimal moisture content of the second compaction test and the first compaction test, and judge whether the first preset condition is met, and the result is not met; continue to carry out the third compaction test, and then calculate the difference between the dry density and the optimal moisture content of the third compaction test and the second compaction test, and judge whether the first preset condition is met, and the result is not met; continue to carry out the fourth compaction test, and then calculate the difference between the dry density and the optimal moisture content of the fourth compaction test and the third compaction test, and judge whether the first preset condition is met, and the result is met, and the compaction test is terminated, that is, in the present invention, it is considered that the fragile filler that has completed the fourth compaction test has reached a stable state.

[0083] Step S150: taking the optimal moisture content determined by the fitting curve of the current indoor compaction test as the optimal moisture content of the fragile filler.

[0084] The optimum moisture content is the moisture content corresponding to the maximum dry density. In the present invention, based on the fitting curve of the fourth compaction test, the optimum moisture content is determined to be 7.6%.

[0085] Step S20, performing multiple indoor compaction tests on the fragile filler with the optimal moisture content in sequence to obtain an indoor crushing degree index of the fragile filler with the optimal moisture content, the indoor crushing degree index including the maximum particle size, the range of the maximum particle size group and the percentage of the maximum particle size group in the total filler.

[0086] In the present invention, the maximum particle size in the indoor crushing degree index is 40 mm, the range of the maximum particle size group is 30 mm to 40 mm, and the percentage of the maximum particle size group in the total filler is 5.68%.

[0087] Please refer to Figure 4 , step S20 comprises:

[0088] Step S210: Screen the weighed test filler step by step to obtain the filler weight of each sieve layer, and obtain the initial grading curve of the filler by accumulating the weight percentage of each grade.

[0089] Step S220, conduct the current indoor compaction test on the test filler with the optimal moisture content, and dry the filler that has completed the current indoor compaction test and then screen it step by step to obtain the filler weight of each sieve layer, and obtain the particle size grading curve corresponding to the current indoor compaction test through the cumulative weight percentage of each grade, wherein the filler with the optimal moisture content is the test filler that has completed the previous compaction test.

[0090] In the present invention, the abscissa of the particle size distribution curve is the particle size, and the ordinate is the percentage of particles smaller than a certain particle size.

[0091] It should be noted that, when the current compaction test is the first compaction test, the filling material of the compaction test is the original filling material obtained (the filling material that has completed 0 compaction tests), that is, the filling material that has not been subjected to the compaction test; when the current compaction test is a compaction test other than the first compaction test, the filling material of the compaction test is the filling material that has completed the compaction test other times minus 1 time, such as when the current time is the second time, then the second compaction test is for the filling material that has completed the first compaction test, and when the current time is the third time, then the third compaction test is for the filling material that has completed the second compaction test, and so on, which are not listed one by one here.

[0092] Step S230: Calculate the relative crushing rate corresponding to the current indoor compaction test based on the particle size gradation curve corresponding to the current indoor compaction test and the initial gradation curve of the filler.

[0093] In the present invention, the calculation formula of relative crushing rate is: ;in It represents the area of ​​the first closed area enclosed by the initial grading curve, the vertical axis, and the straight line segment parallel to the horizontal axis and with the vertical coordinate data of 100%. It represents the area of ​​the second closed region enclosed by the particle size gradation curve, initial gradation curve and vertical axis corresponding to the current compaction test.

[0094] Step S240, obtain the first difference in relative crushing rates corresponding to the current indoor compaction test and the previous indoor compaction test. When the first difference in relative crushing rates is greater than the preset difference in relative crushing rates, repeatedly iterate and execute steps S220 and S230; when the difference in relative crushing rates is less than or equal to the preset difference in relative crushing rates, execute step S250.

[0095] The present invention judges whether the degree of crushing is stable based on the absolute value of the difference in relative crushing rates. When the absolute value of the difference in relative crushing rates is less than or equal to the preset difference in relative crushing rates, it is judged that the degree of crushing tends to be stable, that is, the compaction test is continued and the particle size of the fragile filler will not change too much.

[0096] Step S250: Use the particle size gradation curve corresponding to the current indoor compaction test as the standard gradation curve, and based on the standard gradation curve, obtain the indoor crushing degree index of the fragile filler with the optimal moisture content, the indoor crushing degree index includes the maximum particle size, the range of the maximum particle size group and the percentage of the maximum particle size group in the total filler.

[0097] Specifically: After weighing the sample, first use the standard sieve screening equipment to gradually screen the sample, weigh and record the filler weight of each sieve layer, then calculate the weight percentage of each sieve layer, and obtain the initial grading curve by accumulating the weight percentage of each grade. For details of the initial grading curve, see Figure 5 The curve corresponding to the gradation before crushing.

[0098] Use a measuring cylinder to adjust the moisture content of the filler to 7.6%, and perform a compaction test according to the compaction test steps above. After completing the first compaction test, dry the filler to constant weight, and then use a standard screening device to screen the filler of the first compaction test step by step, weigh and record the sample weight of each sieve layer, and then calculate the weight percentage of each sieve layer, and obtain the particle size distribution curve corresponding to the first compaction test by accumulating the weight percentage of each grade, as shown in the figure. Figure 5 The curve corresponding to the first compaction test under the optimal moisture content.

[0099] Based on the initial grading curve and the particle size grading curve corresponding to the first compaction test, the relative crushing rate corresponding to the first compaction test is calculated.

[0100] Use a measuring cylinder to adjust the moisture content of the filler after the first compaction test to 7.6%, and perform the compaction test according to the compaction test steps above. After the second compaction test, dry the filler to constant weight, and then use standard screening equipment to screen the filler of the second compaction test step by step, weigh and record the sample weight of each sieve layer, and then calculate the weight percentage of each sieve layer, and obtain the particle size distribution curve corresponding to the second compaction test by accumulating the weight percentage of each grade, as shown in the figure. Figure 5 The curve corresponding to the second compaction test under the optimal moisture content.

[0101] Based on the initial grading curve and the particle size grading curve corresponding to the second compaction test, the relative crushing rate corresponding to the second compaction test was calculated.

[0102] Calculate the difference between the relative crushing rate corresponding to the second compaction test and the relative crushing rate corresponding to the first compaction test, and judge the relationship between the absolute value of the difference and the first preset value, and the result is that the absolute value of the difference in relative crushing rates is greater than the first preset value; continue to perform the third compaction test, and obtain the particle size grading curve corresponding to the third compaction test, and then calculate the relative crushing rate corresponding to the third compaction test; calculate the difference between the relative crushing rate corresponding to the third compaction test and the relative crushing rate corresponding to the second compaction test, and judge the relationship between the absolute value of the difference and the first preset value, and the result is that the absolute value of the difference in relative crushing rates is greater than the first preset value; continue to perform the fourth compaction test..., and no further enumeration is given here.

[0103] The initial grading curve of the present invention and the particle size grading curve obtained by multiple compaction tests are detailed in Figure 5 As shown, in the present invention, the particle size gradation curve obtained from the fourth compaction test is used as the standard gradation curve, and the maximum particle size, the range of the maximum particle size group and the percentage of the maximum particle size group in the total filler determined according to the standard gradation curve are used as the maximum particle size of the fragile filler, the range of the maximum particle size group and the percentage of the maximum particle size group in the total filler.

[0104] Step S30: based on the optimal moisture content, multiple layers of fragile filler with preset thickness are laid in sequence on the construction site, and the fragile filler roadbed formed by multiple layers of sub-roadbeds stacked in sequence is obtained by rolling with a roller, and the on-site crushing degree index of each layer of sub-roadbed in the fragile filler roadbed meets the indoor crushing degree index and the compaction degree is greater than or equal to the compaction degree standard value.

[0105] In this step, the optimal moisture content is the optimal moisture content determined in step S10, which is 7.6%.

[0106] In this step, the preset thickness is 30 cm.

[0107] In this step, 5 to 7 layers of 30 cm thick fragile filler are laid in sequence.

[0108] Please refer to Figure 6 and Figure 7 , the construction steps of each sub-roadbed include:

[0109] Step (a), laying a fragile filler of a preset thickness on the construction site, and adjusting the moisture content of the fragile filler to an optimal moisture content.

[0110] Step (b), compacting the fragile filler using a target roller according to a predetermined rolling principle to obtain a fragile filler transition layer.

[0111] Preferably, the target roller is a No. 22 roller, and the predetermined rolling principles include: first perform basic rolling, then perform 5 times of strong vibration rolling, wherein the basic rolling follows the principle of "first slow then fast, first static then vibration", first perform one static rolling, then perform two weak vibrations, and then perform two strong vibrations.

[0112] Preferably, the driving speed for each rolling is controlled at 1km / h~3km / h. More preferably, the driving speed corresponding to the weak vibration is the same as the driving speed corresponding to the strong vibration, and both are 2km / h.

[0113] In the present invention, the strong vibration parameters of the target roller include: exciting force 280 kN, vibration frequency 35 Hz; the weak vibration parameters of the target roller include: exciting force 390 kN, vibration frequency 29 Hz.

[0114] The method for determining the target roller and the predetermined rolling principle includes:

[0115] Step S310: laying a layer of fragile filler with a preset thickness on the test site based on the optimal moisture content, where the test site includes multiple test areas.

[0116] Step S320: Use multiple different types of rollers to conduct on-site compaction tests on different test areas, determine the optimal number of rolling passes corresponding to each type of roller, and obtain the compaction degree and relative crushing rate corresponding to the optimal number of rolling passes for each type of roller.

[0117] In this embodiment, the multiple different types of rollers include four types of rollers, and the tonnages of the rollers are 18 tons, 20 tons, 22 tons, and 26 tons respectively.

[0118] in:

[0119] 18-ton road roller: weak vibration parameters include exciting force 340kN, vibration frequency 28Hz; strong vibration parameters include: exciting force 240kN, vibration frequency 33Hz.

[0120] 20-ton road roller: weak vibration parameters include exciting force 385kN, vibration frequency 28Hz; strong vibration parameters include: exciting force 270kN, vibration frequency 33Hz.

[0121] 22-ton road roller: weak vibration parameters include exciting force 390kN, vibration frequency 29Hz; strong vibration parameters include: exciting force 280kN, vibration frequency 35Hz.

[0122] 26-ton roller: weak vibration parameters include exciting force 435kN, vibration frequency 27Hz; strong vibration parameters include exciting force 315kN, vibration frequency 32Hz.

[0123] In other embodiments, the number of models of road rollers may also be 3, 5, 6, etc., which are not enumerated here.

[0124] It should be noted that the weak vibration and strong vibration parameters of the roller are related to the supplier of the roller. The weak vibration parameters and strong vibration parameters of rollers produced by different suppliers may be different.

[0125] In the present invention, there are 12 test areas, and each type of roller rolls three test areas respectively. The arithmetic mean of the rolling test results is taken to improve the accuracy of the test results. It should be noted that each type of roller can also roll only one test area.

[0126] In the present invention, the rolling test results include compaction degree, relative crushing rate and maximum particle size determined based on the grading curve.

[0127] For ease of understanding, let's take an example. Suppose an 18-ton roller is used to roll in three test areas. The compaction degrees obtained are A1, A2 and A3, the relative crushing rates are B1, B2 and B3, and the maximum particle sizes are C1, C2 and C3. Then the compaction degree corresponding to the 18-ton roller is the sum of A1, A2 and A3 divided by 3. Similarly, the relative crushing rate corresponding to the 18-ton roller is the sum of B1, B2 and B3 divided by 3, and the maximum particle size corresponding to the 18-ton roller is the sum of C1, C2 and C3 divided by 3.

[0128] In step S320, the method for determining the optimal number of rolling passes corresponding to each type of roller includes:

[0129] Step S321: Use a roller to perform basic rolling on the fragile filler on the test area.

[0130] In the present invention, in order to ensure that the roller can travel stably and compact layer by layer, the length of the test area should be more than 20 meters. In order to ensure that the various test areas do not affect each other, the width of each test area should be more than 4 meters. Therefore, the area of ​​a single test area should be more than 80 square meters.

[0131] In this embodiment, the area of ​​the test area is 20 meters long*4 meters wide=80 square meters.

[0132] The foundation rolling follows the principle of "slow first, fast later, static first, vibration later". First, static pressure is carried out, then two weak vibrations are carried out, and then two strong vibrations are carried out.

[0133] Step S322: Continue to perform rolling operations on the fragile filler according to the strong vibration to compact the test area, and perform a sand filling method test on the fragile filler that has completed the current strong vibration to obtain the compaction degree corresponding to the current strong vibration.

[0134] Preferably, each model of roller is subjected to rolling tests in a plurality of test areas, and the compaction degree corresponding to the current strong vibration is the average value of the compaction degrees obtained in the plurality of test areas.

[0135] In the present invention, the sand filling method test is used to detect the compaction degree of the roadbed, and the specific test steps are carried out with reference to the "Standard for Geotechnical Test Methods" (GB / T 50123-2019).

[0136] Step S323, the fillers used in the sand filling method test are dried and screened step by step to obtain the filler weight of each screen layer, and the particle size distribution curve corresponding to the current strong vibration is obtained by accumulating the weight percentage of each classification.

[0137] Step S324: Based on the particle size gradation curve corresponding to the current strong vibration and the initial gradation curve of the fragile filler in the test area, the relative crushing rate and the maximum particle size corresponding to the current strong vibration are obtained.

[0138] In the present invention, the calculation formula of the relative crushing rate has been described in detail above and will not be repeated here.

[0139] In the present invention, the maximum particle size is the abscissa of the rightmost point of the particle size distribution curve.

[0140] Preferably, each model of roller is subjected to rolling tests in a plurality of test areas respectively, and the maximum particle size corresponding to the current strong vibration is the average value of the maximum particle sizes determined in the plurality of test areas.

[0141] It should be noted that the initial gradation curve of the fragile filler on the test area can be obtained by obtaining the fragile filler on the test area, then screening step by step, obtaining the filler weight of each sieve layer, and obtaining the initial gradation curve of the fragile filler by accumulating the weight percentage of each grade; or the initial gradation curve obtained in step S210 can be directly used. In the present invention, the test filler used in the indoor compaction test, the fragile filler used in the test area, and the fragile filler used on the construction site are all taken from the same batch of fragile fillers.

[0142] Step S325, obtaining a second difference in relative crushing rate and a difference in compaction degree between the current strong vibration and the previous strong vibration.

[0143] Preferably, each model of roller is subjected to rolling tests in multiple test areas respectively, and the second difference in relative crushing rate is the difference between the average value of the relative crushing rate of the current strong vibration and the average value of the relative crushing rate of the previous strong vibration; the difference in compaction degree is the difference between the average value of the compaction degree of the current strong vibration and the average value of the compaction degree of the previous strong vibration.

[0144] Step S326: Based on the second difference in relative crushing rate, the difference in compaction degree, and the compaction degree and maximum particle size corresponding to the current strong vibration, determine whether the preset conditions are met. If the preset conditions are not met, the number of strong vibrations is increased by 1, and steps S322 to S325 are iteratively executed; if the preset conditions are met, terminate the test and execute step S327.

[0145] In the present invention, the preset conditions include: the absolute value of the second difference in relative crushing rate is less than or equal to the preset difference in relative crushing rate, the absolute value of the difference in compaction degree is less than or equal to the preset difference in compaction degree, the compaction degree corresponding to the current strong vibration is greater than or equal to the preset compaction degree, and the maximum particle size corresponding to the current strong vibration is less than or equal to the maximum particle size in the indoor crushing degree index.

[0146] In this embodiment, the preset difference of crushing rate is 1.5%, the preset difference of compaction degree is 0.5, the maximum particle size in the indoor crushing degree index is 40 mm, and the preset compaction degree is 95%.

[0147] Step S327, taking the number of strong vibrations corresponding to the current strong vibration as the optimal number of rolling passes.

[0148] Step S330: Based on the compaction degrees and relative crushing rates corresponding to the optimal number of rolling passes of all types of rollers, determine the target roller and the optimal number of rolling passes corresponding to the target roller, and the compaction degree and relative crushing rate corresponding to the optimal number of rolling passes of the target roller are the largest.

[0149] The rolling test results provided by the present invention are shown in Table 2.

[0150]

[0151] Based on the data in Table 2, it can be seen that the target roller is 22 tons and the optimal number of rolling passes corresponding to the target roller is 5 times.

[0152] It should be noted that if the compaction degree and the relative crushing rate are not simultaneously maximum, the maximum compaction degree is used as the condition for determining the target roller.

[0153] Step S340: Determine a predetermined rolling principle based on the optimal number of rolling passes.

[0154] Step (c), obtaining the on-site crushing degree index and compaction degree of the fragile filler transition layer. When the on-site crushing degree index does not meet the indoor crushing degree index and / or the compaction degree of the fragile filler transition layer is less than the compaction standard value, adding at least one strong vibration treatment to the fragile filler transition layer until the on-site crushing degree index of the fragile filler transition layer meets the indoor crushing degree index and the compaction degree of the fragile filler transition layer is greater than or equal to the compaction standard value, thereby obtaining a layer of sub-roadbed; when the on-site crushing degree index meets the indoor crushing degree index and the compaction degree of the fragile filler transition layer is greater than or equal to the compaction standard value, the sub-roadbed construction is completed.

[0155] In the present invention, compaction quality detection includes:

[0156] (1) On-site crushing index detection

[0157] a. Sample collection: Evenly arrange the measuring points on the compacted roadbed. The measuring points should be evenly distributed throughout the construction section to avoid being concentrated in a certain area to ensure the representativeness of the test results. The specific arrangement method of the measuring points is as follows: in the longitudinal direction of the roadbed, a measuring point is arranged every 10 to 20 meters; in the transverse direction of the roadbed, the measuring points are arranged at the center line of the roadbed, the left 1 / 2 and the right 1 / 2. Randomly select a certain number of measuring points for sampling and testing, and mark the sampled measuring points to reduce the influence of human factors. Each measuring point collects about 20 kilograms of test samples, and the collection depth is not less than 20 centimeters.

[0158] b. Sample screening: First, dry the collected test samples to constant weight. Then use standard screening equipment to screen the samples step by step, weigh and record the weight of the test samples in each sieve layer, and draw the gradation curve of the test samples based on the cumulative weight percentage of each grade.

[0159] c. Determine the crushing degree index: Based on the grading curve of the test sample, determine the maximum particle size of the fragile filler, the range of the largest particle size group and the percentage of the largest particle size group in the total filler.

[0160] d. Evaluation of crushing degree: When the maximum particle group range in the test sample is less than or equal to the maximum particle group range obtained in step S250, the maximum particle size in the test sample is less than or equal to the maximum particle size obtained in step S250, and the percentage of the maximum particle size group in the test sample to the total filler is less than or equal to the percentage of the maximum particle size group obtained in step S250 to the total filler, it is considered that the on-site crushing degree index of the test sample meets the indoor crushing degree index.

[0161] (2) Compactness test

[0162] a. Measurement point arrangement: the same as the measurement point arrangement in filler crushing degree detection.

[0163] b. Use the on-site sand filling method to conduct the test. The test steps refer to the sand filling method in the "GB / T 50123-2019 Geotechnical Test Method Standard".

[0164] c. The standard value of compaction degree is controlled 1% higher than the requirement of "JTG / T 3610-2019 Technical Specifications for Highway Roadbed Construction", and the requirements are as follows:

[0165]

[0166] It should be noted that when the compaction quality does not meet the requirements, it means that the on-site crushing degree index does not meet the indoor crushing degree index and / or the compaction degree is less than the compaction degree standard value.

[0167] In the present invention, the standard value of compaction degree is 95%.

[0168] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A construction method for a friable filler roadbed, characterized in that: The following steps are involved: Step S10, performing multiple indoor compaction tests on multiple samples with different moisture contents to determine the optimal moisture content of the fragile filler, wherein multiple indoor compaction tests corresponding to samples with each moisture content are performed in sequence; Step S20, performing multiple indoor compaction tests on the fragile filler with the optimal moisture content in sequence to obtain an indoor crushing degree index of the fragile filler with the optimal moisture content, the indoor crushing degree index including the maximum particle size, the range of the maximum particle size group, and the percentage of the maximum particle size group in the total filler; Step S30: laying multiple layers of fragile filler with preset thickness in the construction site in sequence based on the optimal moisture content, and rolling them with a roller to obtain a fragile filler roadbed formed by stacking multiple layers of sub-roadbeds in sequence, wherein the on-site crushing degree index of each layer of sub-roadbed in the fragile filler roadbed meets the indoor crushing degree index and the compaction degree is greater than or equal to the compaction degree standard value; The construction steps of each sub-roadbed include: Lay a friable filler of preset thickness on the construction site and adjust the moisture content of the friable filler to the optimal moisture content; The fragile filler is compacted by a target roller according to a predetermined rolling principle to obtain a fragile filler transition layer. The method for determining the target roller and the predetermined rolling principle includes: Step S310: laying a layer of fragile filler with a preset thickness on the test site based on the optimal moisture content, where the test site includes multiple test areas; Step S320: Use multiple different types of rollers to conduct on-site compaction tests on different test areas, determine the optimal number of rolling passes corresponding to each type of roller, and obtain the compaction degree and relative crushing rate corresponding to the optimal number of rolling passes for each type of roller; Step S330: based on the compaction degrees and relative crushing rates corresponding to the optimal number of rolling passes of all types of rollers, determine a target roller and the optimal number of rolling passes corresponding to the target roller, wherein the compaction degree and relative crushing rate corresponding to the optimal number of rolling passes of the target roller are greater than the compaction degree and relative crushing rate corresponding to the optimal number of rolling passes of other types of rollers; Step S340, determining a predetermined rolling principle based on the optimal number of rolling passes; The on-site crushing degree index and compaction degree of the fragile filler transition layer are obtained. When the on-site crushing degree index does not meet the indoor crushing degree index and / or the compaction degree of the fragile filler transition layer is less than the compaction standard value, at least one strong vibration treatment is added to the fragile filler transition layer until the on-site crushing degree index of the fragile filler transition layer meets the indoor crushing degree index and the compaction degree of the fragile filler transition layer is greater than or equal to the compaction standard value, so as to obtain a layer of sub-roadbed; when the on-site crushing degree index meets the indoor crushing degree index and the compaction degree of the fragile filler transition layer is greater than or equal to the compaction standard value, the sub-roadbed construction is completed, wherein the on-site crushing degree index meets the indoor crushing degree index specifically when: the range of the maximum particle size group in the on-site detection sample is less than or equal to the range of the maximum particle size group in the indoor crushing degree index, the maximum particle size in the on-site detection sample is less than or equal to the maximum particle size in the indoor crushing degree index, and the percentage of the maximum particle size group in the on-site detection sample to all fillers is less than or equal to the percentage of the maximum particle size group in the indoor crushing degree index to all fillers.

2. The construction method of a friable filler roadbed according to claim 1, characterized in that: The predetermined compaction principles include: first perform basic compaction, and then perform multiple strong vibrations according to the optimal number of rolling times. The basic compaction is specifically: first perform static compaction once, then perform two weak vibrations, and then perform two strong vibrations.

3. The construction method of a friable filler roadbed according to claim 1, characterized in that: Step S10 includes: Step S110, respectively performing the current indoor compaction test on multiple samples with different moisture contents, obtaining multiple dry densities corresponding to the current indoor compaction test, the multiple dry densities corresponding to the multiple samples one by one, wherein the multiple samples are samples that have completed the previous compaction test; Step S120, performing Gaussian fitting on multiple dry densities corresponding to the current indoor compaction test of multiple samples to obtain a fitting curve of the current indoor compaction test, where the abscissa of the fitting curve is the moisture content and the ordinate is the dry density; Step S130, based on the fitting curve of the current indoor compaction test, obtaining the maximum dry density and the optimal moisture content corresponding to the current indoor compaction test; Step S140, obtaining the difference in maximum dry density and the difference in optimal moisture content corresponding to the current indoor compaction test and the previous indoor compaction test, and when the absolute value of the difference in maximum dry density is less than or equal to the preset difference in dry density and the absolute value of the difference in optimal moisture content is less than or equal to the preset difference in moisture content, executing step S150; when the absolute value of the difference in maximum dry density is greater than the preset difference in dry density and / or the absolute value of the difference in optimal moisture content is greater than the preset difference in moisture content, repeatedly iteratively executing steps S110 to S130; Step S150: taking the optimal moisture content determined by the fitting curve of the current indoor compaction test as the optimal moisture content of the fragile filler.

4. The construction method of a friable filler roadbed according to claim 2, characterized in that: Step S20 includes: Step S210, sieving the weighed test filler step by step to obtain the filler weight of each sieve layer, and obtaining the initial grading curve of the filler by accumulating the weight percentage of each grade; Step S220, conduct the current indoor compaction test on the test filler with the optimal moisture content, and screen the filler that has completed the current indoor compaction test step by step after drying, obtain the filler weight of each sieve layer, and obtain the particle size distribution curve corresponding to the current indoor compaction test through the cumulative weight percentage of each grade, wherein the filler with the optimal moisture content is the test filler that has completed the previous compaction test; Step S230, calculating the relative crushing rate corresponding to the current indoor compaction test based on the particle size gradation curve corresponding to the current indoor compaction test and the initial gradation curve of the filler; Step S240, obtaining a first difference in relative crushing rates corresponding to the current indoor compaction test and the previous indoor compaction test, and when the first difference in relative crushing rates is greater than a preset difference in relative crushing rates, repeatedly iterating and executing steps S220 and S230; and executing step S250 when the difference in relative crushing rates is less than or equal to the preset difference in relative crushing rates; Step S250, taking the particle size gradation curve corresponding to the current indoor compaction test as the standard gradation curve, and based on the standard gradation curve, obtaining the indoor crushing degree index of the fragile filler with the optimal moisture content, the indoor crushing degree index includes the maximum particle size, the range of the maximum particle size group and the percentage of the maximum particle size group in the total filler.

5. The construction method of a friable filler roadbed according to claim 4, characterized in that: In step S320, the method for determining the optimal number of rolling passes corresponding to each type of roller includes: Step S321, using a roller to perform basic rolling on the fragile filler on the test area; Step S322, continue to perform rolling operation on the fragile filler according to the strong vibration to compact the test area, perform a sand filling method test on the fragile filler that has completed the current strong vibration, and obtain the compaction degree corresponding to the current strong vibration; Step S323, drying the fillers used in the sand filling method test and sieving them step by step, obtaining the filler weight of each sieve layer, and obtaining the particle size distribution curve corresponding to the current strong vibration by accumulating the weight percentage of each classification; Step S324, based on the particle size gradation curve corresponding to the current strong vibration and the initial gradation curve of the fragile filler in the test area, obtain the relative crushing rate and the maximum particle size corresponding to the current strong vibration; Step S325, obtaining a second difference in relative crushing rate and a difference in compaction degree between the current strong vibration and the previous strong vibration; Step S326: based on the second difference of the relative crushing rate, the difference of the compaction degree, and the compaction degree and the maximum particle size corresponding to the current strong vibration, determine whether the preset conditions are met. If the preset conditions are not met, the number of strong vibrations is increased by 1, and steps S322 to S325 are iteratively executed; if the preset conditions are met, terminate the test and execute step S327; Step S327, taking the number of strong vibrations corresponding to the current strong vibration as the optimal number of rolling passes.

6. The construction method of a friable filler roadbed according to claim 5, characterized in that: The preset conditions include: the absolute value of the second difference in relative crushing rate is less than or equal to the preset difference in relative crushing rate, the absolute value of the difference in compaction degree is less than or equal to the preset difference in compaction degree, the compaction degree corresponding to the current strong vibration is greater than or equal to the preset compaction degree, and the maximum particle size corresponding to the current strong vibration is less than or equal to the maximum particle size in the indoor crushing degree index.

7. The construction method of a friable filler roadbed according to claim 1, characterized in that: There are various different types of rollers including 18 tons, 20 tons, 22 tons, and 26 tons. The target roller is a 22-ton roller, and the optimal number of rolling passes for the target roller is 5 times.

8. The construction method of a friable filler roadbed according to claim 7, characterized in that: The strong vibration parameters of the target roller include: exciting force 280kN, vibration frequency 35Hz; the weak vibration parameters of the target roller include: exciting force 390kN, vibration frequency 29Hz.

9. The construction method of a friable filler roadbed according to claim 1, characterized in that: The friable filler is red sandstone friable filler, and the optimum moisture content is 7.6%.

10. The construction method of a friable filler roadbed according to claim 1, characterized in that: The preset thickness is 30 to 40 cm.

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