Method for evaluating construction uniformity of clay improved copper tailing roadbed

Abstract

The invention belongs to the technical field of roadbed engineering, and particularly relates to a construction uniformity evaluation method for a clay improved copper tailing roadbed. The method comprises the following specific steps: S1, determining the proportion of the clay improved copper tailing roadbed filler; s2, applying the blended clay improved copper tailings to roadbed construction; and S3, carrying out construction detection on the clay-improved copper tailing roadbed, calculating a mixing uniformity coefficient, and comparing the mixing uniformity coefficient with a uniformity coefficient in a laboratory to evaluate the construction uniformity of the clay-improved copper tailing roadbed. According to the method, after roadbed construction is completed, a working project of measuring the compactness through a field sand filling method is combined, the mixing uniformity coefficient is calculated with the deviation between the composition proportion of roadbed filler sampled through the sand filling method and a proportion design result as a parameter, and the construction quality can be effectively evaluated conveniently.

Description

Technical Field

[0001] The present invention belongs to the technical field of subgrade engineering, and particularly relates to a method for evaluating the construction uniformity of a clay-improved copper tailings subgrade. Background Art

[0002] In copper ore beneficiation, 95% of its substances form tailings, which are mainly backfilled into the mine in the form of paste filling and cannot be completely consumed. The main treatment method for a large amount of iron tailings that have not been comprehensively utilized is stacking. This not only forces enterprises to build tailing ponds and bear high infrastructure costs, but also occupies precious land resources.

[0003] At present, with the rapid development of highways, the demand for road construction materials is increasing day by day. The shortage of road construction materials also severely restricts the development of the highway industry. The geometric shape and chemical composition of copper tailings are similar to those of natural aggregates, and they can be used as substitutes for natural aggregates. Subgrade fillers are the road construction materials with the largest demand in highway engineering construction, which can provide a good way for the large-scale consumption of copper tailings.

[0004] Since clay-improved tailings are used as subgrade fillers, the cured cohesive force is enhanced, and at the same time, they have both friction and cohesion. Therefore, it is an excellent subgrade filler. However, there are currently no evaluation indicators and methods for the construction uniformity of clay-improved copper tailings subgrades.

[0005] Therefore, there is an urgent need for a method for evaluating the construction uniformity of a clay-improved copper tailings subgrade to solve the above problems. Summary of the Invention

[0006] In order to overcome the above defects in the prior art, the present invention provides a method for evaluating the construction uniformity of a clay-improved copper tailings subgrade. The present invention can be used to scientifically guide the blending ratio of the two to achieve the best effect, and provide an effective method for evaluating the construction uniformity to ensure good construction quality.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for evaluating the construction uniformity of a clay-improved copper tailings subgrade, the specific steps are as follows:

[0009] S1. Determine the filler ratio of the clay-improved copper tailings subgrade;

[0010] S2. Apply the blended clay-improved copper tailings subgrade filler to the subgrade construction;

[0011] S3. Detect the construction of the clay-improved copper tailings subgrade: Use the sand replacement method to measure the compaction degree of the subgrade construction, chisel off the subgrade filler layer by layer, and then use the water washing method to measure the proportion of copper tailings in each layer of subgrade filler, calculate the mixing uniformity coefficient, and compare it with the uniformity coefficient in the laboratory to evaluate its construction uniformity.

[0012] Preferably, the steps for determining the mixing ratio of the clay-improved copper tailing subgrade filler are as follows:

[0013] (1) Fill a container with copper tailings, tamp it down and level the surface, and measure its tamped density;

[0014] (2) Use SEM to scan the leveled surface of the copper tailings, collect images of the scanned surface, and perform filtering and histogram equalization on the images;

[0015] (3) Extract the perimeter and area of each copper tailing particle in the SEM scanned image;

[0016] (4) Calculate the mixing ratio of clay and copper tailings according to the following formula:

[0017]

[0018] V n = 1 - VV - V w

[0019] In the formula:

[0020] S n - The area of clay wrapping copper tailings in the SEM image field of view, μm 2 ;

[0021] j - The number of copper tailings in the SEM image;

[0022] r o - The average particle size of clay, μm;

[0023] - The perimeter of the kth copper tailing, μm;

[0024] P n - The area ratio coefficient of clay and copper tailings;

[0025] - The area of the kth copper tailing, μm 2 ;

[0026] V n1 - The volume of clay wrapping copper tailings in 1 cubic meter of clay-improved copper tailing subgrade material, m 3 ;

[0027] V w - The volume of copper tailings in 1 cubic meter of clay-improved copper tailing subgrade material, m 3 ;

[0028] S s - The total area of the image field of view, μm 2 ;

[0029] Volume expansion coefficient after δ-clay wraps copper tailings

[0030] V k - Compaction void ratio of copper tailings in 1 cubic meter of clay-improved copper tailings subgrade material, %

[0031] ρ z - Compaction density of copper tailings, g / cm 3 ;

[0032] ρ w - Apparent density of copper tailings, g / cm 3 ;

[0033] V n - Volume of clay in 1 cubic meter of clay-improved copper tailings subgrade material, m 3 ;

[0034] VV - Design void ratio of 1 cubic meter of clay-improved copper tailings subgrade material, %

[0035] Preferably, the size of image acquisition is a square with a side length of 3 mm - 5 mm

[0036] Preferably, in the copper tailings, the content of copper tailings with a particle size greater than 0.045 mm ≥ 50%

[0037] Preferably, in step (1), the moisture content of the copper tailings ≤ 13%

[0038] Preferably, in step (4), the moisture content of the clay ≤ 11%, and the particle size of the clay ≤ 0.02 mm

[0039] Preferably, in step (4), the design void ratio of 1 cubic meter of clay-improved copper tailings subgrade material is taken as 4 - 7%

[0040] Preferably, in step S2, the clay-improved copper tailings subgrade filler is laid in layers, and the compacted thickness filled to the roadbed top ≥ 10 cm, and the loose paving thickness of the subgrade is 30 - 40 cm

[0041] Preferably, in step S4, the number of detection points of the sand replacement method is more than 3; the number of layers for layered chiseling is 3 - 4 layers; the filter screen size of the water washing method is 0.02 - 0.03 mm

[0042] Preferably, in step S4, the calculation method of the mixing uniformity coefficient is as follows:

[0043]

[0044] Where:

[0045] P - Proportion of copper tailings in the proportion design result, %

[0046] ρ w-Apparent density of copper tailings, g / cm 3 ;

[0047] ρ n -Apparent density of clay, g / cm 3 ;

[0048] V w -1 cubic meter volume of copper tailings in clay-improved copper tailings roadbed material, m 3 ;

[0049] V n -1 cubic meter of clay volume in the copper tailings roadbed material, m 3 ;

[0050] -The proportion of copper tailings in the i-th sample, %;

[0051] -The mass of copper tailings remaining on the filter screen in the i-th sample, g;

[0052] -Total mass of the ith sample, g;

[0053] α-passage rate of pure copper tailings at the filter size, %;

[0054] K-uniformity coefficient of clay-improved copper tailings roadbed;

[0055] m- The number of samples chiseled when testing clay-improved copper tailings roadbed using the sand filling method.

[0056] The advantages of the present invention are:

[0057] (1) The present invention adopts image processing technology, and identifies the distribution of clay and copper tailings after interaction according to the image, and considers the effect of clay wrapping copper tailings on the expansion of spatial volume, so as to accurately determine the blending ratio of copper tailings and clay, thereby maximizing the performance of the two materials after combination.

[0058] (2) After the roadbed construction is completed, the present invention combines the on-site sand injection method to determine the compaction degree, takes the deviation between the roadbed filler composition ratio sampled by the sand injection method and the ratio design result as a parameter, takes the mass of the sample as a certain weight, calculates its mixing uniformity coefficient, ensures that the roadbed construction has high quality and performance, effectively fills the gap that its construction uniformity cannot be evaluated, and thus effectively evaluates the construction quality.

[0059] (3) When calculating the construction uniformity coefficient of the clay-improved copper tailings subgrade material of the present invention, by means of stratified and point-by-point sampling, and using the mass of the sample as the weight for calculating the uniformity coefficient, considering the influence of various factors to improve the accuracy of the result, the calculation result can provide important guidance for the optimization of processes such as construction mixing and rolling; the subgrade filler uses copper tailings as the raw material, recycling the industrial waste copper tailings, realizing the resource utilization of waste, resource conservation, high efficiency and environmental protection.

[0060] (4) The present invention provides a scientific and reliable method for determining the best combination of copper tailings and clay, effectively exerting the best performance of the mixture. The proposed construction uniformity evaluation index and method provide important guidance for the optimization of processes such as construction mixing and rolling, ensuring good quality after construction. Through the use of the clay-improved copper tailings subgrade, it promotes the efficient recycling of resources, making waste resources, resources highly efficient, and the results environmentally friendly. Specific embodiments

[0061] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0062] A method for evaluating the construction uniformity of a clay-improved copper tailings subgrade includes the following steps:

[0063] 1. Detect the moisture content and apparent density of copper tailings and clay respectively, screen the copper tailings, and measure the average particle size of the clay to be 0.0042 mm. The other test results are shown in Table 1-2 below:

[0064] Table 1 Test results of raw materials

[0065] Material Water content (%) <![CDATA[Apparent density (g / cm 3 )]]> Clay 10.5 1.6 Copper tailings 12.3 2.2

[0066] Table 2 Proportion of different particle sizes of copper tailings

[0067] Particle size classification ≥0.15mm 0.15 - 0.075mm 0.075 - 0.045mm ≤0.045mm Copper tailings (%) 15.6 19.5 24.3 40.6

[0068] 2. Put the copper tailings into a compaction cylinder with an inner diameter of 92 mm and tamp them to fill the entire compaction cylinder, scrape the surface flat, and measure its tamped density to be 1.408 g / cm 3 .

[0069] 3. Use SEM to scan the flattened surface of the copper tailings, collect images of the flattened surface, the size of the collected images is a 3.3 mm square, and perform filtering and histogram equalization processing on the images.

[0070] 4. Extract the perimeter and area of each copper tailings particle in the SEM scanned image, as shown in Table 3 below:

[0071] Table 3

[0072] Copper tailings particle number Perimeter (um) <![CDATA[Copper tailings particle area (um 2 )]]> 1 235.5 4415.2 2 374.3 5789.6 3 125.9 2872.6 ...... ...... ...... 1389 110.9 2386.3 Total 442525 5374041

[0073] 5. Through the SEM scanned image, extract and count the area of voids, and calculate the mixing ratio of clay and copper tailings according to the following formula, where the designed void ratio VV of the clay-improved copper tailings subgrade material is taken as 5%:

[0074]

[0075]

[0076] V n = 1 - VV - V w

[0077] After calculation, in 1 cubic meter of clay-improved copper tailings subgrade material, the volume of clay is V n = 0.438 m 3 and the volume of copper tailings is V w = 0.512 m 3 .

[0078] 6. According to the above mixing ratio results, calculate the proportion of copper tailings in the mixing ratio as follows:

[0079]

[0080] Adopt the compaction test and CBR test to verify the performance of the mixing ratio results, and the results are shown in Table 4 below:

[0081] Table 4

[0082]

[0083] It can be seen from Table 4 that compared with other mixing ratios, the maximum dry density of the filler obtained by the subgrade material mixing ratio confirmation method of the present invention is the largest, and the CBR value is also the highest, indicating that the filler prepared by the mixing ratio confirmation method of the present invention has better compactness and higher strength.

[0084] 7. Construction of clay-improved copper tailings subgrade: First, prepare the clay and copper tailings. According to the above mixing ratio results, prepare materials according to the requirements of subgrade construction. Distribute the copper tailings and clay according to the mixing ratio results. The loose paving thickness of the subgrade is 35 cm. First, use an excavator to mix the copper tailings and the subgrade once, then use a BOMAG mixer for secondary mixing, use a grader for leveling, use a heavy roller for static compaction 1 - 2 times, vibratory compaction 2 - 3 times, and then static compaction once more.

[0085] 8. The clay-improved copper tailings subgrade during construction is tested. The sand replacement method is used to determine the compaction degree of the subgrade during construction. During the process of determining the compaction degree by the sand replacement method, the clay-improved copper tailings subgrade filler is chiseled in 3 layers. For each layer in the sand replacement method, 4 test points are taken, that is, the number of chiseled specimens is 12, and the clay is washed clean by the water washing method. The mesh size of the filter screen in the water washing method is 0.025 mm. The proportion of copper tailings in each layer is determined. The copper tailings pass through a 0.025-mm filter screen, and the passing rate of copper tailings is 20.3%. The proportion of copper tailings is calculated according to the following formula, as shown in Table 5 below:

[0086]

[0087] Table 5 Calculation results of sampling quality and copper tailings proportion by the sand replacement method

[0088] Sample number Sample mass (g) Screened tailings mass (g) Proportion of copper tailings (%) 1 2540 1119 55.3 2 3152 1522 60.6 3 2687 1336 62.4 4 2654 1218 57.6 5 2402 1250 65.3 6 2876 1481 64.6 7 2205 1121 63.8 8 2987 1452 61 9 3068 1514 61.9 10 2548 1164 57.3 11 2965 1392 58.9 12 3002 1211 50.6

[0089] 9. Calculate the mixing non-uniformity coefficient according to the following formula to evaluate its construction uniformity:

[0090]

[0091] After calculation, its construction mixing non-uniformity coefficient is 3.14. Through indoor tests, 5 groups of specimens are prepared according to the mix ratio, randomly sampled 500 - 1000 g, and the proportion of copper tailings is determined by the above water washing method as shown in Table 6 below:

[0092] Table 6 Calculation results of sampling quality and copper tailings proportion in indoor tests

[0093]

[0094] Calculate the mixing non-uniformity coefficient according to the following formula:

[0095]

[0096] It can be seen through comparison that the on-site mixing uniformity reaches 82.48% of the indoor mixing uniformity, and the mixing uniformity effect is relatively good.

[0097] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for evaluating the uniformity of clay-improved copper tailings roadbed construction, characterized in that: The specific steps are as follows: S1. Determine the proportion of clay-improved copper tailings roadbed filler; S2, applying the mixed clay-improved copper tailings roadbed filler to the roadbed construction; S3. Testing of the clay-improved copper tailings roadbed construction: The sand filling method is used to determine the compaction of the roadbed construction, and the roadbed filling material is removed layer by layer. The water washing method is then used to determine the proportion of copper tailings in each layer of roadbed filling material, and the mixing uniformity coefficient is calculated. It is compared with the uniformity coefficient in the laboratory to evaluate its construction uniformity.

2. A method for evaluating uniformity of clay-improved copper tailings roadbed construction according to claim 1, characterized in that: The steps to determine the proportion of clay-improved copper tailings roadbed filler are as follows: (1) Fill the container with copper tailings, tamp it, scrape the surface flat, and measure its tamped density; (2) Scanning the scraped surface of the copper tailings with SEM, collecting images of the scraped surface, and filtering and histogram equalization processing the images; (3) extracting the perimeter and area of ​​each copper tailings particle in the SEM scan image; (4) Calculate the blending ratio of clay and copper tailings according to the following formula: V n =1-VV-V w Where: S n- Clay area encapsulating copper tailings in the SEM image field of view, μm 2 ; j - The number of copper tailings in the SEM image; r o- Average particle size of clay, μm; - The perimeter of the kth copper tailing, μm; P n- Area ratio coefficient of clay to copper tailings; - The area of ​​the kth copper tailing, μm 2 ; V n1- 1 cubic meter of clay volume encapsulating copper tailings in the clay-improved copper tailings roadbed material, m 3 ; V w- Volume of copper tailings in 1 cubic meter of clay-improved copper tailings roadbed material, m 3 ; S s- Total image field area, μm 2 ; δ - Volume expansion coefficient after clay wraps copper tailings; V k- 1 cubic meter of clay-improved copper tailings roadbed material, %; ρ z- Copper tailings compacted density, g / cm 3 ; ρ w- Apparent density of copper tailings, g / cm 3 ; V n- 1 cubic meter of clay volume in the copper tailings roadbed material, m 3 ; VV - The designed void ratio of 1 cubic meter of clay-improved copper tailings roadbed material is %.

3. A method for evaluating uniformity of clay-improved copper tailings roadbed construction according to claim 2, characterized in that: The size of the image acquisition is a square with a side length of 3mm-5mm.

4. A method for evaluating uniformity of clay-improved copper tailings roadbed construction according to claim 2, characterized in that: In the copper tailings, the content of copper tailings with a particle size greater than 0.045 mm is ≥50%.

5. A method for evaluating uniformity of clay-improved copper tailings roadbed construction according to claim 2, characterized in that: In step (1), the moisture content of the copper tailings is ≤13%.

6. A method for evaluating uniformity of clay-improved copper tailings roadbed construction according to claim 2, characterized in that: In step (4), the moisture content of the clay is ≤11%, and the particle size of the clay is ≤0.02 mm.

7. A method for evaluating uniformity of clay-improved copper tailings roadbed construction according to claim 2, characterized in that: In step (4), the designed porosity of 1 cubic meter of clay-improved copper tailings roadbed material is 4-7%.

8. The method for evaluating the uniformity of the clay-improved copper tailings roadbed construction according to claim 1, characterized in that: In step S2, clay-improved copper tailings roadbed filler is spread in layers until the compacted thickness of the roadbed top is ≥10 cm, and the loose thickness of the roadbed is 30-40 cm.

9. The method for evaluating the uniformity of the clay-improved copper tailings roadbed construction according to claim 1, characterized in that: In step S4, the number of detection points of the sand filling method is greater than 3; the number of layers removed by layering is 3-4 layers; and the filter screen size of the water washing method is 0.02-0.03 mm.

10. The method for evaluating the uniformity of clay-improved copper tailings roadbed construction according to claim 1, characterized in that: In step S4, the mixing uniformity coefficient is calculated as follows: Where: P - The proportion of copper tailings in the mix design results, %; ρ w- Apparent density of copper tailings, g / cm 3 ; ρ n- Apparent density of clay, g / cm 3 ; V w- Volume of copper tailings in 1 cubic meter of clay-improved copper tailings roadbed material, m 3 ; V n- 1 cubic meter of clay volume in the copper tailings roadbed material, m 3 ; - The proportion of copper tailings in the i-th sample, %; - The mass of copper tailings remaining on the filter screen in the i-th sample, g; - Total mass of the i-th sample, g; α - The passing rate of pure copper tailings at the filter size, %; K - Uniformity coefficient of clay-improved copper tailings roadbed; m - The number of samples chiseled when testing clay-improved copper tailings roadbed using the sand filling method.

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