Duct piece pouring method for reducing surface area ratio of voids and pitted surfaces

Abstract

The invention relates to the technical field of tunnel construction, in particular to a duct piece pouring method for reducing the surface area ratio of a honeycomb pitted surface, which comprises the following steps: S1, pouring at least four groups of test duct pieces, and adopting different vibrating frequencies or vibrating durations for different test duct pieces, taking the vibration frequency and the vibration duration of the test segment with the lowest surface area ratio of the honeycomb pitted surface as target frequency and target time respectively; s2, the surface of the steel mold is cleaned, and the steel mold is coated with a water-based release agent; s3, concrete is poured into the steel mold, and a vibrator is used for vibrating the concrete according to the target frequency and the target time; the concrete is cured, and pouring of the shield segment is completed; and S4, the steps from S2 to S4 are repeated till pouring of a preset number of shield segments is completed. The technical problem that a shield segment produced through an existing shield segment pouring method has a high honeycomb pitted surface surface area ratio and cannot meet the construction requirement of a nuclear power drainage tunnel can be solved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for casting tunnel segments that reduces the proportion of honeycomb-like pitted surface area. Background Technology

[0002] Shield tunneling is a commonly used tunnel construction technology. It typically involves using a shield machine to excavate the soil underground and continuously assembling shield segments into a ring behind the shield tail to support the tunnel soil and prevent collapse, thereby ensuring the smooth progress of subsequent construction (such as secondary lining pouring and pipeline installation). Therefore, the quality of the shield segments is an extremely important aspect of tunnel construction. Due to various factors such as environmental temperature differences, pouring distance, and worker skill levels, honeycomb pitting may appear on the surface of the poured shield segments. However, current pouring technology can control the proportion of honeycomb pitting surface area to within 43‰, which can meet the construction requirements of most projects.

[0003] However, with the development of nuclear power technology, in the construction of a nuclear power plant drainage tunnel, the project proposed a new construction requirement that the proportion of honeycomb pitted surface area be less than 40‰. The shield tunnel segments produced by the existing casting technology can no longer meet this construction requirement. However, since the honeycomb pitting problem has not previously caused much hindrance to tunnel construction, there is currently no systematic research in this field on reducing the proportion of honeycomb pitted surface area. Therefore, it is urgent to study the causes of honeycomb pitting and improve the casting method of shield tunnel segments accordingly. Summary of the Invention

[0004] The purpose of this invention is to overcome the technical problem that the shield tunnel segments produced by existing shield tunnel segment casting methods have a high proportion of honeycomb and pitted surface area, which cannot meet the construction requirements of nuclear power plant drainage tunnels, and to provide a segment casting method that reduces the proportion of honeycomb and pitted surface area.

[0005] In a first aspect, the present invention provides a method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area, comprising the following steps: S1. Cast at least four sets of test segments. During casting, use different vibration frequencies or vibration durations for different test segments. Compare the proportion of honeycomb and pitted surface area of ​​each test segment. Use the vibration frequency and vibration duration of the test segment with the lowest proportion of honeycomb and pitted surface area as the target frequency and target time, respectively.

[0006] S2. Clean the surface of the steel mold and apply a water-based release agent to the steel mold.

[0007] S3. Pour concrete into the steel mold and use a vibrator to vibrate the concrete according to the target frequency and target time; cure the concrete to complete the casting of the shield tunnel segments.

[0008] S4. Repeat S2 to S4 until the predetermined number of shield tunnel segments have been poured.

[0009] Preferably, the target frequency is greater than 30 Hz.

[0010] Preferably, the target frequency is 50 Hz.

[0011] Preferably, the vibration time of concrete in S1 and S3 is T1, where 2 minutes ≤ T1 ≤ 5 minutes.

[0012] Preferably, in S1 the vibrator is placed on the end face of the test segment, and in S3 the vibrator is placed on the end face of the shield tunnel segment.

[0013] Preferably, in both S1 and S3, the concrete is vibrated in combination using a handheld vibrator and an attached vibrator placed on the end face of the test segment.

[0014] Preferably, the vibration depth of the vibrator in S1 and S3 is greater than 30 centimeters.

[0015] Preferably, the slump of the concrete in S1 and S3 is D, where 75 mm ≤ D ≤ 95 mm. Preferably, the cement content per cubic meter of concrete in S1 and S3 is M1, where 320 kg ≤ M1 ≤ 370 kg.

[0016] Preferably, the fly ash content per cubic meter of concrete in S1 and S3 is M2, where 60 kg ≤ M2 ≤ 85 kg.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for casting tunnel segments to reduce the proportion of honeycomb and pitted surface areas. Before casting the actual shield tunnel segments, at least four sets of test segments are cast, and comparative tests are conducted on these test segments from two dimensions: vibration frequency and vibration duration. This identifies the target frequency and target time that best suppress honeycomb and pitting. Then, during the production of the shield tunnel segments, the concrete is vibrated according to the target frequency and target time. Furthermore, this invention uses a water-based release agent to coat the steel mold, which further reduces the proportion of honeycomb and pitted surface areas in the shield tunnel segments, enabling them to meet the construction requirements of nuclear power plant drainage tunnels. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the test results of a test segment of a segment casting method for reducing the proportion of honeycomb pitted surface area in Example 1. Figure 2 It is a line graph showing the change in the proportion of honeycomb-like surface area as a function of vibration time; Figure 3 It is a line graph showing the change in the proportion of honeycomb-like surface area with vibration depth; Figure 4 It is a line graph showing the change in the proportion of honeycomb-patterned surface area with vibration frequency; Figure 5 This is a schematic diagram illustrating the statistical relationship between the percentage of honeycomb-patterned surface area and the distance of concrete pouring; Figure 6 This is a schematic diagram illustrating the statistical relationship between the proportion of honeycomb-patterned surface area and slump. Figure 7 This is a schematic diagram illustrating the statistical relationship between the percentage of honeycomb-patterned surface area and waiting time; Figure 8 This is a schematic diagram illustrating the statistical relationship between the percentage of honeycomb-patterned surface area and the amount of cement added per cubic meter of concrete. Figure 9 This is a schematic diagram illustrating the statistical relationship between the percentage of honeycomb-patterned surface area and the amount of fly ash added per cubic meter of concrete. Figure 10 This is a schematic diagram illustrating the statistical relationship between the percentage of honeycomb-patterned surface area and the curing time. Figure 11 This is a schematic diagram illustrating the statistical relationship between the percentage of honeycomb-patterned surface area and the temperature difference of the site. Figure 12 This is a schematic diagram illustrating the statistical relationship between the percentage of honeycomb textured surface area and the type of release agent; Figure 13 This is a statistical chart showing the percentage of honeycomb-patterned surface area of ​​the tunnel lining segments in Example 1; Detailed Implementation The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0019] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0020] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0021] Furthermore, the use of terms such as "first," "second," and "third" in the terminology is merely for distinguishing descriptions of identical or similar components and should not be construed as emphasizing or implying the relative importance of a particular component. Additionally, in the description of embodiments of the present invention, "several," "multiple," and "several" represent at least two. The number can be any number, including 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0022] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0023] Example 1 like Figures 1 to 13 As shown, a method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area includes the following steps: S1. Cast at least four sets of test segments. During casting, use different vibration frequencies or vibration durations for different test segments. Compare the proportion of honeycomb and pitted surface area of ​​each test segment. Use the vibration frequency and vibration duration of the test segment with the lowest proportion of honeycomb and pitted surface area as the target frequency and target time, respectively.

[0024] For example, this embodiment sets up five target time test groups, and sets different vibration durations for each of the five target time groups; and each target time test group includes two vibration frequency test groups using different vibration frequencies, for a total of ten test tube segments. The proportion of honeycomb pitted surface area of ​​the ten test tube segments is detected, and the results are as follows: Figure 1 The test results are shown. According to the test results, the test segment with serial number 6 has the best test results. The vibration frequency and vibration time used for the test segment with serial number 6 can be used as the target frequency and target time.

[0025] S2. Clean the surface of the steel mold (e.g., scrape off concrete residue, rinse the surface of the steel mold with water), and apply a water-based release agent to the steel mold.

[0026] S3. Pour concrete into the steel mold and use a vibrator to vibrate the concrete according to the target frequency and target time; cure the concrete to complete the casting of the shield tunnel segments.

[0027] S4. Repeat S2 to S4 until the predetermined number of shield tunnel segments have been poured.

[0028] It is important to note that Figure 2 The A1 and A2 type shield tunnel segments, and Figure 8 The shield tunnel segment types B1, B2, and K, and Figure 9 , Figure 10 and Figure 12 The shield tunnel segments A1, A2, and A3 are segments made according to the existing shield tunnel segment segmentation method; among them, A1, A2, and A3 are standard segments, B1 and B2 are lead-in segments, and K is the capping segment.

[0029] During the construction of a nuclear power plant drainage tunnel, the project proposed a new construction requirement that the proportion of honeycomb-like pitted surface area be less than 40‰. Therefore, the inventors of this invention systematically analyzed the causes of honeycomb-like pitting. Through on-site investigation, review of construction reports, and brainstorming, the inventors identified the end factors affecting the proportion of honeycomb-like pitted surface area from multiple aspects, including personnel, machinery, materials, methods, environment, and measurement. These factors included: unclear project instructions, unskilled construction workers, uncleaned molds, unreasonable cement content, large aggregate gradation, unreasonable fly ash content, unreasonable release agent selection, unqualified cement, unqualified fly ash, unreasonable vibration depth, unreasonable vibration frequency, inappropriate vibration duration, insufficient curing time, large temperature difference at the site, inappropriate waiting time during concrete pouring, excessive concrete pouring distance, and inappropriate concrete slump.

[0030] Subsequently, the inventors conducted on-site investigations and analyses of various end-factors, addressing issues such as unclear project briefings, unskilled construction workers, improper vibration duration, and uncleaned molds. They also investigated and tested issues including unreasonable vibration depth, unreasonable vibration frequency, excessive concrete pouring distance, inappropriate waiting time during concrete pouring, large aggregate gradation, unreasonable cement content, unreasonable fly ash content, substandard cement, substandard fly ash, insufficient curing time, large site temperature differences, and inappropriate release agent selection. Finally, they conducted on-site inspections of improper concrete slump.

[0031] After the above investigation, analysis, testing, and on-site inspection, the factors that had the greatest impact on the proportion of honeycomb-like pitted surface area were finally determined to be: unreasonable vibration frequency and unreasonable selection of release agent. Specifically, under the existing casting technology, the vibration frequency of shield tunnel segment concrete is generally 30 Hz, and in order to prevent the concrete from adhering to the steel mold, an oil-based release agent is generally applied to the steel mold, which leads to an increase in the proportion of honeycomb-like pitted surface area. In addition, the vibration time also affects the proportion of honeycomb-like pitted surface area.

[0032] Based on the above analysis, before casting the actual shield tunnel segments (shield tunnel segments installed inside the tunnel), this invention first casts at least four sets of test segments (with the same structure as the shield tunnel segments, but not actually installed inside the tunnel). Comparative tests are then conducted on these test segments from two dimensions: vibration frequency and vibration duration. This allows for the identification of the target frequency and target time that best suppress honeycomb and pitting. During the production of shield tunnel segments, the concrete is then vibrated according to the target frequency and target time. Furthermore, this invention uses a water-based release agent to coat the steel mold, which further reduces the proportion of honeycomb and pitting surface area in the shield tunnel segments, enabling them to meet the construction requirements of nuclear power plant drainage tunnels. Cleaning the surface of the steel mold allows for more full utilization of the advantages of the water-based release agent, avoiding any negative impact of residual substances on the subsequent casting quality.

[0033] As for non-essential end factors, these end factors have little impact on the proportion of honeycomb pitted surface area and can be controlled according to normal construction standards; for example, ensuring that the training of staff meets the standards and that the quality inspection results of cement and fly ash are qualified.

[0034] In an optional implementation, the target frequency is greater than 30 Hz.

[0035] The inventors conducted controlled variable experiments on the vibration frequency. While keeping other experimental conditions constant (e.g., vibration time and concrete composition), they varied the vibration frequency and conducted comparative experiments on two types of shield tunnel segments, A1 and A2, obtaining the following results: Figure 4The test results show that as the vibration frequency increases from 30 Hz to 50 Hz, the proportion of honeycomb pitted surface area decreases from 45‰ to 39‰. Therefore, based on the test results, this embodiment sets the vibration frequency of the vibrator to 30 Hz or higher to reduce the proportion of honeycomb pitted surface area.

[0036] In an optional implementation, the target frequency is 50 Hz.

[0037] like Figure 4 As shown, as the vibration frequency increases from 50 Hz to 60 Hz, the proportion of honeycomb pitted surface area no longer decreases significantly. Therefore, in this embodiment, the vibration frequency of the vibrator is set to 50 Hz to achieve a good balance between vibration effect and vibration economy.

[0038] In an optional implementation, the vibration time of the concrete in S1 and S3 is T1, where 2 minutes ≤ T1 ≤ 5 minutes.

[0039] The inventors conducted controlled variable experiments on the vibration time. While keeping other experimental conditions constant (e.g., vibration frequency and concrete composition), they varied the vibration time and obtained the following results: Figure 2 The test results show that as the vibration time increases from 2 minutes to 5 minutes, the proportion of honeycomb-patterned surface area decreases from 47‰ to 42‰; as the vibration time continues to increase from 5 minutes to 7 minutes, the proportion of honeycomb-patterned surface area rises again to 44‰; therefore, this embodiment selects 2 to 5 minutes, which has better test results, as the vibration time to reduce the proportion of honeycomb-patterned surface area.

[0040] In optional embodiments, in S1 the vibrator is placed on the end face of the test segment, and in S3 the vibrator is placed on the end face of the shield segment; for example, a hole is made on the end face of the shield segment template so that workers can hold the vibrator and vibrate the concrete through the hole; or an attached vibrator is directly connected to the end face of the shield segment template.

[0041] Because concrete has poor fluidity at the ends of tunnel segments, honeycomb pitting is more likely to occur at the ends of tunnel segments compared to their inner and outer curved surfaces. According to the inventors' statistics, 91% of honeycomb pitting occurs on the end faces of tunnel segments, while only 6% and 3% occur on the outer and inner curved surfaces, respectively. Therefore, in this embodiment, the vibrator is placed on the end face of the tunnel segment to directly vibrate the end face, thereby reducing the proportion of honeycomb pitting surface area in the tunnel segment with higher efficiency. Furthermore, the positions of the vibrators in S1 and S3 are matched to ensure that the target frequency and target time obtained in S1 can also achieve the same effect in S3.

[0042] In an optional implementation, during the casting of the shield tunnel segments in S3, a vibrator is manually inserted into the concrete. This allows for more flexible adjustment of the vibration position by the worker, and works in conjunction with the attached vibrator on the end face of the shield tunnel segment to further improve the vibration effect and reduce the proportion of honeycomb-like surface area. Correspondingly, during the casting of the test tunnel segments in S1, a combination of manual handheld vibrators and attached vibrators is used to vibrate the test tunnel segments to ensure the effectiveness of the target frequency and target time obtained in S1.

[0043] In an optional implementation, a second-layer analysis of the honeycomb surface of the shield tunnel segment end face is further performed. It is found that 78.1% of the honeycomb surface of the shield tunnel segment end face is concentrated in the inter-ring area, while the tenon surface and the concave tenon surface account for only 12.5% ​​and 9.4% respectively. Therefore, the vibrator can be further placed closer to the inter-ring area of ​​the shield tunnel segment end face.

[0044] In an optional implementation, the vibration depth of the vibrator in S1 and S3 is greater than 30 cm.

[0045] The inventors conducted controlled variable experiments on the vibration depth. While keeping other experimental conditions constant (e.g., vibration frequency and concrete composition), they varied the vibration depth and obtained the following results: Figure 3 The experimental results show that as the vibration depth increases from 30 cm to 60 cm, the proportion of honeycomb-like surface area decreases from 58‰ to 42‰; as the vibration depth continues to increase from 60 cm to 80 cm, the proportion of honeycomb-like surface area rises again to 44‰. Therefore, based on the experimental results, this embodiment sets the vibration depth of the vibrator to be greater than 30 cm to reduce the proportion of honeycomb-like surface area. The vibration depths of the vibrators in S1 and S3 are matched to each other, which can ensure that the target frequency and target time obtained in S1 can also achieve the same effect in S3.

[0046] In an optional implementation, the pouring distance of concrete in S1 and S3 is H, where 25 cm ≤ H ≤ 40 cm.

[0047] The inventors statistically analyzed the relationship between pouring distance and the proportion of honeycomb-like pitted surface area. The statistical results are as follows: Figure 5 As shown, when the pouring distance fluctuates between 25 mm and 40 mm, the deviation of the pouring distance on the proportion of honeycomb-like surface area is only 5‰. Therefore, based on the test results, this embodiment sets the concrete pouring distance to be greater than or equal to 25 mm and less than or equal to 40 mm to reduce the influence of the pouring distance on the proportion of honeycomb-like surface area. The pouring distances of the vibrators in S1 and S3 are matched to each other, which can ensure that the target frequency and target time obtained in S1 can also play the same role in S3.

[0048] In an optional implementation, the slump of the concrete in S1 and S3 is D, where 75 mm ≤ D ≤ 95 mm.

[0049] The inventors statistically analyzed the relationship between slump and the proportion of honeycomb-like pitted surface area. The statistical results are as follows: Figure 6 As shown, when the slump fluctuates between 75 mm and 95 mm, the deviation of the slump effect on the proportion of honeycomb-like surface area is only 4‰. Therefore, based on the test results, this embodiment sets the slump of concrete to be greater than or equal to 75 mm and less than or equal to 95 mm to reduce the influence of slump on the proportion of honeycomb-like surface area. The slump of the vibrators in S1 and S3 are matched to each other, which can ensure that the target frequency and target time obtained in S1 can also play the same role in S3.

[0050] In an optional implementation, the waiting time for concrete pouring in S1 and S3 is T3, where 118 seconds ≤ T3 ≤ 135 seconds.

[0051] The inventors statistically analyzed the relationship between waiting time and the proportion of honeycomb-patterned surface area. The statistical results are as follows: Figure 7 As shown, when the pouring waiting time fluctuates between 118 and 135 seconds, the deviation of the pouring waiting time on the proportion of honeycomb-like surface area is only 0.5%. Therefore, based on the test results, this embodiment sets the concrete pouring waiting time to be greater than or equal to 118 seconds and less than or equal to 135 seconds to reduce the impact of the pouring waiting time on the proportion of honeycomb-like surface area. The pouring waiting times of the vibrator in S1 and S3 are matched to each other, which can ensure that the target frequency and target time obtained in S1 can also play the same role in S3.

[0052] In an optional embodiment, the cement content per cubic meter of concrete in S1 and S3 is M1, where 320 kg ≤ M1 ≤ 370 kg. The inventors statistically analyzed the relationship between the cement content per cubic meter of concrete and the proportion of honeycomb-like pitted surface area. The statistical results are as follows: Figure 8 As shown, when the cement content per cubic meter of concrete fluctuates between 320 kg and 370 kg, the deviation of the cement content per cubic meter of concrete on the proportion of honeycomb-like surface area is only 5.7‰. Therefore, based on the experimental results, this embodiment sets the cement content per cubic meter of concrete to be greater than or equal to 320 kg and less than or equal to 370 kg to reduce the influence of the cement content per cubic meter of concrete on the proportion of honeycomb-like surface area. The cement content per cubic meter of concrete in the vibrators in S1 and S3 is matched to each other, which can ensure that the target frequency and target time obtained in S1 can also play the same role in S3.

[0053] In an optional embodiment, the fly ash content per cubic meter of concrete in S1 and S3 is M2, where 60 kg ≤ M2 ≤ 85 kg.

[0054] The inventors statistically analyzed the relationship between the fly ash content per cubic meter of concrete and the proportion of honeycomb-like pitted surface area. The statistical results are as follows: Figure 9 As shown, when the fly ash content per cubic meter of concrete fluctuates between 60 kg and 85 kg, the deviation of the fly ash content per cubic meter of concrete on the proportion of honeycomb-like surface area is only 5‰. Therefore, based on the experimental results, this embodiment sets the fly ash content per cubic meter of concrete to be greater than or equal to 60 kg and less than or equal to 85 kg to reduce the impact of the fly ash content per cubic meter of concrete on the proportion of honeycomb-like surface area. The fly ash content per cubic meter of concrete in the vibrators in S1 and S3 is matched to each other, which can ensure that the target frequency and target time obtained in S1 can also play the same role in S3.

[0055] In an optional implementation, after the concrete is poured in S1 and S3, the curing time is T2, where 28 days ≤ T2 ≤ 38 days.

[0056] The inventors statistically analyzed the relationship between curing time and the proportion of honeycomb-like pitted surface area. The statistical results are as follows: Figure 10 As shown, when the curing time fluctuates between 28 and 38 days, the deviation of the curing time on the proportion of honeycomb and pitted surface area is only 4.7‰. Therefore, based on the test results, this embodiment sets the curing time of concrete to be greater than or equal to 28 days and less than or equal to 38 days to reduce the influence of curing time on the proportion of honeycomb and pitted surface area. The curing times of the vibrators in S1 and S3 are matched to each other, which can ensure that the target frequency and target time obtained in S1 can also play the same role in S3.

[0057] In an optional implementation, when pouring concrete in S1 and S3, ensure that the temperature difference of the site is less than or equal to 11 degrees Celsius.

[0058] The inventors statistically analyzed the relationship between site temperature difference and the proportion of honeycomb-patterned surface area. The statistical results are as follows: Figure 11 As shown, when the site temperature difference fluctuates between 5 and 8 degrees Celsius, the deviation of the site temperature difference on the proportion of honeycomb pitted surface area is only 4‰. Therefore, based on the test results, this embodiment sets the site temperature difference of concrete to be less than or equal to 8 degrees Celsius to reduce the impact of site temperature difference on the proportion of honeycomb pitted surface area. The site temperature differences of the vibrators in S1 and S3 are matched to each other, which can ensure that the target frequency and target time obtained in S1 can also play the same role in S3.

[0059] The inventors conducted controlled variable experiments on the release agent. Under constant test conditions (e.g., vibration frequency and concrete composition), oil-based and water-based release agents were used on two groups of test segments, respectively, yielding the following results: Figure 12 The test results show that the average percentage of honeycomb surface roughness after using an oil-based release agent is 44‰, while the average percentage of honeycomb surface roughness after using a water-based release agent is 20‰, a difference of 24‰. This demonstrates that the water-based release agent used in this invention can significantly reduce the percentage of honeycomb surface roughness.

[0060] like Figure 13 The table shown is a statistical table of the proportion of honeycomb surface area of ​​shield tunnel segments after adopting the segment casting method of reducing the proportion of honeycomb surface area in this embodiment. As can be seen from the table, this embodiment can reduce the average proportion of honeycomb surface area from 42.91‰ to 34.75‰, which can meet the construction requirements of nuclear power plant drainage tunnels.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for casting tunnel segments that reduces the proportion of honeycomb-like pitted surface area, characterized in that, Includes the following steps: S1. Cast at least four sets of test segments. During casting, use different vibration frequencies and vibration durations for different test segments. Compare the proportion of honeycomb and pitted surface area of ​​each test segment. Take the vibration frequency and vibration duration of the test segment with the lowest proportion of honeycomb and pitted surface area as the target frequency and target time, respectively. S2. Clean the surface of the steel mold and apply a water-based release agent to the steel mold; S3. Pour concrete into the steel mold and use a vibrator to vibrate the concrete according to the target frequency and target time; cure the concrete to complete the casting of the shield tunnel segments. S4. Repeat S2 to S4 until the predetermined number of shield tunnel segments have been poured.

2. The method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to claim 1, characterized in that, The target frequency is greater than 30 Hz.

3. The method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to claim 2, characterized in that, The target frequency is 50 Hz.

4. The method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to claim 2, characterized in that, The vibration time for concrete in S1 and S3 is T1, where 2 minutes ≤ T1 ≤ 5 minutes.

5. A method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to claim 2, characterized in that, In S1, the vibrator is placed on the end face of the test segment, and in S3, the vibrator is placed on the end face of the shield tunnel segment.

6. The method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to claim 5, characterized in that, In both S1 and S3, the concrete was vibrated in combination using a handheld vibrator and an attached vibrator placed on the end face of the test segment.

7. A method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to any one of claims 1 to 6, characterized in that, The vibration depth of the vibrator in S1 and S3 is greater than 30 centimeters.

8. A method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to any one of claims 1 to 6, characterized in that, The slump of concrete in S1 and S3 is D, where 75 mm ≤ D ≤ 95 mm.

9. A method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to any one of claims 1 to 6, characterized in that, The cement content per cubic meter of concrete in S1 and S3 is M1, 320 kg ≤ M1 ≤ 370 kg.

10. A method for casting tunnel segments to reduce the proportion of honeycomb-like pitted surface area according to any one of claims 1 to 6, characterized in that, The fly ash content per cubic meter of concrete in S1 and S3 is M2, 60 kg ≤ M2 ≤ 85 kg.

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