Study on Comprehensive Technology of Preventing Mud Cake of Large Diameter Slurry Shield in Composite Stratum
Round 1
Reviewer 1 Report
1. General comments
Mud cake, as an unavoidable problem in shield tunnels, will not only reduce the speed of construction, but also threaten the construction safety. In this study, the authors propose two calculation methods of cutter head sealing coefficient for large mud cakes, and optimize the scour angle for the medium and small mud cakes. Finally, a dissolution method based on hydrogen peroxide was validated for dissolving small mud cakes. However, there are several issues with this manuscript. It should therefore be systematically revised. The following comments may help enhance the quality of this manuscript.
2. The article uses three different scouring angles of 45º, 70º, and 90º. What is the basis for this grouping? The numerical analysis show that the maximum mud flow velocities corresponding to working conditions 1 and 2 vary greatly(Lines 266 of Page 9), does it suggest that there may be a better angle between 20º and 45º?
3. The effect of hydrogen peroxide solution on permeation is shown in Figure 13 (Lines 401 of Page 15). However, there are many strange peaks and troughs in the graph, and there is not enough detailed analysis in the article.
4. List the inadequacies of current researches and the innovations of this article point by point in the introduction. Here, the reviewer recommends the following articles for the author's references:
A Scientometric Analysis and Visualization of Global LEED Research.
Three-dimensional coupled hydromechanical analysis of localized joint leakage in segmental tunnel linings
Automatic detection method of tunnel lining multi‐defects via an enhanced You Only Look Once network.
5. Some pictures are too blurry, which made the review quite laborious.
Author Response
General Comments: Mud cake, as an unavoidable problem in shield tunnels, will not only reduce the speed of construction, but also threaten the construction safety. In this study, the authors propose two calculation methods of cutter head sealing coefficient for large mud cakes, and optimize the scour angle for the medium and small mud cakes. Finally, a dissolution method based on hydrogen peroxide was validated for dissolving small mud cakes. However, there are several issues with this manuscript. It should therefore be systematically revised. The following comments may help enhance the quality of this manuscript.
Response： Thank you for your valuable suggestions, which are of great help to improving the rigor and scientific nature of the manuscript. The following is our response to your comments.
- Comments: The article uses three different scouring angles of 45º, 70º, and 90º. What is the basis for this grouping? The numerical analysis show that the maximum mud flow velocities corresponding to working conditions 1 and 2 vary greatly(Lines 266 of Page 9), does it suggest that there may be a better angle between 20º and 45 ?
- Response: Thank you for your valuable suggestions, which are very helpful to improve the logic of the article. Make the following explanations according to your questions：
The scouring angle can be selected from 0 ° to 90 °. If any angle is considered, there are too many working conditions that need to be analyzed and compared, so the dichotomy method is used to select 45 ° and 90 ° for design. The original design scouring angle working condition is 20 °, which is between 0 ° and 45 °. Therefore, 70 ° is selected as the corresponding angle between 45 ° and 90 ° for consideration.
- Comments: The effect of hydrogen peroxide solution on permeation is shown in Figure 13 (Lines 401 of Page 15). However, there are many strange peaks and troughs in the graph, and there is not enough detailed analysis in the article.
- Response: According to your suggestion, we have made a detailed explanation of the appearance of "peak" and "valley" in Figure 13, and further explained the soaking effect of hydrogen peroxide solution.
The hydrogen peroxide field soaking was carried out from March 22, 2021 to March 23, 2021.It can be seen from Figure 13 that after soaking the bin body with hydrogen peroxide solution, the penetration of the cutter head has been significantly improved. The average value of the single day penetration is 7.25mm and 7.03mm respectively two days after soaking the bin body, which are far greater than the 2.14mm before soaking the bin body. Since penetration=tunneling speed/rotation speed, and tunneling speed is related to thrust, the thrust will change differently when the shield machine is started and stopped, so it will have different effects on penetration, which leads to "peak" and "valley" of monitoring data. It should be noted that the hydrogen peroxide solution will generate gas during the process of soaking the mud cake. In order to prevent the gas from damaging the stability of the face and inducing the surface subsidence, the overflow gas must be discharged by the jet fan in time and the time of soaking the bin with hydrogen peroxide must be strictly controlled.
- Comments: List the inadequacies of current researches and the innovations of this article point by point in the introduction. Here, the reviewer recommends the following articles for the author's references:
A Scientometric Analysis and Visualization of Global LEED Research.
Three-dimensional coupled hydromechanical analysis of localized joint leakage in segmental tunnel linings
Automatic detection method of tunnel lining multi‐defects via an enhanced You Only Look Once network.
- Response: Thank you very much for the valuable reference materials provided by the reviewers. We have quoted relevant references according to your suggestions, which is very helpful for refining the innovation and readability of this article.
- Comments: Some pictures are too blurry, which made the review quite laborious.
- Response: According to your suggestion, we checked the figures in the full manuscript and replaced the vague figures in the manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The research is interesting and worth publishing. I ask the authors to make a few improvements to the text.:1. In the text you need to enter a few sentences about the software used for numerical simulations (what program? is it a finite element method?).
2. A few sentences about the X-ray scanner.
Author Response
- Comments: In the text you need to enter a few sentences about the software used for numerical simulations (what program? is it a finite element method?).
- Response:
In this paper, ANSYS Fluent software is used for fluid numerical simulation. ANSYS Fluent is a high-performance computational fluid dynamics (CFD) software tool, which uses the finite volume method based on completely unstructured grids, and has a gradient algorithm based on grid nodes and grid elements.
- Comments: A few sentences about the X-ray scanner.
- Response: According to your suggestion, we introduced the basic functions of XRD testing, which helps to improve the readability of the paper.
XRD is the abbreviation of "X-ray diffraction". It uses X-ray to diffract materials, and then analyzes the diffraction pattern to obtain the material composition, internal atomic composition and chemical structure of elements. It is an important material science research technology.
Author Response File: Author Response.pdf
