Temperature Field and Stability Analysis of the Frozen Wall Based on the Actual Position of Freezing Holes

Round 1

Reviewer 1 Report

Comments:

In the present study, the authors investigate the significance of Temperature Field and Stability Analysis of Frozen Wall Based on the Actual Position of Freezing Holes. The subject of the study is interesting and well developed. I recommend the publication of the manuscript after minor revisions. My suggestions are listed below:

·         What is the advantage of freezing method?

·         Novelty of the problem is missing. Please add in the revised version. What a significance exploration prior to published work.

·         Abstract should be enhanced with some major results.

·         If possible, compare your results with published work in the limited cases.

If possible add some very recent papers related to your study.

Author Response

Dear Reviewer:

Thank you for your comments concerning our manuscript entitled “Temperature Field and Stability Analysis of Frozen Wall Based on the Actual Position of Freezing Holes” (ID: applsci-1883359). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied the comments carefully and have made corrections which we hope meet with approval. The main comments in the paper and the responses to your comments are as flowing:

Response to Reviewer 1 Comments

Point 1: What is the advantage of freezing method?

Response 1: The artificial ground freezing method is suitable for any loose rock and soil mass containing a certain amount of water. The freezing technology is effective under complex hydrogeological conditions. It can effectively strengthen the soil mass, improve the bearing capacity of the loose rock and soil mass, and at the same time, it can effectively isolate groundwater. To create a safe construction environment, it is widely used in underground engineering, such as vertical shaft engineering, inclined shaft engineering, foundation engineering, foundation pit excavation and tunnel engineering. The shape and expansion range of the frozen wall can be controlled in real time according to the monitoring system of temperature and groundwater, which can effectively avoid the impact on existing buildings and structures. At the same time, the freezing method construction is essentially a process of heat exchange, which does not produce waste products, and is a green and environmentally friendly construction method. (see Lines 41-44)

 

Point 2: Novelty of the problem is missing. Please add in the revised version. What a significance exploration prior to published work.

Response 2: When the freezing method is used to excavate the shaft, due to the complexity of the deep soil geological environment and the diversity of soil properties, it is necessary to study the freezing temperature field of the deep soil. Therefore, the author takes Qingdong Mine as the research object, based on the actual location of the frozen hole in the field, combined with the soil thermophysical test parameters measured in the laboratory test, the numerical calculation software was used to study the deep soil freezing temperature field in the coal mine shaft. Based on the analysis of the temperature field of the frozen wall, the ultimate bearing capacity and creep deformation of the frozen wall at the topsoil control layer are studied, which provides a safety guarantee for the shaft excavation. The results provide an important reference for the design and construction of deep soil frozen walls.

The novelty of this paper: Based on the actual formation of real frozen holes in the field, the author reveals the spatiotemporal evolution law of the deep soil freezing temperature field.

The ultimate bearing capacity and creep deformation of the frozen wall were calculated based on the low-temperature mechanical parameters of the soil samples taken from the field and combined with the analysis of the temperature field. (see Lines 82-92)

 

Point 3: Abstract should be enhanced with some major results.

Response 3: The abstract has been enhanced with some major results. (see Lines 11-34)

 

Point 4:  If possible, compare your results with published work in the limited cases.

Response 4: In this paper, the method of numerical calculation and theoretical analysis is used to analyze the temperature field and stability of the frozen wall of Qingdong Mine. It is an application in the actual specific engineering background. Due to the limited length of the article, we will not compare the published engineering cases in this article. We will apply this research method to other construction cases using AGF method. It can provide construction and design references for similar freezing projects.

 

Point 5: If possible add some very recent papers related to your study.

Response 5: Relevant references have been added to the text. (see Lines 66-69 and references 7,8,19,20,21)

Author Response File: Author Response.docx

Reviewer 2 Report

lines 76-78. At this point, the review of the literature is essentially incomplete. To date, many studies have been carried out in coupled thermo-hydro-mechanical formulations (Nishimura et al., Tounsi et al., Rouabhi et al., Zhou & Meschke, Zhelnin et al., etc.). What is the peculiarity of the research conducted in this manuscript? What is the novelty in the manuscript?

line 106. Do I understand correctly that the flower tube part is a perforation in the hydrological well through which water can penetrate from the aquifer to the well? If I'm right, then why are there no such perforations in hydrological wells C1 and C2 for the second aquifer?

line 117. How was the design thickness of the frozen wall of 4.2 m calculated?

lines 126, 143. Why are you talking about a two-dimensional coordinate system when equations (1)-(3) have only one spatial coordinate?

line 129. How correct is it to use a model with a clear phase transition front for the case of clays? After all, clays contain a very large amount of bound water. Because of this, even at very low temperatures below -20 degrees Celsius, a lot of unfrozen water can remain in the clay.

line 129. Is the condition of equal temperatures Tu and Tf taken into account at the phase transition boundary?

line 160. Is it appropriate to set a fixed brine temperature on the freeze pipe walls? But what if the brine flow is small enough? At low brine flow rates, it is necessary to take into account the heat transfer coefficient in the brine boundary layer and use the boundary conditions of the third kind (convective boundary condition), and not the first kind (fixed temperature).

line 162. It is not clear how the 2D geometry and computational mesh in Fig. 2 are related to the 1D model (1) - (6).

line 164. is the temperature of the brine measured at the inlet of the stream to the freezing columns or at the outlet of them? They usually differ by 2-4 degrees.

line 169. Something is wrong with the dimension of the latent heat of a phase transition? Very small values ​​in the last column of the table.

lines 186-188. I see that there is a very good agreement between the numerical simulation data and the experimental data. Usually, in our experience, models of the type (1)-(6) do not immediately achieve such a good fit due to their very strong simplification. Did you correct the initial thermophysical properties of soils for their best agreement with the experiment? If yes, it should be reflected in the manuscript.

line 193. In the text, you do not analyze fig. 5 anywhere. Is this figure even needed?

lines 263, 353. Why in fig. 6 the thickness of the frozen wall is called the depth? This confuses the reader. How was the thickness of the frozen wall calculated? What isotherm was used to determine the boundaries of the frozen wall?

line 266. What is the main surface and interface?

line 290. It is not entirely clear how the arbitrary deflection of the freezing pipes was set? Where are the graphical results for this case?

line 296. It is not clear why the authors mention frost heaving. After all, it is not taken into account in the model. And from the conclusions below, one gets the impression that the authors do not understand the difference between frost heaving due to cryogenic suction and migration of moisture, and simple expansion of water during its freezing in the pores.

line 371. Lateral pressure on a frozen wall is linear with depth. Does this formula take into account only lithostatic pressure? Why is there no account of hydrostatic pressure from pore water?

line 426, equation (19) is well known. Reference should be made to other works where it is given. And the derivation of this formula, which is presented above, is redundant, because there is no novelty in it.

line 428. For which soil "c" and "phi" parameters were taken? Do you use long-term strength properties or instant ones?

line 434. Many equations and transformations in this section require comments and explanations, references to the literature. For example, formula (22), assumptions on lines 435, 446. After all, the authors of the article are not the first who uses such an approach.

line 46. Why is the maximum allowable displacement of the shaft wall equal to 5 cm?

It is not all right with the translation of the term "shaft". In some places, the term "wellbore" appears.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has become better, but I still have a few comments on it. They concern authors edits to my previous comments:

Line 134. It is necessary to write in the manuscript by what formula the thickness of the frozen wall was calculated. And you can add about the normative document, where it is recommended to use this formula.

Line 147. You have entered x, y coordinates. This is good. But formula (3) is still in terms of the radial coordinate r. This confuses the reader.

Line 154. I would write this condition Tf=Tu as a formula below formula (3). It's part of your mathematical model.

Lines 189-202. This text is not clear. Write it better. The experimental data was used to adjust model parameters, right?

Line 396. Explain in the manuscript where the formula P=0.013H is taken from.

Author Response

Dear Reviewer:

Thank you for your comments concerning our manuscript entitled “Temperature Field and Stability Analysis of Frozen Wall Based on the Actual Position of Freezing Holes” (ID: applsci-1883359). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied the comments carefully and have made corrections which we hope meet with approval. The main comments in the paper and the responses to your comments are as flowing:

 

Point 1: Line 134. It is necessary to write in the manuscript by what formula the thickness of the frozen wall was calculated. And you can add about the normative document, where it is recommended to use this formula.

Response 1: The authors have made corresponding modifications in the manuscript. (Please see Lines 134-140). We have added the normative document. (Please see reference 31).

 

Point 2: Line 147(Line 155 now). You have entered x, y coordinates. This is good. But formula (3) (formula (4) now) is still in terms of the radial coordinate r. This confuses the reader.

Response 2: The authors have made corresponding modifications. (Please see Line 157 or formula (4))

 

Point 3: Line 154(Line 157 now). I would write this condition Tf=Tu as a formula below formula (3). It's part of your mathematical model.

Response 3: As your suggested, the authors have made corresponding modification. (Please see Line 157 or formula (5))

 

Point 4: Lines 189-202 (Lines 200-214). This text is not clear. Write it better. The experimental data was used to adjust model parameters, right?

Response 4: In order to make the language expression concise and easy to understand, the authors have reorganized the language for expression and made corresponding modifications in the manuscript. (Please see Lines 200-214). Meanwhile, as you said, the experimental data was used to adjust model parameters.

 

Point 5: Line 396 (Line 407 now). Explain in the manuscript where the formula P=0.013H is taken from.

Response 5: We have cited relevant reference in the manuscript. (Please see Line 407 or reference 31).

Author Response File: Author Response.pdf