On-Site Monitoring for the Stability Evaluation of a Highway Tunnel above Goaves of Multi-Layer Coal Seams

Round 1

Reviewer 1 Report

Dear Authors,

Thank you for your paper.

Despite this contribution report some interesting monitoring data, the way in which such result have been here reported is not scientifically sound to me.

First of all, the title should be modified according to me, or the authors have to clearly state what do they mean for “monitoring for the stability evaluation”; moreover, it should be stated even before if the authors are looking to either the serviceability level, or the stability evaluation. Such statement is fundamental because it applies to how the monitoring data are analyzed.

The introduction appears to be not very referenced, in particular first paragraph. I am not an expert in tunneling, but I am sure that huge literature about tunnelling has been reported. In fact I would also advise the authors to use not only Chinese references, also because tunnelling is a widely faced as issue to face all over the world.

On overall I do not find easy to understand the object, the methods and the purpose of this paper. Please try to state what you are studying, why you are studying and how you are actually carrying out such activity. I am saying this because you make reference to some predicitons, or numerical modelling, which are not reported in this paper at all. This is strongly confusing the reader making this paper not easy to read at all.

However, I find interesting the monitoring data you reported, as such I am sure it is just a matter of how this contribution has been organized and written. The English is of a good level, and apart from isolated statements which are not clear (see specific comments), I would say that this is ok.

Some figures are of very poor quality and need to be revised (see specific comments).

As regards the conclusion, I have not understood what do you conclude by this contribution you reported. If those data are just used to report a case history of well drilled tunnel inside a geological and geo-structural complex setup, please state it clearly; rather you make reference to some predictions, making comparison, but this is really not clear to me

Specific comments:

Lines	Comments
31-36	No refs
Fig 1	Missing legend
Fig 2	Legend nearly not readable
Fig 3	Missing legend
172-177	Water injection data from? Which data? Please provide either data or refs
197-209	Please provide either data or refs
Fig 5	Not clear at all
219-220	Not clear. “make predication” what prediction do you mean???
221	Please explain deep monitoring marker.. what are those marker?
228-232	Not clear. Poor English. Please rewrite
231-232	“the secondary lining was predicted, to further predict the stability of the tunnel”? what do you mean by predict. Are you monitoring or predicting. How you predict if you do?
242-243	Not clear. Please rewrite. How? Which value?
245-248	Here Fig 6a is described, even if figure 6 is placed before this point. Please reorganize the structure.
Fig 7	Is really not clear to me. Please try to describe and explain better
261	“Results” of what? Consider that the titles of the chapters have to be modified. Please also check chapter 2 and 3
Fig 9	Is of very poor quality. Graphs are not readable. Check the time axis. Use the same font adopted in fig 10 and 11.
Table 2	What does stages 1, 2 and 3 reflect? What does this mean? These are monitoring data? The same in fig 6? Where are monitored? Please try to be more precise in the description of the monitoring data
281-284	This is not true for all the cases
290-293	Not clear
290-291	“accumulative”?
Fig 10	Not clear why 2 graphs. If there is a correspondence between the tunnels and the plots, please highlight it
Fig 11	What this total residual settlement is? It is not clear. Please explain
300	“numerical calculation”? of what? How? It is the first time in the paper numerical calculation are mentioned.
300-306	It is not clear to me if you are considering either the stability condition (the collapse of the tunnel) or the serviceability condition (relating to the cumulated displacements with time). In the latter case, some serviceability limits have to be adopted for a comparison
Fig 12	Missing legend
339	Which factors have been screened out? It does not seem to me you did this.
339-350	This discussion is not clear
347	“The deformation and displacement were forecasted”?? How? when?
346-350	Not clear
356-357	Not clear
353	Tong et al? the citation scheme is not this one
379-383	Not clear. What a “gob” is?
389-391	I do not agree with this. This sentence goes beyond what you reported in this paper.
393-397	Some of this method are not treated
398-402	Poor English
403-411	Poor English. And I do not agree with what you wrote. Deformation of the tunnel floor has been forecasted? Where? How? Sorry but it is really not well written

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Even though the paper presents interesting on-site monitoring results, some elements need to be addressed prior to publication:

1. It is written 'The literature on the impact of the underlying goaf on the stability of expressways has also emerged in recent years [3-9].' However these 'recent years' include literature 10 - 20 years old. I suggest to implement some novel findings in this domain within the paper.
2. pg 2, line 65 - description of the tunnel: I suggest moving it to the chapter on case study (first part of chapter 2) and to implement some figure of the tunnel cross section.
3. page 3, lines 96 to 101 are irrelevant to the content of the paper.
4. Figure 1 - what is the purple line? And what is blue dashed line?
5. Figure 2 - try to implement better resolution figure.
6. Stress out the position of seams on Figure 2. It is hard to follow the paper text without having the idea on where are these seams.
7. Nothing is given on the tunnel construction method. This should be given considering that the construction method affects all of the monitored parameters.
8. What kind of equipment was used to measure deformation and settlements. Some kind of extensometers with markers at pre-defined depths?
9. Figure 5 - is something missing on this figure? There is only black background shown....
10. Diagrams on Figure 9 are not clear. What is on the vertical axis? Link the markers from figure 8 with lines on figure 9! Increase the figure resolution.
11. Figure 11 - are red and black line in fact different dates? Additionally - there is no consistency in obtained data, it seems that at some parts the wall subsidence increases and in some decreases? Why is that? Elaboration is necessary. What is on horizontal axis - tunnel chainage?
12. Authors compare the results to numerical analysis. But which numerical analysis? There is no information on the type of analysis, on the input for the analysis. This part needs significant enhancement.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors, I have read this manuscript carefully. The issue of building tunnels in rock formations, which are additionally subjected to anthropogenic factors (mines, pits), is important (human life) and extremely complicated, because it depends on many factors modifying the stability of the rock mass. While reading the text, some suggestions came to my mind, which I would like to discuss in the order of the pages: 1. The discussion of literature in the introduction is too modest in my opinion. Especially in such an important undertaking, I believe that the authors should refer to the knowledge of rock mass mechanics more strongly, relying on a greater number of works, including classical ones. 2. In Chapter 2.3 we learn that deck 3 is located just 21-26m below the tunnel. Will these data not show a violation of the safety pillars specified in the mining law for the construction of underground structures? I believe that the readers deserve more detailed explanations in this case. Especially in the context of the sentence in line 160-163 and then in lines 171-172 (and 206), where it seems to give rise to some contradiction. The paragraph (lines 166-177) omits the discussion of what happened to the injection of water into deck 8? 3. Was it not worth discussing the legitimacy or the lack of application of other geophysical methods beyond seismic, since water was injected, why the telluric method was not used? The methodology seems to be sufficiently discussed, although I am not satisfied with it. The authors discuss the subsidence of the rock mass, point to uneven settlement, and say nothing about torsional and bending stresses that may occur in such a settlement model. Perhaps it would be worth referring to it with at least a few sentences? In the Discussion it follows that the tunnel has already been created and is monitored, therefore, in such a problem it seems that the theoretical material is supported by empirical results and at present indicates the correctness of the assumptions (although 8 years is still not enough for such far-reaching conclusions regarding human safety) . Nevertheless, I miss here even memories of how the authors anticipate actions in an extreme situation and what has been undertaken to minimize the damage in such situations. I propose to list the conclusions. It will be more legible this way. 

 

I also hope that this is not the first article, but the beginning of the cycle, because in my opinion this topic deserves extensive discussion and development. 

Author Response

Please seethe attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The version has benefited from the review process, and it has been modified in the weak point it had.

Now it is much better if compared to the first version, and as such I think it is now ready to be published.

However, I have to say that I found your explanations and answers to my comment sometimes too hasty and superficial; I would have appreciated more effort in trying to make such contribution clearer, by adjusting the text. Moreover, I have to highlight also that the reference you added, where the numerical simulation or prediction you were referring to throughout all the paper (Ding, C.J. Study on character and forecast model of residual deformation in mining site D. Thesis, China university mining 531 & Technology , Xuzhou, China, 2009.) is not accessible, and I was not able to find it to consult it.