Testing of a Dual-Steel-Plate-Confined High-Performance Concrete Composite Shaft Lining Structure and Its Application

Round 1

Reviewer 1 Report

1.The introductory chapter describes the current situation in the western zone of the Zhangji coal mine. In this chapter, it would be required to supplement the theoretical background of the issue (knowledge from the literature). Chapter 2.1 “Derivation of Similarity Criteria” is a theoretical basis rather than an experimental program. It would be preferable to break down the different criteria for the elastic model relationship (1) and describe the individual proportional characteristics. For example, Cepsylon  is determined from deformation in the direction of length, width, thickness, or as the intensity of deformation in accordance with the law of volume conservation.   

 2.In Tables 1, 2 and 3, the unit of each factor must be given in brackets, not separated by '/'.

3.Describe the meaning of the parameter “a” or “2a” in Fig. 1, since its meaning is not described in the text.

4.There is no goal or hypothesis defined in the work, therefore the formulation in line 118 is not the most appropriate. Which characteristic is the goal of optimization (maximum or minimum of which characteristic)?

5.How the concrete strength and coefficient “m” were determined in Tab. 3 (number of samples, mean value, variance of measured values, standard deviation ...are not given)?

6.The numbers of the relations in parentheses are missing in lines 215, 237.

7.In Tab.3, the coefficient "m" is not appropriately rounded, it is sufficient to round to two decimal places.

8.The yield strength of the steel is standardly designated as Re, Rp0.2, or s_Y – in line 218 is marked as s_g .

9.In line 225, it is preferable to give 1.971 ÷ 2.520 and after rounding 1.971 ÷ 2.520.

10.Relation 5 would require a description of the k1, k2, k3, k4 constants, because first of all it is necessary to determine by F or T test the significance of the individual factors and then the accuracy of the prediction model (5) e.g. using the multiple determination coefficient R².

11.In lines 237 and 238, it would be more appropriate to round the coefficients to two maximum three decimal places.

12.Verification of models 4 and 5 should be added.

13.The use of relations (1) and (2) should be added.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Summary: 

The paper deals with an application of the shaft drilling method with special considerations for the Zhangji coal mine. The primary goal of the paper is to present developments and achievements of this technology for a record-breaking application and to provide a basis for engineering design and construction. The is a combination of theoretical and laboratory and in-situ experimental work, which is beneficial as it combines different aspects to the problems solving, and a link between theory and application is established. Main contributions of the paper are experimental results of proposed shaft lining design and a case study for the Zhangji mine.

Broad comments:

The paper uses clear and concise scientific language in its approach to the subject matter, which is a clear strength, along with a logical structure and methodology; however, improvements are required in certain important aspects:

1. The abstract is clear and concise, with clear background and methodology description, but it should be shortened to adhere to the Applied Sciences limitation of 200 words (currently 221).

2. Results and conclusions align with the aim, but the conclusion can be improved by listing implications of this particular work with a broader aspect.

3. The references are in large part relevant and all are recent. Appropriate key studies are included, but it is not clear why are certain references placed in the manuscript, i.e. these seem to be forced in places where reliability is mentioned, although references do not deal with this topic - e.g. 22-22, 24-26, 27.

4. The reference list is not formatted in scope with Applied sciences Instructions for Authors.

5. The Introduction offers a clear formulation of the research question and the problem defined as a case study, which should benefit a broad professional public and it does advance the current state in regards to the application of drill shaft mining. However a rework of the first and second paragraph could be done, to not firstly outline the application, but the technology, to introduce into the subject matter. After that formulate the problem with the application at hand.

6. Section 2 offers the definition of important variables for the model, with given explanations for selection and limitations. However, concrete strength grades should be listed with an appropriate normative document per which this grade is valid. The steel grade of outer and inner plates, along with anchor clamps should also be listed in the parameters of the model (also the normative document).

7. In section 2 input materials are listed, but there are no results of testing concrete samples, not testing of steel samples from lining constituents. Provide more details on the measuring devices used during testing and the procedures used (normative document) to obtain these results.

8. Study methods in section 2 are valid, but reliability is questionable. Variability in experimental results can be a serious issue so please elaborate were there only 1 specimen in a series and why? How reliable are such results when there is no evaluation of dispersion? 

9. In section 3 it would be useful to provide figures of failed specimen samples to enable readers insight into obtained mechanisms. Additionally, clear explanations of only samples ZJ1 and ZJ8 are given and no details and comparisons with other 8 samples are provided. Provide at least a comparison of behaviour for samples ZJ2-ZJ7 with two highlighted samples – ZJ1 and ZJ8.

10. In section 3 tables and figures are relevant, but Table 3 could include strain at bearing capacity as this was listed as a goal od the paper.

11. In section 3 certain results are repetitive, i.e. the triaxial compressive stress strength increase is mentioned several times with no clear addition to the data, i.e. it is being overinterpreted. Please edit these mentions and provide a deeper analysis.

12. In the conclusion section, it would be useful to describe what are the opportunities for future research and application.

Specific comments:

1. Line 13: series is miswritten as "serious".
2. Line 58: although it commendable and serves to highlight the importance of work, it is not common to emphasize authors ranks and academic background when referencing work - please remove this to maintain uniformity in referencing.
3. Line 60: references 7-9 are not authored by Hong, who is mentioned in their context. Additionally, how is 9 relevant in regards to the study of inner steel plate confined concrete, being a handbook.
4. Line 61: references 10 and 11, are attributed to Yao and Zhang, but are in fact authored by previously wrongly placed Hong.
5. Line 76: references 12 and 13 are provided as a reading for similarity theory, but reference 14 is closely connected to this topic.
6. Figure 1: it is not clear what is 2a in this figure.
7. Line 215: there appears to be something missing in brackets.
8. Lines 354-358: reference 15 is written twice.

Author Response

Please see the attachment.

Author Response File: Author Response.docx