Numerical Study on Mechanical Properties of Corroded Concrete Pipes before and after Cured-in-Place-Pipe Rehabilitation

Round 1

Reviewer 1 Report

 

The manuscript investigated the mechanical characteristics of the pipeline after CIPP (Cured-In-Place-Pipe) rehabilitation and the effectiveness of CIPP rehabilitation in repairing. To achieve this, a three-dimensional numerical model of the corroded concrete pipe before and after CIPP rehabilitation was established utilizing numerical simulation methods. Also, the numerical model was validated with the full-scale test data from prior research. Further, a series of comparative analyses were conducted to investigate the repair effect of CIPP rehabilitation and the influence of factors such as corrosion degree, corrosion angle, and traffic load magnitude on the corroded pipeline before and after CIPP rehabilitation. The topic is quite interesting, and the results are well presented but the reviewer has following main concerns on the present form of the manuscript:

 

1. Did authors provide meshing for all the components and carried out mesh convergence study. Also, authors did not mention about the time step of the analysis.

 

2. Please elaborate the significance of considering C3D8R elements while carrying out mesh analysis. Represent the mesh configuration of the components used in simulation in such a way that gives a clean and polished look. Following papers may be useful.

 

“Damage Prediction of Underground Pipelines Subjected to Blast Loading

G Patnaik, A Kaushik, MJ Singh, A Rajput, G Prakash, L Borana

Arabian Journal for Science and Engineering, 1-20               2022

 

3D-FE Analysis of RC Tunnel with GFRP Shielding Under Internal Blast Loading

A Kaushik, G Patnaik, A Rajput, G Prakash

Proceedings of SECON’21: Structural Engineering and Construction Management”

 

3. The figure quality needs to be improved. The labelling of the model specified in Figure 2 are not clear.

 

4. Please mention the unit of the specified dimensions in Figure 3(b) and also increase the font size of Figure 3 (a) as well as Figure 4. Also, specify the dimensions of CIPP model presented in Figure 5.

 

5. Formatting of table 1 for better understanding. The parameter notations used in Table 1 needs to be expressed in detail.

 

6. Did authors consider working/operational pressure inside the pipeline so that it can replicate the real-life conditions/situations?

 

7. Kindly mention the name/title of the Chinese Code used for selecting geometry parameters. Is the buried depth of pipe fixed for all the analysis carried out using this model?

 

8. Please mention the type of geometry used for modeling the components (such as deformable, analytical, discrete). Provide the input data of the material model used in the study for better clarity to the readers.

 

9. How the corrosion has been incorporated in the FE simulation. Please clarify.

 

10. The maximum principal stresses, vertical displacement are plotted in the manuscript. However, the failure modes, damage contours, Mises stress contours could also be added to have a clear understanding of the deformation of the pipeline.

 

11. In the comparison of numerical and previous studies, please clarify and state that the setting conditions or parameters are similar or constant.

 

12. The meaning of few lines mentioned in the manuscript is not clear. So, the paper should be thoroughly reviewed for English writing and syntax error.

 

13. In Introduction section, a detailed discussion of the previous studies carried out in this field could also be added to have a better understanding of the current research problem.

 

14. Please format the reference list to ensure consistency with the cited literature in the text of the manuscript.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

 

In their study, the authors utilize a finite element model simulation to investigate and compare the performance of cured-in-place pipe rehabilitation in concrete pipelines and corroded pipes. The findings of the analysis are presented in the study. The paper is well-written, well-structured, and clear about its significance and novelty. Although the results are evident to some extent, this study's findings could aid in comprehending the underlying mechanisms of corrosion and suggest ways to enhance the in-situ repairing process.

 

Some recommendations are as follows:

1.     The pipe, gasket, CIPP, and traffic models should be explained in greater detail. Please consider that not all potential readers can understand at a glance these models.

2.     Section 2.8: needs to be clarified the MAPE results. It is essential because it is evidence that your model behaves similarly to the experiments of Fang et al. Moreover, Figure 6 requires a deeper explanation. It needs to be clarified what OUT Sim, Out Test, etc., mean.

3.     Graphs are overlapping in Figs. 8, 10, and 13 do not allow us to visualize the behavior of the plots. I consider these plots essential to understand the effect of the CIPP. Please find a way to exhibit more detail in the critical zone (the corroded place).

4.     Your study presents many figures, but not all of them are analyzed. Please don’t let the reader interpret your findings.

Please revise some redundant phrases and words repeated very close in the same paragraph.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The present study numerically investigated the effect of a rehabilitation method (called CIPP) on the mechanical properties of corroded pipelines. Although the results are nice and interesting for readers, a major revision is necessary to improve the manuscript structure and justify some missing parameters within the manuscript. Accordingly, the comments are as follows:

-          Abstract, Lines 12-13: Please remove “utilizing 12 numerical simulation methods” and put “in the present study”.

-          Abstract: please add some quantitative results regarding the most crucial factors at the end of the abstract.

-          Page 3, Line 104: Pipeline was modelled as concrete or reinforced concrete? Is there any reinforcement mesh within the concrete?

-          Page 3, Line 105: Properties of CDP used for concrete should be completely mentioned in the manuscript, including compression, tensile, and damage parameters.

-          Section 2.1: Section sensitivity analysis should be depicted within the manuscript.

-          Page 4, Line 134: Please explain the method used for simulating corrosion more.

-          Page 6, Lines 181-182: How did the authors find the normal and tangential stiffness values? Please put reference.

-          Figure 6: Please use “Fang et al. [25] results” instead of “Test” in the legends of this figure.

-          General comment: Please do not use short paragraphs throughout the manuscript.

Minor editing is required regarding English proficiency.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors appropriately improved the manuscript structure.

The current version is Ok, and only a minor editing of English language required.