A Case Study on the Energy Capacity of a Flexible Rockfall Barrier in Resisting Landslide Debris

Round 1

Reviewer 1 Report

Is “landslide debris” the correct phrase? We know channelized debris flows, open hill debris flows, shallow landslides etc. But I never heard “landslide debris” before being used as process. Are you sure to use this phrase? If so, its usage is not correct in many location of the manuscript (e.g. “Landslide debris occurred…”).

L52: I’ve heard only about the V-type in Illgraben. Please, check and verify that U-types were also used there.

L59-63: There are more numerical approaches around (e.g. based on MPM method, see e.g. https://tel.archives-ouvertes.fr/tel-01286617/)

Table 2: replace the phi-sign by a “x”?

Section 3.3: The generation of flexible rockfall barriers the RXI-075 belongs to as well is more or less designed that every single field can withstand 750kJ.
Can it be that not the barrier itself sustained the more than 3000kJ? In other words, only the first impact has to be stopped and the resulting “damn” stops the remaining debris? Please, discuss.

Section 3.4.2: Please, keep in mind that the force deflection behaviour of the used brake rings differs quite a lot whether the rings are activated dynamically or quasi-statically. Usually, only the latter performance is known precisely. For rockfall impacts the rings elgongate within about 0.3s with internally more sliding than frictional effects.

L459: Correct the author names of this reference by using their family names.

Additional references regarding debris-net interaction

https://cdnsciencepub.com/doi/full/10.1139/cgj-2017-0540?casa_token=aCLNIaizhzkAAAAA%3A1ba2SkZjVe8Nkx55Ip2FYUsW_mNu2sXek3UfWAX_U06v8VUpIgYUSNrBb6lbpMwcLKdugc2DPuP2OA

https://upcommons.upc.edu/handle/2117/327389

Author Response

Thank you so much for pointing out the issue, and please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

In this study, the authors have introduced an important and interesting topic by investigating the energy capacity of a flexible rockfall barrier to resist the debris from landslides. The main aim of developing this study is to show the energy impact during the interaction between landslides and flexible barriers. The research focused on the back analysis of the landslide mobility, where the results have shown that the impact energy was three times bigger than the rated energy capacity of the flexible barrier. Moreover, the elongations of brake rings and the deflection of the flexible barrier of the conducted numerical models are considered compatible with the field measurements. Different aspects are evaluated; however, the results should be compared more, and the English writing style should be improved and modified thoroughly since it is changing the aim of discussion in this study. Additionally, I think that this study and datasets have not been utilized to their full extent and the literature review should include more details, which are listed in the comments below. The study is interesting and good results are established, but the authors should address the following comments:

1. In the introduction the authors should discuss more the past case studies regarding the difference between rigid and flexible barriers and what are the advantages of flexible systems when compared to others. Additionally, the types of flexible protection barriers should be categorized and described such as Active Flexible Barriers, Passive Flexible Barriers, and Attenuator Systems. These systems also have many characteristics that should be highlighted concisely and precisely such as the angles of the barriers, position of falling rocks, mesh, energy dissipaters, connections, ductility, deformations, and others. More references should be included the study is lacking references in the introduction part. See the following references:

·  Qin, J.Q., Yin, J.H., Zhu, Z.H. and Tan, D.Y., 2020. Development and application of new FBG mini tension link transducers for monitoring dynamic response of a flexible barrier under impact loads. Measurement, 153, p.107409.

·  Zhu, Z.H., Yin, J.H., Qin, J.Q. and Tan, D.Y., 2019. A new discrete element model for simulating a flexible ring net barrier under rockfall impact comparing with large-scale physical model test data. Computers and Geotechnics, 116, p.103208.

·  Yang, J., Duan, S., Li, Q. et al. A review of flexible protection in rockfall protection. Nat Hazards 99, 71–89 (2019). https://doi.org/10.1007/s11069-019-03709-x.

·  Qian, H., Li, Z., Pei, J., Kang, L., and Li, H., 2022. Seismic Performance of Self-centering Beam-Column Joints Reinforced with Superelastic Shape Memory Alloy Bars and Engineering Cementitious Composites Materials. Composite Structures, p.115782.

2.  It is better to add a paragraph in the introduction that discusses how this research is coping and helping in the implementation of the main sustainable development goals (SDG) that are employed by the United Nations (UN) Agenda. This study is shedding the light on an important structure during disastrous incidents, so the authors should add a paragraph discussing the importance of these critical innovative structural systems and how they can affect the social and economic prosperity of the societies, by giving some supportive case studies of past incidents.

3. The authors should indicate the main design mechanism that mainly results in different failure phenomena such as the types of boundary systems that are used there should be a clearly illustrated to show the efficiency of the design.

4. The design is implemented in an appropriate and detailed way. However, the authors should focus more on the structural design of the flexible barriers. So, the authors should be more extensive by comparing the results from each model and if the design is changed how, it can affect the energy capacity. 

5. The results should be analyzed and discussed extensively in the last section because the authors are not shedding the light on the most important outcome of the research. The results are only being stated without any comparison between them. A comparative section should be added between the different scenarios taking into consideration the variation in typical moments of the interception process and the moving characteristics. In other words, the variation between these models and how it can be compared, and what are the main reasons for this variation. This comparative part will show the readers the important outcomes that have been reached by this research.

6. A paragraph should be added in the conclusion to discuss how this research can help in future work and what are the main gaps that should be investigated.

7. In Figure 1 the reference should be added, and the location of this incident should be also added in the caption of the figure. Moreover, Figure 2 should be adjusted to higher resolution, because in the following form it is not clear. It is better to change the color of the labels on the figure to be clearer for the readers.   

8. The English and writing style should be reviewed and modified thoroughly in the paper there is no connectivity in some parts of the paper. Although the study is important the authors cannot clearly represent their ideas it will be hard for the readers to understand the main ideas being explained since there is a lack of transitions and connectivity between the main ideas.

Author Response

Thanks for your comments, and please see the attachment

Author Response File: Author Response.docx