Numerical Analysis of Instability Mechanism of a High Slope under Excavation Unloading and Rainfall

Round 1

Reviewer 1 Report

In the manuscript "Numerical analysis of instability mechanism of a high slope under excavation unloading and rainfall " the authors study  the fluid structure coupling numerical simulation analysis is carried out for the landslide phenomenon of the left bank high slope of a reservoir project. Considering the influence of formation lithology, fault, excavation unloading, rainfall and water storage, the failure mechanism of the slope under excavation unloading and heavy rainfall is explained based on the three-dimensional finite element numerical simulation results. I recommend the following changes

1. The abstract should precise.

2. The English of the introduction part is poor.

3.  A brief paragraph should be added in introduction part for the finite element method and add the following refs

(a) A finite element approach for analysis and computational modelling of coupled reaction diffusion models, Numerical Methods for Partial Differential Equations, 35 (2) (2019) 830-850

(b) A finite element approach to capture Turing patterns of autocatalytic Brusselator model, Journal of Mathematical Chemistry, 57 (3) (2019) 769-789.

4. Some lines of code for simulation should be added as an appendix.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

In this study, the authors have introduced an important and interesting topic by investigating the instability under the effect of excavation unloading and rainfall. The study built a numerical analysis model to investigate a landslide phenomenon of the left bank high slope of a reservoir project out for the landslide phenomenon of the left bank high slope of a reservoir project. This is employed by taking into consideration the influence of formation lithology, fault, excavation unloading, rainfall and water storage, where different failure mechanisms are represented through finite element models. I think that this study and datasets has not been utilized to its 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 concerns:

1. In the introduction the authors should discuss more the structural modelling-related uncertainties by considering the past case studies regarding the developed models numerically that are performed for the landslide approaches that consider the excavation loading and rainfall. Additionally, the authors should tackle new and critical approaches of the slope deformation characteristics and landslide mechanisms. For instance, the seepage-stress separation method can simulate the slope excavation-rainfall coupling process by analysing the excavation stress field first and then imposing rainfall on the formed boundary. Moreover, the difficulties should be more introduced in this research such as the main difficulties that lie in unsaturated soil slope excavation simulation during the rainfall-excavation process. Due to the pore water in unsaturated soil slopes, the seepage field and stress field cannot be separated in a direct manner. See and add the following references for more information:

·     Li, Q., Wang, Y.M., Zhang, K.B., Yu, H. and Tao, Z.Y., 2020. Field investigation and numerical study of a siltstone slope instability induced by excavation and rainfall. Landslides, 17(6), pp.1485-1499.

·     Yu, X., Gong, B. and Tang, C.A., 2021. Study of the slope deformation characteristics and landslide mechanisms under alternating excavation and rainfall disturbance. Bulletin of Engineering Geology and the Environment, 80(9), pp.7171-7191.

·     Xu, X., Xing, Y., Guo, Z. and Huang, Y., 2021. Stability analysis of rainfall-triggered toe-cut slopes and effectiveness evaluation of pile-anchor structures. Journal of Earth Science, 32(5), pp.1104-1112.

 

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. These, study is shedding the light on an important structure during disastrous incidents, so the authors should add a paragraph discussing the importance of this critical structures and how it 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 engineering geological properties for the area under investigation such as the main rock and soil layers of the studied slope, the permeability, and physical and mechanical properties. 

4. The models are built and simulated in appropriate and detailed way. However, the authors should focus more about the deformation mechanisms. So the authors should be more extensive by comparing the results from each model and adding a comparative studies by including some comparative tables in the results section to show the different results between different storeys. 

5. The results should be analysed and discussed extensively, 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 saturation distribution and pore water pressure distribution of the slope before and after rainfall. 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.

General Comment:

The symbols introduced in this study should be modified since they are not aligned with the text and English should be revised because there is some transitional mistakes.

Author Response

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Author Response File: Author Response.pdf