Stability of MSW Landfill Slopes Reinforced with Geogrids

Round 1

Reviewer 1 Report

This paper analyzes the stability of MSW landfill slopes without reinforcement and with reinforced by geogrids through finite element and limit equilibrium methods. The design of analyzes is reasonable and rigorous. However, this paper takes up too much space to investigate the effect of various parameters on stability of unreinforced slope while only the spacing of geogrids are considered when analyzing reinforced slope. Since the shear strength parameters and unit weight values of solid waste material are in a wide range, Why did these parameters are not considered when analyzing reinforced slope by geogrids? Furthermore, In section “3. Result and Discussion”, it simply described the results of numerical simulation. The results of analyzes was not clearly discussed. Therefore, the manuscript has several limitations that prevents it from being accepted for consideration in the journal, in the reviewer's opinion. These are outlined below for the authors' convenience.

1.         The use of unprofessional vocabulary should be avoided in scientific paper. For example, “shallow slope angles” in line 9.

2.         The title of the manuscript mentioned “Landfill slopes reinforced with geogrids”. The reviewer suggests that the author should investigate the effect of parameters of MSW (Cohesion, Internal friction angle, unit weight etc) on reinforced landfill slope same like the author did on unreinforced slope.

3.         In section “2. Materials and Methods”, the creep deformation and humidity distribution of municipality solid waste (MSW) plays a key role in the stability of MSW landfill slope [1-2]. Given that, the Mohr-Coulomb model can’t accurately represent the macroscopic response without considering the mechanical creep. Please discuss the choice of constitutive models and how it impacts the accuracy of the solution in slope stability.

[1] Ering P, Sivakumar Babu G L. Slope stability and deformation analysis of Bangalore MSW landfills using constitutive model[J]. International Journal of Geomechanics, 2016, 16(4): 04015092.

[2] Yao Y, Li J, Xiao Z, et al. Soil-water characteristics and creep deformation of unsaturated expansive subgrade soil: Experimental test and simulation[J]. Frontiers in Earth Science, 2021: 1141.

4.         In section “3. Result and Discussion”, it lacks of theoretical discussion on analyzes’ results. It is suggested to put in some existing relevant literatures to demonstrate and support the paper’s results.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

In this study, slope stability analyzes of MSW landfills were carried out using finite element and limit equilibrium methods. The stability behavior of the landfill slopes was analyzed for both unreinforced and geogrid reinforced conditions. The idea of this manuscript is clear; However, there are still some problems to be solved. This manuscript can be received after major revision:

(1)    In the introduction: Although there are many studies in the literature on the stability of slopes in landfills, studies on the behavior of geogrid reinforced landfill slopes are very limited. Why are studies on the behavior of geogrid reinforced landfill slopes very limited in previous studies? Is this reinforcement method unreasonable? In addition, friction characteristics between synthetic materials and geotechnical materials also have an important impact on slope stability. The author should state the research achievements in this field in the introduction:

Characterise the geomembrane and geotextile type on the interface creep behaviour at dry condition. Geotextiles and Geomembranes. 2022, 50(2): 312–322. DOI:10.1016/j.geotexmem.2021.11.008.

(2)    In line 145-146: Many models have been established about the constitutive relationship of materials.Why the author chose Mohr-Coulomb model to carry out this research?

(3)    In section 2: Can the author add a detailed description of using the limit equilibrium method to calculate the slope safety factor? Because there is a comparison between the numerical simulation value and the calculated value in the analysis in Section 3.

(4)    In line 333-335: Besides, it is seen that the safety factor values obtained by the limit equilibrium method are slightly higher than the values obtained by the finite element method. Why does this phenomenon exist? The author should give a brief explanation. Similarly, the difference between the numerical simulation value and the calculated value in lines 351-353 should also be explained.

(5)    In section 3.2: Does the author consider the weight of geogrid? The effect of geogrid on slope stability is double-sided. A small amount of geogrid can really play the role of slope reinforcement. However, if too many geogrids are set, the weight of the shear block will increase, and the slope stability will not necessarily be improved.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All comments have been checked and modified well. Now it is suitable for publication.

Reviewer 2 Report

The author has replied to all my questions and made a lot of revisions to the previous manuscript. Now, I am willing to accept this manuscript in present form.