A Deterministic Method for Evaluating Safety Factor of Deep Excavation Stability against Groundwater Inrush Equivalently Considering Soil Uncertainty
Round 1
Reviewer 1 Report
Comments for author File: 
Comments.pdf
Author Response
The text of the study is described in a competent technical language, understandable to the target audience of scientific journals. All terms used correspond to the basic and specific concepts of geotechnics; no discrepancies with generally accepted definitions have been identified. The material presented in the work will be of interest to scientists and specialists working in the field of geotechnical design and construction.
Answer: The authors are greatly thankful to Reviewer #1 for reviewing this manuscript.
Major comments:
(1) Page 3, figure 1, need to correct Diagram wall to Diaphragm wall.
Answer: In the revised manuscript, the author modified the word “Diagram” to “Diaphragm”. Please refer to Fig. 1 (100-102) in the revised manuscript.
(2) Table 1. Most likely, for the deformation moduli E50, Eoed and Eur, the values are written in Pa, and not kPa. Values look too big in kPa (for example for Sand soil A E50 is 1,36e7 kPa, but a concrete have E=2e7 kPa. If it is Pa, so value is normal – 13600 kPa). Perhaps the same problem in table 2 with Su, as well as in table. 3 with E seems too big. Please check the units of measurement.
Answer: This is a unit error as the author forgot to change the values of moduli in kPa. The author modified all the values in kPa. Please refer to Table 1, Table 2 and Table3 (140-142) in the revised manuscript.
(3) What software package was used for finite element calculation? If the author's software development was used, it is worth indicating this. If a well-known commercial product was used, this should also be indicated.
Answer: A commercial product called Flac3D was used in this manuscript, the author harnessed it for the finite element calculation. Please refer to 144-145 in the revised manuscript.
(4) Page 7, formula (6) - maybe it was worth not calling the coefficient the same symbol as shear stress? Might misunderstand some readers. If this is not essential, you can replace the symbol of the calibration factor.
Answer: The original symbol of the calibration factor might misunderstand readers in some cases, the author modified “” to “” as new symbol. Please refer to formula (6) and 280-354 in the revised manuscript.
Author Response File: Author Response.pdf
Reviewer 2 Report
The present study proposed a strength reduction method-based reliability analysis method for deep excavation engineering to investigate the influence of shear strength and its spatial variability of cement-solidified soil on the stability of deep excavation. A review of the full paper found that acceptance in its current form for publication in the journal of Sustainability is not recommended. Reconsider after addressing the following problems:
1. The structure of the paper confused me, following “Introduction, Methodology, Case study, Results and discussion, and Conclusions” to re-organize the paper.
2. English style is the primary problem. Currently, I cannot understand this study clearly unless a native speaker rechecks the grammar and typos.
3. There is too much old literature cited in the reference list. It should replace with some recent literature about soil research and the application of soil uncertainties. Authors can consult:
https://doi.org/10.1016/j.probengmech.2022.103315;
https://doi.org/10.1016/j.compag.2021.105990;
https://doi.org/10.1016/j.ijpvp.2020.104254;
https://doi.org/10.1016/j.catena.2020.104938;
https://doi.org/10.1007/s10661-016-5093-x.
4. Discussions need to increase the broad applicability of the model. I cannot capture the novelty of this work.
Author Response
Reviewer #2:
The present study proposed a strength reduction method-based reliability analysis method for deep excavation engineering to investigate the influence of shear strength and its spatial variability of cement-solidified soil on the stability of deep excavation. A review of the full paper found that acceptance in its current form for publication in the journal of Sustainability is not recommended. Reconsider after addressing the following problems:
Answer: The authors are greatly thankful to Reviewer #2 for reviewing this manuscript.
Major comments:
(1) The structure of the paper confused me, following “Introduction, Methodology, Case study, Results and discussion, and Conclusions” to re-organize the paper.
Answer: In this paper, a method for calculation of safety factor was developed, which was based on deterministic analysis results and probabilistic analysis results of a deep excavation project. So the structure of the paper is followed “Introduction, Numerical Model and Analysis Cases, Analysis of modelling results, Discussion, and Conclusion”. So, the specific process was as follows: the author established a three-dimensional model to simulate the excavation process firstly. Secondly, the deterministic analyses were carried out by giving different cohesion and got a linear function relationship between the safety factor and cohesion, which proved that the current safety factor calculation method in design specification is not suitable for deep excavation with passive zone improvement. Following that, probabilistic analyses were carried out considering the spatial variability of cohesion of cement stabilized bottom layer, which analyzed the effect of the mean value of cohesion and the COV of cohesion on uncertainty safety factor. And then, a calibration coefficient was introduced to define the relationship between uncertainty safety factor and safety factor obtained from deterministic analysis. Finally, a method which can predict the uncertainty safety factor was proposed under the conditions of any cement-solidified soil cohesion and any coefficient of variation of cohesion. Please refer the revised manuscript.
(2) English style is the primary problem. Currently, I cannot understand this study clearly unless a native speaker rechecks the grammar and typos.
Answer: The author rechecked the words and grammar in the revised manuscript. Please refer the revised manuscript.
(3) There is too much old literature cited in the reference list. It should replace with some recent literature about soil research and the application of soil uncertainties. Authors can consult:
Answer: The author has cited some literature provided by reviewer in the revised manuscript. Please refer to 66-70 in the revised manuscript.
(4) Discussions need to increase the broad applicability of the model. I cannot capture the novelty of this work.
Answer: The novelty is to develop a method against a method in a design specification. In current design specification, the safety factor of deep excavation stability against groundwater inrush is generally calculated by the pressure balance method, which considers only the self-weight effect of soil mass at the bottom of deep excavation but does not account for the resistance provided by soil shear strength. Thereby, the author developed a method for calculation of safety factor of stability against groundwater inrush equivalently considering the spatial variability in deep excavation with cement stabilized bottom layer. And this method was proved and can be used in similar cases. Please refer to 76-90 in the revised manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper investigates an interesting topic and the methodology is pertinent and innovative.
There are some points that need to be considered:
Introduction: the novelty against the existing literature needs to be explicitly described.
Numerical model: the boundary conditions needs to be detailed. The authors simply mentioned that the boundaries are constrained without explain how. Please refer to the existing literature.
The results: need to be discussed in more details. Probably adding a new section called "discussion" may help.
For these issues, major revisions are needed
Fo these issues
Author Response
Reviewer #3:
The paper investigates an interesting topic and the methodology is pertinent and innovative. There are some points that need to be considered:
Answer: The authors are greatly thankful to Reviewer #3 for reviewing this manuscript.
Major comments:
(1) Introduction: the novelty against the existing literature needs to be explicitly described.
Answer: The novelty is to develop a method against a method in a design specification called “Ministry of Housing and Urban-Rural Development of the People’s republic of China”. In current design specification, the safety factor of deep excavation stability against groundwater inrush is generally calculated by the pressure balance method, which considers only the self-weight effect of soil mass at the bottom of deep excavation but does not account for the resistance provided by soil shear strength. Thereby, the author developed a method for calculation of safety factor of stability against groundwater inrush equivalently considering the spatial variability in deep excavation with cement stabilized bottom layer. And this method was proved and can be used in similar cases. Please refer to 76-90 in the revised manuscript.
(2) Numerical model: the boundary conditions need to be detailed. The authors simply mentioned that the boundaries are constrained without explain how. Please refer to the existing literature.
Answer: The boundary conditions of the model were as follows: the left and right boundaries constrain displacement in the x direction; front and rear boundaries (y direction) constrain displacement in the y direction; the bottom surface constrains displacement in the z direction; pore-water pressure is allowed to change; a permeable boundary is adopted; and the top surface is a free surface. And a literature was cited in the revised manuscript. Please refer to 124-129 in the revised manuscript.
(3) The results: need to be discussed in more details. Probably adding a new section called "discussion" may help.
Answer: The method was developed based on the deterministic analysis results and probabilistic analysis results, whose development can be seen in the section 4.1. In this section, the author interpreted how to develop the method. In summary, the method can calculate safety factor of stability against groundwater inrush with carrying out the deterministic analysis and probabilistic analysis of two cases when checking the heaving stability of excavation. It is able to save the computing time and resources, and also simplify the design process. Please refer to the section 4.1 and 403-407 in the revised manuscript.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors address all my concerns.
Author Response
The authors address all my concerns
Answer: The authors are greatly thankful to Reviewer #2 for reviewing this manuscript.
Reviewer 3 Report
The comments have been answered. There is only one last concern regarding the role of the water: please discuss this sentence:
"pore-water pressure is allowed to change; a permeable boundary is adopted; and the top surface is a free surface",
in comparison with this literature:
Chung, J.W.; Rogers, J.D. Influence of assumed groundwater depth on mapping liquefaction potential. Environ. Eng. Geosci. 2013, 19, 377–389.
Cheng, H.; Chen, H.; Jia, H.; Zhang, S.; Liu, X. Probabilistic Analysis of Ground Surface Settlement of Excavation Considering Spatial Variable Modified Cam-Clay Model Parameters. Appl. Sci. 2022, 12, 9411. https://doi.org/10.3390/ app12199411
Forcellini D. (2020) “The Role of the Water Level in the Assessment of Seismic Vulnerability for the 23 November 1980 Irpinia-Basilicata Earthquake”. Geosciences 2020;10(6):229. https://doi.org/10.3390/geosciences10060229.
Hartantyo, E.; Brotopuspito, S.K. Sismanto; Waluyo. Correlation of shallow groundwater levels with the liquefaction occurrence cause by May 2006 earthquake in the south volcanic-clastic sediments Yogyakarta, Indonesia. Int. J. Appl. Sci. 2014, 5, 1–8.
Author Response
Reviewer #3:
The comments have been answered. There is only one last concern regarding the role of the water: please discuss this sentence: "pore-water pressure is allowed to change; a permeable boundary is adopted; and the top surface is a free surface".
Answer: The authors are greatly thankful to Reviewer #3 for reviewing this manuscript.
In this paper, the author considered the effect of groundwater on foundation pit excavation, which has a great impact on the strain and stress of soil. The author simulated the draining process in analysis, and pore-water pressure will decrease if groundwater is drained in the soil. Therefore, it is necessary to change pore-water pressure to simulate the interaction between water and soil in draining process.
The method used to change pore-water pressure in FLAC3D is that permeability coefficient of each soil is given and permeable boundary is adopted. Specifically, the hydraulic condition in left, right, front and rear boundaries are constrained, but that in bottom boundary is free, which can simulate the draining in practical engineering. And it can get relatively accurate results.
For the top surface, its displacement is not constrained as there is no stress and it is allowed to deform. Meanwhile, the water can be drained through the top surface, and it is unneeded to constrain its permeable boundary.
In summary, a permeable boundary is adopted to change pore-water pressure and the top surface can be used to drain, which take the effect of water in soil into consideration. And I have cited the related references above, please refer to 157-162 in the revised manuscript.
Author Response File: 
Author Response.docx
