Evaluating the Design Criteria for Light Embankment Piling: Timber Piles in Road and Railway Foundations

Round 1

Reviewer 1 Report

The manuscript was performed to further develop the Swedish design guidelines for geogrid-reinforced timber pile-supported embankments via two- and three-dimensional finite element (FE) simulations. Overall, the work is relatively interesting, and the structure and language are well prepared. Some comments below need to be addressed or considered to improve the technical depth of the manuscript:

1. In the section 4 Light embankment piling especially in lines 99-112, I suggest simplifying this part of writing because there is more common-sense knowledge here.
2. In line 295, the model width (transversal direction of the road) and depth were set to 100 and 31.7 m, respectively. In line 305, the final general mesh size was 5.2 m, with 0.3 m and 0.5 m large elements in the embankment and in the pile group, respectively. Why did the author choose these sizes? Are there any bases? Please explain.
3. In line 12, two- and three-dimensional finite element (FE) simulations were performed to … However, only two-dimensional figures (e.g., Fig. 1 to Fig. 7) are displayed, and I suggest showing three-dimensional figures.
4. In Table 2, why are the parameters of unsaturated unit weight and saturated unit weight the same in the three soil layers?
5. In line 413, the modelled piles had a length of 13 m. Why 13m was selected? Please explain.
6. In the section 7.1-7.3, author shows the simulation results. The result analysis is more like the experimental report. I suggest that the discussion should be compared with the previous research results, are there any research results that can verify the results of this study.
7. The author obtains meaningful conclusions via finite element simulation. Such as, the maximum allowed centre-to-centre distance between piles can potentially be increased to 1.4 m, decreasing the number of piles by as much as one-third. However, are there any indoor tests or field tests or existing results to verify it?
8. The research background analysis is not enough. Some of the latest research results should be added. Some suggested references are listed below.

[1] Chai X J ,  Deng K ,  He C F , et al. Laboratory Model Tests on Consolidation Performance of Soil Column with Drained-Timber Rod[J]. Advances in Civil Engineering, 2021, 2021(1):1-8.

[2] Binhui Ma, Zhuo Li, Kai Cai, Meng Liu, Minghua Zhao, Bingchu Chen, Qiunan Chen, Zhiyong Hu. Pile-Soil Stress Ratio and Settlement of Composite Foundation Bidirectionally Reinforced by Piles and Geosynthetics under Embankment Load [J]. Advances in Civil Engineering, 2021(2):1-10（doi: 10.1155/2021/5575878）

[3] Nurdin S ,  Sawada K ,  Moriguchi S , et al. Design Criterion of Reinforcement on Thick Soft Clay Foundations of Traditional Construction Method in Indonesia[J]. Matec Web of Conferences, 2019, 258.

[4] Binhui Ma, Zhiyong Hu, Zhuo Li, Kai Cai, Minghua Zhao, Chengbin He, Qiunan Chen, Bingchu Chen, Xiaocheng Huang. A Three-Section-Settlement Calculation Method for Composite Foundation Reinforced by Geogrid-Encased Stone Columns [J]. Advances in Civil Engineering, 2021(1):1-10（doi: 10.1155/2021/5576713）

[5] Olson S J . Eisenhower Bridge North Abutment and Approach Settlement: A Case History of Timber Pile Downdrag and Comparative Downdrag Effect on Steel Piles[C]// Geo-Congress 2020. 2020.

 

 

 

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper is a very important paper for the design criteria for light embankment piling – timber piles in road and railway foundations. However, since it is a paper on which interpretation is based, a more diverse range of interpretation is required. (1) Please provide the rationale for setting the range of force against external force as follows. (2) the design criteria for light embankment piling – Because it is to present timber piles, it is necessary to provide criteria for areas divided into several stages, not simple values. In the conclusion, please write an additional analysis part of the paper.
In particular, in order to actually use the criteria presented in this paper, please clearly suggest the points to be taken into account and the limitations of the current analysis model. Also, please describe in detail the direction setting for future research.  

Author Response

Please see the attachment.

Author Response File: Author Response.pdf