Explanation and Application of the Evolving Contact Traction Fields in Shallow Foundation Systems

Round 1

Reviewer 1 Report

General comments

The paper considers the phenomenological equations proposed by Ai et al. (2013) to describe the distribution of normal pressure under a foundation and proposes a modified version of the equation proposed by Taylor et al (2019) for the tangential force under a foundation. The fitting parameters are determined referring to the experimental results by Murzenko and the physical meaning of the parameters is not discussed. It should be noticed that different pressure distributions will likely be observed experimentally for different soils and foundation features. With this methodology the actual soil-structure interaction in terms of foundation stiffness and interface contact properties are disregarded. However, these aspects are nowadays easy to account using well established numerical method such as FEM, FDM, DEM or MPM. The approach is used  to investigate the effect of tangential traction fields in the displacement of the foundation considering a linear elastic half-space, which is very far from reality. Material non-linearity are easily accounted for by implementing advanced constitutive models in standard commercial software.

To this reviewer, the purpose of the paper is not clear and the methodology, although new, does not seem to advance the current state of the art.

The paper is well written and clear, however I think figures can be improved

Specific comments

1. Lines 59-63: discrete interactions between grains can be investigated by DEM, but this paper does not show these results, neither it accounts for this effect. I believe this sentence should be rephrased because it raise high expectation the reader, which are not satisfied
2. L99-101: a very short description of the experiment should be provided here to help the reader in understanding the results presented in Fig 1
3. L113-116: I do not agree with this sentence. Several popular continuum-based methods such as Finite Element Method, Finite Difference Method or Material Point Method can account for material non-linearity (elastiplasticity and non-linear elasticity), interface shear contact and foundation stiffness; moreover, Discrete Element Method can account for intergrain contacts, particle properties and so on
4. L165-167: I do not understand this sentence, why do you think that the mechanism of formation of this wedge is unknown? It can actually be visualized very well by plotting the shear strain or even the displacement in an FEM, FDM or MPM analysis.
5. L199-200: what is the physical meaning of the parameters of eq. 1 (if there’s any)?
6. Table 1: what are load cases N1-N5, please provide a short description for the reader in order to understand the results
7. L219-220: What is the advantage of using the method of superposition of interpolated closed-form solutions over other numerical methods such as FEM, FDM, MPM?
8. L244: the loading surfaces are taken as boundary conditions to calculate the elastic displacement. I do not understand the purpose of this approach. First of all, soil behaviour is not elastic, especially for high load levels; second, I believe that loading pressures are actually a result of the soil-foundation interaction, which is therefore not considered here.
9. 4 and 7: I do not understand this normalization. A displacement is here divided by a length (a) and multiplied by the Young modulus (E), why did you introduce the elastic parameter? The result has the unit of measure of a stiffness (kPa) and I do not understand the purpose of this procedure.
10. 6-8-9-10-11-12-13-14: please use kPa as unit of measure of stresses
11. 8: “the nonphysical…flow” should go in the main text and not in the figure caption
12. 11: the purpose of this figure is to highlight the importance of considering the shear stresses, thus I suggest to plot in the same chart the curves for the same value of N and different values of T
13. 11: “The results…fiels” should be removed from the caption
14. 16-17: to emphasize the effect of contact shear stresses the same should be equal in these 2 figures and title of the legend must be provided.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper needs an extensive revision for soft computing methods and analytical methods of foundations:

1.The evolving methods in types of response surface and genetic and neural networks shoulde be critcially investigated and applied in the study. The followings are recommened for this:

*Güllü, H, Fedakar, H.I., 2017. On the prediction of unconfined compressive strength of silty soil stabilized with bottom ash, jute and steel fibers via artificial intelligence. Geomechanics and Engineering, 12 (3), pp. 441-464

2.The results obtained from the evolving methods should be compared with conventional bearing capacity and settlement formulas. Terzaghi method could be useful for this comparision.

3. The foundation soil is also signficant for foot responses. Thus, a wide of ground improvement will be useful before attempt calculations. A variety of grout applications could be useful or this purpose.

* Canakci, H., Güllü, H. & Dwle, M.I.K. (2018) Effect of Glass Powder Added Grout for Deep Mixing of Marginal Sand with Clay. Arabian Journal for Science and Engineering 43 (4), 1583-1595 (2018). https://doi.org/10.1007/s13369-017-2655-3

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors replied to the reviewer comments and I have no further remarks.

Reviewer 2 Report

In minor, some references in the reference lists should be added by their titles. Discssions could be extended by some critcismf of available Works.

regards