Investigation on the Influencing Factors of K0 of Granular Materials Using Discrete Element Modelling
, Chuang Zhou 2,3, Weiyi Li 2,3, Xiaoqiang Gu 2,3,*, Yongjun Qin 1 and Liangfu Xie 1Round 1
Reviewer 1 Report
Manuscript concerns DEM simulations of impact of factors influencing the pressure ratio of granular materials. Manuscript refers to the basic formulas applied for predicting the pressure ratio in soil. Literature review is very comprehensive. The most important factors are considered. Manuscript is in the scope of the journal. It provides some new information concerning stress transmission in soil. Conclusions are supported by obtained results. It can be recommended for publication after a few minor corrections.
Particular comments:
- Table 1. Lack of consistency in positioning of units.
- Lines 167-173. The laboratory triaxial test should be described and presented comparison of results. The same concerns comparison of DEM triaxial and oedometric tests.
- Voids ratio in range 0.5-0.8 considered in DEM simulations is higher than the real soil voids ratio. Please comment this difference.
Author Response
Point 1: Table 1. Lack of consistency in positioning of units.
Response 1: We have made corrections according to Reviewer's comments. The positioning of the units has been unified (As shown in the attachment WORD file).
Point 2: Lines 167-173. The laboratory triaxial test should be described and presented comparison of results. The same concerns comparison of DEM triaxial and oedometric tests.
Response 2: Thanks for the suggestion of the Reviewer. We add a description for k0 loading in the triaxial test as below:
'Next, for evaluating K0-value, one-dimensional compression is performed in the DEM simulation with the stress path similar to that in laboratory triaxial tests. Due to the difficulty of measuring lateral stress in oedometer tests, triaxial tests are usually performed and an initial isotropic stress is applied to stand the sample before the K0 tests. Therefore, all the samples are initially isotropic consolidated, after which k0 loading is conducted. '
Actually, the authors have used the DEM method to compare k0 obtained from triaxial tests and oedometer tests in another paper [1], and the results showed that k0 values are consistent. Therefore, based on these conclusions, we applied k0 loading in this study with the stress path similar to that in laboratory triaxial tests
The comparison results are shown in the attachment WORD file.
Point 3: Voids ratio in range 0.5-0.8 considered in DEM simulations is higher than the real soil voids ratio. Please comment this difference.
Response 3: We thank the Reviewer for the comments. It's sure that the void ratio 0.5-0.8 adopted in this paper is higher than most real soils. The reason why we considered such value is that, firstly, a large void ratio is not uncommon in the DEM simulations, for example, Guo[2] conducted experiments for samples with a void ratio between 0.676 to 0.810. On the other hand, since the particle used in our study is non-spherical particles, the soil sample will have a larger void ratio than spherical particles under the same stress level.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments on the manuscript “Investigation on the influencing factors of K0 of granular materials using discrete element modelling”
The paper performed discrete element method (DEM) simulations of oedometer tests in order to verify the key factors (initial fabric anisotropy, particle shape, initial void ratio, inter-particle friction angle) influencing K0 of granular materials. In addition, the authors propose a new formula to calculate K0, which is based on empirical observations and takes into account relative density, critical state friction angle and shape factor of particles that constitute the material.
The objective is clearly stated and the results obtained are important and well presented by the authors. The discussion and conclusion are supported by the data, which may be very useful in soil mechanics and geomechanics. Thus, my recommendation is for publication in the form in which the manuscript was submitted by the authors to the journal.
Author Response
The authors would like to express their appreciation to the reviewer for the valuable comments.
