Influence of air injection on the liquefaction-induced deformation mechanisms beneath shallow foundations

Abstract

The authors would like to thank the reviewers again for their time and additional comments. Based on the comments, we have attempted to cover all of their points and made changes of the manuscript, which are detailed below. Reviewer 2:The submitted manuscript presents very valuable information about the liquefaction induced deformation mechanism under the foundation in fully as well as well in partially saturated sands. However, the originality of the paper concerns me since there are figures and content published in another technical paper ("Centrifuge testing to evaluate the liquefaction response of air-injected partially saturated soils beneath shallow foundations" which has just been published in Bulletin of Earthquake Engineering). I would consider this manuscript as a technical note where most of the figures are not included and referred to the published article. The published manuscript and the submitted manuscripts presented the results from the same centrifuge tests. The results were just presented in different manners. There are same figures presented in both manuscripts as below:In the first and second round of revision, the authors were invited to revise the manuscript to address a number of technical comments. In the third round of revision, the most significant issue that has been raised by the reviewer is the originality of the paper. The authors believe that the changes made in the submitted manuscript do go a long way to ensuring that the main concern of the reviewer is addressed within the paper itself.Following the reviewer's comments, the manuscript has been changed significantly. A dataset from a series of two free-field centrifuge tests is included (see the amended Table 1). It is worth stating that the free-field test data has not been published elsewhere. The vast majority of the figures submitted in the second round of revised manuscript are replaced by the original figures. Accordingly, the relevant sections have been rewritten. The content of the paper has been significantly improved by adding more comprehensive discussions and a new dataset. The authors wish to thank the reviewers for this. 2.1-Figure 1 in both manuscripts show the same experimental setup.Answer 2.1-The cross-section of the models is modified following the comment of the reviewer, as given in Fig. 1 in this round of revised paper. Fig. 2 in published manuscript vs Fig. 6 in submitted manuscript. Answer 2.2-Following the reviewer's comment, the acceleration time histories in the previous manuscript ( Fig. 6) are removed from the manuscript and replaced by the shear stress-strain loops, as presented in Fig. 7 in the this round of revised paper. The effect of air injection on the shear stiffness of soil is demonstrated. It is noted that Fig. 2 in the published paper showed only the input (base) acceleration time histories recorded during the tests, whereas Fig. 6 submitted in the second round of revised manuscript presented the horizontal acceleration time histories recorded at different soil layers. Fig.3 in published ma...

Centrifuge testing to evaluate the liquefaction response of air-injected partially saturated soils beneath shallow foundations

“…During the tests, digital images were acquired using a high speed camera to investigate the soil deformations beneath the shallow foundations through particle image velocimetry (PIV) technique. The preparation of air-injected partially saturated soils and image analysis were discussed in detail elsewhere (Zeybek and Madabhushi 2016).…”

“…During the injection of air, some settlements of shallow foundation happened due to the decrease of the effective stresses in the foundation soil. The mechanisms of settlement during this process were explained by Zeybek and Madabhushi (2016). The air-induced settlements observed in the partially saturated models are indicated by horizontal dashed lines.…”

“…The deformation mechanisms developed during the experiments with the heavy foundation were demonstrated by Zeybek and Madabhushi (2016), with a particular focus on the alteration of deformation mechanisms with the injection of air. It was found that deviatoric soil deformations and lateral movement of soils were significantly reduced with Fig.…”

“…Most of this research was qualitative in nature. Zeybek and Madabhushi (2016) have investigated in a quantitative fashion the deformation mechanisms under shallow foundation by creating partially saturated zone in the soil beneath using air injection. This research showed the efficacy of air-injection in reducing the settlements and focused on identifying the changes in the deformation mechanisms going from nearly fully saturated to partially saturated case.…”

Physical modelling of air injection to remediate liquefaction

“…Air injection, among these techniques, can be more attractive for the researchers and engineers due to its applicability in the field (Okamura et al, 2011), its cost-effectiveness and due to it being an eco-friendly liquefaction mitigation method (Okamura and Tomida, 2015). Zeybek and Madabhushi (2017b) have investigated in a quantitative manner the most critical liquefaction-induced deformation mechanisms and their subsequent contributions to the overall foundation settlements for the saturated and airinjected partially saturated soils. It was found that unlike the saturated soil the deviatoric type of deformations under the static and dynamic stresses were significantly minimised by the air injection.…”