Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper provided a prediction of CBR for subgrade soil from DCP. I have some suggestions for the authors.

 1. The mentioned prediction’ was not well presented in the manuscript, it is more of the ‘calibration’. Thus, please reconsider the relationship between the title and the content.

2. The used materisals were SC, how did the author establish the prediction models for SP and SM in Eqs. (3) and (4)?

3. In Table 4, the used Eqs. in Table 1for various soil can obtain a relative high coefficient of determination (𝑅²), this indicated the presented Eqs. had a well application, why did the author provided the new ones which had a lower 𝑅²?

Author Response

This paper provided a prediction of CBR for subgrade soil from DCP. I have some suggestions for the authors.

1. The mentioned prediction’ was not well presented in the manuscript, it is more of the ‘calibration’. Thus, please reconsider the relationship between the title and the content.

 Response: Thank you for your valuable suggestion. The title of the paper has been changed to “Recalibrated Correlations Between Dynamic Cone Penetrometer (DCP) Data and California Bearing Ratio (CBR) in Subgrade Soil”.

2. The used materisals were SC, how did the author establish the prediction models for SP and SM in Eqs. (3) and (4)?

Response: The establishment for SP and SM in Eqs (3) and (4) was achieved by using data from literature, refences no [17-19].

3. In Table 4, the used Eqs. in Table 1 for various soil can obtain a relative high coefficient of determination (?²), this indicated the presented Eqs. had a well application, why did the author provided the new ones which had a lower ?²?

Response: The proposed equations were designated to achieve rapid CBR yet acceptable level of accuracy, although the R² was reduced slightly.

Reviewer 2 Report

Comments and Suggestions for Authors

A good clear well defined abstract. A good introduction and background history, the method of material testing needs augmented with reference and the analysis could be deepened.  This is a good solid paper that will be very helpful to practitioners who need a quick tool for onsite CBR assessment.  The results can be compared with the impact of neural networks and considering should be considered to extending the work to the equilibrium moisture content CBR value.  Currently this is assessed using index properties which is not always idea.  Overall, a good useful paper and a pleasure to read.

Comments on the Quality of English Language

Observations:

 

Line 19         results, thereby enhancing the efficiency….  (a suggestion)

Line 31         I concur with the authors that in the main its fine-grained soils that are the main area for CBR assessment. However, given you are looking at sands and silty sands in the project, this statement needs qualification to cover course grained soils. The removal of the word undrained would help.  Again, this is a suggestion for the authors to consider.

Line 31         structures     

Line 34         the truly representative CBR value is difficult.

Line 35         civil engineers are often faced with the urgent

Lines 41/42   In addition, the DCP equipment is considered compact, accurate and lightweight. Therefore, an efficient correlation between CBR and DCP is required.

Line 45         depicted in Figure 1.  (space needed) and on all other Figures

Line 46         shown in Equation 1 (space needed) and all other Tables and Equations

                              

                     Have the authors any view on the IDOT (1997) line which is an outlier in Figure 1 e.g., soils tested etc. If not, I would comment this its different to the rest and as such should be ignored in the analysis. The numerator α does appear to be very low in comparison with rest of the methods suggested.

Line 54         SC, ML, MH, CL and CH are from which standard? This needs a reference and on Line 56 the reference for Al-Refeai and Al-Suhaibani (1996) needs the governing soil testing standard if different to Line 54.  This will very well documented, in Section 2.0 for the local work.

 

Figure 3        Hammer 8kg.

 

Table 3          what standard was used for the compaction test, was the hammer a light or heavy hammer (2.5 & 4.5 kg is the UK practise), what CBR apparatus was used and what was the rate of testing and the standard stone etc.  These are useful input for designer who will be using this useful paper down the line?

 

Line 140         Wilcesh et al. [19] provided…..  this is a minor typo etc.

 

Line 158        data points were much more scattered or showed a wider variation etc (again a suggestion)

 

                     The application of multivariable regression analysis and or neural network analysis could also be applied to the method of analysis.

 

Author Response

1) A good clear well defined abstract. A good introduction and background history, the method of material testing needs augmented with reference and the analysis could be deepened. 

Response: The material testing methods have been improved to be clearer and more in-depth as shown in Section 2 (lines 93-118). The analysis has been revised as shown in lines 186-191.

This is a good solid paper that will be very helpful to practitioners who need a quick tool for onsite CBR assessment.  The results can be compared with the impact of neural networks and considering should be considered to extending the work to the equilibrium moisture content CBR value.  Currently this is assessed using index properties which is not always idea. 

Overall, a good useful paper and a pleasure to read.

Response: Thank you for your compliments. A comparison of the work proposed here using the index properties with those applying neural networks is provided in the introduction part (lines 42-47).

 

2) Comments on the Quality of English Language

Observations:

Line 19         results, thereby enhancing the efficiency….  (a suggestion)

Response: Adjusted.

Line 31         I concur with the authors that in the main its fine-grained soils that are the main area for CBR assessment. However, given you are looking at sands and silty sands in the project, this statement needs qualification to cover course grained soils. The removal of the word undrained would help.  Again, this is a suggestion for the authors to consider.

Response: Adjusted.

Line 31         structures    

Response: Adjusted. 

Line 34         the truly representative CBR value is difficult.

Response: Adjusted.

Line 35         civil engineers are often faced with the urgent

Response: Adjusted.

Lines 41/42   In addition, the DCP equipment is considered compact, accurate and lightweight. Therefore, an efficient correlation between CBR and DCP is required.

Response: Adjusted.

Line 45         depicted in Figure 1.  (space needed) and on all other Figures

Response: Adjusted.

Line 46         shown in Equation 1 (space needed) and all other Tables and Equations       

Response: Adjusted.

                     Have the authors any view on the IDOT (1997) line which is an outlier in Figure 1 e.g., soils tested etc. If not, I would comment this its different to the rest and as such should be ignored in the analysis. The numerator α does appear to be very low in comparison with rest of the methods suggested.

                        Response: For the IDOT, it is a good example that the existing correlations need to be recalibrated.

Line 54         SC, ML, MH, CL and CH are from which standard? This needs a reference and on Line 56 the reference for Al-Refeai and Al-Suhaibani (1996) needs the governing soil testing standard if different to Line 54.  This will very well documented, in Section 2.0 for the local work.

                        Response: The used standard has been mentioned in line 54 and 56 (new line number 59 and 61, respectively).

Figure 3        Hammer 8kg.

Response: Adjusted.

Table 3          what standard was used for the compaction test, was the hammer a light or heavy hammer (2.5 & 4.5 kg is the UK practise), what CBR apparatus was used and what was the rate of testing and the standard stone etc.  These are useful input for designer who will be using this useful paper down the line?

Response: The standard used in the test has been added in lines 94-107.

Line 140         Wilcesh et al. [19] provided…..  this is a minor typo etc.

Response: Adjusted.

Line 158        data points were much more scattered or showed a wider variation etc (again a suggestion)

Response: Adjusted.

The application of multivariable regression analysis and or neural network analysis could also be applied to the method of analysis.

Response: A suggestion for future study on application of the multivariate data analysis and neural network modelling is provided in the conclusion part.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors provided the reasonable answer for my concerns. Therefor, this manuscript can be accepted from my view.