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Laboratory Characterization of a Compacted–Unsaturated Silty Sand with Special Attention to Dynamic Behavior

Appl. Sci. 2020, 10(7), 2559; https://0-doi-org.brum.beds.ac.uk/10.3390/app10072559

by Andrzej Głuchowski^1,*

, Zdzisław Skutnik²

, Marcin Biliniak³, Wojciech Sas¹

and Diego Lo Presti⁴

Reviewer 1:

Raimondas Šadzevičius

Reviewer 2: Anonymous

Reviewer 3: Anonymous

Appl. Sci. 2020, 10(7), 2559; https://0-doi-org.brum.beds.ac.uk/10.3390/app10072559

Submission received: 31 January 2020 / Revised: 30 March 2020 / Accepted: 3 April 2020 / Published: 8 April 2020

(This article belongs to the Section Acoustics and Vibrations)

Round 1

Reviewer 1 Report

The title of this paper should be corrected - authors have performed a series of tests, including oedometric tests, resonant column tests, bender element tests, and unsaturated triaxial tests, but in the title mentioned only resonant column tests.

Some typing mistakes were founded in the article - see line No.311,384, etc.

The equation for G₀ evaluation, presented by authors, is limited only to sandy silt type of soils, for future investigations I'll suggest to focus attention on organic soils - especially on peat. The unacceptable settlements and other deformations of road bases constructed on peat are often caused due to cyclic and dynamic loads.

Author Response

Respond for Review Report 1 for submission of a paper to an Applied Sciences – MDPI journal

16.03.2020

Dear Reviewer,

We wish to thank You for all the remarks. Below are responses to Comments and Suggestions.

“he title of this paper should be corrected - authors have performed a series of tests, including oedometric tests, resonant column tests, bender element tests, and unsaturated triaxial tests, but in the title mentioned only resonant column tests.”

We have changed the title to more suitable to the contents of this article.

“Some typing mistakes were founded in the article - see line No.311,384, etc.”

The typing mistakes were carefully corrected as reviewer suggested.

“The equation for G₀ evaluation, presented by authors, is limited only to sandy silt type of soils, for future investigations I'll suggest to focus attention on organic soils - especially on peat. The unacceptable settlements and other deformations of road bases constructed on peat are often caused due to cyclic and dynamic loads”

Thank you for this remark. We are going to explore this topic since it is indeed interesting and important one.

We present all changes in the red font style.

Thank you for your remarks on this manuscript.

Sincerely,

Andrzej, Stefano, Zdzisław, Marcin, Wojtek and Diego

Author Response File: Author Response.pdf

Reviewer 2 Report

Please see attached document.

Comments for author File: Comments.pdf

Author Response

Respond for Review Report 2 for submission of a paper to an Applied Sciences – MDPI journal

16.03.2020

Dear Reviewer,

We wish to thank You for all the remarks. Below are responses to Comments and Suggestions.

“… Line 3: double ‘of’ in the title.” And, “The title does not reflect the work related to the odometer tests”

We changed the title of the paper.

Line 53: Is the experimental program of this study based on undisturbed or reconstituted
samples? Please clarify”

The tests in this study was conducted on three undisturbed specimens of boreholes from the three different areas for the resonant column. Additionally, two remoulded specimens was prepared, one for resonant column test and one for the cyclic simple shear test. The additional explanation was added in the manuscript.

“Lines 55 to 56: is the observation of Go increased with confining pressure while Do
decrease agrees with the findings in the literature for silty soils?”

The G₀ and D₀ change observation in this article seems to be partially with the aggrement with the test results reported by us but certainly the different conditions of the test had its impact on the G₀ and D₀ characteristics. The so called in this article remoulding is not explained and we can only assume, that for the cyclic simple shear the air pluviation technique was used, for resonant column test the same technique should be used as well. Nevertheless, the impact of the soil reconstitution method is important.

“Line 123: Gs should be unitless”

We correct this in the manuscript.

“Line 131: Optimum water content with”

We correct this in the manuscript.

“Line 136: provide legends to Figure 1”

The legend to the Figure 1 is provided in Figure caption.

“Line 148: did the authors perform any tests on undisturbed samples? Line 53 indicated
undisturbed samples.”

The tests was conducted ont the reconstituted samples only. The aim of this procedure was to investigate the soil respond as a subgrade soil which is usualy pre-compacted before the road condtruction is conducted.

“Line 167: typo. Test No. 3”

The typo was corrected

“Line 191: Please explain why Casagrande empirical construction method was used to
determine maximum past pressure. There are other energy-based methods also available.”

The work method was used instead the Casagrande method. The results was indeed different then in previous analysis. Thank you for this remark.

“Line 207: what methodology or standard (e.g. ASTM 4015-15) was used to conduct
resonant tests and interpret the data?”

Thank you for this remark. We indeed conducted the resonant column wit respect to ASTM code.

We present all changes in the red font style. Thank you for your remarks on this manuscript.

Sincerely,

Andrzej, Stefano, Zdzisław, Marcin, Wojtek and Diego

Author Response File: Author Response.pdf

Reviewer 3 Report

The reviewed here manuscript is entitled “Use of the resonant column test for evaluating the dynamic characteristics of !of! compacted silty - subgrade”. It is expected to have discussion on the application of resonant column tests, but there are also other types of tests whose results are presented and discussed in the manuscript. The synergy of the performed tests is not well explained. The usage of the term “silty - subgrade” in the title is also questionable. The originality of the objectives and of the used methods is unclear. Even the Authors stated the topic of their study is current, there are few resent references. Moreover, not all the stated objectives in Introduction are actually achieved, e.g. “Characterization of resilient modulus degradation at small strain and intermediate strain range and proposition of a simple model to interpret the results”, etc. The manuscript is poorly structured and is not carefully written in correct and clear English. Given the shortcomings of the presentation and the discussion of the results, the manuscript cannot be recommended for publication in its current version.

General comments

It is not clearly explained what is missing in the previous studies on e.g. small strain shear stiffness for unsaturated soils and, particularly, for unsaturated sandy silt.

The literature survey is chaotic, not complete and not current.

In section “2. Materials and Methods” – it is unclear why both materials and methods are explained in subsection “2.1 Physical properties of the soil”.

The used terminology is questionable at several places along the manuscript, e.g. “effective stress” is often used instead of the correct “net stress” (for instance in Eq. 18 but not only); “saturation ratio”; “water stress”; “forecasting”; “water soil experimental curve”. The Authors considered saturated and unsaturated soil conditions and, therefore, they have to declare the state variables they accepted for their study, e.g. to give the definition of the effective stress for the unsaturated soil.

Particular comments

“These soils are often unsaturated, which 22 positively affects the soil parameters value. The information about the value of these parameters is 23 highly desirable by engineers.” – The word “value” is misused as in both sentences the plural “values” is to be used.

“The results show that sandy silt soil behaves a typical reaction to dynamic 26 loading, which can be modeled by using empirical equations” – unclear statement and needs attention.

“… compaction 27 procedure caused over–consolidation state which value rises with the moisture content during 28 compaction effort” – unclear statement.

In Eq. 1 the coefficient K_2,max is not used

Line 62: “Studies !under! dynamic properties of Piedmont residual soils [10] were done by performing…” – needs attention.

Lines 71-73 – unclear meaning of the text. “73 … to increase of the G/G0 curves with the increase in confining stress…” – improper formulation.

“This relation can presents equation (2):” – needs attention.

“… axial deviator stress” – Is there “lateral” deviatoric stress?

In Figure 1: Points with different colour heed to be explained.

Line 170 “The modulus M change shows a change in stiffness when applied stress increase as well.” – unclear statement.

Line 200: “An important fact is that the surface created by solving the equation (6) shows the existence of the preconsolidation stress” – How equation (6) was solved and what is the unknown there?

Line 210: “acceleration which able to find the modulus and strain level during tests” needs attention.

Line 217 “ß is device constant driven from” needs attention

Line 226 “… show a high dependence on test results characteristics. The shear modulus change has close characteristics …” – needs attention.

Line 233 “The bottom G_0” – needs attention.

Line 239 “Table 2 presents a detailed view of the soil parameters during resonant column studies.” – needs attention.

Line 290 “The effective stress in unsaturated soils will be affected by matrix suction of soil.” is a messy statement.

Line 362 “The compaction process causes preconsolidation state. The oedometric test results show clearly that the preconsolidation is rising with moisture content …” How compaction can cause a soil state is not clear. What is “rising” – the preconsolidation pressure/stress/ or something else? How the change of moisture content is related to the degree of saturation?

--Figure 4. Soil compressibility characteristics with Casagrande empirical construction for preconsolidation pressure determination. – For some of the cases it is obvious that the Casagrande’s graphical method is not properly applied.

There are many typos to be carefully corrected. Terminology and English usage are to be carefully reconsidered.

Author Response

Respond for Review Report 3 for submission of a paper to an Applied Sciences – MDPI journal

17.03.2020

Dear Reviewer,

We wish to thank You for all remarks. Below are respond to Comments and Suggestions.

“The reviewed here manuscript is entitled “Use of the resonant column test for evaluating the dynamic characteristics of !of! compacted silty - subgrade”. It is expected to have discussion on the application of resonant column tests, but there are also other types of tests whose results are presented and discussed in the manuscript. The synergy of the performed tests is not well explained.”

We changed the title of the manuscript to more suitable which presents performed tests and material.

“The usage of the term “silty - subgrade” in the title is also questionable. The originality of the objectives and of the used methods is unclear. Even the Authors stated the topic of their study is current, there are few resent references.”

We extended the literature review. The originality of this study is to combine the pavement engineering with the dynamic test and unsaturated tests. A lot of high-quality tests were performed in the field of unsaturated cyclic loading and in the field of dynamic tests on undisturbed soils. However, none are dedicated to the manuscript’s topic.

“Moreover, not all the stated objectives in Introduction are actually achieved, e.g. “Characterization of resilient modulus degradation at small strain and intermediate strain range and proposition of a simple model to interpret the results”, etc.”

Yes, we removed this bullet point and rewrote this part of the manuscript.

“It is not clearly explained what is missing in the previous studies on e.g. small strain shear stiffness for unsaturated soils and, particularly, for unsaturated sandy silt. The literature survey is chaotic, not complete and not current. ”

We extended the literature reviews, concerning the topic of the article.

“In section “2. Materials and Methods” – it is unclear why both materials and methods are explained in subsection “2.1 Physical properties of the soil.”

We added the additional 2.2 point to the manuscript.

“The used terminology is questionable at several places along the manuscript, e.g. “effective stress” is often used instead of the correct “net stress” (for instance in Eq. 18 but not only); “saturation ratio”; “water stress”; “forecasting”; “water soil experimental curve”. The Authors considered saturated and unsaturated soil conditions and, therefore, they have to declare the state variables they accepted for their study, e.g. to give the definition of the effective stress for the unsaturated soil. ”

We changed the pointed by reviewer wrongly denoted parameters.

““These soils are often unsaturated, which 22 positively affects the soil parameters value. The information about the value of these parameters is 23 highly desirable by engineers.” – The word “value” is misused as in both sentences the plural “values” is to be used. ”