Study on Cyclic Bearing Capacity of Suction Pile Based on Equivalent Cyclic Creep Model
, Zhongyuan Yao 4, Yu Zhang 4, Shu Yan 3, Xiaojiang Guo 3 and Guoliang Dai 1,2
Round 1
Reviewer 1 Report
The paper studied the cyclic cumulative deformation characteristics and equivalent cyclic creep model of soft clay. It's very important for analyzing the bearing characteristics of suction caisson foundation. In opinion of the reviewer, the manuscript should be revised before it can be considered for publication. When the authors revise the manuscript, please consider the following comments:
(1) The introduction of soil preparation and dynamic triaxial test is not detailed enough, It's better to introduce the test process in detail.
(2) The static deviatoric stress is expressed by σs, but in formula (6), The deviatoric stress is expressed by σq, Please check it. It's better to unify the expression of static deviatoric stress and dynamic deviatoric stress.
(3) There are a few grammatical mistakes and not concise English expression in the paper, so I suggest checking it carefully.
(4) The parameter expression in the text shall be unified.
(5) The introduction of soil test is not detailed enough. Lack of necessary soil parameters.
(6) What are the factors cause strain softening and strain hardening phenomenon in the test?
(7) What conditions is the strain softening factor used for? There is no corresponding content in the manuscript.
Author Response
Responses to Reviewers' Comments
Manuscript Title: Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model
Manuscript Number: sustainability-1962390
Authors: Kang Huang, Wenbo Zhu *, Xin Liu, Zhongyuan Yao, Yu Zhang, Shu Yan, Xiaojiang Guo, Guoliang Dai
Journal: sustainability
Dear Editor,
Thank you for your letter and the reviewers' comments concerning our manuscript, " Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model " (sustainability-1962390). All of the comments have been valuable and extremely helpful in our effort to revise and improve the paper. Based on the comments provided by the two reviewers, we have carefully revised the manuscript. Meanwhile, we also reedit the language via professional language editing service institution. The specific responses are as follows:
Reviewer #1:
The paper studied the cyclic cumulative deformation characteristics and equivalent cyclic creep model of soft clay. It's very important for analyzing the bearing characteristics of suction caisson foundation. In opinion of the reviewer, the manuscript should be revised before it can be considered for publication. When the authors revise the manuscript, please consider the following comments:
(1) The introduction of soil preparation and dynamic triaxial test is not detailed enough, It's better to introduce the test process in detail.
Reply: Thank you for the comment. We have added this section in the manuscript.
To determine the soil strength, triaxial compression and extension tests of soft clay were performed under a confining pressures of 50kPa, 100kPa, and 150kPa. The stress-strain curves of saturated soft clay subjected to consolidated undrained (CU) triaxial tests are shown in Figure 2(a). Figure 2(b) provides the stress circles corresponding to failure under triaxial compression (solid curves) and triaxial extension (dashed curves) at different confining pressures, as well as the shear strength envelope (solid line). The stress circles corresponding to triaxial extension failure are close to the strength envelope determined by the stress circles corresponding to triaxial compression failure, indicating that the strength indices associated with triaxial compression failure are the same as those with triaxial extension failure. The Mohr-Coulomb ultimate strength indices of saturated clay were calculated to be c = 18.3 kPa and φ = 19.6°.
(a) Soil stress-strain relationship
(b) Mohr stress circles
Figure 2. Strength characteristics of soft clay
(2) The static deviatoric stress is expressed by σs, but in formula (6), The deviatoric stress is expressed by σq, Please check it. It's better to unify the expression of static deviatoric stress and dynamic deviatoric stress.
Reply: Thank you for the suggestion. We have revised these figures and unify the expression of static deviatoric stress and dynamic deviatoric stress.
(3) There are a few grammatical mistakes and not concise English expression in the paper, so I suggest checking it carefully.
Reply: Thank you for the comment. we have carefully checked the manuscript.
(4) The parameter expression in the text shall be unified.
Reply: Thank you for the comment. we have carefully checked the manuscript.
(5) The introduction of soil test is not detailed enough. Lack of necessary soil parameters.
Reply: Thank you for the comment. We have Added this section in the manuscript.
The specimen soil is taken from the coast of Guanyun. As shown in Figure 1(a), the remolded test soil is consolidated by vacuum preloading method. When the soil consolidation is completed, started the soil cyclic triaxial test by the GDS apparatus (Figure 1(b)). Three confining pressures are selected to conduct cyclic triaxial tests under different cyclic loads. The specific test schemes are shown in Table 1. The stress-strain curves of saturated soft clay are shown in Figure 2. The Mohr-Coulomb ultimate strength indices of saturated clay were calculated to be c = 18.3 kPa and φ = 19.6°.
(a) Soil consolidation (b) GDS apparatus
Figure 1. Cyclic triaxial test
Table 1. Test parameters
|
Type |
Confining pressure (kPa) |
loading rate (kPa/min) |
Frequency(Hz) |
Static deviator stress |
Dynamic deviator stress |
|
|
Consolidation |
50/100/150 |
0.1 |
- |
0/0.4/0.5/0.6/0.8 |
- |
|
|
Cyclic loading |
50/100/150 |
- |
0.1 |
0.4/0.5/0.6 |
0.1/0.2/0.3 |
|
|
0.1 |
0 |
0.3/0.4/0.5/0.6 |
||||
Figure 2. Strength characteristics of soft clay
(6) What are the factors cause strain softening and strain hardening phenomenon in the test?
Reply: Thank you for the comment. When the deflection stress is zero, the value of cyclic cumulative strain is small and the strain develops present strain softening phenomenon. It can be seen from the Figure 7 that when the static deflection stress is 0, the gradient of hysteresis loops under the condition of Nth cycle number were smaller than the gradient of hysteresis loops under the condition of first cycle number. As a result, the gradient of hysteresis loops is constantly decreasing with the number of cycles. Therefore, the strain development of soil presents strain softening phenomenon.
Figure 7: Definition of softening index
Figure 10 Strain hardening analysis
It can be seen from the Figure 10 that as the number of cycles increased, the hysteresis loops were gradually inclined toward the strain reverse direction. The maximum and minimum strains are decreasing with the number of cycles. As a result, the shear modulus of soil is constantly increasing with the number of cycles. Therefore, the strain development of soil presents strain hardening phenomenon.
(7) What conditions is the strain softening factor used for? There is no corresponding content in the manuscript.
Reply: Thank you for the comment. When the deflection stress is zero, the value of cyclic cumulative strain is small and the strain develops present strain softening phenomenon. It can be used to study the cyclic bearing capacity of subgrade in practical engineering according to the actual stress of soil.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The works propose the equivalent cyclic creep model to describe the strain cumulative deformation characteristics and strength hardening characteristics of soft clay. The research has certain practical engineering significance. So, the current manuscript needs a minor revision before considering for potential publication. There are some suggestions in the following:
(1) As we all know that the Merchant model is the creep model of soil, and the equivalent cyclic creep model is improved by the Merchant model. So is it reasonable to use the equivalent cyclic creep model to describe the cyclic accumulation of soil? It's better to explain the equivalent cyclic creep model.
(2) Generally, the cyclic cumulative deformation is related to the number of cycles. In the manuscript, the cyclic cumulative deformation is related to the time, how to make the time equivalent to the number of cycles?
(3) There have some professional terms in the article are not unified. And some words in the article are more complicated.
(4) How to determine the amplitude of static deviatoric stress and cyclic deviatoric stress? There is no relevant explanation in the manuscript.
(5) In Equation (7), there have matrix A, please list the expression of matrix A.
(6) There has a stress control switch in the equivalent cyclic creep model, what is the difference of the stress control switch between the equivalent cyclic creep model and traditional creep element model?
(7) In Figure 12 the strain of the εe and εve didn't explain.
(8) What is the difference between strain softening and strain hardening?
what conditions does strain softening occur? What conditions does strain hardening occur?
Author Response
Responses to Reviewers' Comments
Manuscript Title: Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model
Manuscript Number: sustainability-1962390
Authors: Kang Huang, Wenbo Zhu *, Xin Liu, Zhongyuan Yao, Yu Zhang, Shu Yan, Xiaojiang Guo, Guoliang Dai
Journal: sustainability
Dear Editor,
Thank you for your letter and the reviewers' comments concerning our manuscript, " Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model " (sustainability-1962390). All of the comments have been valuable and extremely helpful in our effort to revise and improve the paper. Based on the comments provided by the two reviewers, we have carefully revised the manuscript. Meanwhile, we also reedit the language via professional language editing service institution. The specific responses are as follows:
Reviewer #2:
The works propose the equivalent cyclic creep model to describe the strain cumulative deformation characteristics and strength hardening characteristics of soft clay. The research has certain practical engineering significance. So, the current manuscript needs a minor revision before considering for potential publication. There are some suggestions in the following:
(1) As we all know that the Merchant model is the creep model of soil, and the equivalent cyclic creep model is improved by the Merchant model. So is it reasonable to use the equivalent cyclic creep model to describe the cyclic accumulation of soil? It's better to explain the equivalent cyclic creep model.
Reply: Thank you for the comment. The equivalent cyclic creep model can not only describe the strain cumulative deformation characteristics but also describe strain weakening characteristics of soft clay. the Merchant model is the creep model of soil, which can describe the cyclic accumulation of soil, the softening index can describe strain weakening characteristics of soft clay.
(2) Generally, the cyclic cumulative deformation is related to the number of cycles. In the manuscript, the cyclic cumulative deformation is related to the time, how to make the time equivalent to the number of cycles?
There is no improved cyclic creep model in the material library of the ABAQUS for constructing the creep constitutive relationship. In Abaqus, the stress-strain rate is generally expressed by incremental method. The increments are expressed by time. In order to realize the improved cyclic creep model in finite element, We equate the number of cycles with time. The equivalent results are as follows:
where w=0.1, The frequency is 0.1.
(3) There have some professional terms in the article are not unified. And some words in the article are more complicated.
Reply: Thank you for the comment. we have carefully checked the manuscript.
(4) How to determine the amplitude of static deviatoric stress and cyclic deviatoric stress? There is no relevant explanation in the manuscript.
Reply: Thank you for the comment. Firstly, the ultimate strength of soil is measured by static test. Then, It can determine the amplitude of static deviatoric stress and cyclic deviatoric stress according to the ultimate strength. The revised contents are as follows:
(5) In Equation (7), there have matrix A, please list the expression of matrix A.
Reply: Thank you for the comment. We have added the expression of matrix A.
(6) There has a stress control switch in the equivalent cyclic creep model, what is the difference of the stress control switch between the equivalent cyclic creep model and traditional creep element model?
Reply: Thank you for the comment. Figure 10 shows the equivalent cyclic creep model. The equivalent cyclic creep model is different from the merchant model. The load applied on merchant model is static load, while the load applied on equivalent cyclic creep merchant model is dynamic load. The cyclic cumulative deformation can be regarded as the creep process of soil. A stress control switch can be paralleled on the Kelvin body. The stress control switch can ensure the maximum cyclic stress. It can be ensure that the stress applied on Kelvin body is the maximum cyclic stress, and the stress applied on hooker body is the sum of static deviator stress and dynamic deviator stress. So the equivalent cyclic creep model can not only describe the strain cumulative deformation characteristics but also describe strain weakening characteristics of soft clay.
the stress control switch of traditional creep element model means that when the total stress is greater than the stress of the stress control switch, Kelvin body will beginning to deform. So the stress control switch of the equivalent cyclic creep model is different from the stress control switch of traditional creep element model.
(7) In Figure 12 the strain of the εe and εve didn't explain.
Reply: Thank you for this suggestion. The relevant contents in the text are now revised as follows:
Figure 12. Improved cyclic creep model
The improved cyclic creep constitutive model of soft clay are shown in Equation (7):
(7)
（8）
(8) What is the difference between strain softening and strain hardening? what conditions does strain softening occur? What conditions does strain hardening occur?
Reply: Thank you for the comment. When the deflection stress is zero, the value of cyclic cumulative strain is small and the strain develops present strain softening phenomenon. It can be seen from the Figure 7 that when the static deflection stress is 0, the gradient of hysteresis loops under the condition of Nth cycle number were smaller than the gradient of hysteresis loops under the condition of first cycle number. As a result, the gradient of hysteresis loops is constantly decreasing with the number of cycles. Therefore, the strain development of soil presents strain softening phenomenon.
Figure 7: Definition of softening index
Figure 10 Strain hardening analysis
It can be seen from the Figure 10 that as the number of cycles increased, the hysteresis loops were gradually inclined toward the strain reverse direction. The maximum and minimum strains are decreasing with the number of cycles. As a result, the shear modulus of soil is constantly increasing with the number of cycles. Therefore, the strain development of soil presents strain hardening phenomenon.
Author Response File: Author Response.pdf
Reviewer 3 Report
Reviewer #1:
Paper Title:
Study on Cyclic Bearing Capacity of Suction Pile Based on Equivalent Cyclic Creep Model
The paper is concerned to an interesting research work related to the strain hardening and softening characteristics of soft clay studied by cyclic triaxial tests. The main development of this work is considered to be the investigation of one method for analyzing the cyclic characteristics of soil and suction pile. The paper is well organized and with acceptable number of references, illustrations and tables. It is also noticed that the authors have followed the manuscript submission instructions. However, English should be considerably improved. At certain points the text is very difficult to understand, due to long sentences, wrong syntaxes, repeated sentences, etc. The authors are urged to make a serious effort in improving English throughout the manuscript. Some examples are presented further on.
The following points should be considered:
Pag. 1 – Abstract - line 16-18: Please rephrase for clearness. Here and along the manuscript don’t use “… the strain develops present…”
Pag. 1 – Abstract - line 19: Please rephrase for clearness. Here and along the manuscript be careful with syntax and grammar “…index are proposed to …”
Pag. 1 – Abstract – line 23: Please rephrase for clearness. Here and along the manuscript be careful with repeated sentences or words. Instead of “…analyzing the cyclic characteristics of soil and the cyclic characteristics of suction pile.”, use “…analyzing the cyclic characteristics of soil and suction pile.”
Pag. 1 – Introduction – line 30: Here and along the manuscript, please use italic for “et al.”.
Pag. 1 – Introduction – line 30-32: Please rephrase for clearness. “Cyclic cumulative deformation of soil around pile caused by cyclic cumulative deformation of pile foundation.”
Pag. 2– line 55 and 56: Please rephrase for clearness. Again, word repeated in the same sentence: “…by considering the cyclic cumulative deformation method considering…”.
Pag. 3– line 70 - 78: This last paragraph of the Introduction is confused, please rephrase for clearness. In fact, it is quite similar with the abstract. Wrong syntax “…, strain softening is used in the strain accumulation model caused the calculation result is not accurate enough.” and “…by cyclic triaxial tests. based on test results,…”
Pag. 3– line 80: Not clear, please clarify: “The specimen soil was chose from Jiangsu Lianyungang.”
Pag. 4– line 90: Please be consistent with format and use it along the entire manuscript and in all the titles. Start title with Caps letter, please correct: “2.1 strain softening results”
Pag. 5 – Figure 2 – Caption with different format from Figure 1. Why is numbered from (g) to (j)? and why the same information is repeated in line legend (if each graphic has only one curve/line, please remove top legend). The meaning of each symbol used in the Figure 2 should be previously referred and explained. In fact, it is called further on only in page 11, please anticipate that reference.
Pag. 5 – line 101: Don’t use the word “We”. Please rephrase. (Same for page 7 line 118.)
Pag. 5 – line 104: Please rephrase for clearness: “…the cyclic deflection stress ratio is larger, the strain amplitude is larger.”
Pag. 6– line 113: Please be consistent with format and use it along the entire manuscript and in all the titles. Start title with Caps letter, please correct: “2.2 strain hardening results”
Pag. 7 – Figure 4 – Again like in Figure 2, why the same information is repeated in line legend (if each graphic has only one curve/line, please remove top legend). Suggestion for easy understanding of the text from line 114 to 117, identify the symbols and Figures referred, for example: “From Figure 4a, when the static load ratio (qs) is 0.4 and the cyclic load ratio (qd) is 0.1, the cyclic cumulative strain is small.”
Pag. 8 – line 131: Please rephrase for clearness. “So the static deviator stress and cyclic deviator stress is greater, the cyclic cumulative strain is higher.”
Pag. 9 – line 141: Figure 6 Development of strain softening (Same caption of Figure 3?, again strain softening?) Please clarify and correct.
Pag. 11 – line 165: Please correct: Instead of “…proposeed….”, use “…proposed “
Pag. 12 – Figure 8 – Please correct the position of top legend, once it is coincident with diagram curves.
Pag. 12 – line 184: Please rephrase for clearness. “It is because of that there have 184 an static deflection stress during cyclic loading.”
Pag. 14 – line 205: Please rephrase for clearness. “where α, n1, n2 and n3 are the fitting parameter, which the fitting parameter value are the 0.14, 3.8….”
Pag. 20 – Figure 17 – The curves cannot be identified with the same color. Please correct it.
– Figure 17c – Caption and legend are different, please correct: (c) Fa=0.6Ff
Pag. 21 – line 284: Please rephrase for clearness. “It can be seen that the cyclic load ratio is higher, the cumulative displacement of the caisson is greater.
Pag. 22 – line 296: Please rephrase for clearness. Again, be careful with repeated sentences or words. Instead of “…analyzing the cyclic characteristics of soil and the cyclic characteristics of suction pile.”, use “…analyzing the cyclic characteristics of soil and suction pile.”
Pag. 23– line 299: Please rephrase for clearness. “In this work, the strain softening and strain hardening phenomenon of soft clay were characterized through cyclic triaxial tests. the strain hardening index and improved cyclic creep model were established to describe the strain hardening and cyclic cumulative deformation phenomenon of soil.”
Author Response
Responses to Reviewers' Comments
Manuscript Title: Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model
Manuscript Number: sustainability-1962390
Authors: Kang Huang, Wenbo Zhu *, Xin Liu, Zhongyuan Yao, Yu Zhang, Shu Yan, Xiaojiang Guo, Guoliang Dai
Journal: sustainability
Dear Editor,
Thank you for your letter and the reviewers' comments concerning our manuscript, " Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model " (sustainability-1962390). All of the comments have been valuable and extremely helpful in our effort to revise and improve the paper. Based on the comments provided by the two reviewers, we have carefully revised the manuscript. Meanwhile, we also reedit the language via professional language editing service institution. The specific responses are as follows:
Reviewer #3:
The paper is concerned to an interesting research work related to the strain hardening and softening characteristics of soft clay studied by cyclic triaxial tests. The main development of this work is considered to be the investigation of one method for analysing the cyclic characteristics of soil and suction pile. The paper is well organized and with acceptable number of references, illustrations and tables. It is also noticed that the authors have followed the manuscript submission instructions. However, English should be considerably improved. At certain points the text is very difficult to understand, due to long sentences, wrong syntaxes, repeated sentences, etc. The authors are urged to make a serious effort in improving English throughout the manuscript. Some examples are presented further on.
The following points should be considered:
（1）Pag. 1 – Abstract - line 16-18: Please rephrase for clearness. Here and along the manuscript don’t use “… the strain develops present…”
Reply: Thank you for the comment. The relevant contents in the abstract are now revised as follows:
The test results show that when the static deflection stress is zero, the value of cyclic cumulative strain is small and the strain develops present strain softening phenomenon. When the static deflection stress is greater than zero, the strain develops present strain hardening phenomenon.
（2）Pag. 1 – Abstract - line 19: Please rephrase for clearness. Here and along the manuscript be careful with syntax and grammar “…index are proposed to…”
Reply: Thank you for the comment. The relevant contents in the abstract are now revised as follows:
Therefore, a strain softening index and strain hardening index were proposed to describe cyclic characteristics of soil.
（3）Pag. 1 – Abstract – line 23: Please rephrase for clearness. Here and along the manuscript be careful with repeated sentences or words. Instead of “…analyzing the cyclic characteristics of soil and the cyclic characteristics of suction pile.”, use “…analyzing the cyclic characteristics of soil and suction pile.”
Reply: Thank you for the comment. The relevant contents in the abstract are now revised as follows:
Moreover, an improved cyclic creep model is established by considering the strain hardening index. Based on the proposed method, which can accurately reflect the cyclic bearing characteristics of suction pile.
（4）Pag. 1 – Introduction – line 30: Here and along the manuscript, please use italic for “et al.”.
Reply: Thank you for the comment. The format of the “et al.” is revised as italic. for example：
( Ye et al., [1]; Kong et al., [2]; Tong et al., [3]; Zhang and Andersen, [4]) ，Yao and Nie [12] and Cai et al. [13]，Idriss et al. [14] and so on.
（5）Pag. 1 – Introduction – line 30-32: Please rephrase for clearness. “Cyclic cumulative deformation of soil around pile caused by cyclic cumulative deformation of pile foundation.”
Reply: Thank you for the comment. We deleted this sentence.
（6）Pag. 2– line 55 and 56: Please rephrase for clearness. Again, word repeated in the same sentence: “…by considering the cyclic cumulative deformation method considering…”.
Reply: Thank you for the comment. The relevant contents are revised as follows:
Chai and Miura [18] established the cyclic cumulative deformation method by considering the number of cycles, static deflection stress level, cyclic deflection stress level and other factors.
（7）Pag. 3– line 70 - 78: This last paragraph of the Introduction is confused, please rephrase for clearness. In fact, it is quite similar with the abstract. Wrong syntax “…, strain softening is used in the strain accumulation model caused the calculation result is not accurate enough.” and “…by cyclic triaxial tests. based on test results,…”
Reply: Thank you for the comment. The relevant contents are revised as follows:
The above research mainly studies the strain softening phenomenon during the test. At the same time, the strain accumulation model by considering the strain softening factor is not accurate enough to describe the cyclic bearing characteristics of soft clay. In the process of cyclic loading, the strain development not only present the strain softening phenomenon, but also present the strain hardening phenomenon according to different static deflection stress. Therefore, the cyclic bearing characteristics of soil are studied through cyclic triaxial tests. At the same time, an equivalent cyclic creep model is established by considering the strain hardening index to describe the cyclic bearing characteristics of suction pile.
（8）Pag. 3– line 80: Not clear, please clarify: “The specimen soil was chose from Jiangsu Lianyungang.”
Reply: Thank you for the comment. The relevant contents are revised as follows:
The specimen soil is taken from the coast of Guanyun.
（9）Pag. 4– line 90: Please be consistent with format and use it along the entire manuscript and in all the titles. Start title with Caps letter, please correct: “2.1 strain softening results”
Reply: Thank you for the comment. The titles are revised as follows:
2.1 Strain softening results
（10）Pag. 5 – Figure 2 – Caption with different format from Figure 1. Why is numbered from (g) to (j)? and why the same information is repeated in line legend (if each graphic has only one curve/line, please remove top legend). The meaning of each symbol used in the Figure 2 should be previously referred and explained. In fact, it is called further on only in page 11, please anticipate that reference.
Reply: Thank you for the comment. The relevant contents are revised as follows:
（g）qd=0.3qf （h）qd=0.4qf
（i）qd=0.6qf （j）qd=0.7qf
Figure 2 stress-strain relationship（σ3=100kPa）
（11）Pag. 5 – line 101: Don’t use the word “We”. Please rephrase. (Same for page 7 line 118.)
Reply: Thank you for the comment. The relevant contents are revised as follows:
It can know that the cyclic deflection stress obviously affects the strain accumulation results.
Figure 3 shows the strain softening under the number of cycles is 1, 10, 1000 and 2000. It can know that the maximum value and the minimum value of strain increases with the number of cycles.
（12）Pag. 5 – line 104: Please rephrase for clearness: “…the cyclic deflection stress ratio is larger, the strain amplitude is larger.”
Reply: Thank you for the comment. The relevant contents are revised as follows:
At the same time, the strain amplitude will increases with the increase of cyclic deviator stress.
（13）Pag. 6– line 113: Please be consistent with format and use it along the entire manuscript and in all the titles. Start title with Caps letter, please correct: “2.2 strain hardening results”
Reply: Thank you for the comment. The titles are revised as follows:
2.2 Strain hardening results
（14）Pag. 7 – Figure 4 – Again like in Figure 2, why the same information is repeated in line legend (if each graphic has only one curve/line, please remove top legend).
（a）qs=0.4qf，qd=0.1qf （b）qs=0.4qf，qd=0.2qf
（c）qs=0.5qf，qf=0.2qf （d）qs=0.5qf，qd=0.3qf
Figure 4 Stress-strain curves（σ3=100kPa）
（15）Suggestion for easy understanding of the text from line 114 to 117, identify the symbols and Figures referred, for example: “From Figure 4a, when the static load ratio (qs) is 0.4 and the cyclic load ratio (qd) is 0.1, the cyclic cumulative strain is small.”
Figure 5(a) shows that when the static load ratio (qs) is 0.4 and the cyclic load ratio is 0.2, the cyclic cumulative strain is small. When the static load ratio (qs) is 0.4 and the cyclic load ratio (qd) is 0.3, the cyclic cumulative strain is bigger than the result of the static load ratio (qs) is 0.4 and the cyclic load ratio (qd) is 0.2. Figure 5(b) shows that when the static load ratio (qs) is 0.5 and the cyclic load ratio (qd) is 0.2, the cyclic cumulative strain is small. When the static load ratio (qs) is 0.5 and the cyclic load ratio (qd) is 0.3, the cyclic cumulative strain is bigger than the result of the static load ratio (qs) is 0.5 and the cyclic load ratio (qd) is 0.2. So the static deviator stress and cyclic deviator stress is greater, the cyclic cumulative strain is higher.
（16）Pag. 8 – line 131: Please rephrase for clearness. “So the static deviator stress and cyclic deviator stress is greater, the cyclic cumulative strain is higher.”
Reply: Thank you for the comment. The relevant contents are revised as follows:
It can be known that the cyclic cumulative strain will increases with the increase of the static deviator stress and cyclic deviator stress.
（17）Pag. 9 – line 141: Figure 6 Development of strain softening (Same caption of Figure 3?, again strain softening?) Please clarify and correct.
Reply: Thank you for the comment. The relevant contents are revised as follows:
Figure 6 Development of strain hardening
（18）Pag. 11 – line 165: Please correct: Instead of “…proposeed….”, use “…proposed “
Reply: Thank you for the comment. The relevant contents are revised in manuscript.
（19）Pag. 12 – line 184: Please rephrase for clearness. “It is because of that there have 184 an static deflection stress during cyclic loading.”
Reply: Thank you for the comment. The relevant contents are revised as follows:
This sentence of “It is because of that there have an static deflection stress during cyclic loading.” was deleted.
（20）Pag. 14 – line 205: Please rephrase for clearness. “where α, n1, n2 and n3 are the fitting parameter, which the fitting parameter value are the 0.14, 3.8….”
Reply: Thank you for the comment. The relevant contents are revised as follows:
(5)
where α, n1, n2 and n3 are the fitting parameter. The value of α is 0.14, the value of n1 is 3.8, the value of n2 is 7.58, and the value of n3 is 0.018; w is the cyclic frequency; qf is ultimate strength of soil; qs is the static deflection stress; qd is the cyclic deflection stress; qa is the reference stress.
（21）Pag. 20 –Figure 17 – The curves cannot be identified with the same color. Please correct it.
Reply: Thank you for the comment. The relevant contents are revised as follows:
(a) Fa=0.4Ff
(b) Fa=0.5Ff
(c) Fa=0.6Ff
Figure 17. Displacement-time curve
（22）–Figure 17c – Caption and legend are different, please correct: (c) Fa=0.6Ff
Reply: Thank you for the comment. The relevant contents are revised as follows:
(c) Fa=0.6Ff
Figure 17. Displacement-time curve
（23）Pag. 21 – line 284: Please rephrase for clearness. “It can be seen that the cyclic load ratio is higher, the cumulative displacement of the caisson is greater.
Reply: Thank you for the comment. The relevant contents are revised as follows:
It can be seen that the cumulative displacement of the caisson will increases with the increase of the cyclic load ratio.
（24）Pag. 22 – line 296: Please rephrase for clearness. Again, be careful with repeated sentences or words. Instead of “…analyzing the cyclic characteristics of soil and the cyclic characteristics of suction pile.”, use“…analyzing the cyclic characteristics of soil and suction pile.”
Reply: Thank you for the comment. The relevant contents are revised as follows:
It can provide a new method for analyzing the cyclic characteristics of soil and the suction pile.
（25）Pag. 23– line 299: Please rephrase for clearness. “In this work, the strain softening and strain hardening phenomenon of soft clay were characterized through cyclic triaxial tests. the strain hardening index and improved cyclic creep model were established to describe the strain hardening and cyclic cumulative deformation phenomenon of soil.”
Reply: Thank you for the comment. The relevant contents are revised as follows:
5 Conclusions
In this paper, the strain hardening characteristics and strain softening characteristics of soft clay are studied by cyclic triaxial tests. Moreover, an improved cyclic creep model is established to describe the strain accumulation and strain hardening characteristics of soil and cyclic characteristics of suction pile. The main conclusions are obtained as follows:
- In the process of cyclic loading, the strain development not only has strain softening phenomenon, but also has strain hardening phenomenon according to the different static deflection stress. Therefore, a strain softening index and strain hardening index were proposed to describe cyclic characteristics of soil.
- An improved cyclic creep model was established by considering the strain hardening index to describe the cyclic cumulative deformation and strain hardening characteristics of soil. Simultaneously, the results from the proposed method agree reasonably well with the measured results. Therefore, the equivalent cyclic creep model can be used to analyze the strain accumulation and strain hardening process of soft clay.
- The improved cyclic creep model was applied to analyze the cyclic bearing characteristics of suction pile. The results show that the finite element results are consistent with the model test results. It can provide a new method for analyzing the cyclic characteristics of soft clay and the cyclic cumulative deformation characteristics of the suction pile.
Author Response File: Author Response.pdf
Reviewer 4 Report
Dear Authors,
The paper explained the Study on the Cyclic Bearing Capacity of Suction Pile Based on two Equivalent Cyclic Creep Models. The manuscript is organized well; however, the following correction should be made before jumping to the next step:
1) More than 75% of the references cited in the introduction are older than 2017, so highly recommended to use recent relevant findings.
2) The format doesn't match the journal template.
3) The base of cyclic tests arranged to reach the softening index; however, a number of out-of-range results can be seen in figure 8 with no further explanation.
4) The hardening index showed better data fitting; however, by increasing the "q" it is more likely to be out. Please add an explanation.
5) The creep model developed well however the fitted model for the suction pile show less data fitting, please add an explanation.
6) Calibration is not provided for the FEM model.
7) English need to be checked by a native English technical speaker.
Author Response
Responses to Reviewers' Comments
Manuscript Title: Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model
Manuscript Number: sustainability-1962390
Authors: Kang Huang, Wenbo Zhu *, Xin Liu, Zhongyuan Yao, Yu Zhang, Shu Yan, Xiaojiang Guo, Guoliang Dai
Journal: sustainability
Dear Editor,
Thank you for your letter and the reviewers' comments concerning our manuscript, " Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model " (sustainability-1962390). All of the comments have been valuable and extremely helpful in our effort to revise and improve the paper. Based on the comments provided by the two reviewers, we have carefully revised the manuscript. Meanwhile, we also reedit the language via professional language editing service institution. The specific responses are as follows:
Reviewer #4:
The paper explained the Study on the Cyclic Bearing Capacity of Suction Pile Based on two Equivalent Cyclic Creep Models. The manuscript is organized well; however, the following correction should be made before jumping to the next step:
1) More than 75% of the references cited in the introduction are older than 2017, so highly recommended to use recent relevant findings.
Reply: Thank you for the comment. The relevant references are add as follows:
- Huo, H. F.; Lei, H. Y. Cyclic properties of normal consolidated clay under coupled effect of static and dynamic stresses. Chinese Journal of Rock Mechanics and Engineering.2015, 34(6), 1288-1295.
- Liu, X. M. Experimental study on characteristics of K0-consolidated stiff clay under traffic loading conditions. Zhejiang University, 2020.
- Zhuang, H. Experimental study on cyclic behavior of Wenzhou reconstituted soft clay under different stress histories. Wenzhou University, 2021.
2) The format doesn't match the journal template.
Reply: Thank you for the comment. We have revised the manuscript according to the journal template. The revised content can be seen in the revised version.
3) The base of cyclic tests arranged to reach the softening index; however, a number of out-of-range results can be seen in figure 8 with no further explanation.
Reply: Thank you for the comment. Due to many variables in the softening coefficient,
it is difficult to accurately fit each test curve by limited fitting parameters. It can be seen from the figure that the maximum deviation between the fitting result and the test result does not exceed 20%. It can be seen that the fitting is generally good. The relevant contents are revised as follows:
(a) σ3=50kPa
(b) σ3=100kPa
(c) σ3 =150kPa
Figure 8: Strain softening index - time curves
The strain softening index and fitting results under different cyclic deflection stresses and different static deflection stresses are shown in Figure 8. It can be observed that the strain - time curve obtained by the strain softening index is consistent with the test results. So the strain softening index can accurately describe the strain softening phenomenon.
4) The hardening index showed better data fitting; however, by increasing the "q" it is more likely to be out. Please add an explanation.
Reply: Thank you for the comment. Each fitting parameter will determines the trend of all curves. Due to many variables in the softening coefficient, it is difficult to accurately fit each test curve by limited fitting parameters. It is the best fitting result under the current parameters. With the increase of “q”, the fitting result deviates slightly from the test result. There are many reasons for this phenomenon. But It can be seen that the fitting is generally good in Figure 11(c).
5) The creep model developed well however the fitted model for the suction pile show less data fitting, please add an explanation.
Reply: Thank you for the comment. It is unnecessary to compare all of the finite element curves. The comparison results are repeated. At the same time, the manuscript is too long. We added a set of comparison curves in Figure 18. It can ensure the comparison results under different stress levels. The add figure as the following:
（a）Fa=0.4Ff，Fcyc=0.1Ff
（a）Fa=0.5Ff，Fcyc=0.2Ff
（b）Fa=0.6Ff，Fcyc=0.3Ff
Figure 18. Displacement-time curve
6) Calibration is not provided for the FEM model.
Reply: Thank you for the comment. In the following paragraph, we calibrated the improved cyclic creep model in finite element method.
To verify the correctness of the improved creep model in Abaqus subroutine, some the test results were selected to compare with finite element results. It can be seen from Figure 13 to Figure 15 that the results from the proposed method agree reasonably well with the measured results. Therefore, the improved cyclic creep model can be used to analyze the strain accumulation and strain hardening process of soft clay.
(a) qs = 0.4 qf (b) qs = 0.5 qf
Figure 13. Cumulative cyclic-strain curves (σ3=50kPa)
(a) qs = 0.4 qf (b) qs = 0.5 qf
Figure 14. Cumulative cyclic-strain curves (σ3=100kPa)
(a) qs = 0.4 qf (b) qs = 0.5 qf
Figure 15. Cumulative cyclic-strain curves (σ3=150kPa)
7) English need to be checked by a native English technical speaker.
Reply: Thank you for the comment. we have carefully revised the manuscript. Meanwhile, we also reedit the language via professional language editing service institution. It can be seen in the revised version.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Reviewer #3: Report 2
Paper Title: Study on Cyclic Bearing Capacity of Suction Pile Based on Equivalent Cyclic Creep Model
Manuscript Number: sustainability-1962390
General comments:
English was considerably improved. But some points continue to need some improvements; furthermore, the manuscript (first contrast) and cover letter (Responses to Reviewers' Comments) are still inconsistent. Some examples are presented further on.
The following points should be considered:
(4) Pag. 1 – Introduction – line 30: Here and along the manuscript, please use italic for “et al.”. It is correct in the reply of cover letter, but still incorrect in the entire manuscript.
(10) Pag. 5 – Figure 2 –Why this Figure 2 is numbered from (g) to (j)? please replace it for (a) to (d).
The meaning of each symbol used in the Figure 2 should be previously referred and explained. In fact, it is called further on only in page 11, please anticipate that reference to the meaning of each symbol, (for instead: qs, qd, p, etc…. )
Pag. 12 – Figure 8 – Please correct the position of top legend (move it to the right), once it is coincident with (or in front of) the diagram curves.
Author Response
Responses to Reviewers' Comments
Manuscript Title: Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model
Manuscript Number: sustainability-1962390R1
Authors: Kang Huang, Wenbo Zhu *, Xin Liu, Zhongyuan Yao, Yu Zhang, Shu Yan, Xiaojiang Guo, Guoliang Dai
Journal: sustainability
Dear Editor,
Thank you for your letter and the reviewers' comments concerning our manuscript, " Study on cyclic bearing capacity of suction pile based on equivalent cyclic creep model " (sustainability-1962390R1). All of the comments have been valuable and extremely helpful in our effort to revise and improve the paper. Based on the comments provided by reviewers, we have carefully revised the manuscript. The specific responses are as follows:
(1) Pag. 1 – Introduction – line 30: Here and along the manuscript, please use italic for “from (g) to (j).”. It is correct in the reply of cover letter, but still incorrect in the entire manuscript.
Reply: Thank you for the comment. The format of the “et al.” is revised as italic in the manuscript. It can be viewed in the revised manuscript-R2.
( Ye et al., [1]; Kong et al., [2]; Tong et al., [3]; Zhang and Andersen, [4]) ，Yao and Nie [12] and Cai et al. [13]，Idriss et al. [14] , Monismith et al. [16], Yasuhara et al. [21] and so on.
(2) Pag. 5 – Figure 2 –Why this Figure 2 is numbered from (g) to (j)? please replace it for (a) to (d).
Reply: Thank you for the comment. The relevant contents are revised as follows:
（a）qs=0.4qf，qd=0.1qf （b）qs=0.4qf，qd=0.2qf
（c）qs=0.5qf，qd=0.2qf （d）qs=0.5qf，qd=0.3qf
Figure 5. Stress-strain curves（σ3=100kPa）
(3) The meaning of each symbol used in the Figure 2 should be previously referred and explained. In fact, it is called further on only in page 11, please anticipate that reference to the meaning of each symbol, (for instead: qs, qd, p, etc…. )
Reply: Thank you for the comment. The relevant contents are revised as follows:
The specimen soil is taken from the coast of Guanyun. As shown in Figure 1(a), the remolded test soil is consolidated by vacuum preloading method. When the soil consolidation is completed, started the soil cyclic triaxial test by the GDS apparatus (Figure 1(b)). Three confining pressures are selected to conduct cyclic triaxial tests under the different static deflection stress (qs) and the cyclic deviatoric stress (qd). The specific test schemes are shown in Table 1. The stress-strain curves of saturated soft clay are shown in Figure 2. The Mohr-Coulomb ultimate strength (qf) indices of soft clay were calculated to be c = 18.3 kPa and φ = 19.6°.
(a) Soil consolidation (b) GDS apparatus
Figure 1. Cyclic triaxial test
Table 1. Test parameters
|
Type |
Confining pressure σ3(kPa) |
loading rate (kPa/min) |
Frequency (Hz) |
Static deflection stress ratio |
Cyclic deflection stress ratio |
|
|
Consolidation |
50/100/150 |
0.1 |
- |
0/0.4/0.5/0.6/0.8 |
- |
|
|
Cyclic loading |
50/100/150 |
- |
0.1 |
0.4/0.5/0.6 |
0.1/0.2/0.3 |
|
|
0.1 |
0 |
0.3/0.4/0.5/0.6 |
||||
Figure 2. Strength characteristics of soft clay
(4) Pag. 12 – Figure 8 – Please correct the position of top legend (move it to the right), once it is coincident with (or in front of) the diagram curves.
Reply: Thank you for the comment. The relevant Figure8 to Figure18 are revised as follows:
Figure 8. Strain softening phenomenon
(a) qs = 0.4 qf (b) qs = 0.5 qf
Figure 14. Cumulative cyclic-strain curves (σ3=50kPa)
(a) qs = 0.4 qf (b) qs = 0.5 qf
Figure 15. Cumulative cyclic-strain curves (σ3=100kPa)
(a) Fa=0.4Ff
(b) Fa=0.5Ff
(c) Fa=0.6Ff
Figure 18. Displacement-time curve
Author Response File: Author Response.pdf
