Mechanism of Sleeper–Ballast Dynamic Impact and Residual Settlements Accumulation in Zones with Unsupported Sleepers
Round 1
Reviewer 1 Report
This manuscript presents a fine study on the mechanism of the sleeper-ballast dynamics in void zones under moving train load primarily based on numerical simulation and analytical models. The research objectives are valid and of interest to peers in the same field. The methodologies and models seem valid and the findings are supported by the data and results presented in the manuscript. The manuscript, however, may be improved by addressing some language issues and clarifying some ambiguities, as follows.
Page 1 Line 19, change “devoted studying” to “devoted to studying”
Page 2 Line 46 and in some other lines, I suggest change “different to” to “different from” as the latter is accepted around the world by the former is not.
Line 75, change “are” to “is”.
Line 103, change “the” to “of the”.
Line 112, change “were” to “was”.
Line 216, grammar error in “are be”.
Line 244, change 2 in “mm2” to a superscript.
In the literature review in Section 2, the authors described several previous studies in quite a high level of details. I feel the review may be simplified to retain the contents that are directly relevant to this study. More details may be added in the critique of the previous studies. This comment is optional. The authors may ignore it at their discretion.
Line 291, “appear” should be “appears”.
Line 304, typo in “ant”?
Line 309, In Figure 3, what does x mean? Does it mean the distance of the locomotive from the sensor location or the location of sensor on the track?
Line 316, change “clear” to “clearly”.
Line 321, the meaning of “two times lower” is ambiguous. Does it mean “33% of that in the first zone”?
Line 326, delete “that”
Line 339, is the unit of bending stiffness correct (MN.m2)?
Line 360, grammar error.
Line 363, change “if” to “of”.
Line 380, in Figure 7, Legend is needed for the lines of three colors.
Line 386, grammar error in “detailed depicted”.
Line 389, change “another” to “other”.
Line 426, should “Lxvx” be “LxVx”? Please explain what “L” represent and what “V” represents.
Line 428, change “lover” to “lower”.
Line 589, please define “settlement intensity”.
Line 633, in which sense the AASHO Road test results are compared with the settlement intensity results of the ballast layer of this study? Because the AASHO Road test was conducted for road pavement structures, not rail track pavement, I am confused here and would like to know more details.
Line 706-707, this sentence is incomplete. Please revise.
Line 713, change “indicates” to “indicate”.
Line 716-717, “two times lower than”. See comment above.
Line 717, typo in “of is the”?
Line 757, change “in” to “at”.
Line 758, should “depend linear of” be “depends linearly on”?
Line 760, change “cause” to “causes”.
The conclusions in Section 9 are too simplistic. I suggest the authors rewrite the conclusions with more details. For example, the last bullet says the impact loading in the void zone causes up to 8 times higher settlement intensity. Does this conclusion apply to all scenarios with various sleeper-ballast structures, void geometries and train loads? If not, the specific scenario in which this statement can be made should be described.
Author Response
We would like to thank the reviewer for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of this manuscript. The corrections are marked in the text.
The paper title is suggested to be modified to ”Mechanism of sleeper-ballast dynamic impact and residual settlements accumulation in zones with unsupported sleepers”
Answers to the questions:
Line 309, In Figure 3, what does x mean? Does it mean the distance of the locomotive from the sensor location or the location of sensor on the track?
- The explanation is appended to the text: distance of the locomotive from the sensor location
Line 321, the meaning of “two times lower” is ambiguous. Does it mean “33% of that in the first zone”?
- The explanation is appended to the text: 50%
Line 339, is the unit of bending stiffness correct (MN.m2)?
- Correct
Line 380, in Figure 7, Legend is needed for the lines of three colors.
- The figure is corrected
Line 633, in which sense the AASHO Road test results are compared with the settlement intensity results of the ballast layer of this study? Because the AASHO Road test was conducted for road pavement structures, not rail track pavement, I am confused here and would like to know more details.
- Both the AASHO Road test and the ORE C161 present the 2-4 degree relation to the loading but in the German literature is conventionally mentioned the first one (the citation is replaced)
Reviewer 2 Report
- Attention should be paid to the large scope of the article, many aspects to be considered, but it is important to single out the essentials and present them as concretely and comprehensibly as possible.
- In the introduction of the article, the authors should highlight the relevance and problems of the topic, emphasize why this topic is important and relevant. Also, it is not appropriate to present pictures (which increase the volume) in the introduction.
- Authors are writing that the literature review present a wide range of studies on numerical simulation of track and vehicle dynamic interaction considering unsupported sleepers. The numerical simulation is produced with help of different complexity models from simple beam models to detailed 3D FEM ones. However, most models serve as a simple imitation of experimental measurements without deep analysis of the interaction mechanics. But you didn't highlighted why is necessary to do deep analysis of numerical simulation of track and vehicle dynamic interaction considering unsupported sleepers.
- On the basis of which data do you state that the DEM modeling of dormitory settlements according to the main ballast loading models in the void area shows almost no increase in the intensity of pre-stressed ballast deposition, despite a 30% increase in maximum loads.
- The conclusions should not be general, but should reflect the authors' contribution reasonably.
Author Response
We appreciate very much the reviewer's efforts in taking the time to assess our manuscript and the valuable suggestions. Our response follows.
1. Attention should be paid to the large scope of the article, many aspects to be considered, but it is important to single out the essentials and present them as concretely and comprehensibly as possible.
- The Authors tried to present the complete solution of the problem. It means not only study some relations but also to answer the question about its reasons. Therefore, the paper has grown to the present volume. Nevertheless, we think the complete results are better to present in one paper.
The topic is suggested to be modified to ” Mechanism of sleeper-ballast dynamic impact and residual settlements accumulation in zones with unsupported sleepers”
2. In the introduction of the article, the authors should highlight the relevance and problems of the topic, emphasize why this topic is important and relevant. Also, it is not appropriate to present pictures (which increase the volume) in the introduction.
- The both two figures in the paper are intended to present the complexity of the problem and at the same time to wake the interest by a very simple explanation why the ballast-sleeper impact appear. The Figures belong rather to the problem statement than to the problem solution. We think the explanation using the Figures is more worth than the same area of text. If the text shortening is indispensable, we would shorten it in the literature review.
3. Authors are writing that the literature review present a wide range of studies on numerical simulation of track and vehicle dynamic interaction considering unsupported sleepers. The numerical simulation is produced with help of different complexity models from simple beam models to detailed 3D FEM ones. However, most models serve as a simple imitation of experimental measurements without deep analysis of the interaction mechanics. But you didn't highlighted why is necessary to do deep analysis of numerical simulation of track and vehicle dynamic interaction considering unsupported sleepers.
- The explanation is highlighted in the text.
4. On the basis of which data do you state that the DEM modeling of dormitory settlements according to the main ballast loading models in the void area shows almost no increase in the intensity of pre-stressed ballast deposition, despite a 30% increase in maximum loads.
- The Fig.18 and 19 present the data.
5. The conclusions should not be general, but should reflect the authors' contribution reasonably.
- The conclusions are improved in the text.
