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Peer-Review Record

Evaluation of the Damping Layer between the Tunnel Lining and Surrounding Rock via a Shaking Table Test

Sustainability 2023, 15(17), 13244; https://doi.org/10.3390/su151713244

by Haoyu Wen¹, Zhiyong Zhou¹, Xianming Li¹, Danqing Song^2,3,*, Zhiqian He⁴ and Chunlei Xin^4,5

Reviewer 1:

Muhammad Zaka Emad

Reviewer 2: Anonymous

Reviewer 3: Anonymous

Sustainability 2023, 15(17), 13244; https://doi.org/10.3390/su151713244

Submission received: 6 July 2023 / Revised: 25 August 2023 / Accepted: 28 August 2023 / Published: 4 September 2023

(This article belongs to the Section Green Building)

Round 1

Reviewer 1 Report

Begin the abstract with a clear introduction that provides context and purpose for the study. Explain why studying the seismic response mechanism of tunnel lining structures and the influence of surrounding rock is important. Provide more specific information about the shaking table model tests. Include details such as the scale of the models, the input seismic excitation used, and the range of variables tested. Explain in more detail how the evaluation method of damping layer efficiency was verified and what specific criteria were used to measure the accuracy of the method. Instead of simply stating that "the effect of the damping layer protection measures is accurate," provide specific quantitative results or performance metrics to support this claim. For example, provide data on the reduction in maximum relative displacement or the decrease in structural response under seismic excitation. Provide more specific information about how the type of surrounding rock and the thickness of the damping layer affect the seismic response of the lining structure. Include quantitative results or trends to illustrate the magnitude of the effects. Explain the concept of the damping coefficient and how it is introduced to optimize the efficiency evaluation method of the damping layer. Provide specific details on how the damping coefficient affects the evaluation and what benefits it brings. Discuss the practical implications of the study's findings. Explain how the results can be used to improve the design and construction of tunnel lining structures to enhance their seismic performance. Consider addressing any potential limitations or further research needed. Ensure the paragraph is well-structured and flows logically. Break it down into smaller sentences or paragraphs to improve readability and make the information easier to follow.

Comments for author File: Comments.pdf

Proof read to check spelling, grammar and punctuation

Author Response

Response to Reviewer 1

Thank you for your valuable advice, I have carefully modified according to your suggestions. The following is my revised reply.

Point 1: Begin the abstract with a clear introduction that provides context and purpose for the Study. Explain why studying the seismic response mechanism of tunnel lining structures and the influence of surrounding rock is important

Response 1: Implemented. Thank you so much for this important suggestion. According to your comments, I have checked and revised the abstract, and the following is the revised abstract.

Abstract: Abstract: This paper primarily investigates the protective effect of the damping layer in tunnel lining structures under dynamic loads. To investigate the seismic response mechanism of tunnel linings and the influence of surrounding rocks under seismic actions, a series of shaking table tests were conducted using the Wenchuan earthquake (magnitude 8.0) as a reference. The results show that the effect of the damping layer protection measures is accurately with the efficiency evaluation method of damping layer under seismic excitation. The lower excitation acceleration, the better the effect. In addition, the damping coefficient is introduced to optimize the efficiency evaluation method of the damping layer. Among the factors influencing the seismic response of lining structures, the type of surrounding rock has a significant impact, while the thickness of the damping layer has a relatively lesser influence. In seismic intensity areas of equal magnitude, an increase in the damping layer’s thickness leads to a more noticeable effect. In the different seismic intensity area, the difference of the protection effect with the change of thickness is no longer obvious with the increase of seismic intensity. Moreover, the presence of a damping layer alters the intrinsic vibration characteristics of the tunnel lining structure, creating a space for deformation between the lining and the surrounding rock.

Point 2: Provide more specific information about the shaking table model tests. Include details such as the scale of the models, the input seismic excitation used, and the range of variables tested.

Response 2: Implemented. Thank you so much for this important suggestion. I have modified and added information about the shaking table test in the article. The similar proportions used in the shaking table test are shown in Table 2. Using Wenchuan seismic wave as input wave, the peak acceleration range is 0.05-0.40. The following is my modification.

Line 119-133: Since the model and prototype are both in the same gravity field, the similarity ratio of acceleration Ca=1. In addition, the similarity ratio of strain Cε=1, and can easily restore the seismic response and failure mode of the prototype. The remaining three similarity indicators including the similarity ratio of elastic modulus (represented by C_E) and density (represented by C_ρ), require orthogonal matching experiments to find suitable similar materials, while the similarity ratio of geometry (represented by C_L) determines the reliability and accuracy of the test results. To consider the limiting performance parameters of the shaking table test system and to maximize the performance of the shaking table, the size of the model box was determined by design and calculation to be 2.5 m (length)×2.5 m (width)×2 m (height) (as shown in Figure 2a). In order to reduce the influence of the scaled model boundary on the experimental results of the shaking table, a foam board with a thickness of 10 cm is set at the junction of the surrounding rock and the model box, and a mortar layer is poured at the bottom (Figure 2b). This method can ensure that the seismic wave propagation is not affected and the similarity relationships for the other control indices are shown in Table 2.

Table 2. Similarity relationship of shaking table model tests

Physical quantities	Dimension	Similarity relationship	Similarity ratio
Dimension	L	CL	1/30
Elastic modulus	FL-2	CE	1/45
Density	FTL-4	Cρ	1/1.5
Poisson’s ratio μ	-	Cμ	1
Stress σ	FL-2	Cσ	1/45
Strain ε	-	Cε	1
Acceleration a	LT-2	Ca	1
Time t	T	Ct	1/5.5

Line232-246: 1.3.5 Test loading scheme

In the Wenchuan earthquake, significant damage occurred to numerous highway tunnels. Therefore, for the dynamic loading experiments, the east-west component of the seismic waves recorded at the Maoxian Seismic Station in the Wenchuan region were used as the input motion at the shake table. The shaking was applied in the horizontal direction perpendicular to the tunnel axis. Considering that the regions with small original seismic response are not valuable to study, the waveform data of 20-165 seconds in the original seismic wave is selected as the test data. and the peak acceleration and duration are compressed according to the time similarity ratio (1:5.5), the compression duration is 30 seconds. Six loading conditions were designed by controlling the peak acceleration of the input seismic waves. They were gradually increased in magnitude from 0.05g, 0.1g, 0.15g, 0.2g, 0.3g, to 0.4g, in ascending order of peak acceleration. The values correspond to the design basic seismic acceleration values for seismic fortification intensity levels 6 to 9, as specified in the “Seismic Design Code for Underground Structure” (GB/T 51336-2018) [24] (see Table 6). It simulates the dynamic response process and final damage state of tunnel lining structures under different peak acceleration conditions with the effect of damping layers. The acceleration time history of the seismic wave is shown in Figure. 7a, and the peak ground acceleration (PGA) of the seismic wave is about 0.4 g, equivalent to a seismic intensity of IX. Most of the energy is released in the first 15 seconds of the wave-form, and the frequency is mainly concentrated in the 0-15 Hz range (as shown in Figure. 7b).

Table 6. The relationship between seismic fortification intensities and the values of designed seismic accelerations

Loading schemes	1	2	3	4	5		6
Design seismic accelerations (g)	0.05	0.10	0.15	0.20		0.30	0.40
Seismic fortification intensity	6	7		8			9

(a) (b)

Figure 7. Strain gauge arrangement and input seismic wave. (a) Acceleration time history curve of input seismic wave; (b) Fourier spectrum of input seismic wave.

Point 3: Explain in more detail how the evaluation method of damping layer efficiency was verified and what specific criteria were used to measure the accuracy of the method. Instead of simply stating that "the effect of the damping layer protection measures is accurate," provide specific quantitative results or performance metrics to support this claim. For example, provide data on the reduction in maximum relative displacement or the decrease in structural response under seismic excitation.

Response 3: Implemented. Thank you so much for this important suggestion. The accuracy of the evaluation method for the effectiveness of the damping layer is obtained according to the comparison between the evaluation results and the experimental results. I have modified the content of the article according to your suggestion and added content ‘3.3 Validation of efficiency evaluation method of damping layer’. The changes are as follows:

Line340-371: According to the comparison between the evaluation results and the experimental results of the damping layer efficiency. As the acceleration increases, the ∆Rb (evaluation value-experimental value) value gradually increases. It can be seen that with the increase of acceleration, the effectiveness evaluation method of damping layer gradually loses its accuracy. At the same time, according to the standard deviation obtained. The evaluation value is more accurate under the action of thicker damping layer. Thicker damping layer can provide better protection for the lining structure and avoid serious damage. Compared with the test results in class IV surrounding rock, the worse conditions of surrounding rock are more likely to cause damage to the lining structure, and the test values are more deviated. Therefore, according to the data analysis of this series of model tests, the level of surrounding rock is more decisive to the seismic response of the lining structure than the thickness of the damping layer.

By analyzing the deviation between the experimental and evaluation values of the damping layer in Class IV and Class V surrounding rock from Figure 9-10, It can be observed that when the surrounding rock conditions and peak acceleration of seismic input are changed, the evaluation results will exhibit errors due to deteriorating rock conditions and increasing acceleration peak values. Based on the experimental results and evaluation results, the dynamic damage coefficient K, obtained through data fitting, ensures the reliability of the evaluation results for the effectiveness of the damping layer. Therefore, in actual engineering, the parameters of the damping layer can be chosen reasonably based on the physical and mechanical parameters of the surrounding rock in the tunnel site and the local seismic fortification intensity.

Point 4: Provide more specific information about how the type of surrounding rock and the thickness of the damping layer affect the seismic response of the lining structure. Include quantitative results or trends to illustrate the magnitude of the effects.

Response 4: Implemented. Thank you so much for this important suggestion. Following your suggestion, a table has been added in the section of the article discussing acceleration response analysis to provide more specific information on how rock type and damping layer thickness affect the seismic response of the lining structure.

Table. 7 Peak acceleration of surrounding rock under different working conditions

Schemes	Surrounding rock	Damping layer	Peak acceleration(g)
Case 1	Class IV	Without damping layer	0.254
Case 2	Class IV	1 cm thickness damping layer	0.124
Case 3	Class IV	2 cm thickness damping layer	0.115
Case 4	Class V	Without damping layer	0.366
Case 5	Class V	1 cm thickness damping layer	0.217
Case 6	Class V	2 cm thickness damping layer	0.144

Table. 8 Peak acceleration of tunnel lining under different working conditions

Schemes	Surrounding rock	Damping layer	Peak acceleration(g)
Case 1	Class IV	Without damping layer	0.192
Case 2	Class IV	1 cm thickness damping layer	0.114
Case 3	Class IV	2 cm thickness damping layer	0.173
Case 4	Class V	Without damping layer	0.287
Case 5	Class V	1 cm thickness damping layer	0.205
Case 6	Class V	2 cm thickness damping layer	0.142

Point 5: Provide specific details on how the damping coefficient affects the evaluation and what benefits it brings.

Response 5: Implemented. Thank you so much for this important suggestion. Based on the comparison between experimental results and evaluation results, it is evident that the seismic isolation layer’s effectiveness evaluation method may have a certain degree of error under high seismic intensity and poor surrounding rock conditions. The seismic dynamic damage coefficient K is obtained through data fitting between experimental values and evaluation values. It ensures that the results of the seismic isolation layer’s effectiveness evaluation maintain a certain level of reliability even under high seismic intensity or poor surrounding rock conditions. In accordance with your suggestion, I have made the following modifications to the original text.

(a)

(b)

Figure 9. Seismic responses of damping layers with different thicknesses in Class IV surround-ing rock (The red line represents the evaluation value). (a) 1cm; (b) 2cm.

(a)

(b)

Figure 10. Seismic responses of damping layers with different thicknesses in Class V surrounding rock (The red line represents the evaluation value). (a) 1 cm；(b) 2 cm.

Point 6: Discuss the practical implications of the study's findings. Explain how the results can be used to improve the design and construction of tunnel lining structures to enhance their seismic performance. Consider addressing any potential limitations or further research needed.

Response 6: Implemented. Thank you so much for this important suggestion. I have added and modified the relevant content according to your request. The following is my modification.

Line515-525: The research results can provide reference and guidance for seismic resistance in tunnel engineering. In the construction of tunnels in high-frequency seismic areas, special attention should be given to sections with poor surrounding rock conditions. In these cases, the seismic response is more pronounced compared to sections with stable rock conditions, and the tunnels are subjected to more severe damage under seismic excitation. Further-more, further research and optimization of seismic isolation methods have been provided. For tunnel sections that utilize damping layers, it is important to select a reasonable thickness for the damping layer to achieve the dual purpose of protecting the tunnel while considering economic feasibility. Additionally, further studies are needed to verify the re-liability of the evaluation methods for the effectiveness of the isolation layer under different seismic wave excitations.

Point 7: Ensure the paragraph is well-structured and flows logically. Break it down into smaller sentences or paragraphs to improve readability and make the information easier to follow.

Response 7: Implemented. Thank you so much for this important suggestion. Based on your suggestions, revisions have been made to the English expressions in the text. Here are the changes made:

Line17-40: Abstract: This study focuses on investigating the efficacy of damping layers and protective measures for tunnel lining structures under dynamic loads. A series of shaking table tests were conducted to examine the seismic response mechanism of tunnel linings and the impact of sur-rounding rock during earthquakes. The accuracy of the damping layer efficiency evaluation method was also verified. The results show that the effect of the damping layer protection measures is accurately with the efficiency evaluation method of damping layer under seismic excitation. The lower excitation acceleration, the better the effect. In addition, the damping coefficient is introduced to optimize the efficiency evaluation method of the damping layer. Among the factors influencing the seismic response of lining structures, the type of surrounding rock has a significant impact, while the thickness of the damping layer has a relatively lesser influence. In seismic intensity areas of equal magnitude, an increase in the damping layer’s thickness leads to a more noticeable effect. In the different seismic intensity area, the difference of the protection effect with the change of thickness is no longer obvious with the increase of seismic intensity. Moreover, the presence of a damping layer alters the intrinsic vibration characteristics of the tunnel lining structure, creating a space for deformation between the lining and the surrounding rock.

Line44-71: Compared with other infrastructure, tunnel generally has good aseismic performance, but the tunnel structure will still suffer damage or even destruction under strong earthquake [1]. Generally, the parts that are vulnerable to earthquake damage are located in the fault fracture zone, the interface between soft and hard rock, adverse geological zones, and locations where there is an abrupt change in the tunnel cross-section shape. There are a large number of tunnel lining structure appeared large scale damage under strong earthquakes, such as the Kobe earthquake in 1995 (magnitude 7.2), the Jiji earthquake in 1999 (magnitude 7.6) and the Wenchuan earthquake in 2008 (magnitude 8.0), etc. In particular, the recent Wenchuan earthquake caused at least 56 highway tunnels in disaster areas occurred varying degrees of earthquake damage [2], and the lining structure of highway tunnel which accounted for 24.72 percent of the length was seriously damaged by the earthquake [3]. At the same time, it has been largely confirmed that the movement of tectonic plates has entered the fifth active period [4]. Notably, China has experienced several major earthquakes in the past decade that posed significant threats to tunnel structures, including the Yushu earthquake in 2010 (magnitude 7.1), the Lushan earthquake in 2013 (magnitude 7.0), the Jiuzhaigou earthquake in 2017 (magnitude 7.0), and the Yibin earthquake in 2019 (magnitude 6.1) [5-8]. At present, the aseismic performance of tunnel has not been paid enough attention in all aspects of tunnel structure [9]. However, if a tunnel structure is severely damaged by a strong earthquake, it may disrupt transportation and become a focus of public [10].

Line78-93: By incorporating a damping layer, the impact of earthquakes can be significantly reduced, leading to decreased destruction and minimized economic losses [12-14]. The original rock-lining structure can be modified to include a rock-damping layer-lining structure, a rock-lining-damping layer structure, or even a rock-damping layer-rock-lining structure [15-16]. By setting a damping layer, the energy from the surrounding rock into the lining is absorbed [16]. Moreover, the presence of the damping layer reduces the overall strength of the lining perimeter system, significantly decreasing the seismic forces acting on the tunnel lining [17]. Specifically, the damping layer can increase the displacement margin of the lining and absorb the relative displacement between the surrounding rock and the lining under dynamic loads [18]. However, if the damping layer is improperly designed or implemented, it can exacerbate the dynamic response of the lining, resulting in more severe damage.

Line98-119: Furthermore, modifying the dimensions of the damping layer allows for adjustments in its seismic performance. By using an appropriately sized damping layer, more effective protection can be achieved [4]. Therefore, additional research is required to develop evaluation methods and indicators that accurately assess the effectiveness of damping layers.

This article conducted large-scale shaking table seismic simulation tests using the Wenchuan earthquake wave as the loading seismic wave. Through similar material design and calculations, a reduced-scale model of tunnel-rock structure was created to simulate a real tunnel project. The seismic action mechanism of the isolation layer was analyzed. The experimental results were compared with the assessment results of the effectiveness of the isolation layer assessment method. It aims to optimize the damping layer from both geometric and material perspectives and enhance its effectiveness. The research results can be applied to the design and construction of transportation tunnels in high-intensity seismic areas. They can also serve as a reliable theoretical reference and technical support for further research on efficiency evaluation models of damping layers and protective measures for tunnel lining structures under other dynamic loads

Line202-212: According to the similarity calculation, the lining thickness of the generalized tunnel lining structure is 2 cm. Orthogonal experiment was designed and uniaxial compressive test was carried out to design similar materials of lining structure. The model for the lining structure was determined as barite: quartz sand: diatomite: gypsum: water = 0.4:0.2:0.6:0.6:1. The corresponding parameters are provided in Table 4.

In the model experiment, the surface of the lining model is coated with a layer of varnish to simulate the waterproof layer on the surface of the lining structure. The lining model is reinforced with square grid steel mesh with 0.8mm diameter reinforcement and 10mm spacing. As shown in Figure 5. The lining model is shown in Figure 3b.

Line246-249: In order to reduce the influence of the lining ends on the damping layer, the strain monitoring cross-sections of the lining structure should be set at the middle position, which is 20 cm away from both ends of the lining structure

Line309-311: They have discovered that under seismic forces, the cross-sectional area of the tunnel structure undergoes alternating cyclic tensile and compressive deformations along two diagonals oriented at a conjugate angle of 45 degrees.

Line385-416: According to the comparison between the evaluation results and the experimental results of the damping layer efficiency. As the acceleration increases, the (evaluation value- experimental value) value gradually increases. It can be seen that with the increase of acceleration, the effectiveness evaluation method of damping layer gradually loses its accuracy. At the same time, according to the standard deviation obtained. The evaluation value is more accurate under the action of thicker damping layer. Thicker damping layer can provide better protection for the lining structure and avoid serious damage. Compared with the test results in class IV surrounding rock, the worse conditions of surrounding rock are more likely to cause damage to the lining structure, and the test values are more deviated. Therefore, according to the data analysis of this series of model tests, the level of surrounding rock is more decisive to the seismic response of the lining structure than the thickness of the damping layer. By analyzing the deviation between the experimental and evaluation values of the damping layer in Class IV and Class V surrounding rock from Figure 9-10, It can be observed that when the surrounding rock conditions and peak acceleration of seismic input are changed, the evaluation results will exhibit errors due to deteriorating rock conditions and increasing acceleration peak values. Based on the experimental results and evaluation results, the dynamic damage coefficient K, obtained through data fitting, ensures the reliability of the evaluation results for the effectiveness of the damping layer. Therefore, in actual engineering, the parameters of the damping layer can be chosen reasonably based on the physical and mechanical parameters of the surrounding rock in the tunnel site and the local seismic fortification intensity.

Line451-467: The presence of a damping layer significantly reduces the seismic strain response of the lining structure, particularly at the arch shoulder. This suggests that the protective effect of the damping layer on the lining structure is more pronounced in conditions where the surrounding rock quality is poor. It is noteworthy that the existence of the damping layer can cause certain rigid deformations in parts originally firmly constrained by the surrounding rock, such as the arch crown, arch foot, and inverted arch. Therefore, to achieve the optimal design and application of the damping layer, it is advisable to enhance the form of the damping layer, which covers the entire cross section of the lining structure, by optimizing the efficiency evaluation equation. This approach aims to maximize the effectiveness of the damping layer while minimizing engineering costs.

Line476-484: However, the amplitude of the acceleration response of the surrounding rock significantly reduces when a damping layer is installed. However, the amplitude of the acceleration response of the surrounding rock significantly reduces by a damping layer is installed. The maximum acceleration of class IV surrounding rock decreased from 0.25 g to 0.11 g due to the presence of the damping layer. Similarly, the maximum acceleration of class V surrounding rock decreased from 0.38 g to 0.14 g. These results clearly demonstrate the significant reduction in the dynamic response of the surrounding rock achieved by implementing a damping layer. Furthermore, increasing the thickness of the damping layer enhances its protective effect.

Line502-505: Based on the results obtained from the measurements of A2 and A3 accelerometers in Figure 13, it can be observed that the spectral curve’s amplitude is significantly smaller when a damping layer is present compared to when it is absent. Furthermore, the amplitude decreases noticeably with an increase in the thickness of the damping layer.

Point 8: According to the requirements in the attachment, I have made the modifications. The modified content is visible in the uploaded file. In addition, below are the answers to the questions mentioned in the attachment：

（1）. Question: how come six DOF?

Response：The term “vibration table with six degrees of freedom” refers to a testing device or system that can simulate vibrations in all six directions of motion: three translations (x, y, z) and three rotations (roll, pitch, yaw).

Manuscript content: This series of shaking table model tests used the three directional and six degree of freedom earthquake simulation shaking table device which in the Chengdu University of Technology, China, Table 1 shows the related performance of the shaking table.

（2）. Question: can you control this?

Response：The table contains performance data of the vibration table. The vibration frequency can be controlled based on the different seismic waveforms.

Manuscript content:

Table 1. Main technical parameters of the shaking table

Technical indicators	Technical parameters
Table size（m×m）	4.0×6.0
Frequency range （Hz）	0.1-60
Degree of vibration freedom	Three directions and six degrees of freedom
Maximum effective load on the table（t）	40
Maximum displacement of the table（mm）	X: ±300 ; Y: ±250; Z: ±150
Maximum velocity of the table（mm/s）	X: ±1500 ; Y: ±1200; Z: ±1000
Maximum acceleration under full load（g）	X: ±1.5 ; Y: ±1.2 ; Z: ±1.0
Maximum allowable overturning moment（t·m）	120

（3）. Question: this lining is different than the one used on site?

Response：The lining is designed from a calculated similarity ratio, which is derived from Buckingham's theorem. Please refer to the reference (Xin, C.L., Wang, Z.Z., Zhou J.M., et al. Shaking table tests on seismic behavior of polypropylene fiber reinforced concrete tunnel lining. Tunnelling and Underground Spance Technology, 2019, (88): 1-15.).

Manuscript content:

（4）. Question: why fly ash?

Response：These materials were selected to meet the target strength values mentioned in the text. The oil is motor oil.

Manuscript content: The mass ratio of river sand, oil and fly ash in the Class IV surrounding rock is determined to be 40:10:50.

（5）. Question: why cracks appear? this is similar to site rock?

Response：The purpose of this picture is to show the simulated surrounding rock material, the photo was taken after the seismic loading, so there are cracks.

Manuscript content:

（5）. Question: why accelerometers are installed at these particular locations?

Response：The layout of accelerometers is determined according to the research objective. The research content of this paper mainly involves the interaction between surrounding rock and structure, so the accelerometers are arranged at the junction of tunnel and surrounding rock. At the same time, according to the different grades of surrounding rock, the accelerometers in the same position of the two kinds of surrounding rock can control the experimental variables as much as possible.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript presents an experimental study aimed at mitigating seismic loads on tunnel structures through the implementation of a damping system. The topic is both significant and relevant, and the findings contribute to the current understanding of how damping systems function under seismic loads.

However, the manuscript necessitates considerable improvement in its English writing style and grammar. Errors are present from the opening sentence of the abstract and continue throughout the manuscript, which detracts from the potentially valuable findings. A thorough revision is needed to ensure that the key results are clearly communicated.

Beyond language and grammar, the manuscript's structure could be enhanced for better coherence and clarity. I suggest including a dedicated section that outlines the testing methodologies and materials prior to the presentation of the test results. This section should also delve into essential assumptions and address potential limitations. Considerations such as scale effects in both rock and concrete should be elaborated upon. The manuscript should clarify how the case study of the Wenchuan earthquake is utilized for validation, and the methods used to quantify the damage. A thorough discussion on these aspects, supported by proper references, should precede the description of the tests and their outcomes.

Furthermore, I have the following specific comments:

I recommend that the abstract includes a numeric value of the Wenchuan earthquake to provide some context of intensity

Line 71: The manuscript mentions various damping methods. It would be useful to know if these methods are currently used in practical applications. If so, can relevant examples or building codes be provided? The current reference cited is a research paper, which may not reflect the practical use of these methods. A figure illustrating the damping mechanism could also be beneficial for reader comprehension.

Figures 9-10: These figures were not easily decipherable. Perhaps a different method of data presentation could be employed to render the results more intuitively comprehensible.

As mentioned, the manuscript necessitates considerable improvement in its English writing style and grammar.

Author Response

Response to Reviewer 2

Thank you for your valuable advice, I have carefully modified according to your suggestions. The following is my revised reply.

Point 1: Beyond language and grammar, the manuscript's structure could be enhanced for better coherence and clarity. I suggest including a dedicated section that outlines the testing methodologies and materials prior to the presentation of the test results. This section should also delve into essential assumptions and address potential limitations. Considerations such as scale effects in both rock and concrete should be elaborated upon. The manuscript should clarify how the case study of the Wenchuan earthquake is utilized for validation, and the methods used to quantify the damage. A thorough discussion on these aspects, supported by proper references, should precede the description of the tests and their outcomes.

Response 1: Implemented. Thank you so much for this important suggestion. According to your suggestions, relevant content of the paper has been modified. Here is the revised version:

Table 2. Similarity relationship of shaking table model tests

Physical quantities	Dimension	Similarity relationship	Similarity ratio
Dimension	L	C_L	1/30
Elastic modulus	FL^-2	C_E	1/45
Density	FTL^-4	C_ρ	1/1.5
Poisson’s ratio μ	-	C_μ	1
Stress σ	FL^-2	C_σ	1/45
Strain ε	-	C_ε	1
Acceleration a	LT^-2	C_a	1
Time t	T	C_t	1/5.5

Line232-246: 1.3.5 Test loading scheme

Table 6. The relationship between seismic fortification intensities and the values of designed seismic accelerations

Loading schemes	1	2	3	4	5		6
Design seismic accelerations (g)	0.05	0.10	0.15	0.20		0.30	0.40
Seismic fortification intensity	6	7		8			9

(a) (b)

Figure 7. Strain gauge arrangement and input seismic wave. (a) Acceleration time history curve of input seismic wave; (b) Fourier spectrum of input seismic wave.

Table 5. Similarity of material for surrounding rock

Project		Density /kg·m-3	Elasticity modulus/GPa	Cohesion/kPa	Internal friction angle/°
Class IV surrounding rock	Prototype value	2100	10	135	38
	Target value	1400	0.22	3	38
	Estimated value	1300	0.06	1.3	33
	Percentage similarity	92.86%	27.27%	43.33%	86.84%
Class V surrounding rock	Prototype value	1700	1.5	50	27
	Target value	1133	0.03	1.1	27
	Estimated value	1100	0.02	0.6	25
	Percentage similarity	97.09%	66.67%	54.55%	92.60%

Table 8．Peak acceleration of surrounding rock under different working conditions

Schemes	Surrounding rock	Damping layer	Peak seismic acceleration(g)
Case 1	Class IV	Without damping layer	0.254
Case 2	Class IV	1 cm thickness damping layer	0.124
Case 3	Class IV	2 cm thickness damping layer	0.115
Case 4	Class V	Without damping layer	0.366
Case 5	Class V	1 cm thickness damping layer	0.217
Case 6	Class V	2 cm thickness damping layer	0.144

Schemes	Surrounding rock	Damping layer	Peak seismic acceleration(g)
Case 1	Class IV	Without damping layer	0.192
Case 2	Class IV	1 cm thickness damping layer	0.114
Case 3	Class IV	2 cm thickness damping layer	0.173
Case 4	Class V	Without damping layer	0.287
Case 5	Class V	1 cm thickness damping layer	0.205
Case 6	Class V	2 cm thickness damping layer	0.142

Table. 9 Peak acceleration of tunnel lining under different working conditions

Point 2: I recommend that the abstract includes a numeric value of the Wenchuan earthquake to provide some context of intensity

Response 2: Implemented. Thank you so much for this important suggestion.

Line17-39: Abstract: This paper primarily investigates the protective effect of the damping layer in tunnel lining structures under dynamic loads. To investigate the seismic response mechanism of tunnel linings and the influence of surrounding rocks under seismic actions, a series of shaking table tests were conducted using the Wenchuan earthquake (magnitude 8.0) as a reference. The results show that the effect of the damping layer protection measures is accurately with the efficiency evaluation method of damping layer under seismic excitation. The lower excitation acceleration, the better the effect. In addition, the damping coefficient is introduced to optimize the efficiency evaluation method of the damping layer. Among the factors influencing the seismic response of lining structures, the type of surrounding rock has a significant impact, while the thickness of the damping layer has a relatively lesser influence. In seismic intensity areas of equal magnitude, an increase in the damping layer’s thickness leads to a more noticeable effect. In the different seismic intensity area, the difference of the protection effect with the change of thickness is no longer obvious with the increase of seismic intensity. Moreover, the presence of a damping layer alters the intrinsic vibration characteristics of the tunnel lining structure, creating a space for deformation between the lining and the surrounding rock.

Point 3：Line 71: The manuscript mentions various damping methods. It would be useful to know if these methods are currently used in practical applications. If so, can relevant examples or building codes be provided? The current reference cited is a research paper, which may not reflect the practical use of these methods. A figure illus, trating the damping mechanism could also be beneficial for reader comprehension.

Response 3: Implemented. Thank you so much for this important suggestion. The research on seismic measures for tunnels is still in a rapidly developing stage. Regarding the use of seismic isolation measures, they have been applied in some practical engineering projects, such as the Da Liang Tunnel（TIAN Siming, WU Kefei, YU Li, et al. Key technology of anti-seismic for railway tunnels crossing active fault zone. Tunnel Construction, 2022, 42(8): 1351）.

Line93-100: Currently, there are two main types of damping layers used in engineering: the plate type and the grouting type [19]. The plate type damping layer generally utilizes engineering rubber [20], while the grouting type damping layer typically employs foam concrete [21]. Both types of damping layer materials are characterized by their ability to deform easily and resist shear failure. As an excellent anti-vibration measure, damping layer has been applied in some practical projects [22]. Furthermore, modifying the dimensions of the damping layer allows for adjustments in its seismic performance. By using an appropriately sized damping layer, more effective protection can be achieved

Point 4：Figures 9-10: These figures were not easily decipherable. Perhaps a different method of data presentation could be employed to render the results more intuitively comprehensible.

Response 4: Implemented. Thank you so much for this important suggestion. I have modified the figures as your suggestion. The modified figures are as follows:

(a)

(b)

Figure 9. Seismic responses of damping layers with different thicknesses in Class IV surround-ing rock (The red line represents the evaluation value). (a) 1cm; (b) 2cm.

(a)

(b)

Figure 10. Seismic responses of damping layers with different thicknesses in Class V surrounding rock (The red line represents the evaluation value). (a) 1 cm；(b) 2 cm.

Point 5. Comments on the Quality of English Language

As mentioned, the manuscript necessitates considerable improvement in its English writing style and grammar.

Response 5: Implemented. Thank you so much for this important suggestion. Based on your suggestions, revisions have been made to the English expressions in the text. Here are the changes made:

Line17-40: Abstract: This study focuses on investigating the efficacy of damping layers and protective measures for tunnel lining structures under dynamic loads. A series of shaking table tests were conducted to examine the seismic response mechanism of tunnel linings and the impact of sur-rounding rock during earthquakes. The accuracy of the damping layer efficiency evaluation method was also verified. The results show that the effect of the damping layer protection measures is accurately with the efficiency evaluation method of damping layer under seismic excitation. The lower excitation acceleration, the better the effect. In addition, the damping coefficient is introduced to optimize the efficiency evaluation method of the damping layer. Among the factors influencing the seismic response of lining structures, the type of surrounding rock has a significant impact, while the thickness of the damping layer has a relatively lesser influence. In seismic intensity areas of equal magnitude, an increase in the damping layer’s thickness leads to a more noticeable effect. In the different seismic intensity area, the difference of the protection effect with the change of thickness is no longer obvious with the increase of seismic intensity. Moreover, the presence of a damping layer alters the intrinsic vibration characteristics of the tunnel lining structure, creating a space for deformation between the lining and the surrounding rock.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript titled as “Efficiency evaluation and optimization method of damping layer between tunnel lining and surrounding rock via shaking table test” studied about tunnel lining by performing serious of experiments to evaluate performance damping layer. Paper is within the scope of journal but needs comprehensive language editing by native speaker. In addition, paper has serious issues to be considered for the revision before considering for the publication. Some issues stated below for the authors:

1. Title of study does not reflect the content of manuscript. Accordingly, title can be modified as follows: “Evaluation of damping layer between tunnel lining and surrounding rock via shaking table test”.

2. Which parameters are considered to describe surrounding soil as rock? There is no information about the surrounding soil except stating rock. Details about soil classification is (as clas IV or V) is needed.

3. Test loading scheme is not clearly described. Authors should clearly describe their method especially for experimental test! For example, did authors applied different levels of earthquakes with sequence? Or earthquakes are applied building separately? This is important since it affect the evaluation of the experimental results with evaluation method.

4. There are missing details or gaps what authors done and what they stated in the manuscript especially in describing the methods and experiment. Authors should abstract their study without leaving any gap and questions. Accordingly, manuscript should be thoroughly read and revised.

5. Selection of appropriate ground motion has utmost important on the structural response and hence the structural behavior. The rationale behind the selection of input seismic wave is not clear and there may be alternative input motions determined from the real earthquakes! Study is limited to a single ground motion and this issue is one of uncertain issue in the study and ground motion characteristics also important on the structural response. Needs clarification!

6. Author states that experimental values deviate from Eq.2. However, according to Figs 9 and 10 method is very close to experimental values. Low standard deviation values also confirm this issue. Needs clarification!

7. Table 7 is not clear, and it is not clear what authors seek to do with Table 7. Equations in the table should be also explained. More information is need and manuscript about this issue is superficial!

8. Study lacks in discussion about the displacement of lining structure with damping layer. Authors provided very slight information about this issue but not discussed in the paper!

9. Alternatives issues and limitations of the study should be also provided!

10. Additional comments, questions and suggestions are provided in the attached file for authors.

Comments for author File: Comments.pdf

Extensive editing of English language required and comprehensive language editing by native speaker is recommended.

Author Response

Response to Reviewer 3

Thank you for your valuable advice, I have carefully modified according to your suggestions. The following is my revised reply.

Point 1: Title of study does not reflect the content of manuscript. Accordingly, title can be modified as follows: “Evaluation of damping layer between tunnel lining and surrounding rock via shaking table test”.

Response 1: Implemented. Thank you so much for this important suggestion. According to your suggestion, I have modified the title of the paper to “Evaluation of damping layer between tunnel lining and surrounding rock via shaking table test”

Point 2: Which parameters are considered to describe surrounding soil as rock? There is no information about the surrounding soil except stating rock. Details about soil classification is (as class IV or V) is needed.

Response 1: Implemented. Thank you so much for this important suggestion. In underground rock engineering, the rock mass surrounding the excavation, which undergoes stress state changes due to excavation, is referred to as the surrounding rock. The criteria for classifying the grades of surrounding rock are as follows (Refer to "Code for Design of Highway Tunnels (JTG D70-2004)"):

The test prototype materials in the paper are shown in table 1. According to the “JTG D70-2004”, the prototype of this test can be classified into class Ⅳ surrounding rock and class Ⅴ surrounding rock

Table 1. Physical and mechanical index of surrounding rock

surrounding rock classification		unit weightγ (KN/m3)	· Elastic reaction coefficient K(MPa/m)	modulus of deformation E(GPa)	Poisson's ratioμ	internal friction angle	· cohesion c(MPa)
Level	· sublevel	unit weightγ (KN/m3)	· Elastic reaction coefficient K(MPa/m)	modulus of deformation E(GPa)	Poisson's ratioμ	internal friction angle	· cohesion c(MPa)
Ⅲ	Ⅲ1	24~25	850~1200	10.7~20	0.25~0.26	44~50	1.1~1.5
Ⅲ	Ⅲ2	23~24	500~850	6~10.7	0.26~0.3	39~44	0.7~1.1
Ⅳ	Ⅳ1	22~23	400~500	3.8~6	0.3~0.31	35~39	0.5~0.7
Ⅳ	Ⅳ2	20~22	200~400	1.3~3.8	0.31~0.35	27~35	0.2~0.5
Ⅴ	Ⅴ1	18~20	150~200	1.3~2	0.35~0.39	22~27	0.12~0.2
Ⅴ	Ⅴ2	17~18	100~150	1~1.3	0.39~0.45	20~22	0.05~0.12

Table 5. Similarity of material for surrounding rock

Project		Density /kg·m-3	Elasticity modulus/GPa	Cohesion/kPa	Internal friction angle/°
Class IV surrounding rock	Prototype value	2100	10	135	38
	Target value	1400	0.22	3	38
	Estimated value	1300	0.06	1.3	33
	Percentage similarity	92.86%	27.27%	43.33%	86.84%
Class V surrounding rock	Prototype value	1700	1.5	50	27
	Target value	1133	0.03	1.1	27
	Estimated value	1100	0.02	0.6	25
	Percentage similarity	97.09%	66.67%	54.55%	92.60%

Point 3: Test loading scheme is not clearly described. Authors should clearly describe their method especially for experimental test! For example, did authors applied different levels of earthquakes with sequence? Or earthquakes are *? This is important since it affect the evaluation of the experimental results with evaluation method.

Response 3: Implemented. Thank you so much for this important suggestion. According to your advice, the section 1.3.5 and Table 6 have been revised. The revised content now describes the experimental plan for gradually loading six loading conditions from low to high peak accelerations. The modified content is as follows:

Line233-251: 1.3.5 Test loading scheme

Table 6. The relationship between seismic fortification intensities and the values of designed seismic accelerations

Loading schemes	1	2	3	4	5		6
Design seismic accelerations (g)	0.05	0.10	0.15	0.20		0.30	0.40
Seismic fortification intensity	6	7		8			9

Point 4: There are missing details or gaps what authors done and what they stated in the manuscript especially in describing the methods and experiment. Authors should abstract their study without leaving any gap and questions. Accordingly, manuscript should be thoroughly read and revised.

Response 3: Implemented. Thank you so much for this important suggestion. According to your suggestion, I have made revisions and additions to provide more detailed information about this study, making the research methods and details easier to understand. The following is the revised content:

Line82-95: This article conducted large-scale shaking table seismic simulation tests using the Wenchuan earthquake wave as the loading seismic wave. Through similar material de-sign and calculations, a reduced-scale model of tunnel-rock structure was created to simulate a real tunnel project. The seismic action mechanism of the isolation layer was analyzed. The experimental results were compared with the assessment results of the effectiveness of the isolation layer assessment method. It aims to optimize the damping layer from both geometric and material perspectives and enhance its effectiveness. The research results can be applied to the design and construction of transportation tunnels in high-intensity seismic areas. They can also serve as a reliable theoretical reference and technical support for further research on efficiency evaluation models of damping layers and protective measures for tunnel lining structures under other dynamic loads

Table 4. Similarity of material for lining structure

Project	Density/kg·m-3	Elasticity modulus (GPa)	Intensity (MPa)
Prototype value	2400	30	20.1
Target value	1600	0.67	0.45
Estimated value	1700	1.0	0.53
Percentage similarity	93.75%	50.75%	82.22%

Table 5. Similarity of material for surrounding rock

Project		Density /kg·m-3	Elasticity modulus/GPa	Cohesion/kPa	Internal friction angle/°
Class IV surrounding rock	Prototype value	2100	10	135	38
	Target value	1400	0.22	3	38
	Estimated value	1300	0.06	1.3	33
	Percentage similarity	92.86%	27.27%	43.33%	86.84%
Class V surrounding rock	Prototype value	1700	1.5	50	27
	Target value	1133	0.03	1.1	27
	Estimated value	1100	0.02	0.6	25
	Percentage similarity	97.09%	66.67%	54.55%	92.60%

Line233-251: 1.3.5 Test loading scheme

Table 6. The relationship between seismic fortification intensities and the values of designed seismic accelerations

Loading schemes	1	2	3	4	5		6
Design seismic accelerations (g)	0.05	0.10	0.15	0.20		0.30	0.40
Seismic fortification intensity	6	7		8			9

Line327-353: According to the comparison between the evaluation results and the experimental results of the damping layer efficiency. As the acceleration increases, the ∆Rb (evaluation value-experimental value) value gradually increases. It can be seen that with the increase of acceleration, the effectiveness evaluation method of damping layer gradually loses its accuracy. At the same time, according to the standard deviation obtained. The evaluation value is more accurate under the action of thicker damping layer. Thicker damping layer can provide better protection for the lining structure and avoid serious damage. Compared with the test results in class IV surrounding rock, the worse conditions of surrounding rock are more likely to cause damage to the lining structure, and the test values are more deviated. Therefore, according to the data analysis of this series of model tests, the level of surrounding rock is more decisive to the seismic response of the lining structure than the thickness of the damping layer.

Point 5. Selection of appropriate ground motion has utmost important on the structural response and hence the structural behavior. The rationale behind the selection of input seismic wave is not clear and there may be alternative input motions determined from the real earthquakes! Study is limited to a single ground motion and this issue is one of uncertain issue in the study and ground motion characteristics also important on the structural response. Needs clarification!

Response 5: Implemented. Thank you so much for this important suggestion. The selection of seismic waves is an important issue in shake table testing. Currently, there are two types of seismic wave selections: actual recorded seismic waves and artificially synthesized seismic waves. The focus of this study is on the seismic performance and optimization of tunnel damping layers. In the Wenchuan earthquake, highway tunnels suffered extensive damage due to seismic effects. Therefore, Wenchuan earthquake waves were selected as the original seismic for the experiments and compressed on the shake table according to a similarity scale to obtain the table input waveform. Furthermore, there is a need for further research on seismic wave selection in shake table testing to develop more appropriate experimental protocols. In accordance with your suggestion, I have reviewed and added relevant references, and improved the description of the seismic wave selection in the paper. The following is the modified content:

Line232-246: 1.3.5 Test loading scheme

Table 6. The relationship between seismic fortification intensities and the values of designed seismic accelerations

Loading schemes	1	2	3	4	5		6
Design seismic accelerations (g)	0.05	0.10	0.15	0.20		0.30	0.40
Seismic fortification intensity	6	7		8			9

References:

Ahmet Demir, Mehmet Palanci and Ali Haydar Kayhan. Probabilistic assessment for spectrally matched real ground motion records on distinct soil profiles by simulation of SDOF systems. Earthquakes and Structures 2021, 21 (4), 395-411

Ahmet Demir, Mehmet Palanci and Ali Haydar Kayhan. Evaluation of Supplementary Constraints on Dispersion of EDPs Using Real Ground Motion Record Sets. Arabian Journal for Science and Engineering, 2020, 45, 8379-8401

Point 6. Author states that experimental values deviate from Eq.2. However, according to Figs 9 and 10 method is very close to experimental values. Low standard deviation values also confirm this issue. Needs clarification!

Response 6: Implemented. Thank you so much for this important suggestion. I have modified the figures as your suggestion. The modified figures are as follows:

(a)

(b)

Figure 9. Seismic responses of damping layers with different thicknesses in Class IV surround-ing rock (The red line represents the evaluation value). (a) 1cm; (b) 2cm.

(a)

(b)

Figure 10. Seismic responses of damping layers with different thicknesses in Class V surrounding rock (The red line represents the evaluation value). (a) 1 cm；(b) 2 cm.

Point 7. Table 7 is not clear, and it is not clear what authors seek to do with Table 7. Equations in the table should be also explained. More information is need and manuscript about this issue is superficial!

Response 7: Implemented. Thank you so much for this important suggestion. K is obtained through data fitting based on the experimental results and evaluation results. Based on your suggestion, an explanation about K has been added in the text. The modified content as follows:

Point 8. Study lacks in discussion about the displacement of lining structure with damping layer. Authors provided very slight information about this issue but not discussed in the paper!

Response 8: Implemented. Thank you so much for this important suggestion.

Point 9. Alternatives issues and limitations of the study should be also provided!

Response 9: Implemented. Thank you so much for this important suggestion. The “displacement margin” mentioned in the text refers to the existence of certain displacement and deformation space between the lining and the surrounding rock. The intended meaning is that the damping layer adds flexible contact between the surrounding rock and the lining, thereby reducing damage. To avoid misunderstandings, I have replaced the relevant vocabulary. Here is the revised content:

Line657-660: (5) The existence of damping layer actually changes the inherent vibration characteristics of lining structures, allowing for a certain rigid displacement margin between the lining and the surrounding rock under seismic forces, thereby reducing the relative deformation

Point 10. Additional comments, questions and suggestions are provided in the attached file for authors.

Response 10: Implemented. Thank you so much for this important suggestion. The relevant revisions have been made according to your annotations.

Point 11. Comments on the Quality of English Language

Extensive editing of English language required and comprehensive language editing by native speaker is recommended.

Response 11: Implemented. Thank you so much for this important suggestion. Based on your suggestions, revisions have been made to the English expressions in the text. Here are the changes made:

Line17-40: Abstract: This paper primarily investigates the protective effect of the damping layer in tunnel lining structures under dynamic loads. To investigate the seismic response mechanism of tunnel linings and the influence of surrounding rocks under seismic actions, a series of shaking table tests were conducted using the Wenchuan earthquake (magnitude 8.0) as a reference. The results show that the effect of the damping layer protection measures is accurately with the efficiency evaluation method of damping layer under seismic excitation. The lower excitation acceleration, the better the effect. In addition, the damping coefficient is introduced to optimize the efficiency evaluation method of the damping layer. Among the factors influencing the seismic response of lining structures, the type of surrounding rock has a significant impact, while the thickness of the damping layer has a relatively lesser influence. In seismic intensity areas of equal magnitude, an increase in the damping layer’s thickness leads to a more noticeable effect. In the different seismic intensity area, the difference of the protection effect with the change of thickness is no longer obvious with the increase of seismic intensity. Moreover, the presence of a damping layer alters the intrinsic vibration characteristics of the tunnel lining structure, creating a space for deformation between the lining and the surrounding rock.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have addressed the comments raised in the first round of review. I recommend publishing the paper after proofreading and ensuring English writing is flawless.

I recommend publishing the paper after proofreading and ensuring English writing is flawless.

Author Response

Response

Thank you for your valuable advice, I have carefully modified according to your suggestions. The following is my revised reply.

Point 1: * Legends should be added to Figs. 9 and 10 as given in the cover letter.

Response 1: Implemented. Thank you so much for this important suggestion. According to your, the content of Figure 9 and Figure 10 in both the original text and the accompanying letter has been unified.

Point 2: * In tables 4 and 5, similarity percentage is not necessary and can be deleted.

Response 2: Implemented. Thank you so much for this important suggestion. According to your advice, I have made corresponding deletions to the original text.

Point 3: * Information about the rock classification is given in cover letter, but not in the text. Some brief information classification of soils should be mentioned in the text.

Response 3: Implemented. Thank you so much for this important suggestion. I have added the target values for parameter selection in this paper’s section on rock classification. The specific changes are as follows:

Line 151-154:“The selected material properties for class IV surrounding rock are as follows: density = 1400kg·m-3, cohesion = 3kPa, internal friction angle = 38°. For class V surrounding rock, the target properties are: density = 1133kg·m-3, cohesion = 1.1kPa, internal friction angle = 27°.”

Point 4: * Quotation of all references should be checked in the manuscript since authors have added new references, but they did not organize in text. For example, the place of citation of Ref 23, Ref 24 and Ref 25(in table 6) is wrong. Ref 23 and Ref 24 must be cited at the last paragraph of section 3.6 where limitations of the study are discussed in terms of seismic wave excitations. Authors should emphasize the effect of record selection on the seismic response Ref 23 and Ref 24 since study is limited to single input motion. In table 6, Ref 25 must be Chinese standard or code. Correct and check the citation place of all references in whole manuscript.

Response 4: Implemented. Thank you so much for this important suggestion. According to your advice, the references in the text have been reedited, and references have been added after Section 3.6.

Point 5: If one of the referees has suggested that your manuscript should undergo extensive English revisions, please address this issue during revision.

Response5: According to the suggestion, the English expression of the article has been revised.

Author Response File: Author Response.docx

Reviewer 3 Report

In general, authors addressed the reviewer comments, but still some issues to be solved as stated below;

* Legends should be added to Figs. 9 and 10 as given in the cover letter.

* In tables 4 and 5, similarity percentage is not necessary and can be deleted.

* Information about the rock classification is given in cover letter, but not in the text. Some brief information classification of soils should be mentioned in the text.

* Quotation of all references should be checked in the manuscript since authors have added new references, but they did not organize in text. For example, the place of citation of Ref 23, Ref 24 and Ref 25(in table 6) is wrong. Ref 23 and Ref 24 must be cited at the last paragraph of section 3.6 where limitations of the study are discussed in terms of seismic wave excitations. Authors should emphasize the effect of record selection on the seismic response Ref 23 and Ref 24 since study is limited to single input motion. In table 6, Ref 25 must be Chinese standard or code. Correct and check the citation place of all references in whole manuscript.

Minor editing of English language required

Author Response

Thank you for your valuable advice, I have carefully modified according to your suggestions. The following is my revised reply.

Point 1: * Legends should be added to Figs. 9 and 10 as given in the cover letter.

Point 2: * In tables 4 and 5, similarity percentage is not necessary and can be deleted.

Response 2: Implemented. Thank you so much for this important suggestion. According to your advice, I have made corresponding deletions to the original text.

Point 3: * Information about the rock classification is given in cover letter, but not in the text. Some brief information classification of soils should be mentioned in the text.

“The selected material properties for class IV surrounding rock are as follows: density = 1400kg·m-3, cohesion = 3kPa, internal friction angle = 38°. For class V surrounding rock, the target properties are: density = 1133kg·m-3, cohesion = 1.1kPa, internal friction angle = 27°.”

Author Response File: Author Response.pdf

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Evaluation of the Damping Layer between the Tunnel Lining and Surrounding Rock via a Shaking Table Test

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