Development of an Integrated 3D Simulation Model for Metro-Induced Ground Vibrations

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

I have reviewed your manuscript titled "Development of an Integrated 3D Simulation Model for Metro-Induced Ground Vibrations". Overall, it is a well-written and valuable contribution to the field. However, there are some minor issues that need to be addressed：

1. Frequent errors in figure/table citations: The manuscript contains frequent instances of the placeholder text "Error! Reference source not found" when citing figures and tables (e.g., Section 3, Section 4). This significantly disrupts the flow and makes it difficult to connect the text to the relevant visualizations. Additionally, Table 1 appears in Section 4.2.1 and then reappears later in Section 4.4.2. Please ensure all figure and table references are correct and consistent throughout the manuscript.
2. Weak evidence for adaptability to diverse scenarios: The abstract and conclusions state that the methodology "can adapt to various urban vibration scenarios", But this is only verified by a single case study of a multi-storey building in Qatar, with specific parameters in. There is no verification with other scenarios, making it difficult to support the claim of broad adaptability.3
3. Limited validation methods lacking field data support: Model validation primarily relies on comparisons with the full Finite Element (FE) model without integrating actual field measurement data (e.g. vibration monitoring results of buildings along metro lines). Consistency between numerical models cannot fully prove the model's applicability to real scenarios.
4. Insufficient elaboration on model assumptions and limitations: Although the soil model is described as a homogeneous isotropic half-space (section4.2.1), but the applicability limitations of this hypothesis to complex geological conditions (such as layered or heterogeneous soil) are not clearly stated.
5. Incomplete Justification for Key Parameters: The selection of 40 fictitious forces as optimal is validated, but the rationale for this specific number (e.g., trade-offs in accuracy vs. computational cost for other quantities) is not thoroughly explained.
6. Insufficient Practical Relevance: Computational efficiency gains (65% time reduction) are validated only at 150 Hz, ignoring critical low-frequency ranges (1–80 Hz) dominant in metro-induced vibrations.

I believe these minor revisions will further enhance the quality of your manuscript. After addressing these points, the paper will be suitable for publication in the journal.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript proposes a novel 3D simulation framework that couples the classic Pipe-in-Pipe (PiP) model with Finite Element Analysis (FEA) via Ansys Parametric Design Language (APDL). The extension of the PiP concept to incorporate full three-dimensional building structures is an encouraging development. Nevertheless, several issues need to be addressed before the paper can be recommended for publication.

(1) Research Motivation (Lines 46–49)

The current justification—“This model is efficient for studying the immediate effects of vibrations near the tunnel, but it needs to be combined … to better predict how vibrations spread to buildings farther away”—is too generic. Please clarify why FEA, rather than other semi-analytical or numerical approaches (e.g., 2.5-D FE-BE, periodic FE-IFE), is the necessary partner for the PiP model. A short paragraph discussing the complementary strengths and limitations of FEA versus these alternatives is required.

(2) Literature Review and Innovation Statement

The literature survey mixes vibration impact, prediction techniques, and modelling methods without a clear thread on how the PiP-FE coupling advances the state of the art. Here is a suggestion on re-structuring the literature review:

• Analytical models (three representative works): Yuan et al. (2017), Ma & Xu (2023, 2024), He & Zhou (2018, 2020).
• Semi-analytical models: PiP and thin-layered methods.
• Numerical models: 2.5D FE-BE (Sheng et al., 2006; Jin et al., 2018), 2.5D FE-IFE (Alves Costa et al., 2010; Yang et al., 2017), periodic FE-BE (Gupta, 2008), periodic FE-IFE (Liu et al., 2023).

Alves Costa P, Rui C, Cardoso A S, et al. 2010. Influence of soil non-linearity on the dynamic response of high-speed railway tracks. Soil Dynamics and Earthquake Engineering, 30(4): 221-235.

Gupta S. 2008. A numerical model for predicting vibrations from underground railways. Leuven: K.U. Leuven.

He C, Zhou S, Di H, et al. Analytical method for calculation of ground vibration from a tunnel embedded in a multi-layered half-space. Computers and Geotechnics, 2018, 99: 149-164.

Jin Q, Thompson D J, Lurcock D E J, et al. 2018. A 2.5D finite element and boundary element model for the ground vibration from trains in tunnels and validation using measurement data. Journal of Sound and Vibration, 422: 373-389.

Liu W F, Li C Y, Ma L X, et al. 2023. A frequency-domain formulation for predicting ground-borne vibration induced by underground train on curved track. Journal of Sound and Vibration, 549: 117578.

Ma M, Xu L H, Liu W F, et al. Semi-analytical solution of a coupled tunnel-soil periodic model with a track slab under a moving train load. Applied Mathematical Modelling, 2024, 128: 588-608.

Sheng X, Jones C J C, Thompson D J. 2006. Prediction of ground vibration from trains using the wavenumber finite and boundary element method. Journal of Sound and Vibration, 293(3-5): 575-586.

Xu L H, Ma M. Analytical solution of ground-borne vibration due to spatially periodic harmonic moving load on a tunnel embedded in layered soil. Journal of Zhejiang University-SCIENCE A, 2023, 24: 637-652.

Yang Y, Liang X, Hung H H, et al. 2017. Comparative study of 2D and 2.5D responses of long underground tunnels to moving train loads. Soil Dynamics and Earthquake Engineering, 97: 86-100.

Yuan Z, Boström A, Cai Y. Benchmark solution for vibrations from a moving point source in a tunnel embedded in a half-space. Journal of Sound and Vibration, 2017, 387: 177-193.

Zhou, S., He, C., Guo, P., Di, H., et.al. Three-dimensional analytical model for coupled track-tunnel-soil system in a multilayered half-space. Journal of Engineering Mechanics, 2020, 146(2), 04019121.

 

Against this background, explicitly position the contribution of the paper, e.g. the PiP model’s computational efficiency is retained, while its inability to represent above-ground building dynamics is overcome by embedding it in a 3-D FEA domain.

(3) Line 328 states “pile foundation,” whereas Table 1 lists “Foundation Type: Shallow.” Pile foundations are generally classified as deep foundations. Please clarify the actual foundation system used in the case study and ensure consistency throughout the manuscript.

(4) The 0.5-m element size is justified only for 150 Hz. However, typical ground-borne vibration rarely exceeds 80 Hz, while structural borne noise in buildings can reach 200–250 Hz. Please provide a rationale for selecting 150 Hz as the upper limit and discuss the sensitivity of results if the analysis band is shifted to 80 Hz or 250 Hz.

(5) Numerous instances of “Error! Reference source not found” appear in the text. Please double-check all cross-references and figure/table links. If these errors were introduced during editorial typesetting, they may be disregarded.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

1. This paper introduces a novel 3D simulation framework that integrates the Pipe-in-Pipe (PiP) model with Finite Element Analysis (FEA) using Ansys Parametric Design Language (APDL). The results exhibit strong agreement between the PiP-FEA and full FEA models across a frequency range of 1–250 Hz, with less than 1% deviation, highlighting the effectiveness of the PiP-FEA approach in capturing the dynamic behavior of ground-borne vibrations.
2. The paper's contents include minor errors, such as lines 220, 250, 257, 301, 395, 442, 461, 472, 543, 558, 582, 604, etc. Please correct them.
3. Please replenish the character description lines 582-588 and add more characters for Figure 18.
4. There are many discrepancies in Figure 15, and the text has to be re-supplied with more explanations, please.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have revised the manuscript based on the reviewers' comments. Now I recommend it for acceptance.

Author Response

We sincerely thank the reviewer for the positive recommendation and for recognizing the improvements made in the revised manuscript. We greatly appreciate the constructive comments and feedback provided during the review process, which have helped us enhance the quality, clarity, and scholarly contribution of the paper.