Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The topic is current, has practical applications, and aligns with the issues of sustainable management.

Critical remarks:
1. References to literature such as [1-12] are too simple. Please refer to the literature and state what you intend to cite in this article.
2. In Chapter 2.3, cite the literature sources for the methods used.
3. The numerical model in Chapter 3.1 is too general, making it difficult for the reader to understand. The model's spatiality should be emphasized, the static and dynamic calculation methods used should be described, the software used, and the finite elements (or other elements) used should be specified. The assumed loads, especially dynamic loads associated with the pressure wave caused by the explosion, should be described and shown in a drawing.
4. Additionally, the calculated values ​​of the materials and the loads assumed in the numerical model should be justified.

The article complies with the Journal's profile after corrections.

Sincerely, Reviewer

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Reviewer’s Decision Letter
Manuscript Title: Study on the Stability of Cemented Backfill Under Blasting Disturbance: A Case Study of Makeng Iron Mine 
Journal: Applied Sciences 
Decision: Minor Revisions Required
This manuscript presents a comprehensive investigation into the stability of cemented backfill under blasting disturbance, combining laboratory experiments, theoretical models, numerical simulations and field monitoring. The Case study of Makeng Iron Mine provides strong practical relevance and the findings contribute valuable insights into backfill strength design and reinforcement strategies. The paper is scientifically sound and well-structured. However, several issues related to clarity, formatting and depth of discussion must be addressed before final publication.

Major Comments
1.    Numerical simulation details
The description of the 3D numerical model lacks sufficient detail on boundary conditions, mesh refinement and validation. Please expand this section to improve reproducibility.
2.    Equations
Equations (12–14) are presented without adequate explanation of variables. A clearer derivation or reference to established blasting mechanics literature is needed.

Minor Comments
3.    Data presentation
Tables 3 and 4 contain formatting errors (e.g., embedded DOI links in numerical values). Can the authors correct these?
4.    Figure captions
Captions for Figures 9 and 10 should be more descriptive, explicitly stating what the data represent.

Comments on the Quality of English Language

Language

Minor grammatical issues and awkward phrasing reduce readability. A thorough language edit is recommended.

The discussion could better connect findings to broader literature on dynamic loading and rock–backfill interface mechanics.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

 

1. Brief summary of the manuscript

 

The abstract is clear and self-contained. It outlines the problem (stability of cemented backfill under blasting during secondary extraction at Makeng Iron Mine), the methods (laboratory testing, theoretical strength calculations, numerical modelling, field monitoring), the key results (optimum mix 78 % slurry concentration and 1:8 binder-to-tailings ratio giving 2.69 MPa UCS; design strength set at 2.45 MPa; mesh reinforcement reducing maximum lateral displacement from 18.85 mm to 7.24 mm), and the practical conclusion.

 

The introduction sets the engineering context reasonably well and justifies the work by noting that dynamic behaviour under blasting has received less attention than static strength and mix design. The literature survey is functional but rather thin; most references are used to support general statements rather than to position the specific contribution against recent quantitative studies on interface stress-wave transmission or progressive damage accumulation in cemented paste backfill.

 

Materials and methods are, on the whole, suitable. Tailings characterisation, mix design, slump and UCS testing follow recognised standards. The suite of analytical models used to estimate required static strength is comprehensive, and the dynamic stress calculation based on peak particle velocity is transparent. The numerical model (FLAC3D, Mohr–Coulomb, sequential extraction with and without geogrid) addresses the practical question of reinforcement effectiveness. Field monitoring with multipoint extensometers provides a useful reality check.

 

Result analysis is largely descriptive. Comparisons with previous experimental or numerical work on blasting-induced damage in backfill are limited; the discussion stays close to the authors’ own data.

 

The conclusions are concise and map directly onto the stated objectives.

 

Figures and tables are generally readable, although several captions and table entries still contain unresolved cross-reference errors (“Error! Reference source not found.”). Table 3 is incomplete in the supplied file, and some contour plots would benefit from clearer scale bars and annotations.

 

2. Manuscript strengths and weaknesses

 

Strengths 

The work combines laboratory mix optimisation, multiple analytical strength models, dynamic stress estimation, three-dimensional numerical simulation and field displacement monitoring in a single case study. This multi-scale approach is valuable for practising mining engineers. The recommendation of a flexible mesh reinforcement and the quantified reduction in lateral displacement are concrete and usable. The selected mix (78 %, 1:8) is shown to meet both transport and strength requirements under the calculated static-plus-dynamic demand.

 

Weaknesses 

The dynamic component remains largely theoretical; no laboratory Split-Hopkinson or drop-weight tests on the actual backfill mixes are reported. Interface behaviour between backfill and rock is identified as critical, yet the numerical model treats the contact in a relatively simple way and the dynamic wave attenuation discussion is not carried through into the simulation. Discussion of results against independent literature is sparse. Residual formatting errors and incomplete tables reduce professionalism. English phrasing is occasionally awkward and would benefit from careful editing by a native technical speaker.

 

3. Major recommendations (point-by-point)

 

• Expand the literature review in the introduction to include recent quantitative studies on stress-wave transmission and progressive damage at the backfill–rock interface. This will better establish the novelty of the combined static-dynamic design approach.
• Either perform or clearly acknowledge the absence of laboratory dynamic testing (SHPB or equivalent) on the selected mix. If only analytical estimates are available, state the limitations more explicitly when setting the 2.45 MPa design strength.
• In the numerical modelling section, provide more detail on the constitutive treatment of the backfill–rock interface and on how (or why) dynamic loading was omitted from the FLAC3D runs.
• Strengthen the discussion by comparing the observed displacement reductions and plastic-zone patterns with at least two or three independent numerical or field studies of reinforced cemented backfill under blasting.
• Correct all unresolved cross-references and complete Table 3 so that every mix design and corresponding strength value is fully visible.

 

4. Minor recommendations (point-by-point)

 

• Standardise terminology: “binder-to-tailings ratio”, “cement-to-aggregate ratio” and “mortar-to-aggregate ratio” are used interchangeably; choose one and apply it consistently.
• Improve figure captions: add explicit scale information and indicate the mining stage for each contour plot.
• Check units and symbols in equations (12)–(14); ensure all variables are defined immediately after first appearance.
• In Section 2.2.3 the cohesion and friction-angle values appear to be derived from empirical correlations rather than direct shear tests; clarify the source.
• Light English editing throughout to remove residual translation artefacts (e.g., “bone glue”, “settlement concentration of tailings”).
• Confirm that the field-monitoring results in Figure 18 correspond to the same stope geometry and reinforcement condition modelled numerically.

 

5. Based on the aspects raised, my recommendation is: Major revision.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

• The manuscript is titled: "Blasting Disturbance" but there is no actual backfill blasting experiment.
• In the Introduction, the research gap can be much more precise. Should it be explicitly emphasized what the previous works did not solve?
• The Structure of the paper lacks a Discussion, with integrated: laboratory results, static strength, dynamic stress, numerical results, monitoring, limitations, comparison with literature.
• The generalization of the results to other mines is excessive; the research was done on one mine, one type of tailings, one cement, one geometry, one blasting system, and one support system.
• No clear discussion of research limitations. This is a big drawback.
• A serious shortcoming of the manuscript is the experimental confirmation of the dynamic behavior of cemented paste backfill (CPB) through the key factors of strain rate, energy damping, and pore water pressure change. It is necessary to demonstrate an appropriate criterion and clearly define an acceptable factor of safety.
• In equation 14, the coefficients are defined with: K=150 and α=1.3, but it is not sufficiently explained where these values ​​come from, or whether they are calibrated for the Makeng mine,
• No validation of calculated dynamic stress
• The authors claim that slurry concentration and binder content significantly influence mechanical properties, but there is no statistical evidence that the effect is "significant". No: ANOVA, regression analysis.
• No real economic optimization of the model.
• Unclear terminology: cement-to-aggregate vs binder-to-tailings. It is not clear enough whether cement, binder, aggregate, and tailings are different components.
• The authors state that after the sedimentation equilibrium, the slurry concentration stabilizes around 68.9%, but then for experiments they use 72–78%. It is not clear how these two results are related.
• Important raw material characterization data are missing, e.g., mineralogy (XRD). For cemented tailings backfill, mineralogy in particular would be useful for interpretation of hydration.
• The authors claim that increasing the concentration increases the OH⁻ concentration, which encourages dissolution of Si–O and Al–O bonds and polymerization. But the work does not include pH measurements, XRD, SEM, EDS, FTIR, or characterization of hydration products. So the mechanism has not been experimentally proven.
• The authors state: cohesion and internal friction angle were obtained through Mohr-Coulomb fitting based on direct shear test results, but then immediately say: estimated according to empirical correlations based on UCS and tensile strength. These are two different ways of determining the parameters. Clarify.
• Show complete data from which the determination of c and ϕ can be verified.
• In numerical simulation: dynamic blasting is not actually simulated. This is very important because the paper talks about blasting disturbance, but the numerical simulation is practically quasi-static.
• No comparison of models and measurements in one common image, which would be very useful: Numerical prediction vs field monitoring
• The paper considers practically only 28 days and short-term mining response. Should show: UCS(t) at least for 3, 7, 14, 28 days. Also, no long-term stability Backfill.
• For the Thomas, Terzaghi, Mitchell, Yang Xin, and Cai Sijing models, the authors provide equations, but the origin of each equation is not clearly stated. This must be addressed with direct references to each model.
• References are not consistently linked to claims. There is, e.g., text: "thereby improving the overall strength of the backfillError! Reference source not found. It's an obvious error in the cross-reference/reference field.
• Linguistic and technical problems are numerous ("ratio of bone glue"; "slump measurement result"; "unmined state" where the context may be unclear; lack of space after the period; "2.45 MPa.."; "Error! Reference source not found"; inconsistent terminology.)

Comments on the Quality of English Language

The language is currently understandable, but not recommended for acceptance without serious language editing.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

The manuscript has practical engineering value and combines laboratory characterisation, analytical assessment, numerical simulation and field monitoring. However, the central claim concerning backfill stability under blasting disturbance is not yet sufficiently supported. In addition, the basis for the selected safety margin, numerical reinforcement parameters, and validation against field observations requires clarification. There are also several technical inconsistencies and manuscript preparation errors that should be corrected. I believe these issues can be addressed without fundamentally changing the study. 

Comments on the Quality of English Language

There are numerous grammatical problems, missing spaces, and inconsistent terminology.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The corrections made significantly improved the quality of the article.

The article is now ready for further processing.

Author Response

Thank you for your positive assessment of our revision. We appreciate your recognition that the corrections have improved the article and that it is ready for further processing.

Reviewer 3 Report

Comments and Suggestions for Authors

The revised manuscript addresses most of the original major comments. One numerical-parameter inconsistency and a still-thin discussion against independent studies remain.

 

Recommendation: minor revision (acceptable after correction of the items below).

 

 

1. Brief assessment of the revision

 

The authors have done substantially more than a cosmetic rewrite. The original review asked them either to run laboratory dynamic tests or to state the limitation of a purely analytical design strength. They added a full SHPB campaign on the selected 78 % / 1:8 mix (Section 2.3.3, Table 6, Figures 11–12) and, in the conclusions, they correctly refuse to treat those DIF values as a full-scale failure threshold. They also built a separate dynamic FLAC3D model (Sections 3.3–3.4) instead of leaving blast loading out of the numerical work. Table 3 is now complete. Cross-reference errors of the “Error! Reference source not found” type are no longer visible in the supplied file. Terminology has been aligned on “binder-to-tailings ratio.” Cohesion and friction angle are now attributed to Mohr–Coulomb fitting of direct-shear results (Section 2.2.3). Field monitoring (Figure 27) is reported for the reinforced condition and the measured peak lateral displacement (8.97 mm) sits in the same range as the supported numerical result (7.24 mm).

 

2. Point-by-point check of the major comments

 

Literature on interface wave transmission. 

The introduction now cites recent quantitative work on reflection/transmission and progressive damage at the backfill–rock contact, including the 26 % drop in near-field volumetric strain and 8–13 % sonic-velocity loss [24,25]. The gap statement is clearer than in the first version. The survey is still short, but the specific request has been met.

 

Laboratory dynamic testing. 

Satisfied. SHPB results, stress-equilibrium check, strain-rate range (50–171 s⁻¹), peak stresses (4.09–19.15 MPa) and DIF (1.52–7.12) are reported. The authors also state that these data do not set the 2.45 MPa design value as an in-situ dynamic failure limit. That caveat is appropriate.

 

Interface treatment and omission of dynamic loading in FLAC3D. 

Satisfied in substance. Both static and dynamic models now describe coincident gridpoints, continuity of stress and displacement, and the explicit decision not to insert a separate interface element (no opening, sliding or debonding). Mesh refinement, zone count, a brief mesh-sensitivity check (~3.2 % change in peak displacement), viscous boundaries, Rayleigh damping and the triangular blast pulse (peak 137.4 MPa) are documented. Dynamic loading is no longer omitted.

 

Comparison with independent studies of reinforced backfill under blasting. 

Only partly addressed. Displacement reduction (18.85 mm → 7.24 mm, 61.60 %) and the ~39.72 % reduction of the shear zone are given, but the discussion still stays inside the authors’ own figures. A short comparison with two or three published numerical or field cases (for example Li et al., 2022; Zhao et al., 2024; related mesh or shotcrete-confinement studies) is still missing. This was a major comment and should be closed with one focused paragraph before acceptance.

 

Formatting and Table 3. 

Table 3 is complete. Residual broken cross-references were not found in this file.

 

3. Minor comments — status

 

- Terminology is now consistent enough for publication. 

- Figure captions are better (unsupported vs mesh; mining stage indicated in several plots) but “nephogram” should be replaced by “contour plot” or “contour map.” 

- Variables in Eqs. (12)–(14) are defined after first use. 

- Source of c and φ is clarified. 

- Some translation residue remains (“wing backfill,” “settlement concentration of tailings” in the caption of Figure 5). A light language pass is still useful. 

- Correspondence between the monitored stope and the supported numerical case is now stated more clearly; the two peak displacements are compatible.

 

Equation (2) is still labelled Cᵤ; it is the curvature coefficient Cc. That is a one-line correction.

 

4. One issue that must be corrected before acceptance

 

Table 9 (dynamic model) assigns the 1:8 backfill an elastic modulus of 36.83 GPa, cohesion of 27.14 MPa and a friction angle of 41.05°. Those values belong to rock, not to the backfill characterised in Table 4 and Table 7 (UCS 2.69 MPa, E ≈ 0.7 GPa, c = 1.76 MPa, φ = 36.37°). If the dynamic run was actually performed with the Table 9 row as printed, the wave impedance, transmitted stress and plastic-zone pattern in Section 3.4 are not those of cemented tailings backfill. The row must be corrected and the dynamic results rechecked, or the authors must show that the published contours were obtained with the laboratory backfill parameters. This is not optional.

 

A smaller inconsistency is the backfill density: 2.12 g/cm³ in Table 4, 2.112 g/cm³ in the blast-stress calculation, 2.54 g/cm³ in Table 9. Align the value used in the dynamic model with the laboratory mix.

 

5. Recommendation

 

The original recommendation was major revision. That bar has largely been cleared: the missing dynamic laboratory work is now present, blast loading is modelled, the interface assumption is stated, Table 3 is complete, and field displacements support the reinforced numerical case.

 

The article can be accepted after a short further revision that (i) corrects Table 9 and confirms that the dynamic results correspond to the laboratory backfill properties, (ii) adds a brief comparison of the displacement and plastic-zone reductions with two or three independent studies, and (iii) tidies the remaining caption and equation-label slips.

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The attached responses are  in correspondence with the comments and are very satisfactory. The main shortcomings of the manuscript have been successfully addressed by conducting new laboratory tests, adding advanced numerical modeling, and adequately limiting excessive claims.

In order to better publication of the results, the authors are recommended to do the following:

• In the response to Comment 7, it was stated that the coefficients (K = 150) and (α = 1.3) are literature data " engineering attenuation parameters adopted for the Makeng calculation”. Given that they are not calibrated based on local measurements, it would be useful for the authors to add a short discussion of the sensitivity of the model in the text - how changing these parameters affects the final design dynamic stress of 2.40 MPa.
• Comment 9 In the absence of ANOVA analysis, the authors have rephrased the claims into describing trends. However, since there are three repeated samples per group, it would be a good idea to show the standard deviation for the mean values ​​in the tables or graphs.

Comments on the Quality of English Language

The English language in the manuscript is functional, grammatically mostly correct, and uses appropriate technical vocabulary, but still requires refinement and minor corrections before final publication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

The revised manuscript has been substantially improved and the authors have responded constructively to the previous concerns. In particular, the distinction between the analytical design strength (2.45 MPa), calculated blast-transmitted stress (2.40 MPa), measured 28-day UCS (2.69 MPa), and SHPB dynamic response is now much clearer, and the limitations of the dynamic numerical model and field validation have been appropriately acknowledged. The integration of laboratory testing, analytical assessment, numerical simulation and field monitoring provides useful practical value. I nevertheless recommend minor revision before acceptance. The authors should avoid referring to 2.45 MPa as a safety margin unless an explicit factor of safety or uncertainty assessment is provided, since it is only slightly higher than the calculated 2.40 MPa transmitted stress. The interface modelling also does not explicitly account for opening, sliding or debonding, and therefore conclusions regarding interface failure should be expressed more cautiously. Similarly, field monitoring demonstrates successful field performance but does not constitute direct validation of the dynamic numerical model. Some additional clarification of SHPB repeatability/variability and the assumptions underlying the simplified triangular blast pulse would strengthen the manuscript. Finally, the manuscript requires another careful English and formatting check. Overall, I consider the study technically sound and suitable for Applied Sciences following these minor revisions.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf