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PLoS One
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PLOS ONE
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10.1371/journal.pone.0307700
PONE-D-24-14746
Research Article
Physical Sciences
Physics
Acoustics
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Acoustics
Sound Pressure
Physical Sciences
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Classical Mechanics
Pressure
Osmotic Pressure
Physical Sciences
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Material Properties
Elasticity
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Acoustic Signals
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Mechanical Stress
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Damage Mechanics
Deformation
Physical Sciences
Physics
Classical Mechanics
Damage Mechanics
Tunnel and underground engineering rock mass water inrush damage and acoustic emission characteristics
Rock mass water inrush disaster and acoustic emission characteristics
https://orcid.org/0000-0003-0127-3548
Zeng Jiajun Conceptualization Formal analysis Methodology Writing – original draft Writing – review & editing 1 *
Pu Chengzhi Conceptualization Methodology Writing – review & editing 2
Wang Qiyun Funding acquisition Validation 1
Shen Qingqing Data curation Formal analysis 1
Zeng Qiang Investigation 1
Yang Zhicheng Investigation 1
1 College of Civil and Construction Engineering, Hunan Institute of Technology, Hengyang, China
2 School of Resource Environment and Safety Engineering, University of South China, Hengyang, China
Trippetta Fabio Editor
Sapienza University of Rome: Universita degli Studi di Roma La Sapienza, ITALY
Competing Interests: The authors have declared that no competing interests exist.

* E-mail: Zengjiajun93@163.com
20 9 2024
2024
19 9 e030770011 4 2024
5 7 2024
© 2024 Zeng et al
2024
Zeng et al
https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

To achieve the actual situation of water pressure stabilization during underground and tunnel water inrush disasters, the team independently developed a stable water pressure test system and conducted fracture and failure tests on fissured rock masses under the coupling effect of 1MPa stable water pressure and stress and without water pressure. Combined with data collected by acoustic emission instruments, the mechanical characteristics of fracture and failure, crack propagation mechanism, and acoustic emission response mechanism of fissured rock masses under the coupling effect of stable hydraulic pressure and stress were studied. The results showed that throughout the entire experimental process, the hydraulic pressure remained continuously stable, with a decrease of only 0.14%; The variation pattern of peak strength of fissured rock mass with increasing crack inclination angle under stable hydraulic pressure changes from a decrease and then an increase in the absence of hydraulic pressure to an increasing trend; The crack propagation length of low angle fissured rock mass is generally higher than that of high angle fissured specimens. The longer propagation path increases the range and effect of hydraulic pressure, and the initial crack propagation length of fissured rock mass under hydraulic pressure is also significantly longer than that of specimens without hydraulic pressure; During the loading process, both the acoustic emission ringing count and damage variable can be divided into four stages. From the cumulative total number of acoustic emission ringing counts, it can be seen that during the loading process, the total number of acoustic emission ringing in fissured rock masses subjected to hydraulic pressure is significantly lower than that of specimens without hydraulic pressure, and the trend is also relatively stable.

Hunan Provincial Natural Science Foundation of China 2023JJ50104 https://orcid.org/0000-0003-0127-3548
Zeng Jiajun Scientific Research Fund of Hunan Provincial Education Department 21B0803 Wang Qiyun Scientific Research Fund of Hunan Provincial Education Department 22B0853 https://orcid.org/0000-0003-0127-3548
Zeng Jiajun Scientific Research Fund of Hunan Provincial Education Department 23B0838 Zeng Qiang Hunan Institute of Technology provincial-level applied characteristic discipline KFB23022 https://orcid.org/0000-0003-0127-3548
Zeng Jiajun National College Student Innovation and Entrepreneurship Training Program Project S202311528042 https://orcid.org/0000-0003-0127-3548
Zeng Jiajun This work is supported by Hunan Provincial Natural Science Foundation of China (2023JJ50104); Scientific Research Fund of Hunan Provincial Education Department (21B0803, 22B0853, 23B0838); Hunan Institute of Technology provincial-level applied characteristic discipline (KFB23022); National College Student Innovation and Entrepreneurship Training Program Project(S202311528042). Those funders play important roles in the study design, data collection and analysis. Data AvailabilityAll relevant data are within the manuscript and its Supporting Information files.
Data Availability

All relevant data are within the manuscript and its Supporting Information files.
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pmc1 Introduction

The hydrogeology and structure forms of the tunnel and underground geotechnical engineering are quite complicated. Water and mud inrush accidents are common, harmful, and difficult to control [1]. Water-rich, high-pressure, and bad geology are the main geological conditions that induce water inrush and mud outburst disasters. Construction disturbance is the external cause of the accident. Under the joint action of hydraulic pressure and engineering disturbance, the surrounding rock medium generates fracture behavior, forming the channel of water inrush and mud outburst, leading to the accident of water inrush and mud outburst, which seriously affects the stability of the surrounding rock. Water inrush is often characterized by uncertain orientation, large water inrush, strong hydraulic pressure, slow water inrush decay, long duration, etc., which is very difficult and harmful to prevent and control [2]. Therefore, it is of great significance to carry out experimental research on mechanical properties and deformation rules of rock mass under the action of hydraulic pressure for effective prevention of water and mud inrush disasters in tunnels and underground engineering.

When encountering fault-fractured zones during mining and tunnel excavation, the granular structure of the fractured surrounding rock is prone to forming water channels, which can easily cause water inrush hazards [3–5]. In order to study the influence of the interaction between rock fractures and water on the fracture and failure mechanism of rock masses, Li [6] conducted hydraulic tests on sandstone specimens containing single fissures. Zhou Zhihua [7] prepared specimens with internal fissures using paper instead of fissures, and conducted uniaxial and cyclic loading and unloading tests on the internal fissure rock mass under the action of osmotic water pressure; Guo Kongling [8], Mei Jie et al. [9] prefabricated elliptical three-dimensional fissured rock specimens and studied the fracture mode of fissured rock mass under the influence of hydraulic pressure. Fu Jin wei [10], Yang Lei [11], and others used transparent resin materials to prepare transparent resin specimens with built-in three-dimensional cracks. They conducted uniaxial compression fracture experiments on crack specimens under the influence of crack hydraulic pressure and studied the initiation and propagation mode of newly formed cracks near the prefabricated crack surface under the influence of crack hydraulic pressure. Cao Ping [12] and Hao Rui qing [13] prepared fissured yellow sandstone specimens, sealed the hydraulic pressure with epoxy resin material, and studied the peak failure strength law and crack propagation and failure mode of fissured rock masses. Wei Chao [14], Li Yong [15], and others designed a water-sealing fixture, using sealing washers and organic glass plates to encapsulate penetrating cracks through hydraulic pressure. They analyzed the influence of hydraulic pressure on the fracture mechanical characteristics of crack specimens and crack propagation and failure modes.

Acoustic emission testing technology can effectively monitor and reflect the evolution and propagation process of internal cracks in materials and is widely used to study the damage and fracture behavior inside rocks [16]. Studying the characteristics of rock damage evolution through acoustic emission is of great guiding significance for a deep understanding of rock fracture mechanisms and the prevention of disasters and accidents caused by rock fracture instability [17]. In recent years, achievements in using acoustic emission as an auxiliary means to study rock damage and fracture behavior have continuously emerged. This experiment will combine acoustic emission to conduct research on the damage evolution of fissured rock masses [18–23].

In order to realize the reality of the water inrush disaster process in underground and tunnel engineering and make the test results more real and reliable, the team developed a set of experimental systems that can continuously provide stable hydraulic pressure in the process of crack propagation. By taking advantage of the characteristics of high compressibility and strong pressure-retaining performance of gas, Gas, and Liquid in one chamber is used, and the liquid is driven by pressure to apply hydraulic pressure. When the water inrush channel deforms and expands (crack initiation and expansion), the water injection channel expands accordingly, and the gas-liquid common cavity in the stable hydraulic pressure device is immediately offset by gas expansion, and the gas has high compressibility, and the tiny expansion can only produce a slight pressure drop, so the permeable hydraulic pressure is relatively stable during crack initiation and expansion. Based on the fracture failure test of fissured rock mass under stable hydraulic-stress coupling and no hydraulic action, combined with acoustic emission data collection, the fracture failure mechanical characteristics, crack propagation mechanism, and acoustic emission response mechanism of fissured rock mass in the process of water inrush in underground and tunnel engineering are systematically studied.

2 Stable hydraulic pressure supply test system

To realize the stable water pressure supply during the flood surge test, the stable hydraulic pressure test system was developed independently. It is mainly composed of a stable hydraulic pressure provider, flowmeter, pressure gauge, acoustic emission instrument, loading device, and control system. The whole test system is shown in Fig 1.

10.1371/journal.pone.0307700.g001 Fig 1 Schematic diagram of the test system (a) system diagram; (b) hydraulic pressure system.

In the previous servo-controlled hydraulic loading system, the crack initiation and propagation were completed instantaneously during the loading process of the specimen, and the volume was expanded instantaneously, so the hydraulic pressure will drop steeply and it is difficult to achieve hydraulic stability during the crack initiation and propagation process of the rock mass. When the crack propagation is accelerated in the middle and late loading period, the volume expansion is also accelerated, and the servo response is difficult to keep up, and the servo drive has high requirements on the device response. When the servo control system receives the signal and increases the hydraulic pressure, then the crack continues to expand, causing the hydraulic pressure to drop, and the pulse-type circulating hydraulic pressure is formed repeatedly in the process of rock mass fracture, which cannot restore the actual hydraulic pressure action in the process of water inrush disaster in the tunnel and underground engineering.

3 Test preparation

The experiment used cement mortar material to prepare rock specimens, with a material ratio of fine sand: white cement (325 grade): water = 2:2:1 (mass ratio). The fine sand was sieved using a 1.25mm aperture sieve, and the part with an aperture less than 1.25mm was washed and dried with water to eliminate the influence of soil in the sand on the experiment. The mold used for specimen preparation is assembled with stainless steel and acrylic plates, with an internal size of length × width × height = 150mm × 50mm × 200mm. When preparing specimens with water injection holes penetrating cracks, 3D printing technology was used to prefabricate stainless steel water injection rods with different inclination angles at the ends. The ends of the rods were bonded with glue and steel sheets. After waiting for the initial setting of the specimen, first pull out the water injection rod, and then pull out the steel sheet to form a through fissure with water injection holes. The schematic diagram of the mold and the 3D specimen are shown in Fig 2.

10.1371/journal.pone.0307700.g002 Fig 2 Schematic diagram of the mold and the 3D specimen.

The steady hydraulic pressure test was carried out in strict accordance with the following steps:

Check the test system, inject 1/3 water into the chamber of the hydraulic pressure supply device, and open the air pump to pressurize the chamber, the air pump is an intelligent numerical control, sets the pressure value range is 1.02MPa~0.98MPa (the accuracy of the air pump is 0.2bar, that is, 0.02MPa, when the air pressure rises to 1.02MPa, the air pump automatically closes. When the air pressure is reduced to 0.98MPa, the air pump automatically opens the pressure), so that the hydraulic pressure of the water supply device chamber is stable at about 1MPa.

Take out the cured sample to be loaded, use a hand-held stone grinder to smooth the surface of the specimen, and increase the tightness of the rubber pad.

Install the sealing fixture: The sealing fixture consists of two 12mm thick steel splints, two 10mm thick transparent acrylic plates, four 3mm thick rubber pads, and four sets of bolts, as shown in Fig 3. First, a steel splint is placed on the bolt, acrylic plate, and rubber pad, the specimen is placed in the middle position, and then the rubber pad, acrylic plate, and steel fixture on the other side are placed in place; this point, a relatively important link is needed: At this time, a syringe is used to inject tap water from the water injection hole of the crack specimen, and observe whether the injected water overflows from the crack surface from the outside, so as to ensure that the water injection hole of the crack specimen is kept through with the prefabricated crack. When the hydraulic pressure is applied, the hydraulic pressure can directly act on the crack surface, and the water should fill the acrylic plate and the hollow position of the specimen as much as possible. Then the bolts were tightened with a torque wrench to keep the four bolts close to each other, and the acrylic plate was not in contact with the specimen after the installation.

The fixture and the specimen are placed on the loading platform as a whole, and the water injection hole is aligned with the water injection hole of the base. The sealing ring is arranged around the water injection hole of the base, and the sealing effect is achieved after the specimen is applied force; Connect the acoustic emission device to complete the acquisition software setting; Each probe was evenly coated with the coupling agent and fixed on the specimen with an acoustic emission support.

During the test, first apply the vertical force up to 2MPa and maintain it (loading rate is 500N/s), then turn on the hydraulic pressure switch, apply the hydraulic pressure, and then continue to apply the vertical force until the specimen is damaged. High-definition digital cameras are used throughout the test, and the failure mode is photographed after the specimen is damaged.

10.1371/journal.pone.0307700.g003 Fig 3 CAD drawing of sealing fixture.

The loading platform of the testing machine is shown in Fig 4. You can see the support, acoustic emission probe, water sealing device, water injection quick connection, etc.

10.1371/journal.pone.0307700.g004 Fig 4 Detailed drawing of testing machine loading platform.

4 Analysis of test results

4.1 Hydraulic stability test results

During the hydraulic pressure stability test, 1MPa was used to stabilize the hydraulic pressure, and the uniaxial compressive stress-strain and hydraulic pressure change curves of the specimen with a built-in crack with a dip Angle of 45° were obtained, as shown in Fig 5. After the initial hydraulic pressure stabilized to 1001.2kPa, no hydraulic pressure was applied at the OA stage. When the applied vertical force reached 2MPa, hydraulic pressure was applied to the inside of the specimen. AB stage is the initial stage of applying stable hydraulic pressure. It can be observed from the curve of hydraulic pressure change that after applying hydraulic pressure, water enters the precast fissure through the water injection hole, and the water quantity in the hydraulic pressure chamber changes slightly, leading to pressure fluctuation. BC stage is the middle stage of applying stable hydraulic pressure. In this stage, a large number of microcracks are generated and expand steadily in the internal crack of the specimen, and the water steadily penetrates the new crack surface in real time and provides hydraulic pressure. At this time, the water volume in the hydraulic pressure chamber continues to decrease slightly, the gas volume continues to increase slightly, and the pressure continues to fluctuate, but the maximum fluctuation in the whole process is only 0.6kPa. About 0.06% of the hydraulic pressure of 1001kPa at that time; At stage CD, a large number of microcracks were connected in the specimen to form macroscopic cracks. At this stage, the specimen deformation was large, but the duration was short and the stress drop rate was fast. At this stage, the hydraulic pressure decreased twice. During the whole test, the hydraulic pressure decreased by 1.4kPa, which was 0.14% lower than the initial hydraulic pressure value. The hydraulic pressure fluctuated slightly and was approximately stable during the whole loading process.

10.1371/journal.pone.0307700.g005 Fig 5 Stress-strain and hydraulic pressure curves.

4.2 Mechanical characteristics

To ensure that there is no water leakage between the loading base and the bottom of the specimen when the hydraulic pressure is applied, the vertical force of the crack specimen is first loaded to 2MPa, that is, the loading is suspended when the hydraulic pressure is 15KN. At this time, the hydraulic pressure device is started, the stable seepage hydraulic pressure of about 1MPa is applied, and then the vertical force is continued until the hydraulic pressure device is closed immediately after the failure of the specimen. Fig 6 shows the stress-strain curve of the crack specimen under 1MPa stable osmotic hydraulic pressure. In Fig 6, the loading curve presents obvious layering.

10.1371/journal.pone.0307700.g006 Fig 6 Stress-strain curves with non-hydraulic and stabilized hydraulic.

The peak uniaxial compressive strength of fissured rock mass with different dip angles under the action of no hydraulic pressure and 1MPa stable osmotic pressure is plotted in Fig 7 (The peak intensity is taken as the average of six sets of data). The graphic results show that the peak uniaxial compressive strength of the crack specimen increases with the increase of crack dip Angle when 1MPa is applied to stabilize the seepage pressure, and the peak strength is the lowest when the crack Angle is 0°. By comparing the peak strength characteristics of fissured rock mass under uniaxial compression without hydraulic pressure and under 1MPa stable osmotic pressure, it is found that the peak strength of fissured rock under stable osmotic pressure is generally higher than that of specimens without hydraulic pressure under the same dip Angle, and the smaller the dip Angle, the larger the gap. The variation law of peak strength with the increase of crack Angle also changes from first decreasing and then increasing to increasing. On the one hand, after the injection of stable hydraulic pressure into the precast crack of the fissured rock mass in the test, the precast crack surface and a part of the surface of the specimen (within the range of the rubber pad of the liquid sealing device) have a softening effect on the fissured rock mass and reduce the bearing capacity of the fissured rock mass. On the other hand, the hydraulic pressure generates continuous tensile stress on the prefabricated crack surface, which promotes the initiation of tension cracks near the prefabricated crack surface. After the crack initiation, the hydraulic pressure device provides continuous and stable hydraulic pressure and synchronously enters the new crack surface at the same time of the crack initiation, which increases the driving force of tensile crack propagation. The peak compressive strength of fissured rock mass decreases as crack propagation and interpenetration are accelerated. Finally, the change law of the peak strength of fissured rock mass with the increase of crack dip Angle under the action of hydraulic pressure is different from that without the action of hydraulic pressure. In this case, the smaller the crack dip Angle is, the greater the influence of hydraulic pressure on the peak strength of fissured rock mass.

10.1371/journal.pone.0307700.g007 Fig 7 Curve of peak strength change of specimen with non-hydraulic and stabilized hydraulic.

The average elastic modulus of crack specimens at each dip Angle under the action of no hydraulic pressure and 1MPa hydraulic pressure was plotted in Fig 8. Under the action of hydraulic pressure, the peak strength of fissured rock mass increases with the increase of crack dip Angle, which is the same as that without hydraulic pressure. However, the larger the crack Angle is, the smaller the curve spacing is. The smaller the dip Angle, the larger the spacing. The strain of fissured rock mass under the same load is larger and the elastic modulus is smaller than that without hydraulic pressure.

10.1371/journal.pone.0307700.g008 Fig 8 Elastic modulus change curve with non-hydraulic and stabilized hydraulic.

4.3 Initial crack growth state

The effect of hydraulic pressure not only affects the macroscopic mechanical characteristics such as peak strength and elastic modulus of fissured rock mass but also affects the stable hydraulic pressure when crack initiation and propagation of fissured rock mass. In the experiment, high-definition digital cameras were used for video acquisition, and the initial crack was intercepted when it expanded to the maximum path. Meanwhile, CAD was used to draw its contour and calculate the crack growth path length proportionally (the length between the crack initiation point and the crack growth endpoint). The drawn uniaxial compression crack initiation mode and crack growth path length of the fissured rock mass under the action of no hydraulic pressure and 1MPa stable osmotic pressure are shown in Table 1. In the process of uniaxial compression of fissured rock mass, the initial initiation crack is generally tensile, and with the increase of vertical stress, the initial crack will continue to propagate but will stop propagate after a certain extent due to insufficient tensile stress at the initial crack tip.

10.1371/journal.pone.0307700.t001 Table 1 Initial crack propagation table of fissured rock mass (unit: mm).

Non-hydraulic	Stabilized hydraulic	
Test result	Diagrammatic sketch	Test result	Diagrammatic sketch	
Non-hydraulic-0°-Test result	Non-hydraulic-0°-Diagrammatic sketch	Stabilized hydraulic-0°-Test result	Stabilized hydraulic-0°-Diagrammatic sketch	
Non-hydraulic-15°-Test result	Non-hydraulic-15°-Diagrammatic sketch	Stabilized hydraulic-15°-Test result	Stabilized hydraulic-15°-Diagrammatic sketch	
Non-hydraulic-30°-Test result	Non-hydraulic-30°-Diagrammatic sketch	Stabilized hydraulic-30°-Test result	Stabilized hydraulic-30°-Diagrammatic sketch	
Non-hydraulic-45°-Test result	Non-hydraulic-45°-Diagrammatic sketch	Stabilized hydraulic-45°-Test result	Stabilized hydraulic-45°-Diagrammatic sketch	
Non-hydraulic-60°-Test result	Non-hydraulic-60°-Diagrammatic sketch	Stabilized hydraulic-60°-Test result	Stabilized hydraulic-60°-Diagrammatic sketch	
Non-hydraulic-75°-Test result	Non-hydraulic-75°-Diagrammatic sketch	Stabilized hydraulic-75°-Test result	Stabilized hydraulic-75°-Diagrammatic sketch	
Non-hydraulic-90°-Test result	Non-hydraulic-90°-Diagrammatic sketch	Stabilized hydraulic-90°-Test result	Stabilized hydraulic-90°-Diagrammatic sketch	

As shown in Table 1, the initial crack propagation mode and path length of the fissured rock mass show that the initial crack propagation length of the fissured rock mass under stable osmotic pressure is significantly greater than that of the specimen without hydraulic pressure. During the test, the stable hydraulic pressure acted steadily on the precast fissure surface, and when the initial crack of the fissured rock mass was initiated, the stable hydraulic pressure immediately poured into the new crack surface. On the one hand, the initial crack was continuously subjected to the tensile stress of the hydraulic pressure, and the initial crack growth was mainly affected by the tensile stress. Therefore, the stable hydraulic pressure promoted the development and growth of the initial crack. On the other hand, the softening effect of the hydraulic pressure on the crack specimen reduced the tensile fracture ability of the fissure rock mass and the threshold of the initial crack initiation. Compared with the initial crack development of the fissured rock mass under different dip angles, the crack propagation length of low-dip fissured rock mass is generally higher than that of the crack specimens with large dip angles, and the propagation path also results in a larger area of hydraulic pressure and a more obvious effect. In terms of mechanical characteristics, the gap between peak strength and elastic modulus is larger at low dip angles.

4.4 Acoustic emission characteristics

4.4.1 Acoustic emission ringing count

According to the acoustic emission test results and combined with the time stress data of the test, the variation curves of acoustic emission ringing count and total ringing count (total ringing count) in the loading process of the fissure rock mass were drawn, as shown in Fig 9 (specimens with 0°, 45°, and 90° crack inclination angles were mainly taken for analysis).

10.1371/journal.pone.0307700.g009 Fig 9 Characteristic curve of acoustic emission ringing count and its total number change.

(a) Non-hydraulic-0°. (b) Stabilized hydraulic-0°. (c) Non-hydraulic-45°. (d) Stabilized hydraulic-45°. (e) Non-hydraulic-90°. (f) Stabilized hydraulic-90°.

As shown in Fig 9, the acoustic emission ringing count of fissured rock mass under different times and stress can be roughly divided into four stages: The first stage is in the initial compaction stage of loading, and the stress is roughly 0~30% of the peak strength. In this stage, the micro-pores inside the fissured rock mass are compressed, while the fissured rock mass made of cement mortar contains more micro-pores. With the closure of the micro-pores, weak elastic waves are released continuously, and more acoustic emission ringing counts of medium and low frequency appear. The second stage is the elastic deformation stage, in which the stress is roughly 30%~50% of the peak strength, most of the micropores inside the fissured rock mass are compressed, the acoustic emission ringing count is stable without large fluctuation, and there is almost no obvious macroscopic fracture behavior inside the rock mass. The third stage is the plastic deformation stage of crack initiation and propagation. At this stage, crack initiation and propagation begin to occur in the fissure rock mass, and there are more middle and high-frequency acoustic emission ringing counts. The fourth stage is the fissure rock mass failure stage, which is near the peak stress, cracks in the fissure rock mass accelerate expansion, mutual penetration leads to final failure, crack surfaces friction with each other, and acoustic emission ringing count rate suddenly increases sharply at the failure moment.

From the cumulative total number of acoustic emission ringing counts, it can be seen that during the loading process, the total number of acoustic emission ringing in the fissure rock mass subjected to stable hydraulic pressure is significantly lower than that in the specimen without hydraulic pressure, and the trend is also relatively stable. During the uniaxial loading process of the fissure rock mass, the acoustic emission ringing count mainly comes from the internal microporous gap compaction closure in the early stage of loading, the crack initiation and propagation in the middle and later stages, and the mutual friction between cracks. The hydraulic pressure acts on the prefabricated crack surface, and as the crack initiation and propagation enter the new crack surface, the acoustic emission ringing count generated by the mutual dislocation friction between cracks is reduced, weakening the acoustic emission signal when the fissure rock mass breaks.

4.4.2 Peak acoustic emission frequency

In the loading process, the peak acoustic emission frequency is the maximum amplitude value of the acoustic emission signal waveform, which is directly related to the size of acoustic emission events. The AE data results of the fissure rock mass with angles of 0°, 45°, and 90° were taken to draw the variation curve of peak frequency in the loading process of the fissure rock mass, as shown in Fig 10. The acoustic emission signals generated by tension rupture have the characteristics of short waveform, short rise time, and high frequency, while the acoustic emission signals generated by shear rupture have the characteristics of long waveform, long rise time, and low frequency [24]. He Manchao et al. [25] believe that the complexity of frequency components indicates the occurrence of multiple rupture modes.

10.1371/journal.pone.0307700.g010 Fig 10 Acoustic emission peak frequency variation curve.

(a) Non-hydraulic-0°. (b) Stabilized hydraulic-0°. (c) Non-hydraulic-45°. (d) Stabilized hydraulic-45°. (e) Non-hydraulic-90°. (f) Stabilized hydraulic-90°.

The peak frequency of the fissured rock mass with no hydraulic pressure and stable osmotic pressure is mainly concentrated in the range of 0~100kHz, followed by the range of 100 ~200kHz, and only a few frequency signals appear in the region above 200kHz. Compared with the fissured rock mass under hydraulic pressure, there are more peak frequency signals in the range of 100kHz~200kHz in the early loading stage without hydraulic pressure, and the distribution of acoustic emission peak frequency signals is more uniform in the loading process of the fissured rock mass under stable hydraulic pressure. These phenomena indicate that the fracture morphology of fractured rock masses is more complex under no water pressure than under stable water pressure.

5 Discussion

5.1 Damage model

Acoustic emission ringing count is one of the characteristic parameters that can better reflect changes in material properties, as it is proportional to the strain energy released by the movement, fracture, and crack propagation of dislocations in the material [26]. This article describes the damage evolution characteristics of fissured rock masses using acoustic emission ringing count and cumulative ringing count as characteristic parameters.

The damage variable can be defined as D=AdA (1)

In the formula: Ad is the cross-sectional area of the rock sample that undergoes compaction, the generation, propagation, convergence, and penetration of new cracks, until macroscopic damage occurs; A is the initial cross-sectional area without damage. If the cumulative acoustic emission ringing count for complete failure of the entire cross-section A of the non-destructive material is C0, then the acoustic emission ringing count Cw for micro element failure per unit area is Cw=C0A (2)

When the cross-sectional damage area reaches Ad, the cumulative acoustic emission ringing count Cd is Cd=Cw=C0AAd (3)

Therefore, there are D=CdC0 (4)

5.2 Damage evolution analysis

According to the damage variable defined by the acoustic emission ringing count in Eq (4), combined with the acoustic emission ringing count in the experiment, the curve of the damage variable changes with loading time, as shown in Fig 11. From the graphical results, it can be seen that the damage evolution process of fissured rock mass during loading can be roughly divided into four stages, as shown in Fig 12.

10.1371/journal.pone.0307700.g011 Fig 11 Damage variable evolution curve.

(a) Non-hydraulic-0°. (b) Stabilized hydraulic-0°. (c) Non-hydraulic-45°. (d) Stabilized hydraulic-45°. (e) Non-hydraulic-90°. (f) Stabilized hydraulic-90°.

10.1371/journal.pone.0307700.g012 Fig 12 Characteristic curve of damage variable stage.

Stage 1: This stage is mainly the stage of pore compaction inside the fissured rock mass. Due to the fact that the rock mass material prepared with cement mortar has more internal pores compared to the real rock, some acoustic emission events will occur during this stage, leading to damage.

Stage 2: This stage is the elastic damage stage, and the fissured rock mass is mainly in the elastic deformation stage. The increase in internal damage is approximately linear, and the acoustic emission events are relatively stable.

Stage 3: During this stage, macroscopic cracks gradually emerge in the fissured rock mass, and the damage to the rock mass gradually reaches a critical value. The cracks continue to initiate and expand, and the acoustic emission activity gradually becomes active. However, compared to specimens without hydraulic pressure, the fissured rock mass under stable hydraulic pressure is affected by the action of permeable water. During the process of crack initiation and expansion, permeable water can enter new crack surfaces, reducing the number of acoustic emission events and making the damage growth of the fissured rock mass similar to that of the elastic damage stage.

Stage 4: This stage is the damage and failure stage. Due to the rapid accumulation of damage to the specimen, the number of acoustic emission events increases significantly, and the damage variable suddenly increases, causing the specimen to fail.

From the evolution process of acoustic emission damage in rocks, it can be seen that the initiation and evolution of cracks and damage, stable development until the occurrence of large-scale crack propagation, and then the entire process from crack propagation to macroscopic fracture of the rock sample. Using the cumulative ringing count of acoustic emission as a characterization parameter to analyze the damage evolution and failure of rocks can better reflect the gradual evolution process from the initiation and propagation of internal cracks to failure. From the curve of damage variables, it can be seen that under stable hydraulic pressure, the changing trend of damage variables in the fissured rock mass is more stable. In the absence of hydraulic pressure, the variation trend of damage variables fluctuates more greatly, and the rate of damage increase is also unstable, indicating that the failure mode of fissure specimens without water pressure is more complex. This conclusion is consistent with the results exhibited by peak frequency.

6 Conclusion

Independently developed a test system that can continuously and stably provide hydraulic pressure in the process of crack initiation and propagation of fissured rock mass, and verified by the characteristic curve of hydraulic pressure variation during the experiment.

Under the effect of stable hydraulic pressure, the change law of peak strength of fissured rock mass with the increase of crack Angle changes from first decreasing and then increasing in the absence of hydraulic pressure to increasing law, and the peak strength and elastic modulus are lower than those of fissured rock mass without hydraulic pressure.

The crack propagation length of low-dip fissured rock mass is generally higher than that of large-dip fissured rock specimens. The propagation path length increases the range and effect of hydraulic pressure, and the initial crack propagation length of the fissured rock mass under hydraulic pressure is also significantly greater than that of the specimens without hydraulic pressure.

The acoustic emission ringing count and damage variable can be roughly divided into four stages. From the cumulative total number of acoustic emission ringing counts, the total number of acoustic emission ringing in fissured rock masses subjected to hydraulic pressure is significantly lower than that in specimens without hydraulic pressure, and the trend is also relatively stable.

Supporting information

S1 Dataset (DOCX)

S2 Dataset (DOCX)

S1 Table (ZIP)

10.1371/journal.pone.0307700.r001
Decision Letter 0
Trippetta Fabio Academic Editor
© 2024 Fabio Trippetta
2024
Fabio Trippetta
https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Submission Version0
20 May 2024

PONE-D-24-14746Tunnel and underground engineering rock mass water inrush damage and acoustic emission characteristicsPLOS ONE

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Comments to the Author

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The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This paper conducted a fracture failure test of fissured rock mass under stable hydraulic pressure using a self-developed stable hydraulic pressure device, verified the feasibility of the test system, and analyzed the acoustic emission characteristics and damage evolution law of the fracture failure process. The research content of this article is novel, and the research results have certain guiding significance for the prevention and control of water inrush disasters in tunnels and geotechnical engineering. Suggest receiving after minor optimizations and improvements.

1. Figure 1 shows the CAD diagram of a stable infiltration water pressure system. Please provide a laboratory diagram of the test system

2. In Section of “2 Test preparation”, The CAD specimen diagram in Figure 1 can depict the dimensions, and there are duplicate labels in the diagram. Please check and correct them

3. In Section of “2 Test preparation”, “After the initial setting of the specimens, the water injection rods were pulled out and the steel sheets were embedded. ” This sentence describes some issues. I would like to know if "the steel sheets were embedded" should be pulled out or embedded at this time?

4. In Section of “Introduction” , "The rock-like materials in this test are made by mixing 425 white cement: fine sand: water at the mass ratio of 5:5:2." I'd like to know how to ensure the homogeneity of the sample ?

5. In the peak intensity of Figure 6, is the data taken as a single specimen or the average of multiple specimens? If it is multiple, please indicate the number of specimens.

6. Please unify the words "osmotic water pressure" and "water pressure" in the paper

7. Please unify the words "osmotic water pressure, water pressure, hydraulic pressure, etc." in the paper.

8. In Figure 8, the time axis is used as the horizontal axis for the acoustic emission ringing count and stress curve. Is it convenient to convert the time axis to strain, and have other studies used time as the horizontal axis to describe it?

9. The color of the right vertical axis in Figure 10 (b) is inconsistent. Please check all information and language throughout the text.

Reviewer #2: The author independently developed a stable permeability hydraulic pressure device, conducted hydraulic-stress coupling tests on fractured rock masses, analyzed the mechanical characteristics and crack initiation modes of fissured rock masses, and explored the acoustic emission and damage characteristics during the loading process. Some useful conclusions were obtained, which are helpful for the prevention and control of water inrush disasters in tunnels and underground engineering. There are still some minor issues in this article that need further optimization and improvement.

1. Introduction, page 3: “ the gas-liquid concavity is used, and the liquid is driven by pressure to apply water pressure. ” Could you please explain the meaning of “the gas-liquid concavity” here.

2. Figure 1 only shows a schematic diagram, without the actual equipment diagram during indoor testing. It is best to describe and explain it in conjunction with the actual diagram.

3. Test preparation, page 4: Figure 1 has duplicate naming. Please check all figures, tables, titles, and other serial numbers to correct any issues.

4. Test preparation, page 4: “The steady water pressure test was carried out in strict accordance with the following steps”. More precise and concise description of the experimental steps during the loading process.

5. The author's review of the latest related research on tunnel safety, rock crack propagation, and non-destructive testing is insufficient. The following latest published literature can provide reference for the author's research:

[1] Case study on the secondary support time and optimization of combined support for a roadway under high in-situ stress. Geomechanics and Geophysics for. Geo-Energy and Geo-Resource. 2024, 10(1): 66. https://doi.org/10.1007/s40948-024-00774-w

[2] Analytical solution of the stress field and plastic zone at the tip of a closed crack. Frontiers in Earth Science, 2024, 12: 1370672. https://doi.org/10.3389/feart.2024.1370672

[3] Experimental study of dynamic characteristics of tailings with different reconsolidation degrees after liquefaction. Frontiers in Earth Science, 2022, 10: 876401. https://doi.org/10.3389/feart.2022.876401

6. Different descriptive words such as “osmotic water pressure”, “osmotic water pressure”, “no hydraulic pressure”, and “non-hydraulic” appear in the text. Please check the relevant vocabulary and provide a unified description

7. In section 3.4.2, the author selected the peak frequency of acoustic emission for analysis. Please further explain the information characterizing the peak frequency of acoustic emission and explain the pattern of acoustic emission frequency.

8. Discussion, page 15: The font size of the first paragraph of this section does not match the font size of the previous and subsequent articles. Please verify and modify it.

9. Figure 10: The color of some image coordinate axes is inconsistent with other graphics. In the analysis, it should be added to analyze the differences in acoustic emission damage under two types of loads: Non-hydraulic and Stabilized hydraulic.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: No

**********

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10.1371/journal.pone.0307700.r002
Author response to Decision Letter 0
Submission Version1
31 May 2024

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Tunnel and underground engineering rock mass water inrush damage and acoustic emission characteristics” ( Manuscript #PONE-D-24-14746 ). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. However, some reviewers did not provide direct comments or questions. Revised portion are marked in “Revised Manuscript with Track Changes”. The main corrections in the paper and the responds to the reviewer’s comments are as flowing:

Responds to the reviewer’s comments:

Reviewer #1: This paper conducted a fracture failure test of fissured rock mass under stable hydraulic pressure using a self-developed stable hydraulic pressure device, verified the feasibility of the test system, and analyzed the acoustic emission characteristics and damage evolution law of the fracture failure process. The research content of this article is novel, and the research results have certain guiding significance for the prevention and control of water inrush disasters in tunnels and geotechnical engineering. Suggest receiving after minor optimizations and improvements.

1. Figure 1 shows the CAD diagram of a stable infiltration water pressure system. Please provide a laboratory diagram of the test system

Response: According to the reviewer's comments, the author has placed the actual diagram of the laboratory testing device in Figure 1.

2. In Section of “2 Test preparation”, The CAD specimen diagram in Figure 1 can depict the dimensions, and there are duplicate labels in the diagram. Please check and correct them

Response: Thank you for the reviewer's reminder. The author has checked and corrected any duplicates in the article.

3. In Section of “2 Test preparation”, “After the initial setting of the specimens, the water injection rods were pulled out and the steel sheets were embedded. ” This sentence describes some issues. I would like to know if "the steel sheets were embedded" should be pulled out or embedded at this time?

Response: “After waiting for the initial setting of the specimen, first pull out the water injection rod, and then pull out the steel sheet to form a through fissure with water injection holes”

4. In Section of “Introduction” , "The rock-like materials in this test are made by mixing 425 white cement: fine sand: water at the mass ratio of 5:5:2." I'd like to know how to ensure the homogeneity of the sample ?

Response: The uniformity of each specimen is ensured through the following methods: during the preparation of specimens, the mix proportions of various materials are strictly controlled, and the materials are placed in the mixer in order. The same mixing time is set for each batch of specimens, and after mixing, they are poured into the mold and vibrated at the same speed and time to form the specimens. After demolding, place it in the same standard curing environment for curing, ensuring the uniformity of each specimen.

5. In the peak intensity of Figure 6, is the data taken as a single specimen or the average of multiple specimens? If it is multiple, please indicate the number of specimens.

Response: The peak intensity in Figure 6 is taken as the average of six sets of data, which will be explained in the corresponding positions in the text.

6. Please unify the words "osmotic water pressure" and "water pressure" in the paper

Response: Thank you to the reviewers for their careful review. The author has checked and unified the wording of the entire article.

7. Please unify the words "osmotic water pressure, water pressure, hydraulic pressure, etc." in the paper.

Response: The author has checked the entire article and made revisions to any inappropriate or inconsistent wording.

8. In Figure 8, the time axis is used as the horizontal axis for the acoustic emission ringing count and stress curve. Is it convenient to convert the time axis to strain, and have other studies used time as the horizontal axis to describe it?

Response: When analyzing acoustic emission data, strain or time is usually used as the horizontal axis, while acoustic emission collection is usually collected in units of time. When using displacement loading mode, the transformation relationship between strain and time is relatively direct, and in this case, strain is usually used as the abscissa for analysis. When using force loading mode, the transformation relationship between strain and time is non-linear, so time is usually used as the horizontal axis for analysis. As shown in the following literature:

Chen Q, Zhengyang S, Yu W, et al. Fractures and Acoustic Emission Features of Non-persistent Jointed Rocks Subjected to Freeze–Thaw-Compression Load: Experimental Insights[J]. Rock Mechanics and Rock Engineering, 2022(1):55.DOI:10.1007/s00603-021-02667-w.

9. The color of the right vertical axis in Figure 10 (b) is inconsistent. Please check all information and language throughout the text.

Response: Based on the comments of the reviewers, the author has made modifications to the positions indicated by the reviewers and checked and improved the image and language information throughout the entire text.

Reviewer #2: The author independently developed a stable permeability hydraulic pressure device, conducted hydraulic-stress coupling tests on fractured rock masses, analyzed the mechanical characteristics and crack initiation modes of fissured rock masses, and explored the acoustic emission and damage characteristics during the loading process. Some useful conclusions were obtained, which are helpful for the prevention and control of water inrush disasters in tunnels and underground engineering. There are still some minor issues in this article that need further optimization and improvement.

1. Introduction, page 3: “ the gas-liquid concavity is used, and the liquid is driven by pressure to apply water pressure. ” Could you please explain the meaning of “the gas-liquid concavity” here.

Response: The improper use of words here has caused difficulties in reading. "The gas liquid concentration" should be "Gas and liquid in one chamber". The author has made modifications.

2. Figure 1 only shows a schematic diagram, without the actual equipment diagram during indoor testing. It is best to describe and explain it in conjunction with the actual diagram.

Response: According to the reviewer's comments, the author has placed the actual diagram of the laboratory testing device in Figure 1.

3. Test preparation, page 4: Figure 1 has duplicate naming. Please check all figures, tables, titles, and other serial numbers to correct any issues.

Response: The author has made corrections to the information mentioned by the reviewer and checked the entire text.

4. Test preparation, page 4: “The steady water pressure test was carried out in strict accordance with the following steps”. More precise and concise description of the experimental steps during the loading process.

Response: Thank you for the reviewer's reminder. The step description here is too long. The author will make appropriate modifications to the description here to make it more precise and concise.

5. The author's review of the latest related research on tunnel safety, rock crack propagation, and non-destructive testing is insufficient. The following latest published literature can provide reference for the author's research:

[1] Case study on the secondary support time and optimization of combined support for a roadway under high in-situ stress. Geomechanics and Geophysics for. Geo-Energy and Geo-Resource. 2024, 10(1): 66. https://doi.org/10.1007/s40948-024-00774-w

[2] Analytical solution of the stress field and plastic zone at the tip of a closed crack. Frontiers in Earth Science, 2024, 12: 1370672. https://doi.org/10.3389/feart.2024. 1370672

[3] Experimental study of dynamic characteristics of tailings with different reconsolidation degrees after liquefaction. Frontiers in Earth Science, 2022, 10: 876401. https://doi.org/10.3389/feart.2022.876401

Response: Thank you for the reviewer's comments. I have reviewed the literature recommended by the reviewers. The following literature has studied the rheological problem of tunnel surrounding rock, which is somewhat related to the underground and tunnel engineering surrounding rock disasters investigated in the article literature. Therefore, it is used as a reference for citation.

“Case study on the secondary support time and optimization of combined support for a roadway under high in-situ stress. Geomechanics and Geophysics for. Geo-Energy and Geo-Resource. 2024, 10(1): 66. https://doi.org/10.1007/s40948-024- 00774-w”

6. Different descriptive words such as “osmotic water pressure”, “osmotic water pressure”, “no hydraulic pressure”, and “non-hydraulic” appear in the text. Please check the relevant vocabulary and provide a unified description

Response: The author has checked the entire article and made revisions to any inappropriate or inconsistent wording.

7. In section 3.4.2, the author selected the peak frequency of acoustic emission for analysis. Please further explain the information characterizing the peak frequency of acoustic emission and explain the pattern of acoustic emission frequency.

Response: Thank you for the reviewer's comments. The author has improved the meaning of acoustic emission frequency and the information expressed in this type of acoustic emission frequency in the article.

8. Discussion, page 15: The font size of the first paragraph of this section does not match the font size of the previous and subsequent articles. Please verify and modify it.

Response: Thank you for the careful review by the reviewer. The author has made corrections to the font and formatting errors in the text.

9. Figure 10: The color of some image coordinate axes is inconsistent with other graphics. In the analysis, it should be added to analyze the differences in acoustic emission damage under two types of loads: Non-hydraulic and Stabilized hydraulic.

Response: The author has made changes to the coordinate information based on the comments of the reviewers. Regarding the analysis section, an analysis of the differences in acoustic emission damage between no water pressure and stable water pressure has been added.

Attachment Submitted filename: Response to Reviewers.docx

10.1371/journal.pone.0307700.r003
Decision Letter 1
Trippetta Fabio Academic Editor
© 2024 Fabio Trippetta
2024
Fabio Trippetta
https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Submission Version1
8 Jul 2024

Tunnel and underground engineering rock mass water inrush damage and acoustic emission characteristics

PONE-D-24-14746R1

Dear Dr. Zeng,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Fabio Trippetta, Ph.D.

Academic Editor

PLOS ONE

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: All my comments have been properly replied or addressed. I think it can be accepted in the present form.

Reviewer #2: The manuscript has been carefully revised and its quality has significantly improved, making it suitable for acceptance.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

**********

10.1371/journal.pone.0307700.r004
Acceptance letter
Trippetta Fabio Academic Editor
© 2024 Fabio Trippetta
2024
Fabio Trippetta
https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
11 Jul 2024

PONE-D-24-14746R1

PLOS ONE

Dear Dr. Zeng,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

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on behalf of

Prof. Fabio Trippetta

Academic Editor

PLOS ONE
==== Refs
References

1 Jingyao Gao , Siyu Peng , Guangqi Chen , Yasuhiro Mitani , Hongyun Fan . Coupled hydro-mechanical analysis for water inrush of fractured rock masses using the discontinuous deformation analysis. Computers and Geotechnics, 2023, 156 :105247. doi: 10.1016/J.COMPGEO.2023.105247
2 Dan Ma , Hongyu Duan , Jixiong Zhang , Haibo Bai . A state-of-the-art review on rock seepage mechanism of water inrush disaster in coal mines. International Journal of Coal Science Technology, 2022, 9 (1 ). doi: 10.1007/s40789-022-00525-w
3 Dan Ma , Hongyu Duan , Jixiong Zhang , Xianwei Liu , Zhenhua Li . Numerical Simulation of Water-Silt Inrush Hazard of Fault Rock: A Three-Phase Flow Model[J]. Rock Mechanics and Rock Engineering, 2022, 55 (8 ):5163–5182. doi: 10.1007/s00603-022-02878-9
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