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Article

Protection Technique of Support System for Dynamic Disaster in Deep Underground Engineering: A Case Study

by
Yunqiu Liu
1,2,
Yuemao Zhao
3,*,
Kun Wang
3,
Gongcheng Li
4 and
Zhengchen Ge
3
1
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China
2
Sionsteel Maanshan General Institute of Mining Research Co., Ltd., Maanshan 243000, China
3
College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China
4
School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049, China
*
Author to whom correspondence should be addressed.
Sustainability 2023, 15(9), 7165; https://doi.org/10.3390/su15097165
Submission received: 2 April 2023 / Revised: 19 April 2023 / Accepted: 20 April 2023 / Published: 25 April 2023
(This article belongs to the Special Issue Analysis and Modeling for Sustainable Geotechnical Engineering)
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Versions Notes

Abstract

:
During excavation in a deep tunnel, dynamic disaster is an extremely severe impact failure. The necessity of an energy-absorbing support system is analyzed for different characteristics of dynamic disaster (rockburst) failure. The energy-absorbing support system design includes a combination of early-warning, energy-absorbing bolts, and other components. This support system is designed to meet the energy requirement of a rockburst disaster based on an early warning. The energy-absorbing rockbolt uses the stepwise decoupling technique to realize the brittle-ductile transition of the structure, which is referred to as a stepwise decoupling rockbolt (SD-bolt). The ultimate force, ultimate deformation, and energy were calculated as 241 kN, 442.3 mm, and 95.89 kJ under static pull-out load. Monitored by a microseismic system, the support system was tested by moderate rockburst disaster impact on site. Considering similar rockburst disaster failure cases, this energy-absorbing support system can reduce rockburst disaster damage to a certain extent and improve overall safety during deep engineering construction.

1. Introduction

Dynamic disaster(rockburst) is usually used to describe a high-energy seismic event resulting in severe shock failure in deep-buried engineering. The severity and difficulty of rockburst disaster prediction make its prevention and control extremely challenging. Therefore, it is critical to understand the rockburst disaster origin mechanism, formation process, and failure characteristics to develop targeted strategies [1]. The techniques for prevention and control of rockburst disasters include the comprehensive use of measures such as Microseismic (MS) monitoring and early warning systems, blast optimization, stress release, and the use of an energy-absorbing support system [2]. Controlling rockburst disaster hazards may protect workers and equipment as well as reduce costs for mine or tunnel owners [3].
In deep-buried engineering, supporting components such as rockbolt need sufficient yield capacity to avoid tensile fracture under severe deformation conditions [4]. Some energy-absorbing rockbolts, such as the cone bolt [5] and the Yield-Lok [6], rely on the rockbolt head to slide inside the material to produce a constant resistance. Other energy-absorbing rockbolts, such as Garford bolt [7], Roofex [8], DC-bolt [9], and novel energy-absorbing rockbolt [10], usually consists of two fixed points, with a constant resistance device in the middle. The D-bolt [11] is an energy-absorbing rockbolt with rockbolt points and a smooth bolt structure, which can reduce the load on the bolt in an environment of major squeezing deformation or rockburst disaster. The CRLD bolt [12] is a new type of rockbolt made of material with a negative Poisson’s ratio, which can effectively limit the hazards that result from large deformation and dynamic disasters. In addition to the rockbolt body, an axial splitting component [13] is demonstrated as an ideal energy absorber for energy-absorbing rockbolts. However, the widespread use of most current energy-absorbing rockbolts described above is limited by cost and deformation capacity expansibility.
Most energy-absorbing support system designs are not integrated with on-site monitoring but are based on basic engineering geological information [14]. When the geological engineering conditions change, the timing, location, and intensity of rockbursts may change, causing support design parameters to become inaccurate and non-targeted. MS monitoring systems are often used at project sites to monitor and evaluate the evolution process of rockbursts [15]. Methods for assessment and management of rockburst risks [16] can be applied to obtain the occurrence probability, potential consequences, and risk intensities of rockbursts during tunnel excavation, which can facilitate the appropriate timing of mitigation measures. The accuracy of rockburst monitoring and early warning is constantly improving [17], and improved accurate monitoring provides a basis for on-site dynamic support design.
A combination of an MS early warning technique and parameterized energy-absorbing support system may be required for different energy intensities [18]. The rockbolt structure design should be able to ensure strong deformation ability under high working resistance. In engineering practice, the evolution law of rockburst may be further revealed, allowing reasonable support strategies to reduce potential loss arising from rockburst damage [19,20,21,22,23,24]. Field tests of energy-absorbing rockbolt are required to demonstrate their actual engineering effect.

2. Rockburst Failure Characteristics and Design of an Energy-Absorbing Support System

2.1. Engineering Background

Tunnel A is located on a plateau in southwestern China, with a maximum buried depth of about 2000 m and the main lithology of hard granite. Based on a preliminary numerical simulation analysis, most areas of the tunnel have a high dynamic disaster tendency. During the construction period, there was varying intensity, frequency, and morphology of rockbursts, with the longest duration of a single burst exceeding 100 h. It is difficult to predict the time, location, and intensity of rockbursts, which can cause physical and psychological stress to construction workers. Furthermore, rockbursts can cause damage to nearby machinery and equipment and result in a shutdown of a specific site, resulting in significant economic losses.
As shown in Figure 1, the construction cycle of a rockburst section includes such procedures as drilling and blasting, ventilation and slag discharge, risk removal and waiting (waiting for the rockburst to stop), and rockburst intensity evaluation and support. The risk removal work should focus on the removal of onion-shaped wall caving and pumice stones to prevent falling. During risk removal and support procedures, slight rockbursts may occur occasionally, but construction workers typically can avoid these events due to early detection of the noise. However, rockbursts sometimes occur without obvious warning noise and can cause rock block ejection accidents. Although wearing hard protective clothing during operation, builders may risk their lives during a construction cycle. To more effectively respond to rockburst disasters, construction units, universities, and other scientific research units typically develop in-depth analyses and studies on geostress near the working face, the intensity of rockburst, early warning of rockbursts, and preventive measures, establishing a platform for observation and early warning of rockburst including MS monitoring and advanced geological forecasting.

2.2. Failure Characteristics of Support System

The support system may not have sufficient impact resistance to sustain moderate and more intense rockburst. Once deep engineering has started, traditional support faces challenges of larger and faster energy release and thus is more likely to fail. For a rockburst of excessively high intensity, insufficient preparation of the impact resistance performance of the support systems in the rockburst area and adjacent areas usually leads to support failure or other problems. As shown in Figure 2, a support system composed of steel arch frames and bolt-mesh-shotcrete systems failed as a whole under the direct impact of a moderate rockburst. Disintegrated arch frame structures and bolts that were broken or pulled out were scattered on the ground, and large-scale caving of the rock mass also occurred. If a sudden rockburst occurred near the working face, it could pose a great threat to the working staff and equipment.
Inadequate connection strength caused the early failure of the support system, while partial structures were well maintained. Before starting deep engineering, traditional support is required to maintain stability. Some nodes in the support system may have high strength, but the overall system strength depends on the nodes of lower strength [25]. In many cases, the rockbolts in a support system do not break, but the shotcrete layer and the metal mesh are damaged by impact. Insufficient construction quality and failure of the rockbolt strength to meet the design strength will also lead to the extraction of rockbolts. As shown in Figure 3, the insufficient connection strength between the reinforced mesh, shotcrete, and rockbolts causes the support system to fail prematurely at the reinforced mesh connection. Finally, the reinforced mesh and shotcrete layer flew out, whereas the rockbolt was not damaged. Usually, an insufficient connection may be due to the need to complete the tunneling as soon as possible in some sections (restriction by the construction period to catch up with the schedule). Additionally, rockbolts (including nuts, plates, and threaded rod bodies) and metal meshes are primarily welded together. According to laboratory test data [26], after welding a Ø22 mm diameter rockbolt to steel mesh, the connection force was usually only 5–10 kN, which was significantly lower than the strength of the screw connection.
In deep high-stress areas, when impact disasters such as dynamic disasters occur, rockbolt structures are usually subject to brittle rupture [27,28]. Therefore, the design of energy-absorbing rockbolts should include a structure that is capable of ductile deformation to dissipate the energy released by dynamic impact through its deformation and ultimate load-carrying capacity. Relevant research showed that decoupling the threads on the rockbolt body from the rebar material through the sealing material can inhibit the expansion of rock mass cracks [29]. In addition, if an energy-absorbing rockbolt includes conventional materials, the cost will be substantially reduced.
An energy-absorbing rockbolt was designed that uses the stepwise decoupling technique to realize the brittle-ductile transition of the structure, which is referred to as a stepwise decoupling rockbolt (SD-bolt). As shown in Figure 4a, the design uses threaded steel rockbolts, and the threaded rockbolt body is wrapped with a thin (40–80 μm) layer of tape. As shown in Figure 4b–d, due to the separation of the rock mass, the rockbolt body shrinks radially when its axial load reaches the yield point and gradually decouples from the rockbolt material. If complete decoupling is not reached in this area, a certain shear force can still be maintained in the coupled area to constrain crack propagation in the rock mass (this is why this is described as stepwise decoupling). Because friction is not eliminated, the stepwise decoupling technique differs from the isolation effect due to partial or complete decoupling previously described in many studies and patents [30]. Ordinary threaded steel rockbolts fracture due to small displacement, and the overall structure can be regarded as a brittle structure [28]. With the use of the stepwise decoupling technique, the overall structure can sustain a large displacement and can be considered a ductile structure. The use of energy-absorbing rockbolts and utilization of the stepwise decoupling technique enables the whole rockbolt structure to achieve a brittle-ductile transition. The rockbolt should first protect itself so that it can adapt to the displacement of the rock, absorb the energy from the rock mass, and realize continuous constraints of rock damage.
An anchorage adjuster in Figure 4a can be used as a supplement when the rockbolt length is too short to increase the rockbolt force of the rockbolt, allowing the brittle-ductile transition. When the rockbolt length is too short, that is, if the rockbolt binding force formed by the coupling between the threaded section and the rockbolt material is lower than the breaking load, the rockbolt will slip and fail. For example, multiple nuts can be added at the end of the rockbolt as rockbolt adjusters.

3. Engineering Applications

3.1. Energy-Absorbing Support System for Moderate Dynamic Disaster

An on-site MS monitoring system was established in the railway tunnel to determine the possible location, timing, and intensity of the rockburst. The temporal and spatial evolution law of MS events during the development of multiple types of rockbursts was subsequently obtained [31]. Long-term MS monitoring in the railway tunnel was used to determine the characteristics of MS activities during the formation of intermittent rockbursts. Early warnings of the intensity of rockburst risks during tunnel excavation are based on dynamic real-time MS data and rockburst early-warning formulas [32]. The use of this method allows the determination of the probability of strain-type and strain-structure slip rockbursts of different intensities [33].
Following the Engineering Rock Mass Classification Standard GB/T50218-2014 [34], the rock mass in the rockburst area is Class II, which means that the excavation face can be stabilized. The main lithology of the tunnel working face and the wall rock is dominated by granite that is gray-white and block-like. There are two sets of joints at the working face. One set of joints ranges between 10° and 60° with joints slightly stretched, are filled but unweathered, and are distributed at the working face and extend to the roof arch. The other set of joints have a range of 280°∠80°, are open, filled, but unweathered, have a spacing of about 1 m, and are distributed on the wall rock on both sides and traverse the tunnel. The wall rock and roof arch rock body in section DK 0 + 203 – DK 0 + 205 are dry without dripping and have relatively developed joints, consistent with Class II. It contains two sets of joints, as shown in Table 1.
A slight rockburst occurred on 9 September 2019, and the position of the working face was around DK 0 + 207. Prior to this working face, a conventional non-energy-absorbing (conventional) support system was installed. After blasting on the morning of 10th September, the face was excavated to DK 0 + 209. The rockburst early warning predicted slight to moderate rockburst in the area ranging from DK 0 + 185 to DK 0 + 220. As shown in Figure 5, a moderate energy-absorbing support system design was recommended. Thus, the construction of an energy-absorbing support system began at chainage DK 0 + 207 on the afternoon of 10th September.
The design parameters of the energy-absorbing support system commonly used in moderate rockburst areas are as follows: 3 m long shell-type pre-stressed hollow grouting rockbolts with a bolt spacing of 1.0 m × 1.0 m, initial shotcrete C25 of 50 mm thickness, Ø6 mm steel mesh spacing of 250 mm × 250 mm, re-sprayed C25 concrete thickness of 50 mm, and no steel arch. To easily compare test results, the energy-absorbing rockbolts on the site optimize only the stepwise decoupling section and the fastening method (nuts). After optimization of the lengths of the stepwise decoupling sections, the structures of the energy-absorbing rockbolts were determined, as shown in Figure 6. The stepwise decoupling section length was set to 500 mm. The length of the exposed fastening section of the rockbolt was set to 200 mm. Moderate rockburst pits are usually 0.5–1 m, and the length of the rockbolt meets the design requirements. Other construction support parameters are shown in Table 2.

3.2. Pull-Out Test of Energy-Absorbing Rockbolt

The quality of construction determines the effect of a designed support system. The relative amount of steel fiber addition and the degree of stirring uniformity determines the overall impact resistance of the support system [35]. The grouting effect of the hollow grouted rockbolts and the coupling and tightening degree of the steel mesh and shotcrete also determine whether the impact resistance of the support system meets the design requirements. A rockbolt effect with the utilization of energy at the same strength as the bolt body is required for the brittle-ductile transition of the rockbolt structure.
As shown in Figure 7 and Table 3, a pull-out test was conducted to test the rockbolt and energy-absorbing effects. After the rockbolt was gradually decoupled and the peak load remained unchanged, the ultimate deformation increased from 30.41 mm to 72.32 mm after the free length was increased. At least two nuts should be provided to fasten the rockbolts to ensure a brittle-ductile transition. In addition, the elongation rate of the hollow grouted rockbolt material used at the site is low. In the future, bolts with higher strength and elongation should be used.

3.3. Response of the Support System under Rockburst Impact

At 20:20:49 on 11 September, blasting operations were carried out, with about 4.1 m tunneled. At 01:25:34 on 12 September, during spoil removal, a moderate rockburst occurred at the left arch shoulder and top arch near the working face. The rockburst generated a large number of microseismic events and affected an area of 0–7 m behind the working face (Figure 8).
The depth of the pit was about 0.5–1 m, indicating moderate rockburst, as shown in Figure 9a. As shown in Figure 9b, the rockbursts were mainly distributed in two close areas. The red area on the right indicates the area of moderate rockburst area near the working face. The blue grid area on the left indicates the location of the energy-absorbing support system. This shows that the moderate rockburst may be constrained in this area.
Rock ejection from the working face caused the glass of the excavator to break, but no casualties (Figure 10b). Although the rockburst occurred above the excavator, it only caused cracking of the support system. The crack depth was more than 100 mm, and the crack width was about 50–60 mm. The bolt yielded after impact and did not break (Figure 10c). Although the support layer cracked, it did not collapse, thus maintaining the safety of personnel and equipment. Additional information is presented in Table 4.

4. Discussion

Failure characteristics of an energy-absorbing support system should be compared for a region with approximately the same engineering geology, a non-energy-absorbing support system, and a medium rockburst. A tunnel blast occurred around 3:40 on October 16, and slag discharge and risk removal procedures were normally carried out. A rockburst began near the vault on the left at 06:30. It peeled off at chainage DK 0 + 635, within 5 m behind the working face, and there were noises and falling blocks. The excavation face of DK0 + 630–640 was able to be stabilized. The lithology of the working face and surrounding rock is granite, and it is gray-white. Two groups of joints were present in the working face. One group of joints was slightly stretched, filled, unweathered, and distributed on the south side of the working face and extended to the south arch shoulder. The other group of joints remained open, with white and dark green fillings, unweathered and extended, distributed in the top arch and surrounding rock on the north side. The surrounding rock and nearby rock masses were dry, and the rock mass classification was judged as Grade II.
Under the rockburst impact of the same intensity, the failure characteristics and damage reduction effects of different types of support systems are different. Under the impact of the moderate rockburst, as shown in Figure 11, the shotcrete layer and partial rockbolts flew out with the rock block. In contrast, under the protection of the energy-absorbing support system, the shotcrete layer only cracked, and the energy-absorbing rockbolt yielded (Figure 10). There was no large-scale caving accident, indicating that the moderate rockburst was constrained. The specific failure characteristics are listed in Table 4. Thus, the utilization of an energy-absorbing support system can effectively prevent and mitigate rockburst damage.
SD-bolt is much cheaper than most energy-absorbing bolts. It is simple in structure and can be transformed by on-site materials. In terms of components, energy-absorbing rockbolt adds little to the economical cost compared to traditional rebar. Many new energy-absorbing rockbolts have been described recently, but most are difficult to use on a large scale because of their high cost. The energy-absorbing rockbolts described here have low costs and are easy to implement. The predicted rockburst intensity can be determined by a rockburst early warning system. The rockbolt will be targeted and will not be evenly distributed for each construction cycle. If this system is used on a large scale, it will reduce the overall cost.

5. Conclusions

(1)
A new type of energy-absorbing rockbolt was described, with a similar cost to that of conventional rockbolts. This rockbolt can support parameterized design according to energy requirements and has strong scalability. In combination with a rockburst early warning system, reasonable support parameters can be determined according to rockburst intensity. This support system has been successfully applied in controlling a moderate rockburst.
(2)
The early warning and dynamic support design obviously improve the ability to avoid serious consequences of rockburst. Using early warning data, a parameterized support system design can improve rockburst prevention and control results. Using real-time rockburst intensity data from the MS early warning platform, an appropriate energy-absorbing rockbolt and other parameters can be designed to meet the support requirements.
(3)
Field tests showed that the energy-absorbing support system could reduce damage arising from rockburst impact. For the same engineering geology and moderate rockburst, the use of the energy-absorbing support system can constrain the damage of moderate rockburst better than a non-energy-absorbing support system. The support system structure withstood the impact of the rockburst, thus protecting workers and equipment.

Author Contributions

Methodology, K.W.; Validation, G.L.; Formal analysis, Z.G.; Writing—original draft, Y.L.; Writing—review & editing, Y.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by [National Natural Science Foundation of China] grant number No. 52004152 and No. 52204142.

Data Availability Statement

The data are included in the original text.

Acknowledgments

The authors gratefully acknowledge financial support from the National Natural Science Foundation of China [grant No. 52004152, 52204142]. We also express our sincere thanks to Northeastern University (Shenyang), China Railway 12 Bureau Group Co., Ltd., and China Railway Eryuan Engineering Group Co., Ltd. for their kind help with the in-situ investigation and technical support.

Conflicts of Interest

The authors confirm no conflict of interest.

References

  1. Kaiser, P.K.; Cai, M. Design of rock support system under rockburst condition. J. Rock Mech. Geotech. Eng. 2012, 4, 215–227. [Google Scholar] [CrossRef]
  2. Feng, X.-T. Rockburst: Mechanisms, Monitoring, Warning, and Mitigation; Butterworth-Heinemann: Oxford, UK, 2017. [Google Scholar]
  3. Moganedi, K.; Stacey, T. Value creation as an approach to the management and control of rockburst damage in tunnels. Tunn. Undergr. Space Technol. 2019, 83, 545–551. [Google Scholar] [CrossRef]
  4. Ortlepp, W.D. The behaviour of tunnels at great depth under large static and dynamic pressures. Tunn. Undergr. Space Technol. 2001, 16, 41–48. [Google Scholar] [CrossRef]
  5. Jager, A. Two new support units for the control of rockburst damage. In Proceedings of the International Symposium on Rock Support, Sudbury, ON, Canada, 16–19 June 1992; pp. 621–631. [Google Scholar]
  6. Wu, R.; Oldsen, J.; Lamothe, M. The Yield-Lok bolt for bursting and squeezing ground support. In Proceedings of the Fifth International Seminar on Deep and High Stress Mining, Santiago, Australian, 6–8 October 2010; pp. 301–308. [Google Scholar]
  7. Varden, R.; Lachenicht, R.; Player, J.; Thompson, A.; Villaescusa, E. Development and implementation of the Garford dynamic bolt at the Kanowna Belle Mine. In Proceedings of the 10th Underground Operators’ Conference, Launceston, Tasmania, 14–16 April 2008; pp. 95–102. [Google Scholar]
  8. Galler, R.; Gschwandtner, G.; Doucet, C. Roofex bolt and its application in tunnelling by dealing with high stress ground conditions. In Proceedings of the World Tunnel Congress, Helsinki, Finland, 21–26 May 2011; p. 200. [Google Scholar]
  9. Yokota, Y.; Zhao, Z.; Nie, W.; Date, K.; Iwano, K.; Koizumi, Y.; Okada, Y. Development of a new deformation-controlled rock bolt: Numerical modelling and laboratory verification. Tunn. Undergr. Space Technol. 2020, 98, 103305. [Google Scholar] [CrossRef]
  10. Hao, Y.; Wu, Y.; Ranjith, P.; Zhang, K.; Hao, G.; Teng, Y. A novel energy-absorbing rock bolt with high constant working resistance and long elongation: Principle and static pull-out test. Constr. Build. Mater. 2020, 243, 118231. [Google Scholar] [CrossRef]
  11. Li, C.C. A new energy-absorbing bolt for rock support in high stress rock masses. Int. J. Rock Mech. Min. Sci. 2010, 47, 396–404. [Google Scholar]
  12. He, M.; Gong, W.; Wang, J.; Qi, P.; Tao, Z.; Du, S.; Peng, Y. Development of a novel energy-absorbing bolt with extraordinarily large elongation and constant resistance. Int. J. Rock Mech. Min. Sci. 2014, 67, 29–42. [Google Scholar] [CrossRef]
  13. Dai, L.; Pan, Y.; Wang, A. Study of the energy absorption performance of an axial splitting component for anchor bolts under static loading. Tunn. Undergr. Space Technol. 2018, 81, 176–186. [Google Scholar] [CrossRef]
  14. Masoudi, R.; Sharifzadeh, M. Reinforcement selection for deep and high-stress tunnels at preliminary design stages using ground demand and support capacity approach. Int. J. Min. Sci. Technol. 2018, 28, 573–582. [Google Scholar] [CrossRef]
  15. Feng, X.-T.; Liu, J.; Chen, B.; Xiao, Y.; Feng, G.; Zhang, F. Monitoring, warning, and control of rockburst in deep metal mines. Engineering 2017, 3, 538–545. [Google Scholar] [CrossRef]
  16. Liu, G.-F.; Feng, X.-T.; Feng, G.-L.; Chen, B.-R.; Chen, D.-F.; Duan, S.-Q. A method for dynamic risk assessment and management of rockbursts in drill and blast tunnels. Rock Mech. Rock Eng. 2016, 49, 3257–3279. [Google Scholar] [CrossRef]
  17. Feng, G.-L.; Feng, X.-T.; Chen, B.-r.; Xiao, Y.-X.; Yu, Y. A microseismic method for dynamic warning of rockburst development processes in tunnels. Rock Mech. Rock Eng. 2015, 48, 2061–2076. [Google Scholar] [CrossRef]
  18. Sun, Z.; Zhang, D.; Fang, Q.; Dui, G.; Chu, Z. Analytical solutions for deep tunnels in strain-softening rocks modeled by different elastic strain definitions with the unified strength theory. Sci. China Technol. Sci. 2022, 65, 2503–2519. [Google Scholar] [CrossRef]
  19. Jia, P.; Nie, Y.; Shi, P.; Jiang, X.; Lu, B.; Zhao, W. Flexural performance of a novel pipe-roof structure and optimization of key parameters. J. Constr. Steel Res. 2022, 199, 107594. [Google Scholar] [CrossRef]
  20. Lu, B.; Jia, P.; Zhao, W.; Zheng, Q.; Du, X.; Tang, X. Longitudinal mechanical force mechanism and structural design of steel tube slab structures. Tunn. Undergr. Space Technol. 2023, 132, 104883. [Google Scholar] [CrossRef]
  21. Sun, Z.; Zhang, D.; Fang, Q.; Huangfu, N.; Chu, Z. Convergence-confinement analysis for tunnels with combined bolt–cable system considering the effects of intermediate principal stress. Acta Geotech. 2022, 1–26. [Google Scholar] [CrossRef]
  22. Sazid, M.; Ahmed, H.A. Stability analysis of shallow depth tunnel in weak rock mass: 3d numerical modeling approach. J. City Dev. 2019, 1, 18–22. [Google Scholar]
  23. Saharan, M.; Jha, B.; Sazid, M.; Kumar, R. Designing cut out distance for continuous miners operation using numerical modelling and rock mechanics instrumentation. In Proceedings of the Workshop on Application of Rock Mechanics-Tools & Techniques, Nagpur, India, 15–17 January 2010; pp. 24–31. [Google Scholar]
  24. Saharan, M.R. Numerical Simulations for Rock Fracturing by Destress Blasting: As Applied to Hard Rock Mining Conditions; VDM Verlag: Saarbrücken, Germany, 2009. [Google Scholar]
  25. Li, C.C.; Mikula, P.; Simser, B.; Hebblewhite, B.; Joughin, W.; Feng, X.; Xu, N. Discussions on rockburst and dynamic ground support in deep mines. J. Rock Mech. Geotech. Eng. 2019, 11, 1110–1118. [Google Scholar] [CrossRef]
  26. Xu, S.; Hou, P.; Cai, M.; Li, Y. An experiment study on a novel self-swelling anchorage bolt. Rock Mech. Rock Eng. 2019, 52, 4855–4862. [Google Scholar] [CrossRef]
  27. Li, C.C. Principle of rockbolting design. J. Rock Mech. Geotech. Eng. 2017, 9, 396–414. [Google Scholar] [CrossRef]
  28. Li, C.C.; Stjern, G.; Myrvang, A. A review on the performance of conventional and energy-absorbing rockbolts. J. Rock Mech. Geotech. Eng. 2014, 6, 315–327. [Google Scholar] [CrossRef]
  29. Chang, X.; Wang, G.; Liang, Z.; Yang, J.; Tang, C. Study on grout cracking and interface debonding of rockbolt grouted system. Constr. Build. Mater. 2017, 135, 665–673. [Google Scholar] [CrossRef]
  30. Masoudi, R.; Sharifzadeh, M.; Ghorbani, M. Partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations. Int. J. Min. Sci. Technol. 2019, 29, 409–418. [Google Scholar] [CrossRef]
  31. Hu, L.; Feng, X.-T.; Xiao, Y.-X.; Wang, R.; Feng, G.-L.; Yao, Z.-B.; Niu, W.-J.; Zhang, W. Effects of structural planes on rockburst position with respect to tunnel cross-sections: A case study involving a railway tunnel in China. Bull. Eng. Geol. Environ. 2020, 79, 1061–1081. [Google Scholar] [CrossRef]
  32. Feng, G.-L.; Feng, X.-T.; Xiao, Y.-X.; Yao, Z.-B.; Hu, L.; Niu, W.-J.; Li, T. Characteristic microseismicity during the development process of intermittent rockburst in a deep railway tunnel. Int. J. Rock Mech. Min. Sci. 2019, 124, 104135. [Google Scholar] [CrossRef]
  33. Xiating, F.; Binrui, C.; Chuanqing, Z.; Shaojun, L.; Shiyong, W. Mechanism, Warning and Dynamic Control of Rockburst Development Process; Science Press: Beijing, China, 2013. [Google Scholar]
  34. GB/T50218-2014; Standard for Engineering Classification of Rock Masses. China Electrical Equipment Industry Association: Beijing, China, 2015.
  35. Ciancio, D.; Mazzotti, C.; Buratti, N. Evaluation of fibre-reinforced concrete fracture energy through tests on notched round determinate panels with different diameters. Constr. Build. Mater. 2014, 52, 86–95. [Google Scholar] [CrossRef]
  36. Feng, X.-T.; Yang, C.-X.; Kong, R.; Zhao, J.; Zhou, Y.; Yao, Z.; Hu, L. Excavation-induced deep hard rock fracturing: Methodology and applications. J. Rock Mech. Geotech. Eng. 2022, 14, 1–34. [Google Scholar] [CrossRef]
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Figure 1. Schematic diagram of the construction cycle in rockburst area.
Figure 1. Schematic diagram of the construction cycle in rockburst area.
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Figure 2. Failure of arch frames and rockbolts under a moderate rockburst.
Figure 2. Failure of arch frames and rockbolts under a moderate rockburst.
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Figure 3. Failure of arch frames and rockbolts under a moderate rockburst.
Figure 3. Failure of arch frames and rockbolts under a moderate rockburst.
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Figure 4. Design of energy-absorbing rockbolt structure. (a) The front area of the rockbolt body is wrapped with thin tape. (b) The crack evolution process of initiation, propagation, and ejection (or large cracks) creates a sudden displacement of the rock mass. (c) In area S, the axial load at B point can easily reach the yield point (① to ②), forming a yield area on the rockbolt. Due to the shrinkage caused by yield, the rockbolt is decoupled from the rockbolt material. Rebar is easily broken because its rockbolt material restrains the expansion of the yield area [28]. However, when the tape reduces the rockbolt restraint effect, the yield and decoupling area expand, resulting in an increase in the yield displacement of the rockbolt (called stepwise decoupling) in stage ③. (d) In area S, the curve of shear force increases from stage ① to stage ②. A certain shear force can still be maintained in the coupled area to constrain crack propagation in the rock mass. However, due to decoupling, the shear stress will disappear in stage ③.
Figure 4. Design of energy-absorbing rockbolt structure. (a) The front area of the rockbolt body is wrapped with thin tape. (b) The crack evolution process of initiation, propagation, and ejection (or large cracks) creates a sudden displacement of the rock mass. (c) In area S, the axial load at B point can easily reach the yield point (① to ②), forming a yield area on the rockbolt. Due to the shrinkage caused by yield, the rockbolt is decoupled from the rockbolt material. Rebar is easily broken because its rockbolt material restrains the expansion of the yield area [28]. However, when the tape reduces the rockbolt restraint effect, the yield and decoupling area expand, resulting in an increase in the yield displacement of the rockbolt (called stepwise decoupling) in stage ③. (d) In area S, the curve of shear force increases from stage ① to stage ②. A certain shear force can still be maintained in the coupled area to constrain crack propagation in the rock mass. However, due to decoupling, the shear stress will disappear in stage ③.
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Figure 5. MS information base for early warning on 10th September.
Figure 5. MS information base for early warning on 10th September.
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Figure 6. The structures of the energy-absorbing rockbolts.
Figure 6. The structures of the energy-absorbing rockbolts.
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Figure 7. Pull-out tests. (a) pull-out test system, (b) Nut slipped, (c) rockbolts broke (length of the stepwise decoupling section is 300 mm due to the amount needed for the jack cylinder), (d) Rockbolt broke (length of the stepwise decoupling section of bolt body is 500 mm, with 300 mm in the jack cylinder).
Figure 7. Pull-out tests. (a) pull-out test system, (b) Nut slipped, (c) rockbolts broke (length of the stepwise decoupling section is 300 mm due to the amount needed for the jack cylinder), (d) Rockbolt broke (length of the stepwise decoupling section of bolt body is 500 mm, with 300 mm in the jack cylinder).
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Figure 8. Cumulative MS information near the moderate rockburst area [36].
Figure 8. Cumulative MS information near the moderate rockburst area [36].
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Figure 9. Cumulative MS information near the moderate rockburst area. (a) Failure of rockburst near the working face (b) Layout of rockburst.
Figure 9. Cumulative MS information near the moderate rockburst area. (a) Failure of rockburst near the working face (b) Layout of rockburst.
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Figure 10. Failure characteristics of energy-absorbing support system under moderate rockburst [36]. (a) Distribution of the rockburst and different types of support systems, (b) Damaged excavator glass, (c) Characteristics of the energy-absorbing support system.
Figure 10. Failure characteristics of energy-absorbing support system under moderate rockburst [36]. (a) Distribution of the rockburst and different types of support systems, (b) Damaged excavator glass, (c) Characteristics of the energy-absorbing support system.
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Figure 11. Characteristics of rockburst failure under non-energy-absorbing support at chainage DK 0 + 635. (a) Layout of rockburst (b) Failure characteristics of energy-absorbing support system under moderate rockburst.
Figure 11. Characteristics of rockburst failure under non-energy-absorbing support at chainage DK 0 + 635. (a) Layout of rockburst (b) Failure characteristics of energy-absorbing support system under moderate rockburst.
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Table
Table 1. Engineering geological conditions in the rockburst area.
Table 1. Engineering geological conditions in the rockburst area.
Rock Mass ClassificationWorking FaceJoint Layout
IISustainability 15 07165 i001Sustainability 15 07165 i002
Table
Table 2. Construction support system parameters.
Table 2. Construction support system parameters.
Supporting MeasureParametersNotes
Initial shotcrete C25thickness 50 mmAdd steel fibers with a total mass ratio of 2%
Ø6 mm steel meshspacing 150 mm × 150 mmThe reinforcing mesh should overlap and be welded together
BoltThe material adopts a hollow grouting bolt, Ø22 mm × 3000 mm, spacing of 1 m × 1 m. The rockbolt plate thickness is 5 mm. The number of nuts is 2The stepwise decoupling section, starting at 200 mm from 1 end, is made of thin tape covering the threaded rod body, with a length of 500 mm.
Table
Table 3. Typical pull-out test results.
Table 3. Typical pull-out test results.
NameStepwise Decoupling Section Length (mm)Number of NutsRockboltage Length (mm)Peak Load (kN)Peak Deformation (mm)Failure Mode
No. 150012300111.7229.17Nuts slipped
No. 230022500151.5130.41Bolt broke
No. 350022300165.5872.32Bolt broke
Note: all bolts used in the test are hollow grouting bolts with a diameter of 22 mm.
Table
Table 4. Failure characteristics of different support system types.
Table 4. Failure characteristics of different support system types.
Support TypeEnergy-Absorbing Support SystemNon-Energy-Absorbing Support System
Rock mass classificationIIII
Characteristics of rockburst space-time4–7 m away from the working face, located at the left arch shoulder, 5 h after blasting5 m away from the working face, left arch shoulder, after blasting
Characteristics of rockburst failureStrip tearing of support layer: 2 m × 1 m × 0.1 mBlock, sheet, and shallow pit, rock ejection or spalling, maximum rockburst pit: 5 m × 5 m × 1.5 m
Characteristics of support system failureshotcrete layer cracked 50–60 mm; the bolt yielded but did not breakBolt pulled out or broken, only a few can reinforce rock mass. Part of the shotcrete and bolt flew out with the rock block
Impact on the projectThe damage of rockburst is restrained, and only simple disposal is needed after the eventThreat to equipment and personnel, and new support needed
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MDPI and ACS Style

Liu, Y.; Zhao, Y.; Wang, K.; Li, G.; Ge, Z. Protection Technique of Support System for Dynamic Disaster in Deep Underground Engineering: A Case Study. Sustainability 2023, 15, 7165. https://doi.org/10.3390/su15097165

AMA Style

Liu Y, Zhao Y, Wang K, Li G, Ge Z. Protection Technique of Support System for Dynamic Disaster in Deep Underground Engineering: A Case Study. Sustainability. 2023; 15(9):7165. https://doi.org/10.3390/su15097165

Chicago/Turabian Style

Liu, Yunqiu, Yuemao Zhao, Kun Wang, Gongcheng Li, and Zhengchen Ge. 2023. "Protection Technique of Support System for Dynamic Disaster in Deep Underground Engineering: A Case Study" Sustainability 15, no. 9: 7165. https://doi.org/10.3390/su15097165

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