J. Cent. South Univ. (2021) 28: 543-555

DOI: https://doi.org/10.1007/s11771-021-4620-2

Numerical analysis of deformation and failure characteristics of deep roadway surrounding rock under static-dynamic coupling stress

WU Xing-yu(吴星宇), JIANG Li-shuai(蒋力帅), XU Xing-gang(徐兴港), GUO Tao(郭涛), ZHANG Pei-peng(张培鹏), HUANG Wan-peng(黄万朋)

State Key Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao 266590, China

Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2021

Abstract: In actual production, deep coal mine roadways are often under typical static-dynamic coupling stress (SDCS) conditions with high ground stress and strong dynamic disturbances. With the increasing number of disasters and accidents induced by SDCS conditions, the safe and efficient production of coal mines is seriously threatened. Therefore, it is of great practical significance to study the deformation and failure characteristics of the roadway surrounding rock under SDCS. In this paper, the effects of different in-situ stress fields and dynamic load conditions on the surrounding rock are studied by numerical simulations, and the deformation and failure characteristics are obtained. According to the simulation results, the horizontal stress, vertical stress and dynamic disturbance have a positive correlation with the plastic failure of the surrounding rock. Among these factors, the influence of the dynamic disturbance is the most substantial. Under the same stress conditions, the extents of deformation and plastic failure of the roof and ribs are always greater than those of the floor. The effect of horizontal stresses on the roadway deformation is more notable than that of vertical stresses. The results indicate that for the roadway under high-stress conditions, the in-situ stress test must be strengthened first. After determining the magnitude of the in-situ stress, the location of the roadway should be reasonably arranged in the design to optimize the mining sequence. For roadways that are strongly disturbed by dynamic loads, rock supports (rebar/cable bolts, steel set etc.) that are capable of maintaining their effectiveness without failure after certain dynamic loads are required. The results of this study contribute to understanding the characteristics of the roadway deformation and failure under SDCS, and can be used to provide a basis for the support design and optimization under similar geological and geotechnical circumstances.

Key words: static-dynamic coupling stress (SDCS); deep roadway; surrounding rock stability; numerical simulation; roadway deformation; plastic failure of surrounding rock

Cite this article as: WU Xing-yu, JIANG Li-shuai, XU Xing-gang, GUO Tao, ZHANG Pei-peng, HUANG Wan-peng. Numerical analysis of deformation and failure characteristics of deep roadway surrounding rock under static-dynamic coupling stress [J]. Journal of Central South University, 2021, 28(2): 543-555. DOI: https://doi.org/10.1007/ s11771-021-4620-2.

1 Introduction

With the continuous increase in mining depths and intensities, the proportion of roadways that are difficult to support, such as those with high ground stress, strong mining influence and broken surrounding rock, is increasing daily, which leads to a prominent phenomenon in which large deformation and serious failure of the surrounding rock of deep roadways occur. The occurrence of dynamic disasters such as large deformation,serious failure and rock burst in the surrounding rock of most deep roadways is also dramatically increasing [1-7]. In mining activities, roadways are often affected by natural disturbances (earthquakes, mine shocks, etc.) and engineering disturbances (excavation, blasting, etc.). More than 80% of coal mine roadways are subjected to frequent dynamic disturbances (e.g., mining-induced stress adjustments, roof weight, seismic events, etc.) [8]. Such complex stress conditions are often referred to as SDCS [9-11]. The deformation and failure characteristics of the surrounding rock under SDCS undergo substantial changes, which is the fundamental cause of dynamic disasters in deep mines. The occurrence of these accidents is a serious threat to the safe and efficient production of coal mines [12]. Therefore, the study or roadway deformation and failure characteristics under SDCS has important scientific value.

Many scholars have conducted in-depth studies on the mechanical properties and failure mechanism of rocks under SDCS conditions. First proposed by LI et al [13], a series of studies on the mechanism of rock impact breaking under the condition of SDCS have been carried out on the basis of drilling machines, INSTRON testing machines and split Hopkinson pressure bar (SHPB) devices. In previous studies [14-21], a series of physical experiments were conducted using rock specimens with different lithologies to explore the effects of different dynamic and static loads on the rock strength under SDCS. However, the studies on these test scales still have certain limitations for engineering applications. Some scholars have performed full research on the macroscopic mechanical behavior of rock masses under SDCS and dynamic behavior of underground structures. SAINOKI et al [22-24] studied the influence of stress and energy on the dynamic behavior of underground structures, such as fault slip and roof fracture, and proposed corresponding reasonable measures to prevent coal and rock dynamic disasters. HE et al [25, 26] discussed the principle of rock burst induced by SDCS and proposed two types of rock burst induced by SDCS in coal mines. Based on this, the idea of monitoring and early warning of the SDCS rock burst is proposed, and the prevention and control principle of the SDCS rock burst is to reduce the effect of dynamic loads. These results have verified the scientific nature of the control methods in engineering practice.

In order to clearly investigate the deformation and plastic failure characteristics of roadways under the SDCS, this paper uses the research method of numerical simulation which can strongly adapt to the complex stress conditions of SDCS. By using dynamic and static numerical calculations of FLAC^3D to simulate the mechanical response of the roadway surrounding rock deformation field and failure field under different SDCS conditions, the influences of the in-situ stress field and dynamic load on the roadway deformation and failure characteristics are revealed. The research results can provide theoretical support for effectively mitigating the deformation and plastic failure of the surrounding rock of the roadway and contribute to guiding the field to adopt a reasonable mining area layout and roadway support design model under the SDCS conditions.

2 Model description

In this numerical analysis, the geological and geotechnical conditions of the 3D model are simplified according to a previous study that was carried out in a coal mine in Henan Province, China [27-29]. The model is 50 m long, 50 m wide and 40 m high. Taking the central axis of the excavated roadway as the symmetry axis, the excavated roadway is set to be 50 m long, 4.8 m wide and 3.2 m high, which are determined based on model sensitivity analysis with regards to the size and mesh density.

The mesh density of the numerical model, might be sensitive to the simulation results. By comparing three models (models #1, #2 & #3) with different mesh densities and the other conditions remaining the same, a suitable model is selected for follow-up research. Figure 1 shows the simulation results of surrounding rock deformation under different mesh densities, and the numbers in brackets are the number of zones in the model. As can be seen, the mesh sensitivity of deformation varies for the roof, ribs and floor. The floor and ribs have a greater tendency to fail under tension, which leads to the effect of the deformation being more significant than that for the roof [27]. As a result, deformations of the floor and ribs are more sensitive to the mesh density. Since there is no notable difference between model #2 and model #3, which has a denser mesh, the mesh density and simulation results are validated. Therefore, model #2 is employed to carry out the simulations in the present study.

Figure 1 Mesh-dependence analysis with respect to surrounding rock deformation

The model top boundary is loaded with a 15 MPa vertical stress to simulate the overburden pressure by assuming that the overlying unit weight is 0.025 MN/m³, and no displacement is allowed in the direction perpendicular to the side boundaries. The cable bolts and rebar bolts are regarded as structural elements. This type of element is embedded in FLAC^3D to simulate roadway support. The roadway support is shown in Figure 2(b), and Table 1 gives the parameter values of various abutment structural elements [27]. This model uses the physical and mechanical parameters of the rock of a coal mine as the original data for subsequent experimental research. The mechanical parameters of intact rock are determined in the laboratory. In order to ensure the authenticity of the rock mechanical parameters, the accuracy of the experimental results and the rigor of research during the numerical simulation, the rock mass mechanical parameters involved in the analysis of all of the numerical simulations and theoretical calculations in the paper are estimated from the intact rock properties using the generalized Hoek-Brown failure criterion [30]. Table 2 shows the rock mass properties [27].

Figure 2 Numerical model:

Table 1 Parameter values of abutment structure elements [27]

Table 2 Mechanical parameters of rock mass [27]

The dynamic analysis in this paper is from the simulation of seismicity induced by underground mining, which may have different origins and different mechanisms of seismic sources, thus leadings to a completely different potential precursor to a strong seismic event. This shows that the rock burst hazard assessment criteria must relate to the seismic hazard assessment, knowledge of the parameters describing the source mechanism of seismic events and values of the peak particle velocity (PPV) in the vicinity of the operational working area. Therefore, this paper simulates the influence of different dynamic load disturbances on the stability of the roadway by changing the PPV [31]. For the dynamic analysis, the boundary conditions of the model are viscous to prevent the model boundary from reflecting the seismic waves. Local damping with a damping coefficient of 0.05 as the damping form was selected. Local damping was originally designed as a means to equilibrate static simulations. However, it has some characteristics that make it attractive for dynamic simulations. The amount of energy removed, △W, is proportional to the maximum transient strain energy, W, and the ratio, △W/W, is independent of the rate and frequency. Since △W/W may be related to the fraction of critical damping, D, we obtain the expression

                                (1)

where α_L is the local damping coefficient.

The vibration is a semisine p-wave applied from the top of the model from top to bottom, the frequency is 20 Hz, and the vibration time is that for one cycle. A strain-softening constitutive model based on the Mohr-Coulomb criterion is adopted. The numerical simulation process is shown in Figure 3. The calculation of the critical calculation timestep △t_crit in the dynamic calculation is as follows:

                     (2)

where C_p is the p-wave speed; V is the tetrahedral subzone volume; is the maximum face area associated with the tetrahedral subzone. The min｛｝ function is taken over all zones, and it includes contributions from the structural and interface modules. A safety factor of 0.5 is used because Eq (2) is only an estimate of the critical timestep. Hence, the timestep used for dynamic runs, △t_d, when no stiffness-proportional damping is used, is

                              (3)

If stiffness-proportional damping is used, the timestep must be reduced, for stability. A formula for the critical timestep △t_β that includes the effect of stiffness-proportional damping:

                  (4)

where ω_max is the highest eigenfrequency of the system, and λ is the fraction of critical damping at this frequency [32].

Figure 3 Flowchart of numerical simulation

3 Effect of in-situ stress field on deformation and plastic failure of roadway surrounding rock

In actual engineering conditions, the roadway is affected not only by the in-situ stress field, but also by natural disturbances and engineering disturbances. Therefore, this chapter analyzes the influence characteristics of the in-situ stress field on the roadway deformation, and explores the main influencing factors of the deformation of the roadway surrounding rock and plastic failure.

KANG et al [33] conducted a series of in-situ stress tests in a number of coal mines in China and built an in-situ stress database with more than 1357 measurements. According to the distribution characteristics of in-situ stress in Chinese coal mines, first five levels of vertical stress have been chosen, which represent typical burial depths of coal mines in China, and then, the five levels of horizontal stress are determined according to the common lateral pressure coefficient (ratio of the maximum horizontal stress to the vertical principal stress, 0.6-1.4) according to the in situ stress database and the distribution characteristics of in-situ stress in Chinese coal mines [34-37].

3.1 Effect of horizontal stress on deformation of roadway surrounding rock

By using the horizontal stress as the simulated variable, the horizontal stress simulation was established for five sets of tests. The horizontal stresses of the five sets were 9, 12, 15, 18 and 21 MPa. The simulation design is shown in Table 3.

Table 3 Model design with different horizontal stresses

As can be seen from Figure 4, the roof sag, ribs convergence and floor heave are greatly affected by the horizontal stress. When the horizontal stress increased from 9 MPa to 21 MPa: the roof sag changed from 58.58 mm to 116.01 mm with a dramatic increase of 98.04%; the ribs convergence changed from 59.01 mm to 104.23 mm with a substantial increase of 76.63%; and the floor heave changed from 21.95 mm to 72.74 mm, which was a remarkable increase of 231.39%. There was a positive correlation between the roadway deformation and horizontal stress. Since the roof and ribs were softer than the floor, the roof sag and ribs convergence were always greater than the floor heave under the same horizontal stress. When the lateral pressure coefficient exceeded 1, the roadway deformation began to increase greatly. Therefore, it is necessary to detect the in-situ stress in a timely manner to determine the lateral pressure coefficient in a project. In order to ensure the normal use of roadways, it is necessary to strengthen the support strength when designing roadways that are strongly affected by horizontal stresses. Roadways should be reasonably arranged to avoid the high horizontal stress position and ensure the safe production of the coal mine.

Figure 4 Roadway deformation with respect to different horizontal stresses

3.2 Effect of horizontal stress on plastic failure of roadway surrounding rock

Figure 5 shows that the extent of plastic failure of the ribs was basically unchanged with increasing horizontal stress. When the horizontal stress increased from 9 MPa to 21 MPa, the extent of plastic failure of the roof expanded from 0.53 m to 4.00 m, and the extent of plastic failure increased by 654.72%. The extent of plastic failure of the floor increased from 0.36 m to 4.00 m, and the extent of plastic failure was extended by 1011.11%. The plastic failure of the roadway surrounding rock under horizontal stress had a substantial influence, and the plastic failure of the roadway surrounding rock was positively correlated with the horizontal stress. In the plastic failure of roadway surrounding rock, under the same horizontal stress, the ribs have a large plastic failure prior to the roof and floor, followed by the obvious plastic failure of the roof, and finally the floor experienced more serious plastic failure. This shows that the plastic failure of the roadway surrounding rock was closely related to the lithology of the surrounding rock, and weak rock was more prone to plastic failure.

Figure 6 shows the changes in the plastic failure ratio of the roof (the plastic failure ratio of the roof is the ratio of the broken part of the roof to the whole part of the roof). The algorithms for the plastic failure ratio of the ribs and the floor are the same as those of the ribs and the floor under different horizontal stress conditions. According to Figure 6, during the process of the horizontal stress increasing from 9 MPa to 21 MPa, the plastic failure ratio of the roof changes from 6.43% to 67.30%. The changes in the plastic failure ratio of the ribs are not obvious, and the value is basically stable at 78.00%. The plastic failure rate of the floor changes from 3.95% to 61.30%, an increase of 15.52 times.

Figure 5 Distribution of roadway plastic failure under different horizontal stresses

Figure 6 Plastic failure ratio with respect to different horizontal stresses

In summary, the plastic failure ratios of the roof and floor of the roadway are strongly affected by the horizontal stress and have a positive correlation with the horizontal stress. The effect of the horizontal stress on the plastic failure rate of the ribs is not obvious, but the failure rate remains high. In this section, the plastic failure severity of the surrounding rock under the same stress conditions is as follows: ribs, roof and floor. Therefore, it is necessary to strengthen the monitoring of the in-situ stress in engineering practice, and strengthen the support of the roof and floor of the roadway affected by high horizontal stresses in a timely manner. When designing the roadway, the layout position of the roadway should be fully considered, and the influence of the horizontal stress on the stability of the roadway should be reduced as much as possible.

3.3 Effect of vertical stress on deformation of roadway surrounding rock

By using the vertical stress as the simulated variable, the vertical stress simulation was established for five sets of tests. The vertical stresses of the five sets were 10, 12.5, 15, 17.5 and 20 MPa. The simulation design is shown in Table 4.

Figure 7 shows that the ribs convergence is substantially affected by the vertical stress. When the roadway depth increases from 400 m to 800 m, the roof sag changes from 59.15 mm to 95.10 mm, which increases by 60.78%; the ribs convergence changes from 61.75 mm to 91.03 mm, which increases by 47.42%; and the floor heave changes from 12.01 mm to 30.00 mm, which considerably increased by 149.79%. There is a positive correlation between the roadway deformation and the vertical stress. The ribs convergence and the floor heave show an approximately linear increase with the vertical stress, while the growth rate of the roof sag increases substantially after the lateral pressure coefficient is greater than 1. At the same depth, the roof sag and ribs convergence are always larger than floor heave. Therefore, for the deep roadway, the support should be strengthened to ensure that the roof sag and ribs convergence occurs in a controllable range.

Table 4 Model design with different vertical stresses

Figure 7 Roadway deformation with respect to different vertical stresses

3.4 Effect of vertical stress on plastic failure of roadway surrounding rock

As shown in Figure 8, when the vertical stress increased from 10 MPa to 20 MPa, the extent of plastic failure of the roof decreased from 3.47 m to 2.93 m, which is a decrease of 15.56%. The extent of plastic failure of the ribs expanded from 2.77 m to 3.69 m, which is an increase of 33.21%. The plastic failure of the roadway surrounding rock was positively correlated with the vertical stress. With the increase in the vertical stress, the failure area of the roof and the ribs expanded from the middle to the depth of the surrounding rock, but the plastic failure area of the floor did not change substantially. This shows that the plastic failure of the roof and ribs was more strongly affected by the vertical stress. Therefore, for roadways with high vertical stress, it is necessary to strengthen the support of the roof and ribs.

Figure 9 shows the changes in the plastic failure ratios of the roof, ribs and floor under different vertical stress conditions. According to Figure 9, it can be seen that during the increase in the vertical stress from 10 MPa to 20 MPa: the plastic failure ratio of the roof shows a trend of first decreasing and then increasing, changing from 43.68% to 43.13%. When the vertical stress is 15 MPa, the plastic failure rate of the roof is a minimum value of 29.42%. The plastic failure rate of the ribs changed from 62.56% to 87.18%, with a substantial increase of 39.35%. The plastic failure rate of the floor does not change substantially, and it basically remains at the same rate. In summary, the roof and the ribs are strongly affected by the vertical stress. The rate of the plastic failure of the ribs is positively correlated with the vertical stress. The plastic failure rate of the roof has a tendency to first decrease and then increase. This is because when the lateral compression coefficient is close to 1, the vertical stress and horizontal stress are mutually restricted, and the surrounding rock stress state is relatively stable. Therefore, when the lateral pressure coefficient is 1, the plastic failure ratio of the roadway is the smallest. This phenomenon is also verified by a previous study on the effect of the lateral pressure coefficient on the shape of plastic zone [38], and the plastic failure ratio decreases at first and then increases when the lateral pressure coefficient is in the range of less than 1 to greater than 1.

Figure 8 Distribution of roadway plastic failure under different vertical stresses

Figure 9 Plastic failure ratio with respect to different vertical stresses

4 Effect of dynamic load on deformation and plastic failure of roadway surrounding rock

4.1 Effect of dynamic load on deformation of roadway surrounding rock

By using the PPV as the simulated variable, the PPV simulation was established for four sets of tests. The PPVs of the four sets were 0.5, 1, 1.5 and 2 m/s. The simulation design is shown in Table 5.

Table 5 Model design with different PPVs

Figure 10(a) shows that the ribs convergence before the dynamic disturbance was 73.13 mm. When the PPV increased from 0.5 m/s to 2 m/s, the ribs convergence changed from 85.61 mm to 138.11 mm, which was a substantial increase of 61.32%. When the PPV was 2 m/s, the ribs convergence was 1.89 times the dynamic disturbance. From Figure 10(b), it can be seen that before the dynamic disturbance, the roof sag was 65.88 mm. When the PPV increased from 0.5 m/s to 2 m/s, the roof sag changed from 108.65 mm to 236.77 mm, with a dramatic increase of 117.92%. When the PPV is 2 m/s, the roof sag is 3.59 times that before the dynamic disturbance. Therefore, after the dynamic load, the roof sag and ribs convergence increased greatly compared with those before the dynamic load. The roof sag after dynamic loading was obviously greater than the ribs convergence. This shows that the roof is more susceptible to the influence of dynamic disturbances. The deformation of the roadway after the dynamic disturbance is several times that before the dynamic disturbance.

Figure 10 Roadway deformation with respect to different PPVs

4.2 Effect of dynamic load on plastic failure of roadway surrounding rock

Figure 11 shows that when the PPV increased from 0 to 1 m/s, the extent of plastic failure of the roof expanded from 2.93 m to 4.00 m, with the extent of failure extent increasing by 36.52%. After the PPV was greater than 1 m/s, the extent of plastic failure of roof was greater than 4 m. When the PPV increased from 0 to 0.5 m/s, the extent of plastic failure of the ribs increased from 3.38 m to 4.00 m, which was an increase of 18.34%. After the PPV was greater than 0.5 m/s, the extent of plastic failure of the ribs was greater than 4 m. When the extent of plastic failure exceeded 4 m, it exceeded the support extent of the ordinary rock bolts. According to the theory of surrounding rock control, the rebar bolt could not be suspended in the upper stable rock layer. In other words, a support method with great working extent was required in all of these cases. With the increase of the PPV, the plastic failure area of the surrounding rock of the roadway continued to expand, and the plastic failure changes of the roof and the ribs were extremely substantial. This shows that the change in the dynamic load has a strong influence on the plastic failure of the surrounding rock of the roadway. With an increase in the dynamic load, the plastic failure of the surrounding rock becomes increasingly serious. This also shows that a strong dynamic disturbance is the main factor leading to rock burst accidents.

Figure 12 shows the changes in the plastic failure ratios of the roof, the ribs and floor under different PPV conditions. According to Figure 12, it can be seen that with the increase of the PPV from 0.5 to 2 m/s, the plastic failure ratio of the roof changed from 57.51% to 95.48%, with a dramatic increase of 66.02%. The plastic failure ratio of the ribs changed from 85.26% to 100%, with an increase of 17.29%, and the plastic failure rate of the floor slowly changed from 9.53% to 13.75%, with a substantial increase of 44.28%. In summary, the plastic failure rate of the roadway has a positive correlation with the dynamic load. The plastic failure rates of the roof and the ribs are quite different from those of the floor. This shows that the dynamic load is very damaging to the roadway roof and the ribs. Therefore, for the roadway that is strongly affected by dynamic load, it is necessary to prevent not only large deformation of the surrounding rock but also large-scale impact failure of the surrounding rock.

Figure 11 Distribution of roadway plastic failure under different PPVs

Figure 12 Plastic failure ratio with respect to different PPVs

5 Discussion

As the mining depth increases, the stress of the in-situ stress rock continues to increase. In addition to the burial depth, the magnitude of the horizontal stress has a very substantial effect on the deformation and failure of the surrounding rock. In other words, a shallow-buried roadway under high horizontal stress might also suffer from excessive deformation and failure. Combined with the research in Section 3 of this paper, we can adopt the following methods to deal with the surrounding rock deformation problem under high stress conditions. First, we need to strengthen the in-situ stress test of the surrounding rock for high horizontal stress roadways [39-40]. The mining sequence is optimized according to the measurement results, and the roadway is arranged at a position where the angle between the maximum horizontal principal stress and the roadway axis is as small as possible, thereby improving the stress state of the surrounding rock [41]. Second, the method of manual pressure relief can be used to reduce or transfer the high stress of the surrounding rock.

According to the research in Section 4, the deformation of the roadway after the dynamic disturbance is several times that before the dynamic disturbance, which indicates that the dynamic load is the trigger of dynamic disasters; such as rock burst, roof collapse. However, traditional rigid bolts allow the deformation of the surrounding rock to generally be less than 200 mm, and cannot adapt to the large deformation and failure of the surrounding rock. For roadways that are strongly disturbed by dynamic loads, rock support methods (rebar/cable bolts, steel set, etc.) that are capable of maintaining effectiveness without failure after certain dynamic loads are required, such as NPR-bolt, D-bolt [42, 43]. Alternatively, roadway strata control technology can be adopted such as by means of synergistic bolting-modification-destressing [44-46].

On the basis of existing research, there are many factors that can be considered for further exploration. For example, the effects of different support schemes on surrounding rock deformation and failure under the condition of SDCS can be analyzed. This can provide effective guidance for engineering practice.

6 Conclusions

In this study, based on the fact that underground roadways are mostly under high stress and frequent-disturbance due to dynamics, a dynamic analysis that can simulate SDCS conditions was conducted for a 3D roadway model. Under the condition that the model parameters and conditions are the same, only changing the stress condition of the roadway allows 14 numerical models to be established. By analyzing the characteristics of the in-situ stress field and dynamic disturbance on the roadway deformation and plastic failure, the factors affecting the roadway stability under SDCS are studied.

According to the simulation results, the horizontal stress, vertical stress and dynamic disturbance have a positive correlation with the plastic failure of the surrounding rock. Among these factors, the influence of the dynamic disturbance is the most obvious. Under the same stress conditions, the extent of deformation and plastic failure of the roof and ribs is always greater than that of the floor. The effect of the horizontal stress on the roadway deformation and plastic failure is more obvious than that of the vertical stress.

Considering the results of the in-situ stress field and dynamic disturbance on the surrounding rock in the previous study, it is concluded that for the roadway under high-stress conditions, the in-situ stress test must be strengthened first. After determining the magnitude of the in-situ stress, the location of the roadway should be reasonably arranged in the design to optimize the mining sequence. For the roadway that is strongly disturbed by dynamic loads, rock supports (rebar/cable bolts, steel set etc.) that are capable of maintaining effectiveness without failure after certain dynamic loads are required.

The results of this study contribute to the understanding of the characteristics of roadway deformation and failure under SDCS, and can be used to provide a basis for support design and optimization under similar geological and geotechnical circumstances.

Contributors

WU Xing-yu performed numerical simulation, data analysis and writing manuscript. Jiang Li-shuai conducted project coordination and supervision. Xu Xing-gang and Guo Tao performed data collation and drawing. Zhang Pei-peng and Huang Wan-peng checked the numerical simulation data. All authors have read and approved the content of the manuscript.

Conflict of interest

WU Xing-yu, JIANG Li-shuai, XU Xing-gang, GUO Tao, ZHANG Pei-peng and HUANG Wan-peng declare that they have no conflict of interest.

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(Edited by YANG Hua)

中文导读

动静载叠加作用下深部巷道围岩变形破坏数值模拟研究

摘要：在深部煤矿开采中，巷道往往处于高地应力和强动力扰动的动静载叠加应力环境。由动静载叠加诱发的围岩严重变形破坏甚至灾变失稳现象屡见不鲜，严重威胁煤矿的安全高效开采。因此，对动静载叠加作用下巷道围岩变形破坏规律的研究具有非常重要的理论价值和工程意义。本文以数值模拟中非线性动力计算为手段，研究了不同初始应力场及不同动载条件对巷道围岩的影响，获得了动静载叠加作用下巷道围岩变形破坏规律。结果表明：水平应力、垂直应力及动力扰动都与巷道围岩塑性破坏呈正相关关系，其中动力扰动对其影响最为明显。在相同应力条件下，巷道顶板和两帮的变形量及塑性破坏范围始终大于底板。水平应力对巷道变形量的影响比垂直应力更加强烈。所以，对于高应力环境中的矿井需加强地应力测试，并在巷道设计时充分考虑巷道布置及开采顺序。对于受动力扰动强烈的巷道，要求支护构件(锚杆、锚索等)在受到一定动力扰动后仍能保持其有效性。这一研究结果有助于进一步了解动静载叠加作用下深部巷道围岩变形破坏规律，并可为相似地质条件下巷道支护设计及优化提供相应的指导。

关键词：动静载叠加；深部巷道；围岩稳定性；数值模拟；巷道变形；围岩塑性破坏

Foundation item: Projects(52074166, 51774195, 51704185) supported by the National Natural Science Foundation of China; Project(2019M652436) supported by the China Postdoctoral Science Foundation

Received date: 2020-07-31; Accepted date: 2020-11-17

Corresponding author: JIANG Li-shuai, PhD, Associate Professor; Tel: +86-532-86057548; E-mail: lsjiang@sdust.edu.cn; ORCID: https://orcid.org/0000-0001-7908-3221