An Analysis of the Impact of Deviatoric Stress and Spherical Stress on the Stability of Surrounding Rocks in Roadway

In this study, a detailed analysis was conducted to evaluate the impacts of the deviatoric stress component and spherical stress component on the stability of surrounding rocks in the roadway via the theoretical analysis and calculation and numerical simulation. Based on the analysis, the distribution laws guiding the main stress differences, plastic zone, convergence of surrounding rocks, and third invariant of stress under various conditions (such as equal spherical stress and unequal deviatoric stress and equal deviatoric stress and unequal spherical stress) were developed, providing an optimization scheme for roadway support misunderstanding under the conditions of high spherical stress field and high deviator stress field. The study further reveals that under the circumstance of the constant spherical stress, the greater the deviatoric stress, the plastic zone range of the surrounding rock of the roadway, the range of tensile deformation of the surrounding rock, the amount of convergence of the surrounding rock, the probability of separation of the roof and floor of the roadway, and the principal stress difference and the main stress, the greater the concentration range of the maximum stress difference is, and the maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway, and the greater the deviatoric stress, the greater the probability that the roof and floor rocks of the roadway will be separated, and the maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway, the greater the deviator stress, the greater the concentration range of the maximum value of the principal stress difference and the principal stress difference; when the deviator stress is constant, the range of the plastic zone and the maximum principal stress difference concentration range of the surrounding rock of the roadway decrease with the increase of the ball stress, and the principal stress difference, the amount of convergence of the surrounding rock, and the range of tensile deformation increase with the increase of the ball stress. The maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway. The principal stress difference increases with the increase of the spherical stress, and the maximum concentration range of the principal stress difference decreases with the increase of the spherical stress. After the method proposed in this paper optimizes the actual roadway support on site, the surrounding rock deformation of the roadway is small and the control is relatively ideal, which basically meets the engineering needs.

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Analysis of Influence of Stress Lode Angle on Stability of Roadway Surrounding Rock

Shock and Vibration ◽

10.1155/2021/6617609 ◽

2021 ◽

Vol 2021 ◽

pp. 1-17

Author(s):

Yihong Liu ◽

Hongbao Zhao ◽

Lei Wang ◽

Tao Wang ◽

Dongliang Ji ◽

...

Keyword(s):

Stress Field ◽

Plastic Zone ◽

Principal Stress ◽

Stress Gradient ◽

Surrounding Rock ◽

Stress Fields ◽

Stress Difference ◽

Distribution Law ◽

Lode Angle ◽

Formula Type

Based on the variation range of the stress lode angle, the in situ rock stress is divided into σ v -type stress field, σ H -type stress field, and σ h -type stress field. Through theoretical analysis, the principal stress difference distribution law and plastic zone distribution pattern around the roadway in different types of stress fields are obtained. Theoretical and numerical simulation calculation results show that under different stress lode angle conditions, the principal stress difference distribution of the surrounding rock of the roadway is greatly different, which has a direct effect on the shape and range of the plastic zone of the surrounding rock of the roadway. In the σ v -type stress field and the σ H -type stress field, the shape of the plastic zone of the roadway surrounding rock is mainly oval and “butterfly,” while in the σ h -type stress field, the shape of the plastic zone of the roadway surrounding rock is mainly oval. The laboratory test proves that the stress gradient has an important effect on the damage degree of the surrounding rock of the roadway. The larger the stress gradient, the higher the strength of the rock mass and the more severe the damage. The change of the stress lode angle will affect the distribution law of the stress gradient of the surrounding rock of the roadway, thus affecting the degree of fragmentation of the surrounding rock. In type σ v and type σ H stress fields, the surrounding rock of the shoulder can be regarded as a key part of the roadway. In the σ h -type stress field, the plastic zones of the surrounding rocks of the roadway are more evenly distributed, and the damage range is less affected by θ. The influence law of the stress lode angle on the stability of the roadway has been well verified by field observation, and effective support measures have been proposed.

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Comprehensive Study on Surrounding Rock Failure Characteristics of Longwall Roadway and Control Techniques

Applied Sciences ◽

10.3390/app11219795 ◽

2021 ◽

Vol 11 (21) ◽

pp. 9795

Author(s):

Xiaojie Yang ◽

Gang Yang ◽

Ruifeng Huang ◽

Yajun Wang ◽

Jianning Liu ◽

...

Keyword(s):

Principal Stress ◽

Theoretical Calculations ◽

Maximum Principal Stress ◽

Surrounding Rock ◽

Support Design ◽

Geological Conditions ◽

Concentration Degree ◽

The Stability ◽

Roadway Deformation ◽

And Control

Research on underground coal mines has primarily focused on the stability of roadways. Mining activities lead to significant damage to the surrounding rocks and also degrade the support to the roadways. Considering the 21309 roadway of the Huojitu coal mine as a case study, this work comprehensively analyzed the characteristics of the surrounding rock using three methods: theoretical calculations, FLAC3D numerical modeling, and field observations. The results indicate that, under the influence of secondary mining, the failure range and stress concentration degree of the surrounding rock are considerably higher than those under the influence of primary mining. In this case, the maximum damage range in the surrounding rock can reach 1.8 m, the maximum principal stress can reach 19.82 MPa, and the ratio of the maximum principal stress to the minimum principal stress can reach 1.95. According to the results, the previous support design for roadways was optimized and applied in the field. Field monitoring revealed that the roadway deformation was effectively controlled, and the optimized support design was safe and reliable. This study is expected to serve as a reference for support designs or optimization under similar geological conditions.

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Study on Sensitivity Parameters Analysis of Grouting Reinforcement Underpassing Existing Subway Tunnel by Numerical Modeling

Advances in Civil Engineering ◽

10.1155/2021/8868216 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Zaiqiang Hu ◽

Bin Ma ◽

Xingzhou Chen ◽

Lili Chen

Keyword(s):

Pore Pressure ◽

Principal Stress ◽

Surrounding Rock ◽

Surface Settlement ◽

Stress Difference ◽

Reinforcement Effect ◽

Subway Tunnel ◽

Grouting Pressure ◽

Grouting Reinforcement ◽

The Stability

When carrying out construction that underpasses existing subway tunnels, the surrounding rock is frequently disturbed. Therefore, it can loosen easily and become unstable, which makes its stability difficult to control. Here, we considered an existing subway tunnel in a certain subway section and used orthogonal experiments to design a simulation program as well as the UDEC (Universal Distinct Element Code) simulation software to determine the influences of four factors (i.e., grout density, grouting pressure, dynamic shear force, and viscosity) on the grouting reinforcement effect. The following results were obtained: (1) the combination of the construction method and the grouting parameters strongly influences the reinforcement effect on the surrounding rock of the tunnel. The grouting pressure is not directly proportional to the stability of the surrounding rock. The dynamic adjustment of the relationship between the grouting pressure and the grout density can effectively improve the stress state of the surrounding rock of the tunnel, control surface settlement and deformation, and reduce the section reduction rate of the tunnel. (2) The distribution of joints is closely related to the failure area and form of the surrounding rock of the tunnel. For surrounding rock with well-developed joint fissures, an excessively high grouting pressure should not be used as they are unstable. (3) The effective bearing range of grouting-reinforced surrounding rock is dependent on the pore pressure and principal stress difference. The area where the pore pressure is 70–80% of the initial grouting pressure is the effective bearing range of the grouting-reinforced surrounding rock. The stability of the surrounding rock increases with decreasing principal stress difference and increasing range. (4) The actual monitored data show that the surface settlement can be effectively reduced by handling of grouting reinforcement parameters flexibly, which can meet the control standards.

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Displacement Solution of Salt Cavern with Shear Dilatation Behavior Based on Hoek-Brown Strength Criterion

Advances in Civil Engineering ◽

10.1155/2019/6735623 ◽

2019 ◽

Vol 2019 ◽

pp. 1-16 ◽

Cited By ~ 1

Author(s):

Huabin Zhang ◽

Qingqing Zhang ◽

Laigui Wang

Keyword(s):

Plastic Zone ◽

Elastic Strain ◽

Large Strain ◽

Structural Characteristics ◽

Strength Criterion ◽

Surrounding Rock ◽

Salt Formation ◽

Salt Cavern ◽

The Stability ◽

Influence Degree

In this study, an analytical solution of stress, strain, and displacement, in the elastic and plastic zone is proposed. The solution is derived on the basis of ideal elastoplastic mechanical model of spherical salt cavern with shear dilatation behavior, by adopting Hoek-Brown (H-B) criterion. The solution obtains not only in small and large strain stage but also in creep stage. The proposed solution is validated, by comparison of the obtained results with numerical results in FLAC3D. The results indicate that the result obtained adopting the H-B criterion is closer to that one obtained adopting the Mohr-Coulomb (M-C). The H-B criterion is more applicable for the salt cavern construction as it considers the structural characteristics of the rock salt formation. The displacement difference obtained by two different methods decreases with the increase of GSI or running pressure, but it increases with the enlarged angle of dilation. The influence of different assumptions of elastic strain of plastic zone on displacements is more significant under large strain conditions. The influence of the angle of dilation on displacements is more obvious when the elastic strain of plastic zone is given to stationary values, and the influence degree increases with the enlarged angle of dilation. Under the same conditions, the creep displacement decreases with the increase of GSI, and both the creep displacement and the effect degree enhance with the enlarged dilation angle. The proposed solutions can be used in the stability analysis of surrounding rock in the construction and operation of salt cavern storage.

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Study on In Situ Stress Measurement and Surrounding Rock Control Technology in Deep Mine

Geofluids ◽

10.1155/2020/8839333 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Zhongcheng Qin ◽

Bin Cao ◽

Yongle Liu ◽

Tan Li

Keyword(s):

Stress Field ◽

Principal Stress ◽

Coal Mine ◽

Maximum Principal Stress ◽

In Situ Stress ◽

Measured Data ◽

Surrounding Rock ◽

In Situ Stress Measurement ◽

Surrounding Rock Control

In situ stress is the direct cause of roadway deformation and failure in the process of deep mining activities. The measured data of in situ stress in the Shuanghe coal mine show that the maximum principal stress is 44.94~50.61 MPa, and the maximum principal stress direction is near horizontal direction, which belongs to tectonic stress field. The maximum horizontal principal stress is 1.66~1.86 of the vertical stress. The horizontal principal stress controls the deep stress field. According to the measured data of in situ stress, the high-strength prestress bolt and cable collaborative support form is designed in the Shuanghe coal mine. Based on the stress field research of bolt and cable, the optimal prestress ratio of bolt and cable is proposed as 3. When the prestress ratio of bolt and cable is constant, the smaller the length ratio of bolt and cable is, the better the effect of prestressed field formed by cooperative support is. The results are applied to the support design of the mining roadway in the Shuanghe coal mine. Through the field monitoring test results, it is found that the maximum roof subsidence is 86 mm, the maximum floor deformation is 52 mm, and the maximum deformation of two sides is 125 mm. The surrounding rock control effect of the roadway is good, and the surrounding rock deformation conforms to the engineering technology standard requirements. The research results of this paper can provide some reference for the surrounding rock support of high ground stress mining roadway under similar conditions.

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Roadway Surrounding Rock under Multi-Coal-Seam Mining: Deviatoric Stress Evolution and Control Technology

Advances in Civil Engineering ◽

10.1155/2020/9891825 ◽

2020 ◽

Vol 2020 ◽

pp. 1-18

Author(s):

Dongdong Chen ◽

En Wang ◽

Shengrong Xie ◽

Fulian He ◽

Long Wang ◽

...

Keyword(s):

Plastic Zone ◽

Coal Seam ◽

Coal Pillar ◽

Surrounding Rock ◽

Deviatoric Stress ◽

Mine Pressure ◽

Coal Face ◽

Surrounding Rock Control ◽

Seam Mining ◽

Peak Value

Multi-coal-seam mining creates surrounding rock control difficulties, because the mining of a coal face in one seam can affect coal faces in another. We examine the effects of multi-coal-seam mining on the evolution of the deviatoric stress distribution and plastic zone in the roadway surrounding rock. In particular, we use numerical simulation, theoretical calculation, drilling detection, and mine pressure observation to study the distribution and evolution characteristics of deviatoric stress on Tailgate 8709 in No. 11 coal seam in Jinhuagong mine when the N8707 and N8709 coal faces in No. 7-4 coal seam and the N8707 and N8709 coal faces in No. 11 coal seam are mined. The evolution laws of deviatoric stress and the plastic zone of roadway surrounding rock in the advance and behind sections of the coal face are studied, and a corresponding control technology is proposed. The results show that the peak value of deviatoric stress increases with the advance of the coal face, and the positions of the peak value of deviatoric stress and the plastic zone become deeper. The deflection angle of the peak stress after mining at each coal face and the characteristics of the peak zone of deviatoric stress and the plastic zone of the roadway surrounding rock under the disturbance of multi-coal-seam mining are determined. In conclusion, the damage range in the roadway roof in the solid-coal side and coal pillar is large and must be controlled. A combined support technology based on high-strength and high pretension anchor cables and truss anchor cables is proposed; long anchor cables are used to strengthen the support of the roadway roof in the solid-coal side and coal pillar. The accuracy of the calculated plastic zone range and the reliability of the combined support technology are verified through drilling detection and mine pressure observation on site. This research can provide a point of reference for roadway surrounding rock control under similar conditions.

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Deviatoric Stress Evolution Laws and Control in Surrounding Rock of Soft Coal and Soft Roof Roadway under Intense Mining Conditions

Advances in Materials Science and Engineering ◽

10.1155/2020/5036092 ◽

2020 ◽

Vol 2020 ◽

pp. 1-18

Author(s):

Dongdong Chen ◽

Chunwei Ji ◽

Shengrong Xie ◽

En Wang ◽

Fulian He ◽

...

Keyword(s):

Numerical Simulation ◽

Plastic Zone ◽

Theoretical Calculations ◽

Coal Pillar ◽

Surrounding Rock ◽

Deviatoric Stress ◽

Anchor Cable ◽

Soft Coal ◽

Working Face ◽

Failure Line

Aiming at the problem of large deformation and instability failure and its control of soft coal and soft roof roadway under intense mining, laboratory experiments, theoretical calculations, Flac3D numerical simulation, borehole peeping, and pressure observation were used to study the deflection characteristics of the deviatoric stress of the gas tailgate and the distribution and failure characteristics of the plastic zone in the mining face considering the strain softening characteristics of the roof and coal of roadway, and then the truss anchor cable-control technology is proposed. The results show the following: (1) The intense mining influence on the working face will deflect the peak deviatoric stress zone (PDSZ) of the surrounding rock of the gas tailgate. The influence distance of PDSZ is about 20 m in advance and 60 m in lag; the PDSZ at the gob side of the roadway is located in the range of 3–5.5 m from the surface of the coal pillar, while the coal wall side is mainly located in the range of 3–4.5 m at the shoulder corner and bottom corner of the solid coal. (2) The intense mining in the working face caused the nonuniform expansion of the surrounding rock plastic area of the gas tailgate. The two shoulder angles of the roadway and the bottom of the coal pillar have the largest damage range, and the maximum damage location is the side angle of the coal pillar (5 m). Angle and bottom angle of coal pillar are the key points of support control. (3) The plastic failure line of the surrounding rock of the gas tailgate is always between the inner and outer contours of the PDSZ, and the rock mass in the PDSZ is in a stable and unstable transition state, so the range of anchor cable support should be cross plastic failure line. (4) The theoretical calculations and numerical simulation results agree well with the drilling peep results. Based on the deflection law of the PDSZ and the expansion characteristics of the plastic zone, a truss anchor cable supporting system with integrated locking and large-scale support function is proposed to jointly control the roof and the two sides, which effectively solves the problem of weak surrounding rock roadway under severe mining deformation control problems realizing safety and efficient production in coal mines under intense mining.

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Stability Analysis and Derived Control Measures for Rock Surrounding a Roadway in a Lower Coal Seam under Concentrated Stress of a Coal Pillar

Shock and Vibration ◽

10.1155/2020/6624983 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Zhuoyue Sun ◽

Yongzheng Wu ◽

Zhiguo Lu ◽

Youliang Feng ◽

Xiaowei Chu ◽

...

Keyword(s):

Coal Seam ◽

Numerical Simulations ◽

Principal Stress ◽

Coal Pillar ◽

Control Measures ◽

Stress Difference ◽

Coal Seams ◽

The Stability ◽

Close Distance ◽

Close Distance Coal Seams

Numerical simulations have often been used in close-distance coal seam studies. However, numerical simulations can contain certain subjective and objective limitations, such as high randomness and excessively simplified models. In this study, close-distance coal seams were mechanically modeled based on the half-plane theory. An analytical solution of the floor stress distribution was derived and visualized using Mathematica software. The principal stress difference was regarded as a stability criterion for the rock surrounding the roadway. Then, the evolution laws of the floor principal stress difference under different factors that influence stability were further examined. Finally, stability control measures for the rock surrounding the roadway in the lower coal seam were proposed. The results indicated the following: (1) The principal stress difference of the floor considers the centerline of the upper coal pillar as a symmetry axis and transmits radially downward. The principal stress difference in the rock surrounding the roadway gradually decreases as the distance from the upper coal pillar increases and can be ranked in the following order: left rib > roof > right rib. (2) The minimum principal stress difference zones are located at the center of the left and right “spirals,” which are obliquely below the edge of the upper coal pillar. This is an ideal position for the lower coal seam roadway. (3) The shallowness of the roadway, a small stress concentration coefficient, high level of coal cohesion, large coal internal friction angle, and appropriate lengthening of the working face of the upper coal seam are conducive to the stability of the lower coal seam roadway. (4) Through bolt (cable) support, borehole pressure relief, and pregrouting measures, the roof-to-floor and rib-to-rib convergence of the 13313 return airway is significantly reduced, and the stability of the rock surrounding the roadway is substantially improved. This research provides a theoretical basis and field experience for stabilizing the lower coal seam roadways in close-distance coal seams.

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Stability Analysis of Tunnel Surrounding Rock Based on Coupled Fluid-Solid Theory

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.90-93.1900 ◽

2011 ◽

Vol 90-93 ◽

pp. 1900-1903

Author(s):

Fu Ming Wang ◽

Xiao Long Li ◽

Yan Hui Zhong ◽

Xiao Guang Chen

Keyword(s):

Stability Analysis ◽

Plastic Zone ◽

Coupling Effect ◽

Plastic Zone Size ◽

Wall Rock ◽

Surrounding Rock ◽

Maximum Deformation ◽

Calculation Results ◽

The Stability ◽

Tunnel Depth

Taking Chaijiazhuang Tunnel of Lingnan Expressway as project background, the stability analysis of surrounding rock was performed based on the coupled fluid-solid theory. The distributions of stress field, displacement field and plastic zone of rock mass after excavation of tunnel were discussed considering coupled effect between flow and stress under the condition of different rock level and tunnel depth. Compared with the calculation results of not considering coupling effect, the maximum deformation, maximum principle stress and plastic zone size of wall rock were obviously increased when considering coupling effect, which showed a remarkable influence of coupled fluid-solid effect on the stability of tunnel surrounding rock. Some conclusions were drawn and may provide some guidance to the design and construction of tunnels in water-rich strata.

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Analytical Solution of Tunnel Surrounding Rock for Stress and Displacement Based on Lade–Duncan Criterion

Advances in Civil Engineering ◽

10.1155/2018/5363658 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

MingZheng Zhu ◽

Yugui Yang ◽

Feng Gao ◽

Juan Liu

Keyword(s):

Internal Friction ◽

Plastic Zone ◽

Yield Criterion ◽

Surrounding Rock ◽

Rock Stress ◽

Deformation And Failure ◽

Displacement Based ◽

The Stability ◽

Coulomb Criterion

The deformation and failure of tunnel surrounding rock is the result of tunnel excavation disturbance and rock stress release. When the local stress of surrounding rock exceeds the elastic limit of rock mass, the plastic analysis of surrounding rock must be carried out to judge the stability of tunnel. In this study, the Lade–Duncan yield criterion is used to calculate the analytic solutions for the surrounding rock in a tunnel, and the radius and displacement of the plastic zone are deduced using an equilibrium equation. The plastic zone radius and displacement based on Lade–Duncan criterion and Mohr–Coulomb criterion were compared by using single-factor analysis method under the different internal friction angles, in situ stresses, and support resistances. The results show that the solutions of the radius and displacement of plastic zone calculated by the Lade–Duncan criterion are close to those of Mohr–Coulomb criterion under the high internal friction angle and support resistance or low in situ rock stress; however, the radius and displacement of the plastic zone calculated by the Lade–Duncan criterion are larger under normal circumstances, and the Lade–Duncan criterion is more applicable to the stability analysis of the surrounding rock in a tunnel.

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