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

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.

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

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Liu Rui ◽  
Zhu Quanjie
Keyword(s):  
Plastic Zone ◽  
Principal Stress ◽  
Tensile Deformation ◽  
Stress Component ◽  
Maximum Principal Stress ◽  
Surrounding Rock ◽  
Deviatoric Stress ◽  
Stress Difference ◽  
Deviator Stress ◽  
The Stability

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.

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

Geofluids ◽  
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.

scholarly journals Deformation and Failure Mechanism of Surrounding Rock in Mining-Influenced Roadway and the Control Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jicheng Feng ◽  
Shuaifeng Yin ◽  
Zhiheng Cheng ◽  
Jianjun Shi ◽  
Haoyu Shi ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Failure Mechanism ◽  
Principal Stress ◽  
Pressure Ratio ◽  
Confining Pressure ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Morphologic Change ◽  
Deformation And Failure ◽  
Implicit Equation

Aiming at the problem of surrounding rock deformation and failure of mining roadway and its control, a mechanical model of the circular roadway under the mining environment is established, and the implicit equation of the plastic zone boundary is derived. By analyzing the morphologic evolution law of the surrounding rock plastic zone in the mining roadway, the key factors affecting the morphologic change of the plastic zone are obtained, that is, the magnitude and direction of principal stress. The influence law of the magnitude and direction of principal stress on the plastic zone of the mining roadway is analyzed by using numerical simulation software, and the deformation and failure mechanism of surrounding rock of the mining roadway is revealed. The results showed that the size and morphology of the plastic zone were closely related to the confining pressure ratio (η). Taking the boundary of η valuing 1, the larger or smaller η value was, the more serious the deformation and failure of surrounding rock would be; the morphology of the plastic zone changed with the deflection of the principal stress, with the location of the maximum plastic zone influenced by the principal stress direction. For the surrounding rock control in the mining-influenced roadway, it is advised to take the following methods: firstly, it is necessary to consider how to reduce or remove the influence of mining on surrounding rock, improve the stress environment of surrounding rock, and reduce the failure depth of the plastic zone, so as to better maintain the roadway. Secondly, in view of the deformation and failure characteristics of the mining roadway, the fractional support method of “yielding first and then resisting” should be adopted, which applies the cable supplement support after mining instead of the one-off high-strength support during roadway excavation, so as to control the malignant expansion of the surrounding rock plastic zone and prevent roof falling accidents.

Measurement and the Distribution Law of In Situ Stresses at Deep Depth of Xingcun Coal Mine

2012 ◽  
Vol 450-451 ◽  
pp. 1601-1607 ◽  
Author(s):  
Jiong Wang ◽  
Zhi Biao Guo ◽  
Feng Zhou ◽  
Feng Bin Su ◽  
Bao Liang Li
Keyword(s):  
Stress Field ◽  
Principal Stress ◽  
Coal Mine ◽  
Stress Measurement ◽  
In Situ Stress ◽  
Distribution Law ◽  
Principal Stresses ◽  
In Situ Stress Measurement ◽  
In Situ Stress Field

Many kinds of in situ stress measurement methods are used nowadays, two most common of which are the overcoring and the hydraulic fracturing methods. In order to study the distribution law of in situ stress field in the deep position of Xingcun coal mine, 4 points of in situ stress measurement were carried out in underground roadways at the -1200 m level adopting the overcoring method. The hollow included technique was used to measure the 4 points of in-situ stress. According to the analysis of the measurement data, the results indicated that: (1) Among the three principal stresses on all measurement points, two principal stresses were nearly horizontal and one was nearly vertical. Furthermore, the maximum horizontal principal stress was more than the vertical principal stress, and the magnitude of vertical stress was equal to the weight of overburden rock mass;(2)The value of the maximum horizontal principal stress reached 52.3 MPa , the directions mainly concentrated on the extension of N42°W – N85°W, and the obliquity mainly concentrated on the extension of -29° – 10°;(3)The ratio of maximum horizontal principal stress to vertical principal stress was 1.42 - 1.64 with an average value of 1.55. The result presented that the in situ stress field in Xingcun coalmine at the depth of -1200m was dominated by tectonic horizontal stress. According to the results above, we gained the in situ stress states and the distribution law in the measured region. At the same time, it can offer reasonable basic parameters for underground roadway layout and support design of Xingcun coalmine.

scholarly journals Effect of Principal Stress Field on the Development of Plastic Zone ahead of the Gateroad

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4356
Author(s):  
Hongtao Liu ◽  
Linfeng Guo ◽  
Xidong Zhao ◽  
Pengfei Wang
Keyword(s):  
Stress Field ◽  
Plastic Zone ◽  
Principal Stress ◽  
Maximum Principal Stress ◽  
Coal And Gas Outburst ◽  
Lagrangian Analysis ◽  
Important Indicator ◽  
Gas Outburst ◽  
Minimum Principal Stress ◽  
Long Time

The distribution of a plastic zone ahead of a gateroad plays a significant role in maintaining the long-term stability of mining spaces. For a long time, the principal stress field such as the values, the direction, etc. have been observed to have impacts on plastic zone development, but has not been looked into deeply and systematically. To this end, the influence of principal stress field including the maximum principal stress (P1), the angle between the P1 direction and the Z-axis (α), the minimum principal stress (P3), and the ratio of maximum principal stress to minimum principal stress (P1/P3) on the expansion of the plastic zone ahead of the gateroad is investigated by the (Fast Lagrangian Analysis of Continua) FLAC3D models. The results show that: (1) The plastic zone volume increases first and then decreases with the increase of α, and the direction of butterfly-shaped plastic zone ahead of gateroad is rotating with the evolution of α. (2) The plastic zone volume ahead of excavation face increases gradually with the increase of P1/P3. Mutagenicity of butterfly-shaped plastic zone occurs ahead of the gateroad under a certain value of P1/P3. (3) With the increase of P1 and decrease of P3, the plastic zone volume is of exponential growth. The plastic zone volume approaches infinity when the critical value of maximum principal stress ([P1]) and the minimum principal stress ([P1]) is obtained. (4) The study of the effect of principal stress field on the expansion of plastic zone ahead of the gateroad is helpful for revealing the mechanisms of coal and gas outbursts. The critical stress state of butterfly-shaped plastic zone mutagenicity ahead of the gateroad can be used as an important indicator for assessing the risk of coal and gas outburst. The research can also guide the prevention of coal and gas outburst ahead of the gateroad.

scholarly journals Study on Three-Dimensional Stress Field of Gob-Side Entry Retaining by Roof Cutting without Pillar under Near-Group Coal Seam Mining

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 552 ◽  
Author(s):  
Xiaoming Sun ◽  
Yangyang Liu ◽  
Junwei Wang ◽  
Jiangbing Li ◽  
Shijie Sun ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Stress Field ◽  
High Stress ◽  
Peak Stress ◽  
Horizontal Stress ◽  
Surrounding Rock ◽  
Distribution Law ◽  
Working Face ◽  
Pillar Mining ◽  
Seam Mining

In order to explore the distribution law of stress field under the mining mode of gob-side entry retaining by roof cutting without pillar (GERRCP) under goaf, based on the engineering background of 8102 and 9101 working faces in Xiashanmao coal mine, the stress field distribution of GERRCP and traditional remaining pillar was studied by means of theoretical analysis and numerical simulation. The simulation results showed that: (1) in the front of the working face, the vertical peak stress of non-pillar mining was smaller than that of the remaining pillar mining, and it could effectively control stress concentration in surrounding rock of the mining roadway; the trend of horizontal stress distribution of the two was the same, and the area, span and peak stress of stress the rise zone were the largest in large pillar mining and the minimum in non-pillar mining. (2) On the left side of the working face, the vertical stress presented increasing-decreasing characteristics under non-pillar mining mode and saddle-shaped distribution characteristics under the remaining pillar mining mode respectively. Among them, the peak stress was the smallest under non-pillar mining, and compared with the mining of the large pillar and small pillar, non-pillar mining decreased by 12–21% and 3–10% respectively. The position of peak stress of the former was closer to the mining roadway, indicating that the width of the plastic zone of the surrounding rock of the non-pillar mining was smaller and bearing capacity was higher. In the mining of the large and small pillar, the horizontal stress formed a high stress concentration in the pillar and 9102 working face respectively. In non-pillar mining, the horizontal stress concentration appeared in solid coal, but the concentration area was small.

scholarly journals Influence of Three-Dimensional Stress Field Variation on Fracture Evolution Characteristics of a Roof

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xuyang Shi ◽  
Zhaolin Li ◽  
Qingxiang Cai ◽  
Wei Zhou ◽  
Wenshuai Li
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Principal Stress ◽  
Three Dimensional ◽  
Surrounding Rock ◽  
Fracture Characteristics ◽  
Principal Stress Direction ◽  
True Triaxial ◽  
Fracture Evolution ◽  
Macroscopic Fracture

Excavation disturbance on the dynamic variation of the three-dimensional stress field is the main cause for the dynamic disasters of the surrounding rock mass of the roof. The stress condition in the surrounding rock mass of the roof during entry excavation and its impact on entry stability are systemically studied in this study. It is found that the surrounding rock mass of the roof is mainly influenced by the combined effect of the stress unloading and stress transference induced by entry excavation. A servo-controlled true triaxial material testing system is used to conduct the true triaxial loading and unloading experiments of rocks under different stress paths. The influence of different stress paths, especially the variation of the principal stress direction, on the mechanical characteristics and fracture characteristics of rocks is investigated. The results indicate that the variation of the principal stress direction has a significant impact on the macroscopic fracture characteristics of the rock. The main macroscopic fracture plane of the rock highly depends on the intermediate principal stress. The fracture evolution of the roof rock mass during entry excavation is analyzed. The results show that the change of the three-dimensional stress field induces the formation of complex fracture networks in the surrounding rock mass of the roof. The roof is likely to dislocate horizontally and collapse. The corners of the entry are seriously damaged. Based on the above findings, a support scheme is proposed to maintain the stability of a gob-side entry. The field experience suggests that the support scheme can achieve good results.

scholarly journals Surrounding Rock Failure Characteristics and Water Inrush Mechanism of Roadway above the Aquifer in Nonuniform Stress Field

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xiaofei Guo ◽  
Yongen Li ◽  
Jun Li ◽  
Hongyu Liu ◽  
Xianjie Ma ◽  
...  
Keyword(s):  
Stress Field ◽  
Plastic Zone ◽  
Water Inrush ◽  
Rock Failure ◽  
Surrounding Rock ◽  
Force Model ◽  
Confined Water ◽  
Nonuniform Stress ◽  
Maximum Radius ◽  
Nonuniform Stress Field

The expansion of the roadway surrounding rock failure zone may connect the floor aquifer and cause the roadway water inrush. In order to reveal the mechanism of the roadway water inrush above confined water, we established the force model of the roadway surrounding rock above confined water in nonuniform stress field and studied the shape characteristics and expansion law of the roadway surrounding rock plastic zone. The results show that the roadway surrounding rock will form three kinds of plastic zone under different lateral pressure coefficients: circular, elliptical, and butterfly; when the shape of plastic zone is circular or elliptic, the maximum radius increases linearly with the increase of regional stress; when the shape is butterfly, the maximum radius increases exponentially with the increase of stress. Under the condition of a larger bidirectional stress ratio, the surrounding rock of the roadway will show butterfly-shaped failure, and small stress change will cause malignant expansion of the plastic zone; when the plastic zone is connected with the underlying aquifer, confined water of floor will enter the rock mass from the water diversion point and eventually flood into the roadway, causing floor water inrush.

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