Comparison of Shape Characteristics of Plastic Zone Around Circular Tunnel Under Different Strength Criteria

2020 ◽  
Vol 36 (6) ◽  
pp. 849-856
Author(s):  
H. Y. Shi ◽  
Z. K. Ma ◽  
Q. J. Zhu ◽  
J. J. Shi ◽  
Z. Q. Zhao
Keyword(s):  
Plastic Zone ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Strength Criterion ◽  
Stress Change ◽  
Circular Tunnel ◽  
Strength Criteria ◽  
Lateral Pressure Coefficient ◽  
Low Sensitivity ◽  
Shape Characteristics

ABSTRACTThe butterfly plastic zone theory based on Mohr Coulomb criterion has been widely used in coal mine production. In order to verify the universality of the theory, it is necessary to compare the distribution of plastic zone under different strength criteria. Based on the elastic-plastic mechanics, the principal stress distribution function around the circular tunnel is deduced in the paper, and the boundary and radius of the plastic zone under different strength criteria are calculated. The results show that the change laws of the plastic zone around the circular tunnel under different strength criteria has the following commonness: firstly, with the increase of the lateral pressure coefficient, the shape of the plastic zone presents the change laws of “circle ellipse butterfly”; Secondly, with the increase of the lateral pressure coefficient, the radius of the plastic zone is exponential distribution, while the characteristic value is different when the radius of the plastic zone is infinite. At same time, it shows that the butterfly plastic zone has a low sensitivity dependence on the strength criterion, no matter which strength criterion is adopted, and the butterfly plastic zone will inevitably appear in the surrounding rock mass of circular tunnel in the high deviator stress environment; The plastic zone with butterfly shape is highly sensitive to the stress change, and the small stress change may promote the expansion of the plastic zone. This result is significant for us to understand and prevent rock engineering disasters and accidents.

scholarly journals Analysis of plastic zones in surrounding rocks around a circular tunnel considering the effect of intermediate principal stress and heterogeneity

2019 ◽  
Vol 275 ◽  
pp. 03007 ◽  
Author(s):  
Shuxin Deng ◽  
Yonglai Zheng ◽  
Lipo Feng ◽  
Le Van Tuan ◽  
Cuizhou Yue ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Principal Stress ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Plastic Zone Size ◽  
Intermediate Principal Stress ◽  
Circular Tunnel ◽  
Lateral Pressure Coefficient ◽  
Calculation Results ◽  
Coulomb Criterion

Based on a modified Mohr-Coulomb criterion with a non-uniform coefficient, a calculation method of plastic zone boundary of surrounding rocks in a circular tunnel in non-uniform stress field is established. Both the effects of intermediate principal stress and heterogeneity are studied. With the increase of the intermediate principal stress, the plastic zone size of the surrounding rocks will decrease first and then increase. Lateral pressure coefficient has an effect on the shape of the plastic zone. With the increase of lateral pressure coefficient, the plastic zone gradually becomes uniform, and the failure of surrounding rock develops upward and downward from both sides. As non-uniform coefficient increases, the material is more uniform and the effect of intermediate principal stress on the plastic zone is less significant. If the effect of intermediate principal stress is not taken into account, the calculation results tend to be consistent with results calculated by the Mohr-Coulomb criterion, which are considered to be conservative.

scholarly journals Analytical Solution of a Circular Opening considering Nonuniform Pressure and Its Engineering Application

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Peng Wu ◽  
Yanlong Chen ◽  
Liang Chen ◽  
Xianbiao Mao ◽  
Wei Zhang
Keyword(s):  
Analytical Solution ◽  
Plastic Zone ◽  
Young’S Modulus ◽  
Lateral Pressure ◽  
Young's Modulus ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Circular Opening ◽  
Lateral Pressure Coefficient

Based on the Mohr–Coulomb criterion, a new analytical solution of a circular opening under nonuniform pressure was presented, which considered rock dilatancy effect and elastic-brittle-plastic failure characteristics. In the plastic zone, the attenuation of Young’s modulus was considered using a radius-dependent model (RDM), and solution of the radius and radial displacement of plastic zone was obtained. The results show that many factors have important impact on the response of the surrounding rock, including lateral pressure coefficient, dilation coefficient, buried depth, and Young’s modulus attenuation. Under nonuniform pressure condition, the distribution of plastic zone and deformation around the opening show obvious nonuniform characteristic: with the increasing of lateral pressure coefficient, the range of plastic zone and deformation decrease gradually at side, while they increase at roof and floor, and the location of the maximum value of support and surrounding rock response curve transfers from side to roof. Based on the analytical results and engineering practice, an optimization method of support design was proposed for the circular opening under nonuniform pressure.

Numerical Study on Tunnel Mechanics in Jointed Rock Mass with Finite Element Method

2011 ◽  
Vol 99-100 ◽  
pp. 790-795
Author(s):  
Ming Gao Zhang ◽  
Heng Bin Wu ◽  
Ze Ping He ◽  
Ting Qiang Zhou
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Plastic Zone ◽  
Lateral Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Lateral Pressure Coefficient ◽  
Element Method

Tunnel mechanics mainly depend on joints properties in layered and jointed rock mass, and most of the present methods adopted in numerical analysis are distinct element method. Combining to the Gaixiaba tunnel, considering the jointed properties such as dip angles, distances and lateral pressure coefficient, the finite element models are made in this paper. Results show that the plastic zone and total displacement presented a symmetric distribution with the axial of joints dip, and the plastic zone is very similar to the results suggested by Goodman. The dip angles, distances of joints and lateral pressure coefficient have significant effect on the tunnel mechanics.

scholarly journals Mechanical Model of Underground Shaft Coal Pocket and Deformation of Silo Wall in Coal Mines

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yongping Wu ◽  
Mingyin Liu ◽  
Wenyu Lv ◽  
Bosheng Hu
Keyword(s):  
Mechanical Model ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Coal Mines ◽  
Back Analysis ◽  
Strength Criterion ◽  
Maximum Tensile Stress ◽  
Pressure Coefficients ◽  
Lateral Pressure Coefficient ◽  
Deformation Law

In order to provide a theoretical basis for the design of underground shaft coal pocket and support parameters in coal mines, a mechanical model and a dynamic analysis of the silo wall are established based on the engineering background of Ganhe Coal Mine. The numerical calculation is carried out by using the new model. The back analysis of the silo wall damage in the actual project is carried out, and the deformation law and fracture mechanism of the silo wall affected by different lateral pressure coefficients are analyzed and studied research. Based on the Mohr–Coulomb strength criterion, five sets of orthogonal simulation experiments were carried out for lateral pressure coefficients of 0.6, 0.8, 1.0, 1.2, and 1.4, respectively. The results show that the lateral pressure coefficient is the main factor affecting the deformation of the silo wall, the radial displacement of the silo wall increases gradually with the increase of the lateral pressure coefficient, and the displacement follows the quadratic polynomial function distribution. The maximum tensile stress area of the silo wall is located in the middle and lower part of the shaft coal pocket, which better explains the engineering phenomenon that the actual fracture location of the silo wall is mostly concentrated in the middle and lower part of the underground shaft coal pocket. The targeted repair technology can be used for reference in engineering.

scholarly journals Numerical Study on Damage Zones Induced by Excavation and Ventilation in a High-Temperature Tunnel at Depth

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4773
Author(s):  
Jianyu Li ◽  
Hong Li ◽  
Zheming Zhu ◽  
Ye Tao ◽  
Chun’an Tang
Keyword(s):  
High Temperature ◽  
Lateral Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Fracture Morphology ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Geothermal System ◽  
Mechanical Coupling ◽  
Lateral Pressure Coefficient

Geothermal power is being regarded as depending on techniques derived from hydrocarbon production in worldwide current strategy. However, it has artificially been developed far less than its natural potentials due to technical restrictions. This paper introduces the Enhanced Geothermal System based on Excavation (EGS-E), which is an innovative scheme of geothermal energy extraction. Then, based on cohesion-weakening-friction-strengthening model (CWFS) and literature investigation of granite test at high temperature, the initiation, propagation of excavation damaged zones (EDZs) under unloading and the EDZs scale in EGS-E closed to hydrostatic pressure state is studied. Finally, we have a discussion about the further evolution of surrounding rock stress and EDZs during ventilation is studied by thermal-mechanical coupling. The results show that the influence of high temperature damage on the mechanical parameters of granite should be considered; Lateral pressure coefficient affects the fracture morphology and scale of tunnel surrounding rock, and EDZs area is larger when the lateral pressure coefficient is 1.0 or 1.2; Ventilation of high temperature and high in-situ stress tunnel have a significant effect on the EDZs scale; Additional tensile stress is generated in the shallow of tunnel surrounding rock, and the compressive stress concentration transfers to the deep. EDZs experiences three expansion stages of slow, rapid and deceleration with cooling time, and the thermal insulation layer prolongs the slow growth stage.

Experimental determination of the lateral pressure coefficient in the die of a compacting press by the method of optically active inserts

1974 ◽  
Vol 8 (8) ◽  
pp. 496-499
Author(s):  
V. A. Belousov ◽  
�. �. Kol'man-Ivanov ◽  
I. E. Semenov-Ezhov ◽  
N. A. Stepanov ◽  
I. P. Sukharev
Keyword(s):  
Experimental Determination ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Optically Active ◽  
Lateral Pressure Coefficient

scholarly journals Numerical Simulation on Large Deformation of Weak Rock Mass Tunnel Under High Geostress

2018 ◽  
Vol 175 ◽  
pp. 03025
Author(s):  
Feng Zhou ◽  
Hongjian Jiang ◽  
Xiaorui Wang
Keyword(s):  
Rock Mass ◽  
Large Deformation ◽  
Lateral Pressure ◽  
Simulation Analysis ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Analog Simulation ◽  
Lateral Pressure Coefficient ◽  
High Geostress ◽  
The Stability

The problem about the stability of tunnel surrounding rock is always an important research object of geotechnical engineering, and the right or wrong of the result from stability analysis on surrounding rock is related to success or failure of an underground project. In order to study the deformation rules of weak surrounding rock along with lateral pressure coefficient and burying depth varying under high geostress and discuss the dynamic variation trend of surrounding rock, the paper based on the application of finite difference software of FLAC3D, which can describe large deformation character of rock mass, analog simulation analysis of surrounding rock typical section of the class II was proceeded. Some conclusions were drawn as follows: (1) when burying depth is invariable, the displacements of tunnel surrounding rock have a trend of increasing first and then decreasing along with increasing of lateral pressure coefficient. The floor heave is the most sensitive to change of lateral pressure coefficient. The horizontal convergence takes second place. The vault subsidence is feeblish to change of lateral pressure coefficient. (2) The displacements of tunnel surrounding rock have some extend increase along with increasing of burying depth. The research conclusions are very effective in analyzing the stability of surrounding rock of Yunling tunnel. These are going to be a reference to tunnel supporting design and construction.

Study on Influence Factors of Underground Joint Rock Cavern Displacement

2013 ◽  
Vol 353-356 ◽  
pp. 1515-1518
Author(s):  
Zhen Wang ◽  
Chun Han
Keyword(s):  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Influence Factors ◽  
Two Dimensional ◽  
Tunnel Excavation ◽  
Lateral Pressure Coefficient ◽  
Rock Cavern ◽  
The Many ◽  
Rock Tunnel ◽  
Joint Rock

The safety response of joint rock underground tunnels is one of the many problems that draw the attention of geology specialists and scholars. Adopting two dimensional discrete element method, a numerical model of joint rock underground cavern is established to study its stability. The buried depth and the lateral pressure coefficient are considered respectively. The result shows: when the lateral pressure coefficient is identical, the depth is bigger the displacement is more bigger, and the displacement is strong influenced by the buried depth when the lateral pressure coefficient is big; In the same depth the tunnel is buried, the tunnel rocks displacement is slightly influenced by the lateral pressure coefficient when it is small, but the influence is seriously as the lateral pressure coefficient is big. The simulation in the context can be used to provide guide for joint rock tunnel excavation and supporting.

scholarly journals Prediction of Collapse Scope of Deep-Buried Tunnels Using Pressure Arch Theory

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yingchao Wang ◽  
Hongwen Jing ◽  
Qiang Zhang ◽  
Ning Luo ◽  
Xin Yin
Keyword(s):  
Stress Field ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Stress Fields ◽  
Tunnel Engineering ◽  
Circular Tunnel ◽  
Multiple Factors ◽  
Ground Stress ◽  
Tunnel Collapse ◽  
Main Influence

Tunnel collapse remains a serious problem in practice. Effective prediction methods on tunnel collapse are necessary for tunnel engineering. In this study, systematic study on the pressure arch was presented to predict tunnel collapse. Multiple factors under different conditions were considered. First, the pressure arch was described as a certain scope in comparison with the lowest pressure arch line. Then, a deep-buried circular tunnel was selected as the investigated object. Its collapse scope was analyzed using the lowest pressure arch line. Meanwhile, the main influence from the ground stress field was considered. Different modes of ground stress fields were investigated in detail. The results indicate that the collapse scope varies with different ground stress fields. Determination on the collapse scope is strongly affected by the judgment standard of the pressure arch. Furthermore, a selected case was analyzed with the pressure arch. The area and the height of tunnel collapse were calculated with multiple factors, including ground stress field, judgment standard, and lateral pressure coefficient. Finally, selected results were compared with relevant previous researches, and reasonable results were obtained. The present results are helpful for further understanding of the tunnel collapse and could provide suitable guidance for tunnel projects.

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