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

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.

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

Energies ◽

10.3390/en14164773 ◽

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.

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

MATEC Web of Conferences ◽

10.1051/matecconf/201817503025 ◽

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.

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Parabolic-Apex Numerical Back-Analysis of Mechanics Parameters of Surrounding Rock

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.204-208.196 ◽

2012 ◽

Vol 204-208 ◽

pp. 196-201 ◽

Cited By ~ 1

Author(s):

Jian Cong Xu ◽

Yi Wei Xu

Keyword(s):

Young’S Modulus ◽

Young's Modulus ◽

Pressure Coefficient ◽

Back Analysis ◽

Surrounding Rock ◽

In Situ Monitoring ◽

Monitoring Data ◽

3D Fem ◽

Physical Mechanics

The parabolic-apex numerical back-analysis method (PNBM) was proposed to obtain such physical-mechanics parameters as Young's modulus and lateral pressure coefficient of surrounding rock by 3D FEM numerical analysis based on in-situ monitoring data. Taking Xiang-an Subsea Tunnel (located in Xiamen, Fujian Province, China) for example, adopting the PNBM using ABAQUS software, three dimensional elastic-plastic FEM-PNBM of tunnel surrounding rock was validated using in-situ monitoring data. The results show as follows: Using the PNBM, not only may high calculation precision be obtained, better meeting the demand of actual projects, but also more reasonable and reliable physical mechanics indices of surrounding rock such as Young's modulus and lateral confinement pressure coefficient, may be obtained. The applicability and the simplicity of this proposed method also support its usefulness.

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Influence of Side-Pressure Coefficient on Deformation of Tunnel Surrounding Rock and Bolt Axial Force

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.741.138 ◽

2015 ◽

Vol 741 ◽

pp. 138-142 ◽

Cited By ~ 1

Author(s):

Feng Hai Ma ◽

Yan Wang ◽

Zhi Bin Wang

Keyword(s):

Axial Force ◽

Lateral Pressure ◽

Pressure Coefficient ◽

Side Wall ◽

Horizontal Displacement ◽

Internal Force ◽

Surrounding Rock ◽

Lateral Pressure Coefficient ◽

Finite Element Software ◽

Side Pressure

Internal force and deformation of surrounding rock and supporting structure of the nonlinear research is the use of finite element software ADINA by ideal elastic-plastic constitutive model.Results show that the lateral pressure coefficient increased from 0 to 1, and even decrease sharply arch sedimentation of surrounding rock, side wall horizontal displacement towards the hole along the radial direction development gradually reduced to 0 and reverse to the hole, when the lateral pressure coefficient is less than 0.5, bolt axial force biggest change is not obvious, when lambda increases gradually, the largest bolt axial force significantly increased.

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

MATEC Web of Conferences ◽

10.1051/matecconf/201927503007 ◽

2019 ◽

Vol 275 ◽

pp. 03007 ◽

Cited By ~ 1

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.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.99-100.790 ◽

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.

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

Journal of Mechanics ◽

10.1017/jmech.2020.45 ◽

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.

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The Interaction Mechanism of Surrounding Rock and Supporting Structure in High Geostress Extrusion Fault

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.3588 ◽

2011 ◽

Vol 243-249 ◽

pp. 3588-3598 ◽

Cited By ~ 1

Author(s):

Zhi Min Chen ◽

De An Zhao ◽

Yun Yan Yu

Keyword(s):

Lateral Pressure ◽

Pressure Coefficient ◽

Surrounding Rock ◽

Deformation Characteristics ◽

Horizontal Deformation ◽

Support Structure ◽

Supporting Structure ◽

Lateral Pressure Coefficient ◽

Geological Conditions ◽

High Geostress

Muzhailing tunnel of Lanyu railway is located in the western part of Qinling Mountain, its geological conditions are very complex. There is an extrusion fault, f16, in the Dazhangou inclined shaft, and the strata are consist of slate, sandston and carbonaceous slate. The measured geostress results showed that this location is in a very high level of geostress state, the maximum horizontal principal geostress is nearly vertical to Dazhangou inclined shaft and the measured horizontal lateral pressure coefficient is 3.79. Soft rock crushing, high geostress state, high horizontal lateral pressure coefficient and other factors led to the poor stability for the shaft. During the construction process of the shaft, the deformation characteristics are showed as strong horizontal deformation, rapid and large rate initial deformation, and long duration. According to rock lithology conditions, geostress conditions, supporting structure and dynamic construction, deformation characteristics of the shaft, the large horizontal deformation was caused by the interaction of high horizontal lateral pressure coefficient and poor geological conditions and other factors, but the main reasons of the large horizontal deformation were recognized as uneven vertical and horizontal load, extreme adverse load conditions of support structure, based on the theoretical and 3D numerical analysis. Through the analysis of the interaction of support structure and the surrounding rock, the smaller deformation in front of the working face during tunnel excavation is took place, the less stress release would be took place and the larger the ultimate load would be on the support structure. Tremendous stress was withstood by the arch crown, larger wall tensile stress was appeared at side wall, the support structure is in a poor stress state. This paper provides a theoretical basis for dynamic design and construction of the Dazhangou inclined shaft and Muzhailing tunnel.

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