scholarly journals A Numerical Study of Underground Cavern Stability by Geostress Characteristics

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Xiao-Jing Li ◽  
Li-Ge Wang ◽  
Wei-Min Yang
Keyword(s):  
Numerical Study ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Surrounding Rock ◽  
High Mountain ◽  
Burial Depth ◽  
Underground Cavern ◽  
Rock Cavern ◽  
The Stability ◽  
Cavern Stability

The stability of underground cavities is of increasing importance considering the predominant cavity locations built up in high mountain and canyon environments. Such cavity locations are characterized by a high initial in situ stress, which results in brittle fracture and deformation of the surrounding rock during cavity construction. This paper presents a numerical study of underground cavern stability considering four factors, namely, mechanical property of surrounding rock, cavern burial depth, lateral pressure coefficient in horizontal direction, and the angle included between plant longitudinal axis and horizontal principal stress. Analytical methods including the key point displacement in side wall, plastic zone volume, and splitting fracture volume are used to characterize the stability of underground cavern. A modified formula to predict side wall displacement is proposed based on prior work, which is applicable to 3D computation model by taking horizontal geostress in two directions into account. Eventually, the optimal layout of underground cavern is put forward under different conditions of geostress field.

Analyzing the Strength and Stability of Large Underground Cavern Group with Different Generator Socket Construction Schemes Based on Three Dimensional Numerical Simulation

2007 ◽  
Vol 353-358 ◽  
pp. 2537-2540
Author(s):  
An Nan Jiang
Keyword(s):  
Three Dimensional ◽  
Side Wall ◽  
Surrounding Rock ◽  
Lower Side ◽  
Geological Investigation ◽  
Simulation Accuracy ◽  
Underground Powerhouse ◽  
Underground Cavern ◽  
Construction Step ◽  
The Stability

Shuibuya hydroelectric project is the most upstream power station in the Qingjiang cascade development of China. The power plant is designed as underground powerhouse, from seventh to eighth construction step, how to ensure the stability of surrounding rock mass of generator socket and controlling the displacement of lower side wall where the soft stratum located in is a key problem. To solve the problem, the three dimensional numerical model of the underground powerhouse was established based on the results of geological investigation. Then, the detailed construction processes, including the replacement of soft rock, excavation as well as support, were numerically simulated. In order to improve the simulation accuracy, the rock mechanics parameters were back analyzed based on in-situ monitor data before sixth construction step, then using Mohr-Coulomb criterion, the paper simulated and analyzed the damage zones of surrounding rock and displacement of lower side wall corresponding to different schemes. The best scheme was recommended by synthetically considering the stability indexes of each scheme. The study had a scientific meaning to guide Shuibuya project construction. Introduction When the underground cavern is excavated, the initial ground stress is released

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.

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.

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

2015 ◽  
Vol 741 ◽  
pp. 138-142 ◽  
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.

scholarly journals Parameter optimization of double side wall method for soft surrounding rock tunnel

2019 ◽  
Vol 136 ◽  
pp. 04021
Author(s):  
Zhihua Yang ◽  
Rumiao He ◽  
Ke Li ◽  
Hongyan Guo
Keyword(s):  
Side Wall ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Radius Of Curvature ◽  
Tunnel Excavation ◽  
The Stability ◽  
Rock Tunnel ◽  
Double Wall ◽  
Wall Method

When the Xiaojiazhai tunnel is constructed by the double-wall method, different curvature radii have different effects on controlling the stability of the surrounding rock and speeding up the construction progress. By numerically simulating the tunnel excavation under different radius of curvature, it is concluded that R is adopted respectively. The deformation displacement of surrounding rock is =11.6m∠520 and R=5.76m∠1060. The maximum horizontal displacement and vertical displacement are smaller when R=5.76m∠1060 is selected. According to the analysis results, when R=5.76m∠1060 is selected, the deformation of surrounding rock can be controlled to ensure the safety of construction and provide reference for future construction.

The Stability Impact Study for Blasting near Underground Caverns

2012 ◽  
Vol 256-259 ◽  
pp. 1172-1176
Author(s):  
Cheng Man Sha ◽  
En De Wang ◽  
Jian Fei Fu ◽  
Gen Qun Hou ◽  
Tian Bao Zhang
Keyword(s):  
Damage Effect ◽  
Seismic Gap ◽  
Surface Cracks ◽  
Impact Study ◽  
Underground Cavern ◽  
Underground Caverns ◽  
Collapse Models ◽  
The Stability ◽  
Cavern Stability

Nowadays, the safety effection study of the surface explosion operations on underground cavern safety become more and more important along with engineering construction's development. In this paper, effection of open stope surface explosive operations on underlying gap cavern as an example on studying the effection of blasting shock on underground cavern stability with the method of field monitoring and numerical simulation.When the explosion source and seismic gap are almost in the same level, the longitudinal wave leads the role of damage effect. The most dangerous part of the mined-out area is the spandrel. The collapse models of mined-out area manifest are as follows, cracks appear on 45. Inclined top of surface in mined-out area, the spandrels appear broken, surface cracks expand further, broken parts of spandrel are aggravated, arch waist are in jog and the side collapse inward in the end.

Numerical Investigation into Rockburst Proneness of Deep-Buried Tunnels with Arch-Shaped Wall

2011 ◽  
Vol 250-253 ◽  
pp. 1192-1195
Author(s):  
Xin Yu Wang ◽  
Zhu Shan Shao ◽  
Yu Ming Cui
Keyword(s):  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Tarim River ◽  
Tarim River Basin ◽  
Rock Stress ◽  
Factors Affecting ◽  
Tunnel Design ◽  
The Stability ◽  
Surrounding Rock Stress

During the construction of the deep-buried tunnels, high surrounding rock stress and the rockburst are the important factors affecting the stability of surrounding rock. Xiabandi hydraulic engineering is the key project in Tarim River basin. Due to the deep buried excavation, rockburst is particularly prominent and should be received adequate attention. According to the rockburst practice during construction, numerical analysis is adopted to study the stress characteristics along depth with the same lateral pressure coefficient. Furthermore, the rockburst tendency along the tunnel with different burying depth is investigated. The conclusion is of great value to guide the rockburst control during the tunnel design and construction.

Numerical Simulation Study of Crack Development Induced by Transient Release of Excavation Load during Deep Underground Cavern

2014 ◽  
Vol 638-640 ◽  
pp. 851-857
Author(s):  
Yi Luo ◽  
Xin Ping Li
Keyword(s):  
Numerical Simulation ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Simulation Method ◽  
Deformation And Failure ◽  
Underground Cavern ◽  
Surface Development ◽  
Calculation Results ◽  
Deep Underground ◽  
Structural Surface

The cracking and developing of structural surfaces is one of the main causes for surrounding rock mass large deformation and failure in deep underground cavern excavation. A numerical simulation method for discontinuous structural surface development is proposed based on the transient unloading of excavation load during underground cavern excavation. The program will automatically evaluate every substep in the dynamic calculation, and determine if the development stops and the cracking direction based on dynamic fracture mechanics. The penalty function is adopted to simulate the opening and sliding characteristic of structural surfaces. And the cracking path would be shown by iterative calculation. Results show that, the lateral pressure coefficient (LPC) is the main factor of cracking direction. When structural surface is shallow to the side wall, the crack would develop to the surface of the side wall. When it is deep enough into the side wall, the cracking might stop before it goes to the surface of the side wall. The accuracy of this simulation is verified by the comparison to relative laboratory tests.

The Study on Mechanical Properties of Karst Tunnel

2011 ◽  
Vol 243-249 ◽  
pp. 3399-3402
Author(s):  
Bin Li ◽  
Tai Yue Qi
Keyword(s):  
Mechanical Properties ◽  
Numerical Models ◽  
Side Wall ◽  
Surrounding Rock ◽  
Karst Tunnel ◽  
Safety Coefficient ◽  
Coefficient Distribution ◽  
Unfavorable Effect ◽  
Adverse Influence ◽  
The Stability

Several numerical models were built by FLAC3D to simulate tunnel with karst around spandrel, tunnel with karst around springe, tunnel with karst around inverted arch and tunnel with karst around side wall. The influence of karsts on the deformation of lining and the safety coefficient distribution of surrounding rock after excavation was analyzed. The results from the numerical modeling suggest as follows: karst around spandrel has extremely unfavorable effect on the deformation of lining and the safety of surrounding rock above the vault, karst around side wall also seriously affect the stability of tunnel due to the asymmetry pressure on tunnel caused by karst, consequently, auxiliary measures should be taken to handle these two cases; karst around springe and karst around inverted arch has limited adverse influence on the overall safety of tunnel, backfill measures are enough to handle these two cases.

scholarly journals Numerical Simulation of Stress Arching Effect in Horizontally Layered Jointed Rock Mass

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1138
Author(s):  
Xiao Huang ◽  
Huaining Ruan ◽  
Chong Shi ◽  
Yang Kong
Keyword(s):  
Rock Mass ◽  
Pressure Coefficient ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Beam Structure ◽  
Underground Engineering ◽  
Joint Spacing ◽  
Arching Effect ◽  
The Stability

Stress arching effect during the excavation of broken surrounding rock in underground engineering has an important influence on the stability of surrounding rock after underground excavation. To determine the stress arching effect in horizontally layered jointed rock mass, the stress arching characteristics of surrounding rock mass after excavation is analyzed in this study by using a series of numerical tests. The formation mechanism of stress arch is revealed through a comparison of the stress characteristics of a voussoir beam structure and theoretical analysis of multi-block mechanical relationship of jointed rock mass. The method for determining the boundaries of a stress arching zone is proposed, and the influence of various factors on a stress arch is further discussed. Results show that after the excavation of horizontally layered jointed rock mass, the stress arch bunch (SAB) is formed in the lower strata above the cavern, and the global stress arch (GSA) is formed in the higher strata, both of which are symmetrical arch stress patterns. The SAB is the mechanical manifestation of the voussoir beam structure formed by several low-level sandstone layers, and the GSA is caused by the uneven displacement between blocks. Compared with the GSA, the SAB is more sensitive to various influencing factors. The extent of stress arching zone decreases with the increase of an internal friction angle of the joint, lateral pressure coefficient, and overburden depth. In addition, the joint spacing of rock strata is conducive to the development of a stress arch. Results can provide technical support for deformation control and the stability analysis of broken surrounding rock in underground engineering.

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