3-D FLAC Numerical Analysis of Rheological Character and Stability of Underground Caverns Surrounding Rock Mass of Xiao Langdi Key Water Control Project

2006 ◽  
Vol 306-308 ◽  
pp. 1473-1478
Author(s):  
Wei Shen Zhu ◽  
Jian Hua Liu ◽  
Shu Cai Li
Keyword(s):  
Numerical Analysis ◽  
Back Analysis ◽  
Surrounding Rock ◽  
Construction Process ◽  
Water Control ◽  
Long Period ◽  
Underground Caverns ◽  
Rheological Character ◽  
Measured Displacement

A brief description is given to the visco-plastic constitutive model of 3-D FLAC software and some treating methods for the numerical analysis. The excavation steps and the exerting time of excavation loads are determined in the light of the real construction process. The rockmass mechanical parameters are determined according to back analysis of in-situ measured displacement data. The analysis results of displacement and stability of the opening complex surrounding rocks in the construction process and in a long period of time after excavation completion are given.

Study on Deformation and Damage of Rock Mass Subject to High In Situ Stress by Using a Elastoplastic Damage Model and Considering the Impact of Weak Planes

2013 ◽  
Vol 838-841 ◽  
pp. 705-709
Author(s):  
Yun Hao Yang ◽  
Ren Kun Wang
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Damage Model ◽  
Back Analysis ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
High In Situ Stress ◽  
Underground Caverns ◽  
The Impact

Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

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

2012 ◽  
Vol 204-208 ◽  
pp. 196-201 ◽  
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.

Numerical Analysis of 3-D FLAC on Supporting Effects of Underground Caverns Surrounding Rockmass of Xiao Lang Di Key Water Control Project

2006 ◽  
Vol 306-308 ◽  
pp. 1467-1472
Author(s):  
Jian Hua Liu ◽  
Wei Shen Zhu ◽  
Shu Cai Li
Keyword(s):  
Numerical Analysis ◽  
Process Simulation ◽  
Simulation Method ◽  
Field Method ◽  
Geometrical Model ◽  
Water Control ◽  
Excavation Process ◽  
Underground Caverns ◽  
Shotcrete Lining ◽  
Supporting Structures

This present paper describes the process and methods of the numerical analysis, including yielding criterion, 3-D geometrical model, rock mass mechanical parameters, initial geostress field, method to simulate excavation process, simulation method for supporting structures. Then, the paper gives the computational results of rock deformation and stability for the large cavern group and comparisons for three cases: with no supporting structures; with bolts and shotcrete lining but no prestress-cables and with all the supporting structures of bolts, cables and lining. Finally, the paper reaches several conclusions.

Application of GA-BP to Back Analysis of Rock’s Parameters

2013 ◽  
Vol 671-674 ◽  
pp. 175-179
Author(s):  
Guo Feng Wang ◽  
Wen Zhao ◽  
Yong Ping Guan ◽  
Shen Gang Li
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Back Analysis ◽  
Surrounding Rock ◽  
Railway Tunnel ◽  
Training Time ◽  
Material Parameters ◽  
Underground Caverns ◽  
Excavation Stability ◽  
Selection Of

The selection of material parameters relates to the excavation stability of the underground caverns. However, back analysis is an efficient method to evaluate mechanical parameters. Given the defects of BP neural network, such as low capability of generalization and long training time, by using GA, which have global optimization ability to optimize the BP neural network weights. The parameter of surrounding rock was designed by uniform and orthogonal method, not only reduced the iterative time also improved the accuracy of the prediction. The proposed method is further illustrated with its application to the underground cavern of Lvchunba railway tunnel. Based on the surrounding rock’s parameters obtained by back analysis, the displacement of the surrounding rock was predicted. The results showed that the error between numerical calculation value and actual monitoring value was 13.2%,-8.3%,-8.9%,9.4% respectively.

scholarly journals Numerical Simulation of Blast Vibration and Crack Forming Effect of Rock-Anchored Beam Excavation in Deep Underground Caverns

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
XinPing Li ◽  
JunHong Huang ◽  
Yi Luo ◽  
Qian Dong ◽  
YouHua Li ◽  
...  
Keyword(s):  
Rock Mass ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Vibration Velocity ◽  
Blasting Vibration ◽  
Finite Element Software ◽  
Underground Cavern ◽  
Underground Caverns ◽  
Blasting Excavation

Aiming at surrounding rock damage induced by dynamic disturbance from blasting excavation of rock-anchored beam in rock mass at moderate or far distance in underground cavern, numerical model of different linear charging density and crustal stress in underground cavern is established by adopting dynamic finite element software based on borehole layout, charging, and rock parameter of the actual situation of a certain hydropower station. Through comparison in vibration velocity, contour surface of rock mass excavation, and the crushing extent of excavated rock mass between calculation result and field monitoring, optimum linear charging density of blast hole is determined. Studies are also conducted on rock mass vibration in moderate or far distance to blasting source, the damage of surrounding rock in near-field to blasting source, and crushing degree of excavated rock mass under various in situ stress conditions. Results indicate that, within certain range of in situ stress, the blasting vibration is independent of in situ stress, while when in situ stress is increasing above certain value, the blasting vibration velocity will be increasing and the damage of surrounding rock and the crushing degree of excavated rock mass will be decreasing.

scholarly journals In Situ Monitoring and Numerical Experiments on Vertical Deformation Profiles of Large-Scale Underground Caverns in Giant Hydropower Stations

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Hao Wu ◽  
Jian Liu ◽  
Xiaogang Wang ◽  
Lipeng Liu ◽  
Zhenhua Tian
Keyword(s):  
Large Scale ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Rock Deformation ◽  
Vertical Deformation ◽  
Spatial Response ◽  
Underground Caverns ◽  
Hydropower Stations ◽  
The Relationship

Spatial response is a feature of rock deformation in regions surrounding large-scale underground caverns and includes significant vertical components due to the construction method of layered excavation. This vertical response is different to the longitudinal response of excavation deformation surrounding shallow tunnels. The study of longitudinal deformation profiles (LDPs), which describe the spatial response of longitudinal tunnel excavation and surrounding rock deformation, is a mature field. However, there has been no independent discussion of the relationship between vertical excavation and the spatial response of deformation in large-scale underground caverns nor the incremental characteristics of layered excavation. In this paper, we define the attenuation function λ x of unloading strength based on theoretical analyses and numerical simulations. We also propose the concept and form of the vertical deformation profile (VDP) curve for the first time and apply it to the Baihetan and Lianghekou Hydropower Stations. After fitting the complete VDP curve with a Levenberg-Marquardt algorithm, we verify its validity by comparing predicted data with in situ monitoring data. The curve can be used to quantitatively analyze the relationship between layered excavation and incremental deformation of surrounding rock, providing a basis for the rapid evaluation of staged deformation during the excavation of large underground caverns. This study has practical significance for the control of deformation in rock surrounding excavations and decision-making during the construction progress.

Influence of Environmental Variation of Underground Excavation on Support Safety

2017 ◽  
Vol 865 ◽  
pp. 354-359
Author(s):  
Jun Lai Cao ◽  
Xi Wen Xi ◽  
Li Peng Liu
Keyword(s):  
Safety Factor ◽  
Strength Criterion ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Burial Depth ◽  
Tunneling Method ◽  
Underground Caverns ◽  
Disturbance Factor ◽  
Support Time

It is very important for engineering design to study the excavation and support time of underground caverns based on the New Austrian Tunneling Method (NATM). The sensitivity of surrounding rock of underground wall and in-situ stress of field are analyzed by Hoek-Brown strength criterion, which is widely used in geotechnical engineering. The results show: With the increase of burial depth, the magnitude of in-situ stress increases, the safety factor of structure becomes a form of power function, with the increase of GSI, the safety factor is reduced first and then increased by polynomial form change, with the increase of rock mi, the safety factor gradually increased, but the range of change is not obvious, with the increase of the rock disturbance factor D, the safety factor gradually increases. Note that, with the increase of these parameters, and sometimes the safety factor to show an increasing trend, but at this time should pay attention to the deformation of the surrounding rock has been great, the surrounding rock prone to destabilization damage.

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