The Failure Process Analysis on a Numerical Model of a Branching-Out Tunnel under Lateral Overload Action

2008 ◽  
Vol 33-37 ◽  
pp. 129-132
Author(s):  
Qiang Yong Zhang ◽  
Yong Li ◽  
Wei Shen Zhu ◽  
Jian Guo Zhang ◽  
Han Peng Wang
Keyword(s):  
Physical Model ◽  
Process Analysis ◽  
Failure Process ◽  
In Situ Stress ◽  
Complicated Structure ◽  
Construction Costs ◽  
Western Development ◽  
New Type ◽  
The Stability ◽  
In Situ Stress Field

As the implementations of the western development in China, more and more tunnels will get through the western mountains in China. In order to economize the construction costs, a new type of underground structural form called branching-out tunnel must be applied. The failure process of the branching-out tunnel under lateral overload action is also greatly complicated, which is related with the depth of the mountains, the branching-out angle, the in-situ stress field, the thickness of the middle wall and so on. This paper uses the 3D-physical model of geo-mechanical model tests to study the stability and failure process of this complicated structure, especially the part of the middle wall. The physical model is built up in a new kind of analogy material. In the process of the whole experiments, different lateral pressures imposed on both of the lateral planes of the physical model. According to different lateral pressures, we have attained the change of the stress and displacement field and looked into the failure process of the pivotal positions in the branching-out tunnel. We also use finite element method analysis software RFPA (Realistic Failure Process Analysis) to simulate the whole failure process of the branching-out tunnel. Finally, we have got the load-bearing safety reliability of this complicated structure through comparative analysis of physical modeling and numerical simulation.

Numerical Simulation on Failure Mechanism of Rock Slope Using RFPA

2011 ◽  
Vol 50-51 ◽  
pp. 568-572 ◽  
Author(s):  
Nu Wen Xu ◽  
Chu Nan Tang ◽  
Chun Sha ◽  
Ru Lin Zhang
Keyword(s):  
Rock Slope ◽  
Slip Surface ◽  
Process Analysis ◽  
Failure Process ◽  
Numerical Code ◽  
Natural State ◽  
Left Bank ◽  
Good Tool ◽  
Deep Rock ◽  
The Stability

This research applied a numerical code, RFPA2D (Realistic Failure Process Analysis) to evaluate the stability and investigate the failure mode of the high rock slope during excavations based on Strength Reduction Method (SRM). The corresponding shapes and positions of the potential slip surfaces are rationally simulated in different stages, and the related safety coefficients are obtained, which agrees well with the allowable minimum safety factors of the slope. The numerical results show that the safety coefficient drops from 1.25 at the natural state to 1.09 after excavation, and then increases to 1.35 after slope reinforcement. Moreover, the potential slip surface of the left bank moves into deep rock mass after taking support measures, which demonstrates the reinforcement is reasonable and efficient. The study shows that cracks and faults will cause crucial influences on the slope stability, and RFPA2D is a good tool to directly display the potential slip surface of the slope, which will offer valuable guidance for bolt support.

Stress and Strain Analysis of Waste Dam and Stability Analysis of Landfill

2015 ◽  
Vol 744-746 ◽  
pp. 702-705 ◽  
Author(s):  
Li Hua Liang ◽  
Su Lin Kuang ◽  
Zhi Jun Diao
Keyword(s):  
Strain Analysis ◽  
Material Model ◽  
In Situ Stress ◽  
Stress And Strain ◽  
Linear Elastic ◽  
Construction Design ◽  
Dam Stability ◽  
The Stability ◽  
In Situ Stress Field

Stress and strain of waste dam were analyzed based on the construction design and situations in the field. In situ stress field was calculated according to linear elastic material model and deformation was simulated according to hyperbolic nonlinear plastic model. On the basis of the deformation and stress analysis, dam stability was evaluated according to the deformation by total stress method. The result shows that the stability of the dam can meet the specification requirements and be operated normally even if the deformation occurs when solid waste are heaped up to 0-12 m according to the preliminary design scheme.

Stability Analysis of Diversion Tunnels in Jinping II Hydropower Station Project

2008 ◽  
Vol 575-578 ◽  
pp. 1287-1292
Author(s):  
Chuan Qing Zhang ◽  
Xia Ting Feng ◽  
Hui Zhou ◽  
Shu Ling Huang ◽  
Quan Jiang
Keyword(s):  
Rock Mass ◽  
High Stress ◽  
Great Depth ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Hydropower Plant ◽  
Linear Regression Method ◽  
Technical Problems ◽  
The Stability ◽  
In Situ Stress Field

Surrounding rock mass stability is one of the key technical problems in the design of the diversion tunnels in Jinping II Hydropower Plant Project. The major difficulties lie in three facts: (1) high stress induced by the great depth; (2) the brittle failure characters of marble; (3) the interaction of these four tunnels. A systemic procedure is introduced in this paper. Firstly, the integration of the code FLAC3D and the multivariate linear regression method is adopted to back analyze the in situ stress field. Then the mechanical parameters of the surrounding rock mass are back analyzed based on the PSO (Particle Swarm Optimization) algorithm and the code FLAC3D. The stress release method is adopted in the numerical analysis of the excavating and supporting process of tunnels by the code FLAC3D. Finally, the multi indexes integration method is presented to analyze and evaluate the stability of the tunnels and to validate the rationality of the design scheme.

A numerical study on the regional in situ stress field of the Keshen section and interface dislocation in the composite salt-gypsum layer

2020 ◽  
Vol 8 (4) ◽  
pp. T803-T811
Author(s):  
Shiyuan Li ◽  
Fuyao Li ◽  
Yufan Qiu ◽  
Yu Yan
Keyword(s):  
Stress Field ◽  
Numerical Study ◽  
In Situ Stress ◽  
Wellbore Integrity ◽  
Salt Layer ◽  
Gypsum Formation ◽  
Casing Damage ◽  
The Stability ◽  
In Situ Stress Field

Salt rock found in the stratum of the sedimentary basin is considered to be exemplary in terms of quality among the class of cap rocks, and it engulfs a certain proportion of the world’s hydrocarbon resources. In recent years, approximately 40% of newly discovered hydrocarbon resources in China have been detected under deep salt layers. Statistics suggest that nearly 40% of drilling accidents and 50% of casing damage incidents occur near the layer interfaces within a composite salt-gypsum formation. For the in-depth characterization of processes such as deformation and damages occurring at the interfaces, analysis of the regional in situ stress field characteristics and distribution in salt structures is vital. For this purpose, the structure of the Keshen section of the Kelasu structural belt under the Tarim Oilfield was studied. Our study establishes a geomechanical model, which tends to be mainly based on constitutive elastic and rheological models (applicable to different layers, i.e., the upper salt layer, salt layer, and presalt layer). Furthermore, the stability of the composite salt-gypsum layer and prediction of formation stress were evaluated. Investigation of drilling accidents and wellbore integrity problems revealed that the perturbation at the interfaces was not earnestly contemplated. The results show a discontinuous pattern in the regional in situ stress distribution in all of the salt layers. The salt layer is characterized by creep behavior with differential stress of less than 1.0 MPa. The interface between the upper layer and the salt layer tends to bear inconsistent deformation of approximately a few centimeters along the wellbore wall.

scholarly journals Research on Supporting Method for High Stressed Soft Rock Roadway in Gentle Dipping Strata of Red Shale

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 423
Author(s):  
Chunde Ma ◽  
Jiaqing Xu ◽  
Guanshuang Tan ◽  
Weibin Xie ◽  
Zhihai Lv
Keyword(s):  
Failure Process ◽  
High Stress ◽  
Soft Rock ◽  
In Situ Stress ◽  
Mechanical Parameters ◽  
Deformation And Failure ◽  
Deep Mine ◽  
Plastic Energy ◽  
Roadway Stability ◽  
Phosphate Mine

Red shale is widely distributed among the deep mine areas of Kaiyang Phosphate Mine, which is the biggest underground phosphate mine of China. Because of the effect of various factors, such as high stress, ground water and so on, trackless transport roadways in deep mine areas were difficult to effectively support for a long time by using traditional supporting design methods. To deal with this problem, some innovative works were carried out in this paper. First, mineral composition and microstructure, anisotropic, hydraulic mechanical properties and other mechanical parameters of red shale were tested in a laboratory to reveal its deformation and failure characteristics from the aspect of lithology. Then, some numerical simulation about the failure process of the roadways in layered red shale strata was implemented to investigate the change regulation of stress and strain in the surrounding rock, according to the real rock mechanical parameters and in-situ stress data. Therefore, based on the composite failure law and existing support problems of red shale roadways, some effective methods and techniques were adopted, especially a kind of new wave-type bolt that was used to relieve rock expansion and plastic energy to prevent concentration of stress and excess deformation. The field experiment shows the superiorities in new techniques have been verified and successfully applied to safeguard roadway stability.

Research on 2D Limit Equilibrium Method of Slopes Considering the Effect of Horizontal In Situ Stress

2013 ◽  
Vol 671-674 ◽  
pp. 245-250
Author(s):  
Wen Hui Tan ◽  
Ya Liang Li ◽  
Cong Cong Li
Keyword(s):  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
In Situ Stress ◽  
Open Pit ◽  
Open Pit Mines ◽  
Equilibrium Method ◽  
Iron Mine ◽  
The Stability ◽  
Slice Method

At present, in-situ stress was not considered in Limit Equilibrium Method (LEM) of slopes, the influence of in-situ stress is very small on the stability of conventional slopes, but in deep-depressed open-pit mines, the influence should not be neglected. Formula for calculating the Factor of Safety (FOS) under the effect of horizontal in-situ stress was deduced using General Slice Method (GSM) of two-dimensional (2D) limit equilibrium method in this paper，a corresponding program SSLOPE was built, and the software was used in a deep- depressed open-pit iron mine. The results show that the FOS of the slope decreased by 20% when horizontal in-situ stress is considered, some reinforcements must be taken. Therefore, the influence of in-situ stress on slope stability should be taken into account in deep open –pit mines.

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