scholarly journals Determination of safety factor for rock mass surrounding tunnel by sudden change of equivalent plastic strain in strength reduction method

2021 ◽  
Author(s):  
Dok Yong Jong ◽  
Ui Jun Jang ◽  
Yong Nam Ri ◽  
Un Chol Han
Keyword(s):  
Rock Mass ◽  
Plastic Strain ◽  
Safety Factor ◽  
Reduction Method ◽  
Sudden Change ◽  
Equivalent Plastic Strain ◽  
Strength Reduction ◽  
Strength Parameter ◽  
Strength Reduction Method ◽  
Simulation Results

Abstract A safety factor of rock mass surrounding the tunnel can be determined using the strength reduction method (SRM), however, it is the most important to solve the criterion of critical state. For the stability estimation of rock mass surrounding tunnel, there is need to discuss that it is preferable to use the same criteria for the slope, such as non-convergence of finite element calculation, penetration of plastic strain and sudden change of horizontal displacement. A safety factor can be determined by sudden change of equivalent plastic strain in relationship between a reduction coefficient of strength parameter and equivalent plastic strain. This method is based on the elasto-plastic FEM and the SRM by ABAQUS and Mohr-Coulomb yield criterion. Simulation results using this method show how a safety factor varies with geometries, friction angles and cohesions for circle and square tunnels. Simulation results also show a safety factor varying with quality change of rock mass, pore water pressure and tunnel depth.

scholarly journals Strength Reduction Method for Stability Analysis of Local Discontinuous Rock Mass with Iterative Method of Partitioned Finite Element and Interface Boundary Element

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Tongchun Li ◽  
Jinwen He ◽  
Lanhao Zhao ◽  
Xiaona Li ◽  
Zhiwei Niu
Keyword(s):  
Rock Mass ◽  
Iterative Method ◽  
Boundary Element ◽  
Safety Factor ◽  
Reduction Method ◽  
Strength Reduction ◽  
Contact Forces ◽  
Strength Reduction Method ◽  
Interface Boundary ◽  
Discontinuous Rock

SRM (strength reduction method) with iterative method of PFE (partitioned fnite element) and IBE (interface boundary element) is proposed to solve the safety factor of local discontinuous rock mass. Slope system is divided into several continuous bodies and local discontinuous interface boundaries. Each block is treated as a partition of the system and contacted by discontinuous joints. The displacements of blocks are chosen as basic variables and the rigid displacements in the centroid of blocks are chosen as motion variables. The contact forces on interface boundaries and the rigid displacements to the centroid of each body are chosen as mixed variables and solved iteratively using the interface boundary equations. Flexibility matrix is formed through PFE according to the contact states of nodal pairs and spring flexibility is used to reflect the influence of weak structural plane so that nonlinear iteration is only limited to the possible contact region. With cohesion and friction coefficient reduced gradually, the states of all nodal pairs at the open or slip state for the first time are regarded as failure criterion, which can decrease the effect of subjectivity in determining safety factor. Examples are used to verify the validity of the proposed method.

Analysis of Unstable Rock-Mass Stability Based on Limit Equilibrium Method and Strength Reduction Method

2016 ◽  
Vol 858 ◽  
pp. 73-80
Author(s):  
Ying Kong ◽  
Hua Peng Shi ◽  
Hong Ming Yu
Keyword(s):  
Rock Mass ◽  
Failure Mode ◽  
Posterior Margin ◽  
Reduction Method ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Strength Reduction ◽  
Strength Reduction Method ◽  
Rock Masses ◽  
Unstable Rock

With the slope unstable rock masses of a stope in Longsi mine, Jiaozuo City, China as the target, we computed and analyzed the stability of unstable rock masses using a limit equilibrium method (LEM) and a discrete element strength reduction method (SRM). Results show that the unstable rock masses are currently stable. Under the external actions of natural weathering, rainfall and earthquake, unstable rock mass 1 was manifested as a shear slip failure mode, and its stability was controlled jointly by bedding-plane and posterior-margin steep inclined joints. In comparison, unstable rock mass 2 was manifested as a tensile-crack toppling failure mode, and its stability was controlled by the perforation of posterior-margin joints. From the results of the 2 methods we find the safety factor determined from SRM is larger, but not significantly, than that from LEM, and SRM can simulate the progressive failure process of unstable rock masses. SRM also provides information about forces and deformation (e.g. stress-strain, and displacement) and more efficiently visualizes the parts at the slope that are susceptible to instability, suggesting SRM can be used as a supplementation of LEM.

Analysis of Earth-Rockfill Dam Slope Stability by Strength Reduction Method Based on Nonlinear Strength

2011 ◽  
Vol 243-249 ◽  
pp. 2271-2275
Author(s):  
Shu Yu ◽  
Li Hong Chen ◽  
Ze Ping Xu ◽  
Ning Chen
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Reduction Method ◽  
Slip Surface ◽  
Strength Reduction ◽  
Strength Parameter ◽  
Strength Reduction Method ◽  
Critical Slip Surface ◽  
Rockfill Dam ◽  
The Earth

In the design process of the earth-rock dam, the slope stability problem was always focused on. The shear strength of rockfill in the earth-rock dam had strong nonlinear characteristics. The characteristic directly affected the factor of safety (FOS) of stability of dam slope and the determination of the critical slip surface. The shear strength parameter of rockfill was related to the minimum principal stress σ3 closely. And the value of σ3 had close relationship with the deformation characteristics of filling material and the process of dam filling etc. Strength reduction method has been widely used in solving the FOS of slope stability, and this method has the advantage on the searching of the critical slip surface. Combining the deformation and stress analysis of earth-rockfill dam filling process and the strength reduction method, this paper proposes a comprehensive method of dam slope stability analysis.

Numerical Simulation of Safe Distance between Concealed Karst Cave and Tunnel Based on Shear Strength Reduction Method Safety Factor Catastrophe

2014 ◽  
Vol 501-504 ◽  
pp. 1753-1756
Author(s):  
Yong Biao Lai ◽  
Mang Shu Wang ◽  
Xin Hua You
Keyword(s):  
Numerical Simulation ◽  
Safety Factor ◽  
Reduction Method ◽  
Strength Reduction ◽  
Karst Cave ◽  
Strength Reduction Method ◽  
Safe Distance ◽  
Shear Strength Reduction Method ◽  
Concealed Karst Cave ◽  
Shear Strength Reduction

The numerical simulation method of safe distance between concealed karst cave and tunnel based on shear strength reduction method safety factor catastrophe is proposed. The safety factor of different distance between concealed karst cave and tunnel can be obtained using strength reduction finite element method numerical calculation with the finite element solution non convergence as the standard rock damage, then compare the safety factor of different distance, the catastrophe of safety factor corresponding to the distance is the safe distance between concealed karst cave and tunnel, and the plastic zone of rock stratum between concealed karst cave and tunnel is reaching run-through state, which is verified by engineering example.

Static and Dynamic Stability Analysis on Artificial Rock Mass Slope Using Strength Reduction Method

2013 ◽  
Vol 368-370 ◽  
pp. 1774-1780
Author(s):  
Shi Yan ◽  
Hai Tao Du ◽  
Qi Le Yu ◽  
Han Yan
Keyword(s):  
Rock Mass ◽  
Stability Analysis ◽  
Slope Stability ◽  
Dynamic Stability ◽  
Rock Slope ◽  
Reduction Method ◽  
Strength Reduction ◽  
Strength Reduction Method ◽  
Artificial Rock ◽  
Static And Dynamic Stability

This paper focuses on stability analysis of an artificial rock mass slope by a nonlinear finite element method (FEM). For a long time, rock slope stability problem is always an important research issue in the field of geotechnical engineering, which is related to human life and property safety as well as engineering security and efficiency. Therefore, the stability analysis and evaluation on rock slope is of great significance. The static and dynamic stability analysis on the artificial rock mass slope of WuAn power plant in China is carried on respectively in this paper by using the strength reduction method and FLAC3D software. In this analysis, static and dynamic instability criterions are enumerated, and the static and dynamic safety factors are calculated with the developed criterions of the displacement mutation, respectively. The analysis results show that the artificial rock mass slope is basically stable. It indicates that analyzing slope stability with strength reduction method is feasible.

Stability Analysis of Dump Slope Based on FEM Strength Reduction Method

2014 ◽  
Vol 501-504 ◽  
pp. 51-55 ◽  
Author(s):  
Chao Peng ◽  
Dong Ji ◽  
Liang Zhao ◽  
Zhen Yu Qian ◽  
Fen Hua Ren
Keyword(s):  
Safety Factor ◽  
Reduction Method ◽  
Strength Reduction ◽  
Production Costs ◽  
Open Pit ◽  
Strength Reduction Method ◽  
Reduction Algorithm ◽  
Safety Factors ◽  
Dump Slope ◽  
The Stability

An analysis on safety factor of slope through c - φ reduction algorithm by finite elements method is presented. When the system reaches instability, the numerical non-convergence occurs simultaneously. The safety factor is then obtained by c φ reduction algorithm. This paper, which combines with the actual situation of Jinduicheng open pit mine, analysis the stability of the limit height of the dump based on strength reduction of finite element method. And the value of slope safety factor is 1.25 to 1.30. The results show that calculating safety factors of the slope by ANSYS is in full conformity with the basic requirement of safety. That means, the dump is stable, which can reduce the production costs and benefit the enterprise.

scholarly journals Study on the Influence of Rainfall Infiltration on the High rock Slope of Open-pit Mine Stability using a New Nonlinear Strength Reduction Method

2021 ◽  
Author(s):  
Tianbai Zhou ◽  
Lingfan Zhang ◽  
Jian Cheng ◽  
Jianming Wang ◽  
Xiaoyu Zhang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Rock Slope ◽  
Reduction Method ◽  
Strength Reduction ◽  
Open Pit Mine ◽  
Open Pit ◽  
Strength Reduction Method ◽  
Rock Slopes ◽  
High Rock Slope ◽  
The Stability

Abstract Due to long-term mining, a series of high and steep rock slopes have been formed in the open-pit mine. For high rock slopes, rainfall infiltration is the main cause of landslide. Therefore, the stability analysis of high rock slope under rainfall has become a key issue in the open-pit mine engineering. In this work, aiming at the high stress condition of high rock slope, the instantaneous internal friction angle and instantaneous cohesion of rock mass under different stress states are deduced, and the a nonlinear strength reduction method for high rock slope is established according to the relationship between normal stress and shear stress of rock mass under the Hoke-Brown criterion. The numerical calculation results show that the factor of safety (FOS) for high rock slope calculated by the proposed method is more reasonable. Taking the southwest slope of Dagushan Iron Mine as the research background, the safety factors of high rock slope under different rainfall conditions are calculated by COMSOL Multiphysics. And the stability analysis of high rock slope in open-pit mine under rainfall are carried out.

Study on Analysis of Deposits Highway Slope Stability and Treatment

2011 ◽  
Vol 105-107 ◽  
pp. 1245-1249
Author(s):  
Yi Fang Feng ◽  
Hua Zhi Zhang
Keyword(s):  
Numerical Simulation ◽  
Slope Stability ◽  
Reduction Method ◽  
Strength Reduction ◽  
Strength Reduction Method ◽  
Deformation Characteristics ◽  
High Line ◽  
Geological Conditions ◽  
Deformation Features ◽  
Simulation Results

Taking Yangjiawuchang Bridge 2 Slope Project on the national key high line of Hangzhou to Lanzhou in China as example, the deformation characteristics of typical profile 4-4’ of the deposits highway slope project was studied by means of numerical simulation (FLAC3D). Based on the deformation fields, the slope deformation features were analyzed. According to the slope coefficient that was solved by strength reduction method, the slope stability was evaluated. In consideration of numerical simulation results and field geological conditions, the combination engineering treatments of surface drainage, paring-earthwork and unloading and slope temporary protection were selected. Moreover, the paring-earthwork areas were calculated and optimized. The simulation results can be based on to guide the engineering treatment, meanwhile, the results can provide reference for the similar engineering.

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