Analyzing the influential elements of FLAC strength reduction method of slope safety factor determined

2014 ◽  
pp. 571-574
Keyword(s):  
Safety Factor ◽  
Reduction Method ◽  
Strength Reduction ◽  
Strength Reduction Method ◽  
Slope Safety

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.

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 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 A Quantitative Evaluation Method Based on Back Analysis and the Double-Strength Reduction Optimization Method for Tunnel Stability

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jinglai Sun ◽  
Fan Wang ◽  
Xinling Wang ◽  
Xu Wu
Keyword(s):  
Safety Factor ◽  
Evaluation Method ◽  
Reduction Method ◽  
Back Analysis ◽  
Optimization Method ◽  
Strength Reduction ◽  
Strength Reduction Method ◽  
Combined Method ◽  
Tunnel Stability ◽  
Real Coded Genetic Algorithm

Quantifying tunnel stability using the proposed combination of back analysis and the strength reduction method (SRM) is useful during construction. To feasibly and reliably obtain geotechnical parameters for the surrounding rock (which vary in different places), a real-coded genetic algorithm is used in setting the initial parameters of the neural network to improve the prediction accuracy of the parameters via back analysis by reasonably selecting the selection operator, crossover operator, and mutation operator. After obtaining the parameters, the proposed SRM, i.e., the optimization double-strength reduction method (ODSRM), which is based on the optimization method, is used to evaluate stability. By using this method, the cohesion and friction angle have different reduction factors that are more reasonable and accurate. The combined method is verified in an application to the Yu Liao Tunnel, where it is demonstrated that the combined method can use the measured displacements to obtain the safety factor. Compared with the traditional method, the proposed back analysis method can reduce errors in the predicted performance, and unlike the SRM, the ODSRM can avoid overestimating the safety factor with the same reduction factor. Finally, the presented methods can reduce the amount of calculation required and are convenient for evaluating tunnel stability with displacement.

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.

An Analysis of Slope Stability of Sand Embankment with Shear Strength Reduction (SSR) Method

2010 ◽  
Vol 152-153 ◽  
pp. 1017-1023 ◽  
Author(s):  
Shu Tang Liu ◽  
Wei Dong Cao ◽  
Ying Yong Li ◽  
Yong Shun Yang
Keyword(s):  
Slope Stability ◽  
Safety Factor ◽  
Reduction Method ◽  
Strength Reduction ◽  
Land Resource ◽  
Strength Reduction Method ◽  
Side Slope ◽  
Content Ratio ◽  
The Stability ◽  
Shear Strength Reduction

Comparing with conventional expressway embankment filled with clay only, the sand embankment tipped by intensely-weathered rock (IWR) can effectively reduce the consumption of cultivated land resource caused by the construction of expressway engineering. So it is significant to research the constructions of sand embankment tipped by IWR if local sand resources are enough. Combined with the construction of Qing-Lin freeway, in China, the slope stability of the embankment filled with sand and tipped by IWR outside was analyzed in the paper, and the analysis was conducted by the strength reduction method. The effects of the changes of compaction, water content, ratio of slope, height of the embankment and different IWR-width on the safety factor of the slope stability were investigated. The results indicate that, when the height of embankment is constant, the ratio of slope is the most important factor which influences the stability of side slope, and the IWR-width does not have a decisive effect on the safety factor on subsoil condition and it can be determined according to the convenience of site construction.

Loess Cave Dwellings’ Safety Factor Based on SRM

2012 ◽  
Vol 557-559 ◽  
pp. 2316-2319
Author(s):  
Ji Shou Niu ◽  
Huan Yang
Keyword(s):  
Safety Factor ◽  
Reduction Method ◽  
Yellow River ◽  
Green Building ◽  
Strength Reduction ◽  
The Yellow River ◽  
Strength Reduction Method ◽  
Abaqus Software

The loess cave dwellings are very common along the Yellow River in China，which are really green building. This paper focus on the influence of cave leg’s width on the safety factor. Abaqus software and Strength Reduction Method are used. Results show that existing cave leg width is safe enough.

Researches on the Stability of Deeply-Buried Water Diversion Tunnel Based on Strength Reduction Method

2013 ◽  
Vol 303-306 ◽  
pp. 2876-2879
Author(s):  
He Jun
Keyword(s):  
Safety Factor ◽  
Reduction Method ◽  
Relative Displacement ◽  
Scientific Basis ◽  
Strength Reduction ◽  
Water Diversion ◽  
Strength Reduction Method ◽  
Diversion Tunnel ◽  
The Stability ◽  
Coulomb Criterion

In view of the complexity of the deeply-buried water diversion tunnel and adopting the advantage of slope strength reduction method, this research takes advantage of strength reduction method to study the stability of diversion tunnel. Based on the instance of Jinping II hydropower, this paper analyzes Yantang Formation III surrounding rocks buried 2500m deep below the ground, adopts the Mohr-Coulomb criterion, takes the cavern displacements or relative displacement as buckling critical criterion, and finally concludes that the safety factor is 1.5 in this instance, not far from 1.2 in the norm. It is thus reasonable to use strength reduction method to study the stability of the deeply-buried water diversion tunnel. The method can get safety factor easily and objectively and can provide scientific basis for evaluating the deeply-buried water diversion tunnel and the design for the supporting structure.

Research about Influence of Loess Cave Dwelling’s Leg Width on Safety Factor by Strength Reduction Method

2011 ◽  
Vol 71-78 ◽  
pp. 1609-1612
Author(s):  
Ping Gong Guo ◽  
Li Ping Tong
Keyword(s):  
Safety Factor ◽  
Reduction Method ◽  
Yellow River ◽  
Green Building ◽  
Strength Reduction ◽  
The Yellow River ◽  
Strength Reduction Method ◽  
Abaqus Software

The loess cave dwelling are very common along the Yellow River in China，which are really green building. This paper focus on the influence of cave leg’s width on the safety factor. Abaqus software and Strength Reduction Method are used. Results show that existing cave leg width is safe enough.

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.

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