A new criterion for defining the failure of a fractured rock mass slope based on the strength reduction method

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.368-370.1774 ◽

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.

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

10.21203/rs.3.rs-914757/v1 ◽

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.

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The Stability Analysis of Underwater Slopes Based on Strength Reduction Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.2690 ◽

2011 ◽

Vol 243-249 ◽

pp. 2690-2693

Author(s):

Lin Yan Li ◽

Yin Liu ◽

Hao Chen ◽

Heng Bin Wu

Keyword(s):

Rock Mass ◽

Stability Analysis ◽

Reduction Method ◽

Limit Equilibrium ◽

Limit Equilibrium Method ◽

Strength Reduction ◽

Strength Reduction Method ◽

Equilibrium Method ◽

Erosion Effect ◽

The Stability

Present methods for stability analysis of underwater slopes are mostly confined to laboratory experiments and limit equilibrium method. This paper is based on strength reduction method, considering the deformation parameters of rock mass to discuss the stability of underwater slopes. Comparing the consequences, the sliding planes and safety factors agreed well with the result of limit equilibrium method. The applicability of strength reduction method for underwater slopes stability was well proved. When analyzing after changing the water depth, it was showed that there are more erosion effect induced and reduction for the parameters of rock mass, but little influence on the safety factor of underwater slopes.

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

10.21203/rs.3.rs-211035/v1 ◽

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.

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

Mathematical Problems in Engineering ◽

10.1155/2015/872834 ◽

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.

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Casing Shear Deformation Analysis of Shale Gas well Based on Shale Formation Strength Reduction Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.944.991 ◽

2019 ◽

Vol 944 ◽

pp. 991-998

Author(s):

Yi Jin Zeng ◽

Jun Li ◽

Shi Dong Ding ◽

Zhang Xu ◽

Wei Lian

Keyword(s):

Rock Mass ◽

Wall Thickness ◽

Shale Gas ◽

Fractured Rock ◽

Strength Reduction ◽

Fractured Rock Mass ◽

Fracturing Process ◽

Shale Formation ◽

Cement Sheath ◽

Casing Deformation

The problem of casing deformation caused by fault slippage due to the hydraulic fracturing process in Changning-Weiyuan area, Sichuan Province, has seriously affected the economic benefits of shale gas wells. In order to clarify the relationship between the strength of fractured rock mass, the size of fractured rock mass, and the parameters of cement sheath, based on the characteristics of artificial shale formation during hydraulic fracturing, the shale strength is reduced. The finite element model of the casing, cement sheath and formation is analyzed, and the deformation law of the casing during the shale strength reduction process is analyzed. The results show that the greater the reduction of the strength of the shale, the greater the risk of shear deformation of the casing. The fracturing height has a great influence on the casing deformation, which increases substantially linearly, and the crack width has little effect on the casing deformation. 2 The Young’s modulus of the cement sheath has little effect on the deformation of the casing, and reducing the Young’s modulus of the cement sheath cannot effectively alleviate the deformation of the casing. Increasing the wall thickness of the cement sheath increases the contact area between the cement sheath and the formation, and the degree of deformation increases. 3 increasing the wall thickness of the casing can alleviate the deformation degree of the casing, and the wall thickness of the casing should be optimized during the fracturing process. The research results have a certain guiding role for the prevention and treatment of casing deformation.

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