Dynamic Relaxation Applied To Continuum And Discontinuum Numerical Models In Geomechanics Pdf

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A Practical Approach to Challenges in Meshing Mining Models

What problems can be solved? The flowchart is provided and applied to analyze the stability of UPC in this paper. With the guide of the flowchart, the damage index Di is used as a failure type gravity-controlled or stress-induced judgment indicator. Through the calculation of three typical engineering, the problems of random blocks stability, dynamic calculation, and support system evaluation are studied, respectively, with the help of the DEM code 3DEC. The method and results of this paper can give reference to engineering projects of its category. Vast underground caverns are used for a variety of purpose in civil engineering. Stability of underground openings under different conditions is an essential issue in construction [ 1 ].

An imperative task for successful underground mining is to ensure the stability of underground structures. This is more so for deep excavations which may be under significantly high stresses. In this manuscript, we present stability studies on two tunnels, a horseshoe-shaped and an inverted arch-shaped tunnel, in a deep coal mine in China, performed using the 3DEC distinct element code. The rock mass mechanical property values for the tunnel shapes have been estimated through a back-analysis procedure using available field deformation data. The back-analysis has been carried out through a pseudo-time dependent support installation routine which incorporates the effect of time through a stress-relaxation mechanism. Additionally, the importance of incorporating stress relaxation before support installation has been illustrated through the increased support factor of safety and reduced grout failures. The calibrated models have been analyzed for different supported and unsupported cases to estimate the significance and adequacy of the current supports being used in the mine and to suggest a possible optimization.

DECM: A Discrete Element for Multiscale Modeling of Composite Materials Using the Cell Method

John, Christopher M. This paper provides a brief review of some of the achievements and comments on current deficiencies and future developments. Over 20 years ago the Committee Rock Mechanics defined our discipline as 'that branch of mechanics concerned with the response of rock and rock masses to the force fields of their physical environment. Authors of papers presented at that symposium were clearly striving to find means of applying the analytical tools of mechanics, largely developed in other disciplines, to the solution of general classes of problems involving the behaviour of rock masses.

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discrete element modelling (DEM)

Show all documents Particle breakage criteria in discrete element modelling The key task then is relating available particle strength data, for the case of diametric compression, to some characteristic measure of particle stress which may result from any number of complex loading configurations. Any suitable measure of characteristic particle stress in DEM must be easily linked to the stresses measured experimentally, i. Furthermore, the ideal measure of particle stress must be physically reasonable and give the correct results with regard to experimental data, i. Following McDowell and Bolton , the emergence of a fractal particle size distribution PSD implies that any suitable breakage regime must take into consideration the coordination number, whereby smaller particles which have higher strengths but fewer contacts suffer higher stresses than comparatively larger particles lower strengths but more contacts —otherwise, if it were simply the weakest particles that are most likely to crush, then the result would be a uniform matrix of fine particles, behaviour which is not evident in geotechnical literature.

A generalized weighted residual method is used to formulate the discrete element method DEM for rigid or deformable bodies. It is shown that this approach provides a unified methodology for deriving many of the different discrete element techniques in current use today. This procedure is used to develop a number of different element formulations for use in problems in which the distinct bodies exhibit complex deformation behaviour such as beam or plate flexure, membrane action, and additional reinforcement of a jointed discontinuum. A number of examples are also presented which illustrate the usefulness of different discrete element types in engineering analyses of discontinuum problems. Report bugs here. Please share your general feedback. You can join in the discussion by joining the community or logging in here.

Tunnelling processes lead to stress changes surrounding an underground opening resulting in the disturbance and potential damage of the surrounding ground. Especially, when it comes to hard rocks at great depths, the rockmass is more likely to respond in a brittle manner during the excavation. Continuum numerical modelling and discontinuum techniques have been employed in order to capture the complex nature of fracture initiation and propagation at low-confinement conditions surrounding an underground opening. In the present study, the hybrid finite-discrete element method FDEM is used and compared to techniques using the finite element method FEM , in order to investigate the efficiency of these methods in simulating brittle fracturing. Following the comparison of these models, additional analyses are performed by integrating discrete fracture network DFN geometries in order to examine the effect of the explicit simulation of joints in brittle rockmasses. The results show that in both cases, the FDEM method is more capable of capturing the highly damaged zone HDZ and the excavation damaged zone EDZ compared to results of continuum numerical techniques in such excavations. Significant changes in the stress regime and material properties of a rockmass are the result of the construction of underground openings [ 1 ].


The paper presents a description of the methods used to model rock as DEM simulation of an underground structure subjected to dynamic loading Morris et al. bring to the geomechanics community recent advances in numerical modeling sion regarding continuum versus discontinuum methods is in-.


A GENERALIZED FORMULATION OF THE DISCRETE ELEMENT METHOD

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Abstract The goal of this review paper is to provide a summary of selected discrete element and hybrid finite—discrete element modeling techniques that have emerged in the field of rock mechanics as simulation tools for fracturing processes in rocks and rock masses. The fundamental principles of each computer code are illustrated with particular emphasis on the approach specifically adopted to simulate fracture nucleation and propagation and to account for the presence of rock mass discontinuities. This description is accompanied by a brief review of application studies focusing on laboratory-scale models of rock failure processes and on the simulation of damage development around underground excavations. The goal of this review paper is to provide a summary of selected discrete element and hybrid finite— discrete element modeling techniques that have emerged in the field of rock mechanics as simulation tools for fracturing processes in rocks and rock masses. Production and hosting by. A large body of experimental research shows that the failure process in brittle rocks under compression is characterized by complicated micromechanical processes, including the nucleation, growth and coalescence of microcracks, which lead to strain localization in the form of macroscopic fracturing Lockner et al. The evolution of micro-cracking, typically associated with the emission of acoustic energy AE , results in a distinctive non-linear stress—strain response, with macroscopic strain softening commonly observed under low-confinement conditions Brace et al.

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Koliji, A. The Hongrin north dam is a double curvature concrete arch dam located in western Swiss Prealps, which attains m high. The right bank abutment of the dam mainly consists of intensively jointed Neocomian limestone and exhibits zones of potential instability.

This paper presents a new numerical method for multiscale modeling of composite materials. In particular, it offers the same degree of detail as the CM, on the microscale, and manages the discrete elements individually such as the DEM—allowing finite displacements and rotations—on the macroscale. Moreover, the DECM is able to activate crack propagation until complete detachment and automatically recognizes new contacts.

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