Simulation of induced rock mass fracturing process based on lattice model cellular automata

2011 ◽  
Author(s):  
Nan Feng ◽  
Cai Sijing
Keyword(s):  
Rock Mass ◽  
Cellular Automata ◽  
Lattice Model ◽  
Fracturing Process ◽  
Rock Mass Fracturing

scholarly journals Numerical Modeling on Hydraulic Fracturing in Coal-Rock Mass for Enhancing Gas Drainage

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Zhigang Yuan ◽  
Yaohua Shao
Keyword(s):  
Mathematical Model ◽  
Rock Mass ◽  
Hydraulic Fracturing ◽  
Gas Flow ◽  
Numerical Solutions ◽  
Fracture Initiation ◽  
Engineering Practice ◽  
Gas Drainage ◽  
Fracturing Process ◽  
Coal Rock

The mechanism of how hydraulic fracturing influences gas drainage in coal-rock mass is still not clear due to its complex mechanism. In this work, statistical distributions are firstly introduced to describe heterogeneity of coal-rock mass; a novel simultaneously coupled mathematical model, which can describe the fully coupled process including seepage-damage coupling during hydraulic fracturing process and subsequent gas flow during gas drainage process, is established; its numerical implementation procedure is coded into a Matlab program to calculate the damage variables, and it partly uses COMSOL solver to obtain numerical solutions of governing equations with damage-flow coupling; the mathematical model and its implementation are validated for initial damage pressure and mode of a single solid model without considering flow-damage coupling, as well as fracture initiation pressure and influence of heterogeneity on damage evolution of hydraulic fracturing considering flow-damage coupling; and finally, based on an engineering practice of hydraulic fracturing with two boreholes, the mechanism of how hydraulic fracturing influences gas drainage is investigated, numerical simulation results indicate that coal-rock mass pore-fissure structure has been improved, and there would exist a gas migration channel with characteristics of higher porosity and lower stresses, which demonstrates significant effects and mechanism of hydraulic fracturing on improving coal-rock permeability and enhancing gas drainage. The research results provide a guide for operation of hydraulic fracturing and optimal layout of gas drainage boreholes.

A Multiparticle Lattice-Gas Model for Hydrodynamics

1998 ◽  
Vol 09 (08) ◽  
pp. 1221-1230 ◽  
Author(s):  
A. Masselot ◽  
B. Chopard
Keyword(s):  
Cellular Automata ◽  
Lattice Model ◽  
Lattice Boltzmann ◽  
Lattice Gas ◽  
Two Dimensions ◽  
The Other ◽  
Many Body ◽  
The Many ◽  
Ballistic Annihilation ◽  
Fluid Parameters

Cellular automata (CA) and lattice-Boltzmann (LB) models are two possible approaches to simulate fluid-like systems. CA models keep track of the many-body correlations and provide a description of the fluctuations. However, they lead to a noisy dynamics and impose strong restrictions on the possible viscosity values. On the other hand, LB models are numerically more efficient and offer much more flexibility to adjust the fluid parameters, but they neglect fluctuations. Here we discuss a multiparticle lattice model which reconciles both approaches. Our method is tested on Poiseuille flows and on the problem of ballistic annihilation in two dimensions for which the fluctuations are known to play an important role.

THE EFFECT OF TEMPERATURE OF ROCKS ON MICROCLIMATIC CONDITIONS IN LONG GATE ROADS AND GALLERIES IN COAL MINES

2014 ◽  
Vol 59 (1) ◽  
pp. 189-216 ◽  
Author(s):  
Janusz Cygankiewicz ◽  
Józef Knechtel
Keyword(s):  
Rock Mass ◽  
Coal Extraction ◽  
Effect Of Temperature ◽  
Coal Oxidation ◽  
Temperature Changes ◽  
Air Stream ◽  
Finite Differences Method ◽  
Microclimatic Conditions ◽  
Rock Mass Fracturing

Abstract The aim of this study was to examine the effect of the temperature of surrounding rocks on enthalpy and temperature of air flowing along several model mine workings. Long workings surrounded by non- -coal rocks as well longwall gates surrounded by coal were taken into consideration. Computer-aided simulation methods were used during the study. At greater depths the amount of moisture transferred into a mine working from the rock mass is two orders of magnitude smaller than the moisture that comes from external (technological) sources, mainly from coal extraction-related processes, therefore in the equation describing temperature changes only the terms representing the flux of heat from rocks were included. The model workings, for calculation purposes, were divided into sections, 50 m in length each. For each of the sections temperature of its ribs and temperature and stream of enthalpy of air flowing along it were calculated with the use of the finite differences method. For workings surrounded by non-coal rocks two variant calculations were carried out, namely with or without technological sources of heat. For coal surrounded workings (longwall gates) a new method for determination of heat from coal oxidation was developed, based on the findings by Cygankiewicz J. (2012a, 2012b). Using the results of a study by J.J. Drzewiecki and Smolka (1994), the effects of rock mass fracturing on transfer of heat into the air stream flowing along a working were taken into account.

Cellular Automata to Simulate Crack Propagation of Quasi-Brittle Materials

2011 ◽  
Vol 90-93 ◽  
pp. 748-751 ◽  
Author(s):  
Jun Lian He ◽  
Ming Tian Li
Keyword(s):  
Cellular Automata ◽  
Crack Propagation ◽  
Lattice Model ◽  
Experimental Results ◽  
Homogeneous Material ◽  
Cellular Automata Model ◽  
Secondary Cracks ◽  
Good Accordance ◽  
Cellular Automaton Method ◽  
Theoretical Results

Crack propagation in quasi-brittle material such as rock and concrete is studied by a new numerical method, lattice cellular automata. Cellular automaton method is an efficient method that simulates the process of self-organization of the complex system by constructing some simple local rules. It is of the advantage of localization and parallelization. Lattice model can transform a complex triaxial problem into a simpler uniaxial problem as well as consider the heterogeneity of the materials. Lattice cellular automata integrate advantages of both cellular automata and lattice model. In this paper the importance of the study of crack propagation, fundamentals and applications of cellular automata are briefly introduced firstly. Then the cellular automata model is presented, and in order to verify lattice cellular automata, the propagation of mode-I crack in homogeneous material is studied. Results of the numerical simulation are in good accordance with the experimental results and theoretical results of classical fracture mechanics. Furthermore, based on lattice cellular automata, the crack propagation of single crack under uniaxial compression was simulated. During the crack growth the wing crack and secondary cracks were found. The simulation results were consistent with the experimental results.

Micromechanical Analysis of Excavation Damaged Zone in Anisotropic Rock Mass

2006 ◽  
Vol 324-325 ◽  
pp. 81-84
Author(s):  
Shu Hong Wang ◽  
Deng Pan Qiao ◽  
Peng Jia ◽  
Nan Zhang
Keyword(s):  
Rock Mass ◽  
Numerical Model ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Numerical Code ◽  
Loading Conditions ◽  
Underground Excavations ◽  
Anisotropic Rock ◽  
Rock Structure ◽  
Fracturing Process

Rock is a heterogeneous and anisotropic compound material, containing many shear surfaces, cracks, weak surfaces and faults. Damage and failure in a rock mass can occur through sliding along persistent discontinuities, or fractures. A new micromechanical approach to modeling the mechanical behavior of excavation damaged or disturbed zone (EDZ) of anisotropic rock is presented based on knowledge of the inhomogeneity of rock. In this numerical model, damage is analyzed as a direct consequence of microcracks growth. A study of the effect of elastic and failure anisotropy plus inhomogeneity on the underground excavations reveals that the modes of failure can be significantly influenced by the rock structure on the small and large scales. Fractures that develop progressively around underground excavations can be simulated using a numerical code called RFPA (Realistic Failure Process Analysis). This code incorporates the microscopic inhomogeneity in Young’s modulus and strength characteristic of rock. In the numerical models of a rock mass, values of Young’s modulus and rock strength are realized according to a Weibull distribution in which the distribution parameters represent the level of inhomogeneity of the medium. Another notable feature of this code is that no a priori assumptions need to be made about where and how fracture and failure will occur – cracking can occur spontaneously and can exhibit a variety of mechanisms when certain local stress conditions are met. These unique features have made RFPA capable of simulating the whole fracturing process of initiation, propagation and coalescence of fractures around excavations under a variety of loading conditions. The results of the simulations show that the code can be used not only to produce fracturing patterns similar to those reported in previous studies, but also to predict fracturing patterns under a variety of loading conditions. The numerical model was able to reproduce the associated complex stress patterns and the microseismic emission distribution for a variety of rock structural conditions.

scholarly journals A PREDATOR–PREY MODEL BASED ON THE FULLY PARALLEL CELLULAR AUTOMATA

2003 ◽  
Vol 14 (09) ◽  
pp. 1237-1249 ◽  
Author(s):  
MINGFENG HE ◽  
HONGBO RUAN ◽  
CHANGLIANG YU
Keyword(s):  
Child Care ◽  
Cellular Automata ◽  
Sexual Reproduction ◽  
Mutation Rate ◽  
Lattice Model ◽  
Linear Size ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Model Based ◽  
Definition Of

We presented a predator–prey lattice model containing moveable wolves and sheep, which are characterized by Penna double bit strings. Sexual reproduction and child-care strategies are considered. To implement this model in an efficient way, we build a fully parallel Cellular Automata based on a new definition of the neighborhood. We show the roles played by the initial densities of the populations, the mutation rate and the linear size of the lattice in the evolution of this model.

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