Realistic Failure Process Analysis
Realistic Failure Process Analysis
Chunan TANG, PhD, Prof.,
Dalian University of Technology & Mechsoft
Dalian, Liaoning, China
One day (5 hours of presentations and 2 hours of RFPA training)
Pre-conference (27th September 2016)
Start at 09:00, end at 17:00, lunch from 13:00-14:00. Tea breaks and lunches provided.
Monash University, Clayton campus, Clayton, Vic 3800, Australia
Course materials :
Hard copy of course PPT, a CD with a basic version of RFPA, manual and RFPA related publications.
Course Description :
Many rock engineering problems involve potential and actual unstable rock failure, such as rockbursts, coal and gas outbursts and crack development in hydraulic fracturing. For this reason, the brittle failure of rock has received considerable attention. Various models and fracture criteria have been invoked in attempts to capture the essential features of the mechanisms which lead to brittle fracture in intact rock and the rock mass. Although much progress has been made and theories and models, such as fracture mechanics and damage mechanics, have provided techniques to solve fracture problems in rock, few approaches are capable of capturing fracture initiation, propagation and coalescence and hence of investigating fracture-induced progressive failure of rock.
A major difficulty in modeling the fracture mechanisms for rock subjected to various loads is the fact that rock is a natural, composite material which is Discontinuous, Inhomogeneous, Anisotropic and Not Elastic (DIANE). It is not possible to analytically examine and evaluate the mechanical behavior of a DIANE rock exhibiting an unstable failure process. The problem becomes more intractable if gas or fluid, as in coal and gas outbursts, hydraulic fracturing, etc., is involved. In most of the cases, analytical models have to be simplified, ignoring important factors influencing the mechanical behavior of rock.
Numerical models that simulate the detailed fracturing sequence are thus useful for understanding rock failure mechanisms on both the small and large scales. In this short course, a newly developed numerical code, the Realistic Failure Process Analysis (RFPA) model, is firstly introduced. Then, examples are presented in the course illustrating how the overall macroscopic response of a brittle rock can be simulated by integration of the interactions between smaller-scale elements. Also, through the modeling of slope or tunnel collapse sequences, it will demonstrate that RFPA is possible to analyze large-scale practical problems.
This RFPA Short Course includes five parts. The first part gives a brief introduction of the RFPA principle. The second, third and fourth parts demonstrate varies of potential applications of RFPA in modeling rock failure under laboratory condition, modeling rock failure considering rock reality and modeling rock failure under field circumstances. The fifth part provides a fast training of using RFPA code to basic and specific rock mechanics problems.
Many operational questions, such as listed below, regarding RFPA can be face to face answered during the course:
- Why is it nonlinear for rock or concrete behaviour?
- What makes RFPA different from other FEM code?
- How does heterogeneity be considered in the RFPA model?
- Why RFPA can model rock failure like a particle model?
- How can the RFPA model parameters be selected based on experimental or field data?
A clear and logical approach to such issues is provided through the course with the five parts including RFPA principle, RFPA application and RFPA fast training. Participants will gain a good understanding of the physics and mechanics involved in RFPA.
This course is intended for Geoscientists, Material scientist, Engineers, students working in the filed of rock mechanics, geomechanics, civil engineering and material science. Mechanics experts in university and institutes, engineers and post-graduate students who are involved in rock or brittle material failure process analysis, design and construction activities associated with rock and concrete failure problems in or on fractured materials or structures will benefit from the short-course. A basic understanding of rock or concrete mechanics and computational mechanics is desirable for participants, but the course is self-contained; those never exposed to computational mechanics will rapidly pick up the major principles and become skillful in using RFPA code because materials are presented from a mechanical and physical point of view. Even those specialized in numerical methods will find new ideas and methods that will affect how they approach well analysis for complicated rock and concrete failure problems.
Course Objective :
The objective of the short course is to describe the features of RFPA method, to show how it can be used for failure process analysis of materials such as rock or concrete and associated civil engineering structures and to train attendants how to use it.
Course Outline :
The course consists of five parts, which are roughly one or two hours for each part. Discussions and questions during the presentations are encouraged.
PART I: INTRODUCTION
PART II: MODELING ROCK FAILURE UNDER LABORATORY CONDITIONS2.1 Uniaxial tensile failure
2.2 Indirect tensile failure
2.3 Uniaxial compressive failure
2.4 Factors affecting the failure behavior
2.5 Confinement and shear
2.6 Loading and unloading
2.7 Dynamic loading
PART III: MODELLING ROCK FAILURE CONSIDERING ROCK REALITY
3.1 Effects of heterogeneity
3.2 Coalescence of fractures
3.3 Anisotropy of layered and jointed rocks
3.4 Time dependent
3.5 Fluid flow and coupled behavior
3.6 Thermal effects and coupled modeling
PART IV: MODELLING ROCK FAILURE UNDER ENGINEERING CIRCUMSTANCES
4.1 Slope failure
4.2 Tunnel and cavern failure
4.3 Strata movement adjacent to coal mines
4.4 Gas outbursts in coal mines
4.5 Rock cutting
4.6 Particle breakage and comminution
4.7 fracture spacing
PART IV: CONCLUDING REMARKS
Dr. Tang, as a chair Professor (funded by Cheung Kong Scholar Programme from State Education Ministry), was the Director of the Center for Rock Instability and Seismisity Research (CRISR) of Dalian University of Technology, and Chief Scientist of Mechsoft. He was also the Vice President of the Chinese Society of Rock Mechanics CSRM, and the China National Group Chairman of International Society of Rock Mechanics. In 1984, he started his Ph.D research, in Northeastern University, Shenyang, P.R.China, and got his Ph.D in 1988. In 1991, he continued his post-doctoral work in Imperial College, London, UK (worked with Prof. J.A.Hudson). Then, as an academic visitor, he had lots of experience working in Canada, Sweden, Singapore, Switzerland and Hong Kong. He leads several major research projects in rock mechanics, especially on rock failure process analysis and monitoring in civil engineering. His work is funded by the “Trans-Century Training Programme Foundation for Outstanding Young Scholars in China” from the State Education Ministry and by the "Special Natural Science Foundation for Outstanding Young Scholars in China" from National Nature Science Foundation. He is also the Chief Scientist leading a 973 program supported by Chinese government for fundamental research. So far, he has published about 300 technical papers on rock failure mechanisms and civil engineering, and is the author of five Chinese books of rock mechanics and the principle author of “Rock Failure Mechanism” published by CRC (Taylor & Francis Group, 2010, UK).
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