some new developments in rock mechanics research and
TRANSCRIPT
Some New Developments in Rock Mechanics Research and Application
Jian Zhao
Wuhan University, 30 October 2014
Research • Micromechanics and critical scale • Rock dynamics and fracturing • Induced seismicity and earthquake Application • Earthquake assessment and rock engineering design • Shale gas, hot rock geothermal, carbon sequestration • Mass mining and rapid excavation
Developments in Rock Mechanics Research and Application
Micromechanics is adopted in all solid mechanics disciplines, it offers better scientific explanation on how materials
behave and fail. Different disciplines focus on different scales.
Micromechanics and Critical Scale
ICAMS, 2013
The scale of micromechanics are varying depending on the approaches, e.g., molecular dynamics (MD), Critical Distance
(CD), and particle flow.
In rock mechanics, Critical Distance (CD) and particle flow are usually adopted.
Micromechanics and Critical Scale
Micromechanics Research: • Defining Critical Distance for various rocks; • Defining micromechanics constitutive relation; • Proving micromechanics constitutive relation is intrinsic; • Reconstituting macro behaviour of rock material.
Micromechanics and Critical Scale
Taylor, 2009 EFM
2
0
)(2
σπICK
a =∆
Taylor, 2007 EFM
Constitutive Laws of Micromechanics
Micromechanics and Critical Scale
Micro trans- and inter-granular fracture model (QB Zhang, PhD 2014)
)()(16
)2
3sin2
)(sin()()2
3cos2
cos3)(()(
)(),(
12I1I
22
2II2II
22
2I2I
1TGd
2IGd
vkvA
vkvAvkvA
vGvG
βββββ +++
=
Zhang and Zhao, 2013 EFM
Micromechanics Numerical Methods and Modelling
Micromechanics and Critical Scale
Distinct lattice spring model (GF Zhao, PhD 2010)
UDEC with cohesive model (T Kazerani, PhD 2011)
Particle manifold method (L Sun, PhD 2012)
Laboratory Testing and Micromechanics Observation
Micromechanics and Critical Scale
3D X-ray CT for imaging geomaterials at Monash University’s rock mechanics laboratory (Courtesy of PG Ranjith)
Dynamic behaviour of materials, including rock materials, joints and masses is still relatively less understood, primarily limited by observation means.
Rock Dynamics and Fracturing
Modified after Zhao et al, 1999 TUST
Observed Rate Dependent Strength of Rock Materials
Rock Dynamics and Fracturing
Zhang and Zhao, 2014 RMRE
I: [10-5, 101] s-1
II: [101, 600] s-1
III: [600, 3000] s-1
Experimental Techniques of Rock Dynamics Testing
Rock Dynamics and Fracturing
Zhang and Zhao, 2014 RMRE
High-speed Digital Image Correlation with SHPB
Rock Dynamics and Fracturing
Photron SA1.1 + macro lens
2''2
''
ZNCC
]),([]),([
]),([]),([
m
M
Mi
M
Mjjim
M
Mi
M
Mjji
M
Mi
M
Mjmjimji
gyxgfyxf
gyxgfyxfC
−−
−×−=
∑ ∑∑ ∑
∑ ∑
−= −=−= −=
−= −=
Zhang and Zhao, 2013 IJRMMS
Triaxially Compressed Hopkinson Bar (TriHB)
Rock Dynamics and Fracturing
Schematic
Numerical simulation
Zhao and Cadoni, 2013 SNF Report
Rock Dynamic Strength Criteria and Micromechanics Model
Rock Dynamics and Fracturing
Sliding wing crack model (Li et al, 2001 IJNAMG)
Intermediate strain rate (Zhao and Li, 2000 IJRMMS) High strain rate (Zhang and Zhao, 2013 IJRMMS)
0.90
1.00
1.10
1.20
0.0 1.0 2.0 3.0 4.0 5.0Normalized strain rate
Nor
mal
ized
str
engt
h
Conf_pressure=20MPaConf_pressure=50MPaConf_pressure=80MPaConf_pressure=110MPaConf_pressure=140MPaConf_pressure=170MPa
2000 IJRMMS
Wave Propagation across Rock Joints and Rock Mass
Rock Dynamics and Fracturing
Experiment
Numerical modelling
Analytical solution XF Deng, PhD 2013
Wu, PhD 2013
Analytical Solutions of Stress Wave Propagation in Rocks
• Virtual wave source method (Li et al, 2010 JGR) • Displacement & stress discontinuity model (Zhu and Zhao, 2011 GJI) • Time-domain recursive method (Li et al, 2012 GJI) • Modified recursive method (Zhu et al, 2012 JAG) • Thin-layer interface model (Li et al, 2013 JAG)
Rock Dynamics and Fracturing
Zhu, PhD 2011
Laboratory Experiments Wave Propagation in Rocks
• Multiple parallel rock fractures • Different fracture spacing and
orientations • Different fracture apertures and filled
materials
Rock Dynamics and Fracturing
Wu, PhD 2013
Numerical Modelling of Stress Wave Propagation in Rocks
• Distinct lattice spring model (Zhu et al, 2011 C&G) • Particle manifold method (Zhao and Sun, 2012 G&G) • UDEC and 3DEC (Deng et al 2012 RMRE, Zhu et al 2013 RMRE)
Rock Dynamics and Fracturing
Zhu, Deng and Zhao, 2011-13 RMRE
Zhao and Sun 2012 G&G
Induced seismicity becomes an increasing concern with energy technologies that involve injection or withdrawal of fluids from deep rocks.
Induced Seismicity and Earthquake
Evans, 2012 Geothermics
Ellsworth, 2013 Science
Research on Induced Seismicity • Energy release and and wave generation during joint
shearing • Effects of joint geometry and roughness on wave
generation • Induced seismicity
due to hydro-fracturing
• Coupling of hydro-thermo-mechanics and seismicity
Induced Seismicity and Earthquake
Ellsworth, 2013 Science
Laboratory Experiments on Induced Seismicity
Induced Seismicity and Earthquake
Wave generation during plate shearing. Wu and Zhao, 2013 EM
Measurements of energy and wave generated and transmitted during rock
fracturing using 3D Hopkinson bar. Zhao, 2009 SNF Proposal
Development of Induced Seismicity Models • Joint shearing – seismicity model • Rock fracturing – seismicity model
Induced Seismicity and Earthquake
Wu and Zhao, 2013 EM
Californian Fault Lab Scale
Goebel and Sammis, 2013 PAG
To be able to assess earthquake potential (by understanding seismic wave generation, propagation and transformation);
To have design methodology for large engineering structures in and on rocks subjected to earthquake and dynamics loads.
Earthquake Assessment and Rock Engineering Design
Deng, PhD 2013
To develop techniques creating desired fracture network for shale gas and HR geothermal system.
Shale Gas, Hot Rock Geothermal, Carbon Sequestration
Zhao, 1994 Geothermics
World’s largest (?) high-pressure, high-temperature testing chamber: sample size 750×750×750 mm, temperature 450 ˚C, σ1≠ σ2≠ σ3= 350 MPa, multiphase flow. Courtesy of PG Ranjith.
To estimate flow in fractured rock masses (and permeability Of rock materials and rock masses) for various fluids, including at super-critical state;
To assess sustainable heat transfer in hot rock geothermal system;
To characterize deep subsurface geology and rock fractures for CO2 confinement.
Shale Gas, Hot Rock Geothermal, Carbon Sequestration
Courtesy of PG Ranjith
To assess and to manage induced earthquakes in shale gas and deep geothermal system.
Shale Gas, Hot Rock Geothermal, Carbon Sequestration
Spatial distribution of identified fault planes and hypocenters of induced seismicity at Basel (Mukuhira et al, 2011 GRC).
To develop rock mass characterization system for mass caving mining;
To develop tools for modelling and managing rock mass movement;
To develop better techniques for controlled rock fragmentation.
Mass Mining and Rapid Excavation
Elmo et al, 2013 ASCE IJG
To apply TBM for rapid excavation in mine tunnels that usually are of complex geology and varying grounds.
Mass Mining and Rapid Excavation
Courtesy of AlpTransit
Acknowledgements ZHANG Qianbing, EPFL, Switzerland, helped with preparation. LI Jianchun, CAS, China, reviewed some of the contents. RANJITH PG, Monash U, Australia, provided information and images. Past and current PhD students on rock dynamics in the last 5 years: ZHAO Gaofeng, UNSW, Australia KAZERANI Tohid, Nottingham U, UK ZHU Jianbo, HK PolyU, HK SUN Liang, PetroChina, China DENG Xifei, China Rail Construction, China WU Wei, Stanford U, USA ZHANG Qianbing, EPFL, Switzerland
Developments in Rock Mechanics Research and Application