GEOP 615 Experimental Rock Deformation

Syllabus

Professors Frederick Chester
and Andreas Kronenberg

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Lecture Topics

I. Introduction and Overview of Rock Behavior

A.

Role of experimental rock mechanics in modern structural geology, geodynamics, and engineering geology (historical and current perspectives)

B.

What is the effect of depth (pressure, temperature), strain rate and lithology on behavior of intact rock?
1. Effect of confining pressure on the brittle-ductile transition
2. Effect of temperature and stress on ductile flow
3. Effect of rock type

C.

How do rocks with pre-existing fractures or faults behave?
1. The friction test in triaxial and other apparatus
2. Byerlee's relation
3. Effect of fault orientation and confining pressure on reactivation
4. Friction and the brittle-ductile transition

D.

What is the philosophy of scientific experimentation?
1. Experimental approach
2. Reasons to do experiments
3. Role of experimental rock deformation in modern structural geology, engineering geology, and geodynamics

II. Experiments on the processes of brittle failure

A.

What is the mechanical behavior and associated changes in physical properties leading up to failure?
1. Non-linear elasticity and hysteresis
2. Volumetric strain, seismic velocity, resistivity, and microcracking

B.

How do faults initiate and grow?
1. Griffith theory
2. Modes of crack growth observed in rock
3. Mechanisms of fault propagation

C.

What is the post-failure mechanical behavior?
1. Stiffness and stability
2. Modifying stiffness of apparatus and control of instability

D.

How is brittle failure different in low and high porosity rocks?
1. Microscopic stress concentrators and flaws
2. Dilatancy and porosity collapse

E.

Can we predict ultimate strength and the occurrence of failure?
1. Mohr-Coulomb failure criteria
2. Effect of the intermediate principal stress
3. Pore fluid pressure and the law of effective stress
4. Cap models
5. Anisotropic mechanical behavior

F.

Scale dependence of fracture and faulting

III. Experiments on mechanical behavior during ductile flow

A.

How does strain rate depend on other parameters?
1. Trade-off between temperature and time
2. Stress dependence
3. Testing techniques and data analysis

B.

How can we use flow laws to describe behavior at geologic rates?
1. Laws for steady-state flow and deformation mechanism maps
2. Extrapolation and error analysis
3. Simple versus pure shear

C.

Chemical effects and hydrolytic weakening

D.

Transient behavior and high strain softening processes

E.

Phyllosilicates

MIDTERM EXAM

IV. Experimental studies of faulting and folding in layered rock

A.

Why do we construct physical models?
1. Insights to complex systems
2. Theory of scaling physical models
3. Partially scaled models

B.

How have rock models been used to study faulting and folding?
1. Beam bending models
2. Fault-fold interaction
3. Wrench fault models

 

V. Experimental study of pressure solution and creep compaction of sediments

A.

What are the processes of sediment densification?
1. Mechanical compaction
2. Cementation
3. Time-dependent compaction

B.

What is the experimental evidence for grain scale pressure solution processes?
1. Hypotheses of pressure solution process
2. In situ experiments
3. Creep compaction experiments

C.

How can we predict the relative roles of brittle and pressure-solution processes in creep compaction?
1. Direct observations of fabrics, microcracks, etc.
2. Test of constitutive laws
3. Role of fluid, grain size, clays

 

VI. Experimental studies of friction and the earthquake instability

A.

How can experiments study earthquakes?
1. The stick-slip hypothesis
2. Effects of pressure, temperature, rock type, gouge layers on stability
3. Role of stiffness

B.

How do we describe the constitutive behavior for friction surfaces?
1.Adhesion theory of friction
2. Time dependence of friction
3. Rate and state dependent friction

C.

Can experimental results be applied to understand natural fault instability?
1. Stability in frictional systems
2. Scaling problems
3. Friction mechanisms and fault fabric development
4. Simulating hypocentral conditions

VII. Using experimental results to define the rheology of the lithosphere

A.

Why do the continental and oceanic lithospheres behave differently?
1. Strength versus depth profiles
2. Quartz, feldspar and olivine
3. Description of polycrystalline and polyphase behavior

B.

Some important remaining questions on the mechanical behavior of the lithosphere
1. Brittle-plastic transition and semi-brittle behavior
2. Strain localization
3. Deformation during Phase Transitions
4. Deep focus earthquakes

 

FINAL EXAM

Laboratory Schedule

First Week

Introduction to Lab, Demonstration of Triaxial Experiment

Second Week

Mechanical operation of LSR Triaxial Apparatus, Lab Safety and Rock Preparation Equipment

Third Week

Measurement methods, Instrumentation, Use of Rock Preparation Equipment (Scheduled 1-on-1's)

Fourth Week

Data Reduction, Conversion Factors, and Error Analysis, Use of Triaxial Apparatus (Scheduled 1-on-1's).

DUE, Fourth Week

Choice of Sedimentary Rock Type for Suit of Experiments to Traverse the Brittle-Ductile Transition, along with Experimental Plan and Strategy

Fifth Week

Theory of Design, Process Control, and Novel Experimental Apparatus

Sixth Week

Student Oral Presentations of Experimental Results--the Brittle-Dutile Transition

Eighth Week

Proposals Due for Individual Experimental Projects

Last Week

Papers and Oral Presentations of Individual Experimental Projects

Grading

4 Credit Hours

Midterm Exam

20%

Final Exam

25%

Brittle-Ductile Transition Experiments

10%

Individual Lab Project and Paper

35%

Oral Presentations and Participation

10%


See other course syllabi...

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GEOP 489 Special Topics in Geophysics: The Hawaiian Volcanoes

 

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