HR: 08:20h
AN: T21D-02 INVITED     [Abstracts]
TI: Results Of A Pilot Study To Investigate The Feasibility Of Using New Experimental Techniques To Measure Sliding Resistance At Seismic Slip Rates
AU: * Prakash, V
EM: vikas.prakash@case.edu
AF: Case Western Reserve University, Department of Mechanical and Aerospace Engineering, Cleveland, OH 44106 United States
AU: Yuan, F
EM: fxy11@case.edu
AF: Case Western Reserve University, Department of Mechanical and Aerospace Engineering, Cleveland, OH 44106 United States
AB: Determining the shear resistance on faults during earthquakes is a high priority concern for researchers involved with fault and rock mechanics. Knowledge of shear resistance and how it depends on slip velocity, slip distance, normal stress, etc. is required fundamental information for understanding earthquake source physics. Reliable laboratory data on slip resistance of geological materials at high slip speeds, realistic displacements, and elevated normal stresses do not currently exist in spite of progress in this direction. This is because it is technologically difficult to conduct the relevant experiments. More recently, at CWRU, as a part of a pilot study funded by SCEC, two relatively new experimental techniques have been employed to investigate high-speed friction in analog materials and rocks. These experimental techniques are (a) plate impact pressure-shear friction experiment, and (b) the modified torsional Kolsky bar friction experiment. The plate impact experiments were employed to study a variety of friction states with normal stress varying from 0.5 to 1 GPa and slip speeds ranging from 1 to 25 m/s. The torsional Kolsky bar experiments were employed to study interfacial friction at normal stress ranging from 20 to 150 GPa and slip velocities of up to 10 m/s. Using these techniques plate impact pressure-shear friction experiments were conducted on soda-lime glass and fine grained novaculite rock, while the modified torsional Kolsky bar was used to conduct experiments on borosilcate glass specimens. The choice of soda-lime and borosilicate glass were dictated by a number of previous studies which have shown that the frictional behavior of glass is almost identical to that of rock. These experiments have provided the time resolved history of interfacial tractions, i.e. the friction stress and the normal stress, and the interfacial slip velocity. For the glass-on-glass experiments the interface shows no-slip initially, followed by slip weakening, strengthening and then seizure. For the novaculite rock the initial no-slip and the final seizure conditions are absent. It is interesting to note the range of the measured coefficient of friction for glass, which varies from 0.5 to as high as 1.3. These high values of coefficient of friction are in sharp contrast to metals where the coefficient of friction has been observed to be between 0.1 and 0.25 under similar loading conditions. Moreover, interfacial temperatures as high as 1500 degrees centigrade are estimated, which are close to the melting point of glass.
DE: 8010 Fractures and faults
DE: 8100 TECTONOPHYSICS
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting