273517 Discrete Modeling of Void Porosity in Rock Cutting

Wednesday, October 31, 2012: 10:36 AM
322 (Convention Center )
Jorge A. Mendoza, Civil Engineering, University of Pittsburgh, Pittsburgh, PA, Jeen-Shang Lin, National Energy Technology Laboratory, U.S. Department of Energy, And Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA and Isaac K. Gamwo, National Energy Technology Laboratory, US Department of Energy, Pittsburgh, PA

A numerical study on the mechanical behavior of rock during cutting is investigated using the discrete element method. The rock is represented by a dense packing of circular or spherical particles that are bonded together at their contact points. Such packing arrangement may lead to a wide range of porosity depending on the rock being modeled. Very low void porosity rock, say 3%, requires unrealistic computational time to simulate the rock cutting. We have created rock samples of different void porosity, such as 15%, 10% and 8% for mechanical tests. Discrete element method uniaxial tests conducted on these samples gave results consistent with the current understanding as to how the strength and modulus would increase with the reduction of the void porosity. Scratch tests were then carried out on these samples. We further carried out tests on a different set of samples generated with a fixed 16% void ratio but other microproperties were recalibrated to give the correct bond modulus and bond strength corresponding to samples of low void porosity samples. The results of the cutting tests based on the fixed void porosity were found to be essentially the same as those that void porosity were not explicitly modeled.  Details of this important finding will be presented in the meeting.

 


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