[SIO GP Seminars] TODAY: 3:00 PM: Yariv Hamiel, IGPP

[Robin Matoza]

a reminder

Begin forwarded message:

> From: Robin Matoza <rmatoza at ucsd.edu>
> Date: January 26, 2007 7:19:19 AM PST
> To: gp-seminars at sio.ucsd.edu
> Subject: [SIO GP Seminars] TODAY: 3:00 PM: Yariv Hamiel, IGPP
>
> Geophysics Seminar Reminder-
>
>  ========================
>
> Friday, January 26, 3:00 PM
>   (refreshments served at 2:45 PM)
>   Munk Conference Room
>
> 													Yariv Hamiel, IGPP
>
>   "Poroelastic damage rheology: dilation, compaction and failure of  
> rocks"
>
>
>   =====================
>
>
> ABSTRACT
> A formulation for mechanical modeling of interaction between  
> fracture and fluid flow is presented. The model combines the  
> classical Biot's poroelastic theory with a damage rheology model.  
> The theoretical analysis based on the thermodynamic principles,  
> leads to a system of coupled kinetic equations for the evolution of  
> damage and porosity. Competition between two thermodynamic forces,  
> one related to porosity change and one to microcraking, defines the  
> mode of macroscopic rock failure. At low confining pressures rock  
> fails in a brittle mode, with strong damage localization in a  
> narrow deformation zone. The thermodynamic force related to  
> microcraking is dominant and the yield stress increases with  
> confining pressure (positive slope for yield curve). The role of  
> porosity related thermodynamic force increases with increasing  
> confining pressure, eventually leading to decrease of yield stress  
> with confining pressure (negative slope for yield curve). At high  
> confining pressures damage is non-localized and the macroscopic  
> deformation of the model corresponds to experimentally observed  
> cataclastic flow. In addition, the model correctly predicts  
> different modes of strain localization such as dilating shear bands  
> and compacting shear bands. Numerical simulations in 3D that  
> demonstrate rock-sample deformation at different modes of failure  
> are also presented. The simulations reproduce the gradual  
> transition from brittle fracture to cataclastic flow. The  
> development provides an internally consistent framework for  
> simulating coupled evolution of fracturing and fluid flow in a  
> variety of practical geological and engineering problems such as  
> nucleation of deformation features in poroelastic media and fluid  
> flow during seismic cycle.
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