Defomiation of Wilcox shale: Undrained strengths and effects of strain rate

Oh Myoung Kwon, Andreas K. Kronenberg

Research output: Contribution to conferencePaper

6 Citations (Scopus)

Abstract

Mechanical and fluid transport properties of brine-saturated illite shale from the Wilcox Formation have been investigated to examine the effects of strain rate on fracture strength and to determine the conditions over which rates of deformation and internal fluid flow compete. Permeability (k) measurements predict time scales for fluid pressure equilibration mat are long relative to those of deformation experiments; values of k are small even at relatively low effective pressures Pe (assumed = Pc - Pf) and they drop below 10-20 m2 at pressures of ≥ 5 MPa. Failure strengths (σ13) of Wilcox shale specimens saturated (as nearly as can be achieved) with brine and shortened at strain rates of 2.8×l0-7 ϵ ≤8.2×10-3 s-1 fit an exponential law ϵ = A exp{α(σ13)} of the same form as determined for Wilcox shale specimens deformed at much higher pressures in the absence of pore fluids. The positive slope and comparable value of a (= 0.29 MPa-1) to that determined for specimens without pore fluids (α = 0.3 MPa-1) suggest that Wilcox shale exhibits undrained behavior at strain rates > 10-7 s-1 and that strain rate effects associated with pore pressure perturbations and pore fluid transport occur at much lower strain rates.

Original languageEnglish
Pages757-765
Number of pages9
Publication statusPublished - 1994 Jan 1
Externally publishedYes
Event1st North American Rock Mechanics Symposium, NARMS 1994 - Austin, United States
Duration: 1994 Jun 11994 Jun 3

Other

Other1st North American Rock Mechanics Symposium, NARMS 1994
CountryUnited States
CityAustin
Period94/6/194/6/3

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ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Kwon, O. M., & Kronenberg, A. K. (1994). Defomiation of Wilcox shale: Undrained strengths and effects of strain rate. 757-765. Paper presented at 1st North American Rock Mechanics Symposium, NARMS 1994, Austin, United States.