Evaluation of a permeability-porosity relationship in a low permeability creeping material using a single transient test

摘要

A method is presented for the evaluation of the permeability-porosityrelationship in a low-permeability porous material using the results of asingle transient test. This method accounts for both elastic and non-elasticdeformations of the sample during the test and is applied to a hardened class Goil well cement paste. An initial hydrostatic undrained loading is applied tothe sample. The generated excess pore pressure is then released at one end ofthe sample while monitoring the pore pressure at the other end and the radialstrain in the middle of the sample during the dissipation of the pore pressure.These measurements are back analysed to evaluate the permeability and itsevolution with porosity change. The effect of creep of the sample during thetest on the measured pore pressure and volume change is taken into account inthe analysis. This approach permits to calibrate a power lawpermeability-porosity relationship for the tested hardened cement paste. Theporosity sensitivity exponent of the power-law is evaluated equal to 11 and isshown to be mostly independent of the stress level and of the creep strains.