Determination de la resistance en compression uniaxiale et du module d'elasticite d'un materiau poreux a l'aide d'un essai de poinconnement

The purpose of this research is to verify the applicability, on a very porous and ductile material, of an indentation test that can estimate the Young's modulus and the uniaxial compressive strength. A parameter, the module d'enfoncement permanent (MEP), is presented in this research for the purpose of establishing a possible correlation between indentation test results and uniaxial compressive strength determined by standard test methods.;The proposed test method implies cyclic loading using a constant load increment throughout the test procedure. In this manner indentor penetration can be analyzed in its elastic and plastic components. The Young's modulus is obtained by calculating the average secant modulus of the unloading part of the load-penetration curve while the unconfined compressive strength is determined by a model of interpretation that makes use of the permanent penetration caused by indentor loading. The permanent penetration modulus (MEP) is presented in this research as a mean to properly estimate the unconfined compressive strength of rock by resorting mainly on indentor geometry and its permanent penetration.;A laboratory test program consisting in 214 indentation tests and 39 unconfined compressive tests was performed on a material for which the porosity would range from 40% to 70%. Good agreement between the unconfined compressive strength results determined by both conventional and indentation tests was found. The ratio between MEP and unconfined compressive strength was practically constant for the range of porosity tested indicating a possible correlation. However the proposed indentation test tends to underestimate the Young's modulus in comparison to values obtained by the conventional method.