Experimental Studies And Modeling Of Mechanical Properties Of A Porous Rock

In this work, a series of experimental investigations has been performed. According to the experimental results, two plastic deformation mechanisms have to be taken into account: plastic pore collapse and plastic shearing. Based on the extensive experimental investigations, a new elastoplastic model has been proposed, taking into account the two plastic mechanisms related to the microstructure of porous chalks. Influences of water interaction on the mechanical behaviour of porous chalks have been studied. On the macroscopic scale, the elastic modulus and the plastic parameters for both pore collapse and plastic shearing processes are expressed as functions of water saturation degree. The time dependent creep deformation has also been incorporated in the unified model. The creep deformation is seen as the macroscopic consequence of the progressive destruction of cemented solid contact surface between grains. The elastic modulus and the plastic properties are affected by the dissolution process. Furthermore, the undrained mechanical behavior of the porous chalk has been studied. Numerical simulations have been compared with experimental data for various loading conditions, including hydrostatic and triaxial compression tests, as well as creep tests, on oil and water saturated samples under drained or undrained condition. It has been shown that the proposed model describe correctly the main features of the mechanical behaviour of the porous chalk and the influences of water interaction.