Consolidation problem solution with a coupled hydro-mechanical formulation considering fluid compressibility

There are two principles which may be referred to as essentials to describing soil and rock behavior. The mechanical behavior is associated to the law of conservation of linear momentum, allowing forces balance analysis and the hydraulic behavior is characterized by mass conservation. These phenomena are related: stress-strain state is affected by fluid pressures and vice-versa. Therewith, it is intuitive the understanding of the importance of coupled analyses, which are certainly a more precise manner of describing how mechanical and hydraulic behavior are connected. Given certain difficulties related to the modeling process, porous media numerical model representation is usually simplified. In certain cases, simplifications do not imply on losses in results and behavior prediction. However, some situations require more comprehensive approaches, with development of previously neglected conditions. The main objective of this paper is to present a formulation for fully coupled hydro-mechanical analyses considering fluid and solids compressibility. This formulation, implemented in Finite Element program ALLFINE [1,2,3], was tested for a one-dimensional consolidation case. A sensitivity analyses for the fluid compressibility parameter using modified Cam-clay constitutive model showed that this consideration affects fluid pressure responses significantly, with a delay in fluid pressure dissipation during consolidation process. The simulations results were compared to Terzaghi’s analytical solution for the onedimensional consolidation problem. Also, the comparison of the simulation results to the analytical responses clearly shows the differences between using linear elastic and elastoplastic models. In simulations for different stress levels with the modified Cam-clay model, it is possible to capture a flow induction effect due to high stress levels

Consolidation problem solution with a coupled hydro-mechanical formulation considering fluid compressibility

There are two principles which may be referred to as essentials to describing soil and rock behavior. The mechanical behavior is associated to the law of conservation of linear momentum, allowing forces balance analysis and the hydraulic behavior is characterized by mass conservation. These phenomena are related: stress-strain state is affected by fluid pressures and vice-versa. Therewith, it is intuitive the understanding of the importance of coupled analyses, which are certainly a more precise manner of describing how mechanical and hydraulic behavior are connected. Given certain difficulties related to the modeling process, porous media numerical model representation is usually simplified. In certain cases, simplifications do not imply on losses in results and behavior prediction. However, some situations require more comprehensive approaches, with development of previously neglected conditions. The main objective of this paper is to present a formulation for fully coupled hydro-mechanical analyses considering fluid and solids compressibility. This formulation, implemented in Finite Element program ALLFINE [1,2,3], was tested for a one-dimensional consolidation case. A sensitivity analyses for the fluid compressibility parameter using modified Cam-clay constitutive model showed that this consideration affects fluid pressure responses significantly, with a delay in fluid pressure dissipation during consolidation process. The simulations results were compared to Terzaghi’s analytical solution for the onedimensional consolidation problem. Also, the comparison of the simulation results to the analytical responses clearly shows the differences between using linear elastic and elastoplastic models. In simulations for different stress levels with the modified Cam-clay model, it is possible to capture a flow induction effect due to high stress levels