Mechanical Stability Modelling of Peatland with Coupled Hydro-Mechanical Approach

The mechanical stability of the peatlands is essential to be analyzed because it influences gas emissions and has a significant effect on global carbon cycling. Peatlands have the highest carbon storage capacity compared with the other terrestrial ecosystems because of their water-saturated environment. The total carbon stored in peatlands is about 600 gigatonnes or 30% of global soil carbon stock. The rate of carbon accumulation in peatlands is around 0.09-0.5 gigatonnes per year and equivalent to 1%-5% of yearly global greenhouse emissions. The mechanical stability of the peat will depend on the peat shear strength and the behavior of the pore fluid. We present initial results from a simulation model to analyze peat mechanical stability using a coupled hydro-mechanical approach. Compared to the uncoupled method, this formulation is conceptually more complete because the solid displacement and pore fluid pressure are solved simultaneously. To validate the algorithm, we compare the numerical solution with the analytical solution of Mandel’s problem. We assume the peatland shape is semi-ellipse when viewed in a vertical cross-section (two-dimension). We use two layers model, saturated and unsaturated, to accommodate peatland characteristics with the substrate properties are impermeable, stiff, and no deformation.