دانلود رایگان مقاله انگلیسی مدل سازی زمینه ای فاز شکاف نرم در مکانیک خاک - وایلی 2018

This work outlines a rigorous framework for the ductile failure of frictional materials in elastic-plastic soil mechanics undergoing large strains. Describing soil crack formation can be achieved in a convenient way by recently developed continuum phase field approaches to fracture, which are based on the regularization of sharp crack discontinuities [1]. This avoids the use of complex discretization methods for crack discontinuities, and can account for complex crack patterns. For frictional materials, a non–associative Drucker–Prager-type elastic-plastic constitutive model suitable for a wide range of applications in soil mechanics is developed. It is linked to a failure criterion in terms of the elastic-plastic work density that drives the fracture phase field. We demonstrate the modeling capabilities and algorithmic performance of the proposed formulation by a representative numerical example that describes soil crack formation using elastic-plastic fracture mechanics.

3 Numerical examples

We point out the capabilities of the model by investigating the pullout behavior of an anchor plate in soil as shown in the experimental results [5]. The geometric setup and boundary conditions are illustrated in Figure 1 (a). Due to the symmetry of the BVP only half of the specimen is discretized using the modified enhanced assumed strain element CG4 in the simulation, which is proven to be a locking-free element and overcomes hourglass modes [6]. Figure 1 (b,c) demonstrate the distribution of the crack phase field d and the hydrostatic pressure p at the final deformation state. Tensile stresses are observed under the lower side of the anchor plate when the plate is pulled upwards. The crack starts to initiate in this tensile area when the elastic and plastic energies reach a critical value ψc and propagates from the anchor corners to the boundaries at about 60◦ from the loading direction. For visualization of the crack surface, deformed regions with d ≈ 1 are not plotted in Figure 1 (c).