Evaluation of permeability of soil & rock aggregate using meshless numerical manifold method

Abstract

Soil & Rock Aggregate (SRA) is ubiquitous in nature and an excellent fill material in engineering. The presence of SRA rock blocks in number and size-difference makes it impossible to simulate each rock block separately in engineering computations. A practical way is to regard SRA as an equivalent continuum and to evaluate properties of the equivalent continuum using numerical methods. In this way, it is hopeful to overcome big errors of laboratory tests due to removing big blocks. Randomness of SRA rock blocks in shape and orientation renders clumsy mesh dependent methods such as finite element methods. By using finite elements to form mathematical patches, the numerical manifold method (NMM), called FE-NMM, reduces to some degree mesh dependency, but still involves a huge number of operations in cover-cutting and information-rebuilding while generating physical covers. Specifying node influence domains in the moving least squares (MLS) as mathematical patches, and MLS shape functions as the weight functions of the physical patches, this study develops the procedure MLS-NMM to evaluate SRA permeability, completely avoiding extra labor in FE-NMM. Many complicated deployments of rock blocks in SRA are designed and analyzed, suggesting significant advantages of MLS-NMM over FE-NMM. Meanwhile, some interesting results are observed.