Abstract:

Based on the analysis of the mechanical features and fundamental theory of geological materials, Shen et al.(2002 and 2003) proposed the framework of breakage mechanics for geomaterials and the concept of binary-medium model(BMM). Recently, we have carried out much research, including tests, theory and numerical simulation, on the structured geomaterials on the basis of the binary-medium model concept. Plane tests of the samples assembled by geo-structural blocks were conducted to investigate the breakage mechanism of structured geomaterials. It was experimentally found that the structural blocks will gradually break and transform to the weakening bands; and both of them will bear the loading together during the loading, testifying mechanical idealization of breakage mechanics for structured geomaterials. A new method of preparing for structured soils was explored; and the mechanical and strength characteristics of artificially prepared structured soils were studied under different stress paths. The binary-medium model for geomaterials was extended and verified that it could be used to simulate the brittleness change of geomaterials and experimental results of structured soils and sandstones under triaxial stress conditions well. Based on the concept of the binary-medium model for geomaterials, a mesoscopic numerical method which can simulate the breakage processes of geomaterials was proposed; and a strength criterion for structured soils was put forward finally.

Key words: binary-medium model (BMM), breakage mechanics, structural blocks, structured soils, tests, mesoscopic numerical analysis, strength criterion