Fracture and size effect characters of cemented sand

In the past three decades, fracture mechanics (FM) of brittle and quasibrittle materials have developed mainly in concrete applications and has yet to gain its rightful place in the geotechnical field. There are many examples in the geotechnical literature, especially those related to brittle and stiff soils, where traditional approaches of analysis have proven to be inadequate. While geotechnical problems are inherently complex in nature, the use of computational fracture mechanics have been shown to provide a powerful tool that could be used to investigate and solve many application problems in geomechanics and geotechnical engineering. This paper addresses the application of FM concepts and theories in analysis of cemented soils. In addition to theoretical aspects, experiments were conducted to evaluate the application of FM to cemented soils. Three-point bending beam tests with crack mouth opening displacements (CMOD) conducted on cemented sand samples showed that fracture parameters, such as CMOD, indeed could play an important role in investigation of such soils. Using this unambiguous material parameter, field engineers might have a reliable measure that could prove to be useful in stability assessment of earth structures and soil structure system. By studying size effect on cemented sand, strong relationship was established between critical CMOD and failure, which might be a very useful index and analysis tool in geotechnical engineering practice.