The concrete community in the United States has reached the point where it needs a standard test for measuring the fracture toughness of concrete. A concrete standard might be obtainable by adapting existing standards for cemented carbides and rock. These standards use the short rod specimen geometry and two associated test methods. The combination of specimen geometry and test methods may have...

A sound knowledge of mechanical properties of rocks at high temperatures and pressures is essential for modelling volcanological problems such as fracture of lava flows and dike emplacement. In particular, fracture toughness is a scale invariant material property of a rock that describes its resistance to tensile failure. A new fracture mechanics apparatus has been constructed enabling fracture...

[1] Joint sets within sedimentary basins are commonly interpreted to have formed by tensile failure in conditions where pore fluid pressure was elevated. Such tensile fractures are inferred to be a part of the process that relieves high fluid pressure by locally increasing rock permeability. In spite of the importance of this feedback mechanism, the detailed mechanics of hydraulic fracture gene...

Rock fracture mapping is very important in many applications related to rock mechanics. The toughest task is the extraction of the fractures from the images of the rocks. Time series model has been used in this paper for segmentation of fractures from the rock images. The model is compared with orthodox edge detection algorithms. A first order autoregressive image model has been implemented. Th...

A continuum damage mechanics (CDM) based constitutive model has been developed to describe elastic, plastic and damage behavior of porous rocks. The pressure sensitive inelastic deformation of porous rocks together with their damage mechanisms are studied for drained and undrained conditions. Fracture mechanics of microcrack andmicro-void nucleation and their coalescence are incorporated into t...

The initiation, propagation, coalescence and failure mode of brittle jointed rock mass influenced by fissure water pressure have always been studied as a hot issue in the society of rock mechanics and engineering. In order to analyze the damage evolution process of jointed rock mass under fracture water pressure, a novel numerical model on the basis of secondary development in fast Lagrangian a...

We present a borehole failure model which is based on fracture mechanics and layer buckling theories and compare its prediction with experimental data. The model assumes that the main mechanism of borehole collapse takes place in the form of layers buckling near the borehole surface. The model introduces a combination of fracture mechanics parameters with dimension of length that scale the size...

The fracture front in concrete, as well as rock, is blunted by a zone of microcracking, and in ductile metals by a zone of yielding. This blunting causes deviations from the structural size effect known from linear elastic fracture mechanics (LEFM). The size effect is studied first for concrete or rock structures, using dimensional analysis and illustrative examples. Fracture is considered to b...