Plain concrete structures such as dams or retaining walls, as well as rock structures such as tunnels, caverns, excavations, and rock slopes, have commonly been designed by elastic-perfectly plastic analysis in which the tensile yield strength of the material is taken as zero. The paper analyzes the safety of this "notension" design in the light of the finiteness of the tensile strength of conc...

Fluid migration and distribution are important aspects of the evolution of sedimentary basins. An essential parameter affecting fluid flow is permeability. Even mm thick fractures have permeabilit ies many orders of magnitude above surrounding sediments, and thus have the potential of focusing fluid flow. It is a major task to establish the importance of these fractures as fluid conduits. One a...

We study numerically the roughness exponent zeta of an in-plane fracture front slowly propagating along a heterogeneous interface embedded in an elastic body, using a model based on the evolution of a process zone rather than a fracture line. We find zeta=0.60+/-0.05. For the first time, simulation results are in close agreement with experimental results. We then show that the roughness exponen...

We compare the roughness of minimal energy(ME) surfaces and scalar “quasi-static” fracture surfaces(SQF). Two dimensional ME and SQF surfaces have the same roughness scaling, w ∼ L (L is system size) with ζ = 2/3. The 3-d ME and SQF results at strong disorder are consistent with the randombond Ising exponent ζ(d ≥ 3) ≈ 0.21(5 − d) (d is bulk dimension). However 3-d SQF surfaces are rougher than...

There are increasing amounts of evidence that earthquake rupture is a mixed process between what is called frictional slip failure and fracture of intact rock mass. In fact, there is a strong possibility that what is called a 'barrier' or 'asperity' on earthquake faults is a local patch of high rupture growth resistance whose strength equals the strength of intact rock. In addition, the lithost...

Hydraulic fracturing and matrix stimulation are two major methods of the reservoir stimulation. Hydraulic fracturing, which is the newest technique and technically more complex, is very useful in low permeability reservoirs. Although it has been used widely in hydrocarbon production wells, it is a new method in Iran. In this paper, the effect of sufficient barrier layers on hydraulic fracturing...

A three-dimensional fully-coupled poroelastic displacement discontinuity method is developed and used to analyze the temporal variation of opening and slip of a natural fracture in a reservoir in response to the sudden application of fluid pressure in the fracture surfaces. Numerical results show that a hydraulic fracture opens in an increasing manner with time as the rock moves towards a drain...

Roughness of rock fractured surfaces is one the most important factors controlling fluid flow in masses. quantification prime importance for modelling ground waters as well reservoir mechanics. In this study, with aid high-resolution 3D X-ray CT scanning and image processing techniques, roughness four different types reconstructed a resolution 16.5 microns. Moreover, correlation structure funct...

Some fundamental mechanisms associated with cooling/heating of the rock in the context of drilling and reservoir stimulation in enhanced geothermal systems are described. The role of temperature and pore pressure in wellbore failure and fracture width is considered using analytical and boundary element models. Results indicate that cooling induces a pore pressure drop inside the formation that ...

Cracks in a rock mass subjected to a uniaxial stress will be preferentially closed depending on the angle between the fracture normal and the direction of the applied stress. If the prestress fracture distribution is isotropic, the effective elastic properties of such a material are then transversely isotropic due to the preferred alignment of the cracks. Velocity measurements in multiple direc...