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We present the recent results of our work which is concerned with the determination of the spatial locations of faults, fractures and heterogeneities around a tunnel by advanced seismic imaging techniques.So far we have extended existing 2D imaging techniques to 3D. We have implemented 3D versions of “Kirchhoff prestack depth migration” (KPSDM), “Fresnel Volume Migration” (FVM) and “Reflection-Image-Spectroscopy”...
In this paper, a probabilistic analysis is presented to compute the probability density function (PDF) of the ultimate bearing capacity of a shallow strip footing resting on a rock mass. The rock is assumed to follow the modified Hoek–Brown failure criterion. Vertical and inclined loading cases are considered in the analysis. In this study, the deterministic models are based on the kinematic approach...
The Hubbert and Willis (1957) [1] fracture criterion has been widely adopted to predict longitudinal fracture initiation in vertical or horizontal wellbores. Current transverse fracture criteria predict fracture by comparing the axial stress in the wellbore wall with the tensile strength of rock. It is shown in this paper that the axial stress is not a good predictor of transverse fracture initiation,...
The difficulties associated with performing a direct uniaxial tensile test on a rock specimen have led to a number of indirect methods for assessing the tensile strength. This study compares experimental results of direct and indirect tensile tests carried out on three rock types: Brisbane tuff, granite and sandstone. The standard Brazilian indirect tensile test caused catastrophic crushing failure...
The present paper provides an overview of key coupled thermo-hydro-mechanical (THM) processes in clay formations that would result from the development of a high-level radioactive waste repository. Here, in this paper, clay formations include plastic clay such as the Boom Clay of Belgium, as well as more indurated clay such as the Callovo-Oxfordian and Upper Toarcian of France and Opalinus Clay of...
The results of 26 plate load tests carried out at the Bakhtiary dam site were analyzed to define and characterise the mechanisms governing the rock mass deformation during the tests. Tests were categorized into groups based on the relative direction of loading to the orientation of major discontinuity sets running through the rock mass. Five mechanisms were distinguished as the main modes controlling...
Despite the significance of rockfall hazards in Australia, this phenomenon is still poorly characterised in many regional environments. In particular, the relationship between slope/rock properties and rockfall motion parameters needs better definition. In the context of rockfall prediction, it is important to quantify the normal and tangential restitution coefficients (referred to as k n ...
Fracture and friction behaviors of Aue granite (Erzgebirge, Germany) under confined asymmetric load are simulated using a clumped particle model. In contrast to conventional circular bonded particle assemblies, clumped particle models consist of groups of neighboring individual particles tied together to mimic unbreakable larger grains of irregular shape (clumps). An optimized clumped model is used...
This research addresses the thermomechanical response of a saturated sandstone in a geothermal reservoir. Several experiments were performed using a triaxial testing system to investigate thermal effects on poroelastic parameters of Flechtinger sandstone, an outcropping equivalent of the (Rotliegend) reservoir rock. In drained experiments, confining pressure was cycled, pore pressure was maintained...
A definite shut-in pressure in hydrofracturing techniques is needed for obtaining the correct information on the in-situ stress regime in a rock mass. The relation between the behavior of hydraulically induced fractures and the condition of remote stress is considered to be the major reasons of an ambiguous shut-in pressure in hydrofracturing pressure-time history curves. This paper describes the...
The stress field developed in an intact Brazilian disc is determined assuming that the externally imposed radial pressure is not uniform but rather it varies according to a sinusoidal law along the loaded rims of its periphery. In addition it is considered that friction forces are developed at the loading platen–disc interface. The problem is solved using the complex potential method adopting the...
A nonlinear Drucker–Prager and Matsuoka–Nakai unified (DPMNu) failure criterion for geomaterials is developed using the Haigh–Westergaard (HW) coordinates. This criterion ensures convenience in its application due to its simple formulation with separated HW invariants. Explicit formulations are presented to evaluate the material constants in the current criterion. In the meridian plane the criterion...
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