This tutorial demonstrates how to generate a 3D volume mesh from surface geometry imported from DXF or STL files. Both hexahedral-dominant and tetrahedral meshes can be generated automatically using the "zone generate from-geometry ..." command in FLAC3D 7. The results of various keywords are shown.
This tutorial will demonstrate a method to create a hybrid mesh of tetrahedral zones to model the rock mass and hexahedral zones to model a concrete liner. Hexahedral zones for the liner are preferred in order to more accurately capture plastic strains in this region. The meshing is done by utilizing the Itasca Griddle volume mesher plug-in for Rhino 3D. Importing the final mesh into FLAC3D, for future finite volume modeling, is also demonstrated.
Continuum numerical modeling is inherently limited when the rock behavior involves mechanisms such as spalling and bulking. The Bonded Block Model (BBM) approach simulates the initiation of cracks that can coalesce and/or propagate leading to extension and shear fracturing, as well as the rock (e.g., intact, jointed, or veined) strength dependency on confinement.
We assess the performance of the Ground Penetrating Radar (GPR) method in fractured rock formations of very low transmissivity (e.g. T ≈ 10−9–10−10 m2/s for sub-mm apertures) and, more specifically, to image fracture widening induced by high-pressure injections. A field-scale experiment was conducted at the Äspö Hard Rock Laboratory (Sweden) in a tunnel situated at 410 m depth. The tracer test was performed within the most transmissive sections of two boreholes separated by 4.2 m. The electrically resistive tracer solution composed of deionized water and Uranine was expected to lead to decreasing GPR reflections with respect to the saline in situ formation water.
A major use of DFN models for industrial applications is to evaluate permeability and flow structure in hardrock aquifers from geological observations of fracture networks. The relationship between the statistical fracture density distributions and permeability has been extensively studied, but there has been little interest in the spatial structure of DFN models, which is generally assumed to be spatially random (i.e., Poisson). In this paper, we compare the predictions of Poisson DFNs to new DFN models where fractures result from a growth process defined by simplified kinematic rules for nucleation, growth, and fracture arrest.
Calibration of geomechanics models using microseismic data is key to creating reliable predictive tools. This presentation reviews the geomechanical model used for: stress characterization, microseismic modeling to assess the risk associated with faults activation and induced seismicity, and evaluation of designs and operational strategies. Both hydraulic fracturing and hydro-shearing of discrete fracture network were important components of stimulation of EGS and zonal isolation can play a key role in effective stimulation of an EGS along the entire length of the horizontal well.