Influence of anisotropy on rock physical and mechanical properties.

Abstract

The main focus of this thesis is to study some basic rock mechanical and physical anisotropic properties of selected rocks. The study is mainly conducted in laboratory conditions to examine property variation in rocks and their inter-relationships. In order to present a clear contribution in understanding the influence of anisotropic characteristics of rocks on physical and mechanical properties, a series of average grain diameter examination, ultrasonic wave velocity test, fluid permeability test, uniaxial compressive strength test, Brazilian test, fracture toughness and triaxial compression test were conducted on four rock types known to be anisotropic. In order to achieve the mentioned experimental goals, sedimentary, metamorphic and igneous rock samples were randomly collected from different continent around the globe (Czech Republic, Japan, South Korea and South Africa). In each selected sample, a definition scheme was introduced based on directionality as Axis-1, Axis-2 and Axis-3 and planes perpendicular to each axis were defined as Plane-1, Plane-2 and Plane-3. In this thesis, classification scheme for cored samples obtained from directional coring was also introduced; samples from perpendicular direction are called Type-1 and those from Parallel direction are called Type-3. The anisotropic grain size distribution and micro-cracks orientation are successful describe by estimaing the average grain diameter distribution with microcracks orientation and propagation by observation made on thin sections in three perpendicular planes. This was performed for separate rock block using a polarization microscope. The rock blocks were also found to possess stronger degree of anisotropy of elastic wave velocity when compared between tested samples. With strong anisotropic wave velocity, I was able to determine the direction of higher and lesser propagation of wave. The results obtained from ultrasonic wave velocity test are in strong correlation with grain size distribution at measured axis orientation...