Non-oriented Core Research Articles

Obtaining initial data for forecast engineering geological model construction

Objective and relevance. Technologies in mining and geology are intensely developing making the present research particularly relevant. The research considers the problems of obtaining reliable and high-quality data on the degree and nature of rock mass fracturing in a solid mineral deposit. These are fundamental data required to construct a forecast engineering geological model of a deposit. The engineering geological model is usually based on a structural geological model with the addition of various geomechanical parameters used in generally accepted international classifications for rock stability analysis, in particular, RMR (Bieniawski), MRMR (Laubscher), and Q-system (Barton). Methods of research. The authors describe the procedure for obtaining classification geomechanical parameters of a rock mass according to the data from oriented and non-oriented core drilling of special engineering geological (geomechanical) boreholes. Research results. The main factors and conditions for reliable data acquisition are given. Among the most important ones are: economic feasibility and validity of geomechanical boreholes drilling as well as their number; features of the geological and structural composition of a deposit as a condition for borehole location selection; proper organization of the drilling process aimed at obtaining high-quality core material; characteristics of geomechanical description of the core, depending on the rating system of rock mass classification applied. Scope of results. By way of example, deposits with different geological and structural conditions are listed where the described procedure was applied. High-quality and reliable information about the structural and tectonic features of the rock mass allows to create and fill the engineering geological model with data and solve the problems of stability analysis for almost any area of the future mine working.

A novel in-situ stress measurement method incorporating non-oriented core ground re-orientation and acoustic emission: A case study of a deep borehole

The measurement of in-situ stress is a critical prerequisite for the mining design and the stability analysis of surrounding rock in deep mining engineering. In this study, a novel re-oriented core acoustic emission (RCAE) method incorporating the non-oriented core ground re-orientation and AE techniques was proposed for in-situ stress measurement. First, the principle of non-oriented core ground re-orientation is established according to the spatial coupling relationship between the drilling trajectory and the core surface characteristics. Then, an innovative apparatus was designed for recovering the original spatial orientation of non-oriented cores. Furthermore, the measurement procedures of RCAE method are described in detail, involving suitability analysis, outdoor operations, core re-orientation, specimen preparation, AE test and stress calculation. Using this method, a case study for in-situ stress measurement was performed in an ultra-deep borehole (2360 m) of the Sanshandao gold mine, China. Meanwhile, the verifications of measurement accuracy were conducted based on the tectonic stress inversion and the underground overcoring method. The results show that the measurement accuracy of RCAE method is acceptable, especially the horizontal maximum principal stress and its azimuth measured are well matched with those measured by other methods. In addition, the field applications indicate that the in-borehole procedure of RCAE method only requires drilling trajectory measurement without excessive complex operations, and the adequate measuring depth of this method in the case area is up to 3841 ± 521 m according to the damage stress threshold analysis. Therefore, the RCAE method could break through the challenges caused by the restricted measuring space and large measuring depth when no deep underground access exists. Moreover, the non-oriented cores can be rapidly re-oriented on the ground, which could expand the application value of ordinary geological boreholes in the field of deep geostress and tectonic measurement.

A New Structure of a Gap-Reactor to Reduce Electromagnetic Vibrations

Magnetostriction is an inherent property of an electrical steel sheet (ESS). Experimental measurements have revealed that the magnetostrictions of Grain-oriented and Non-oriented ESSs are mostly opposite in their directions. Based on this, a novel structure of gap reactor is suggested to reduce the mechanical vibration of the reactor. The new structure follows the conventional manufacturing process, and is built by stacking Grain-oriented and Non-oriented cores alternately while a conventional one is by only Grain-oriented or Non-oriented core. In order to verify the effectiveness of the proposed structure, the electromagnetic vibration, stress and displacement of the reactor are analyzed based on the magneto-elastic coupled analysis. The measured magnetization and magnetostriction data of the ESSs are adopted during the numerical calculation. Prototypes of new and traditional structures with the same design parameters were also built and electromagnetic-induced vibration were measured and analyzed. Both the computational and experimental results showed that the proposed structure made much less electromagnetic vibration than the conventional one. Moreover, the noise level around the reactors were measured and the average noise level around the improved prototype was reduced by 16.7%.

Macroscopically homogeneous deformation in injection molded polypropylene induced by annealing studied with microbeam X-ray scattering

In a previous study (Shinohara et al., Macromolecules, 2012, 45, 1398–1407), we have found that the annealing of injection molded polypropylene makes its macroscopic deformation fairly homogeneous despite the existence of a non-oriented core layer composed of the spherulite structure. In this study, to elucidate the mechanism for the homogeneous deformation behavior induced by annealing, we conduct a scanning microbeam x-ray scattering measurement of injection molded polypropylene under uniaxial stretching and analyze the structural change at each layer for the first time. It is observed that a plastic deformation of the crystals at each layer of the annealed sample is suppressed compared to that of an as-prepared sample. Furthermore, in the highly oriented layers of the annealed sample, homogeneous cavitation accompanied by the formation of the void with a narrow size distribution is observed. We conclude that the homogeneous cavitation induces strain hardening in the oriented layers, and that the hardened oriented layers dominate the total deformation behavior.

RE-ORIENTANTION METHODS OF CORE SAMPLES: IMPLICATIONS TO SEDIMENT CORES FROM N. GREECE

The different methods of re-orientation of core samples are discussed in the present study. In order to obtain results from core samples concerning the direction of the formation, their permeability and their anisotropy, it is essential first to bring all the pieces of the core into their initial position with regard to the North and to the horizontal (in-situ). In this study we emphasize particularly to the palaeomagnetic technique. This re-orientation method uses the magnetic components of the rocks (especially the viscous component) in order to determine the direction with regard to the North (declination). Also, the anisotropy method which helps us to correct the angle to the horizontal (inclination) is described here. Finally we applied the last two methods in non-oriented core samples from N. Greece and the significant importance of the re-orientation techniques to the palaeomagnetic studies is shown.

Mesoscopic Analysis of Diamictite in Semiconsolidated, Non-Oriented Core

A commercial engraving tool can be used to carefully disaggregate and vibrate matrix and cement away from stones in semiconsolidated diamictite core. Stone fabrics and planar structures in the core can be measured using a transparent protractor placed over a parallel-lined transparent template that is aligned with an arbitrary North line on the core to determine trends and strikes. Plunges and dips can be read using the dip needle of a geologic compass. These data, combined with stone surface features, shape, and provenance, allow interpretation of sediment genesis and processes where outcrops are rare or of poor quality.

Mesoscopic Analysis of Diamictite in Semiconsolidated, Non-Oriented Core: RESEARCH METHODS PAPERS

ABSTRACT A commercial engraving tool can be used to carefully disaggregate and vibrate matrix and cement away from stones in semiconsolidated diamictite core. Stone fabrics and planar structures in the core can be measured using a transparent protractor placed over a parallel-lined transparent template that is aligned with an arbitrary North line on the core to determine trends and strikes. Plunges and dips can be read using the dip needle of a geologic compass. These data, combined with stone surface features, shape, and provenance, allow interpretation of sediment genesis and processes where outcrops are rare or of poor quality.