Ostrava, Czech Republic
Ostrava, Czech Republic

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Petr W.,Institute of Geonics CAS | Lubomir S.,Institute of Geonics CAS | Jan N.,University of Wollongong | Petr K.,Institute of Geonics CAS | Tomas K.,Institute of Geonics CAS
Procedia Engineering | Year: 2016

The strain gauge probes of different construction are typically used for determination of stress state rock mass. The modified overcoring method known as the Compact Conical ended Borehole Overcoring method (CCBO) for stress state determination in rock mass was designed in Institute of Geonics of the CAS (IGN) in cooperation with Kumamoto University in Japan. The implemented adjustment of the overcoring method consists mainly in omitting the overcoring phase (stress relief phase). The probe is glued directly to the conically shaped end of a borehole. The data logger located within the conical probe enables continual strain monitoring directly in the conically shaped end of the borehohole during the overcoring procedure. The conical probe used to monitor stress changes, named Compact Conical ended Borehole Monitoring (CCBM), can continuously monitor rock strain changes in key locations due to mining. Many stress measurements using both strain gauge probes CCBO and CCBM were carried out in the last decade. These measurements were performed in varied rock mass adjacent to mine excavations. Most of the stress measurements were carried out in Carboniferous sedimentary rocks as part of the experimental work in the Czech part of the Upper Silesian Coal Basin (USCB). Several stress measurements were carried out during the mine development operations and associated geotechnical exploration work while constructing the Milasín - Bukov underground gas storage (BUGS) [1], as well as the Bukov Underground Research Laboratory (BURL) [2]. Both underground facilities were designed within Rožná and Olší uranium deposits situated on the north-eastern margins of the Strážek Unit consisting of the metamorphic rock formations. Several measurements were carried out in granitic environments (igneous rocks) as part of the international "Large-Scale Monitoring" (LASMO) project in Grimsel (Switzerland) and in Josef underground laboratory (Bohemian massif). The article presents the basic principles and the methodology of stress measurements in rock mass using strain gauge probes and the data analysis from the variable rock environments. © 2016 The Authors. Published by Elsevier Ltd.

Hlavac L.M.,VSB - Technical University of Ostrava | Bodnarova L.,Brno University of Technology | Janurova E.,VSB - Technical University of Ostrava | Sitek L.,Institute of Geonics CAS
Baltic Journal of Road and Bridge Engineering | Year: 2012

The concrete samples with various erosion states simulating road or bridge damage were disintegrated by pure continuous water jets generated from pressure 380 MPa and by pulsing water jets generated from low pressure 30 MPa. The erosion states of samples were prepared applying several laboratory techniques simulating the concrete aging under the conditions corresponding to the use in practice. The influence of the erosion state on the disintegration rate was tested because water jet techniques are very effective in selective disintegration of damaged concrete without significant erosion of the unbroken concrete unlike pneumatic drills or other impacting machines usually used for such a work. The comparison of both the depth of penetration and the ratio of volume disintegration regarding the input power is performed. All results are discussed regarding their application in practice and further development of special routings.

Hlavac L.M.,VSB - Technical University of Ostrava | Hlavacova I.M.,VSB - Technical University of Ostrava | Vasek J.,Institute of Geonics CAS | Jandacka P.,VSB - Technical University of Ostrava | And 4 more authors.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

The power of the high-velocity waterjets has been utilized for intentional disintegration of material particles, namely minerals. Firstly, the garnet particles were tested and studied being used usually as the most common abrasive additives for waterjets improving their cutting abilities. Later on, other mineral particles have been investigated because there are some practical applications of them. Primarily, the product generated inside the mixing chamber and the focusing tube has been studied. Subsequently, the special colliding chamber has been designed and produced enabling the collision of the two opposite moving waterjets containing material particles. This device was named "Water Jet Driven Particle Collider", shortly WJDPC. The product created in the collision of the opposite moving particle containing waterjets has particle sizes covering partially both the nano-scale and the micro-scale. The investigation of parameters influencing the amount of particles with sizes in respective dimension scales is the topic of the contribution. Some samples of special materials were studied and tested. The discussion of the results of the computational modeling of the suction process and its influence on the final product is included. All results are discussed regarding their application in practice and further development of special routings for material particle preparation. Copyright © 2009 by ASME.

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