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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Numerical analysis of the interaction between rockbolts and rock mass for coal mine drifts in Vietnam

Le Van, Cong 05 August 2009 (has links) (PDF)
The thesis describes the application of anchors in mining and tunneling and gives an up-to-date overview about anchor types, design principles and the interaction mechanisms between anchors and rockmass. A constitutive model was developed, implemented and tested for the 2- and 3-dimensional numerical codes FLAC and FLAC3D to simulate non-linear anchor behaviour including unloading and reloading. The interaction between rockbolts and rockmass was studied in detail via numerical simulations for 5 Vietnamese coal mines. An extended version of the so-called c-Φ reduction method and a new introduced reinforcement factor were applied to quantify the effect of bolting. Mine specific and generalised relations were deduced to quantify the influence of anchor length and distance between anchors on the effect of bolting.
2

Numerical analysis of the interaction between rockbolts and rock mass for coal mine drifts in Vietnam

Le Van, Cong 19 December 2008 (has links)
The thesis describes the application of anchors in mining and tunneling and gives an up-to-date overview about anchor types, design principles and the interaction mechanisms between anchors and rockmass. A constitutive model was developed, implemented and tested for the 2- and 3-dimensional numerical codes FLAC and FLAC3D to simulate non-linear anchor behaviour including unloading and reloading. The interaction between rockbolts and rockmass was studied in detail via numerical simulations for 5 Vietnamese coal mines. An extended version of the so-called c-Φ reduction method and a new introduced reinforcement factor were applied to quantify the effect of bolting. Mine specific and generalised relations were deduced to quantify the influence of anchor length and distance between anchors on the effect of bolting.
3

Das Tragverhalten der Firstankerung beim Abbau von flach einfallenden Kaliflözen unter besonderer Beachtung dynamischer Beanspruchungen durch das Gewinnungssprengen: Grundlagen, experimentelle Untersuchung, Modellbildung und numerische Simulation

Frühwirt, Thomas 14 June 2023 (has links)
Mit dem neu entwickelten Berechnungsmodell für vorgespannte Spreizkopfanker zur Firstsicherung im Kali- und Steinsalzbergbau können die Ankertechnologie und das Tragverhalten der Anker realistisch berücksichtigt werden. Für das Last-Verformungsverhalten bei Scherbeanspruchung und dynamischer Beanspruchung durch Sprengerschütterungen werden auf experimenteller Basis theoretische Modellvorstellungen neu entwickelt und numerisch umgesetzt. In einem in situ-Sprengversuch können wesentliche Erkenntnisse zum Schwingungsverhalten des Salinargesteins im unmittelbaren Nahbereich einer Gewinnungssprengung gefunden werden. Mit Hilfe messtechnisch instrumentierter Anker wird der Verlauf der Vorspannkraft während des gesamten Sprengzyklus gemessen. Aus der Berechnung und Analyse komplexer numerischer Modelle werden Aussagen zum Einfluss des Ankerabstandes von der Firstkante auf die Vorspannkraftreduktion abgeleitet und das Ankerverhalten unter dem Einfluss des mehrfachen Übersprengens im Gewinnungszyklus diskutiert. / The newly developed calculation model for pre-stressed expansion-shell rock bolts for roof support in potash and rock salt mining enables the bolting technology and the load-bearing behavior of the rock bolts to be realistically taken into account. For the load-deformation behavior under shear stress and dynamic stress due to blasting vibrations, theoretical model concepts are newly developed on an experimental basis and numerically implemented. In an in situ blasting test, fundamental insights into the vibration behavior of the saline rock in the immediate vicinity of a mining blast can be found. With the help of instrumented rock bolts, the development of the pre-stressing force is monitored during the entire blasting cycle. From the calculation and analysis of complex numerical models, statements on the influence of the bolt's distance from the face on the pre-stressing force's reduction are derived and the bolt's behavior under the influence of multiple overblasting in the extraction cycle is discussed.

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