SVIBOR - Project code: 1-05-033

MINISTRY OF SCIENCE AND TECHNOLOGY

Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69
E-mail: ured@znanost.hr

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Project code: 1-05-033


ROCK FAILURE CRITERIA FORMULATED BY DEFORMATION AS THE ASSUMPTION FOR THE ANALYSIS OF UNDERGROUND ROOMS STABILITY


Main researcher: HUDEC, MLADEN (16744)


Assistants
Type of research: applied
Duration from: 04/30/91. to 04/30/94.
Papers on project (total): 42
Institution name: Rudarsko geološko naftni fakultet, Zagreb (195)
Department/Institute: Department of mining and geotechnics
Address: Pierottijeva 6
City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)41 44-08-20
Fax: 385 (0)41 44-00-08
E-mail: bp@mapbf.pbfrng.hr
Summary: Upon excavations of underground rooms and tunnels using NATM it has been found that the real state of stress is not the only relevant criterium for rock and rooms stability. Stress measurements in rocks (in situ) during excavations are rather complicated and uncertain, however there are more simpler methods of deformation measurements in underground rooms. Mechanical characteristics of rocks are usually very complex, because rocks show characteristics of anisotropy, viscosity, plasticity, as well as appearance of discontinuities on the strata plains and fisure systems.Therefore, the rock around the rooms is more a quasi-continuum then continuum such as suppose in continuum mechanics. The alternative is the block theory, representing the rock composed of rigid blocks, but this represents also a very rough approximation. Presenting all the properties and failure criteria by means of stress is not fully justified in the case of rocks. The main thesis of this paper is that the stability loss, extreme shape changes and even rooms collapse will appear when rock and support deformations reach critical values. In the current rock mechanics literature it is common to express failure criteria by critical stresses. These criteria will be formulated through deformations, dilatations and sliding, i.e. spherical and distortional components of deformation tensors, in the form suitable to be included into FDE, FEM and BEM programmes.

Keywords: CONTINUUM MECHANICS, ROCK MECHANICS, FAILURE CRITERIA, FINITE ELEMENT METHOD, BOUNDARY ELEMENT METHOD, TUNNELS, THEORETICAL MECHANICS

Research goals: The main goal was the definition of rock failure criteria through components of deformation tensor in order to raise the credibility of stability calculation of underground rooms during excavation. These rock failure criteria should be included into preliminary calculations of support systems and linings which use FEM and BEM, as well as included the control upon everyday measurements of convergency in underground rooms and tunnels. This will improve the safety of underground objects during excavations and exploitations. Numerical procedures, especially those referring to the FEM for plastic and viscous elements would be in this way simplified and shortened, because the calculations and stress control phases in each step could be excluded.

OTHER ACHIEVEMENTS


  1. Name: Skripta za predmet Podzemne prostorije i tuneli: "RAVNI - Metoda konačnih elemenata"
    Type of achievement: Teaching aids and educatio
    Authors: Mladen Hudec, Lidija Frgić, Bruno Paris

  2. Name: Skripta za predmet Podzemne prostorije i tuneli: "MKE - Program konačnih elemenata"
    Type of achievement: Teaching aids and educatio
    Authors: Mladen Hudec, Lidija Frgić, Bruno Paris

  3. Name: Skripta za predmet Podzemne prostorije i tuneli: "RUBNI - Metoda rubnih elemenata"
    Type of achievement: Teaching aids and educatio
    Authors: Mladen Hudec, Frgić Lidija, Bruno Paris

  4. Name: Skripta za predmet Otpornost materijala: "Repetitorij i tablice za vježbe iz Otpornosti materijala"
    Type of achievement: Teaching aids and educatio
    Authors: Mladen Hudec, Lidija Frgić
Other information about the project.
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