Model za procjenu posmične čvrstoće diskontinuiteta u masivnim vapnencima

doctoral thesis

• Title: Model za procjenu posmične čvrstoće diskontinuiteta u masivnim vapnencima : doktorski rad
• Title (english): Model for the shear strength estimation of discontinuities in massive limestones : doctoral thesis
• Author: Ivana Dobrilović; MBZ: 391043
• Mentor: Petar Hrženjak (mentor)
• Committee member: Biljana Kovačević Zelić (predsjednik povjerenstva)
• Committee member: Petar Hrženjak (član povjerenstva)
• Committee member: Nataša Štambuk Cvitanović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mining, Geology and Petroleum Engineering; Zagreb
• Defense date and country: 2021-03-31, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mining, Petroleum and Geology Engineering; Mining
• Universal decimal classification (UDC): 622 - Mining

Abstract

U radu je prikazana problematika procjene posmične čvrstoće diskontinuiteta, koja naročito dolazi do izražaja u masivnim vapnencima kod kojih stijenke diskontinuiteta mogu biti izrazito hrapave i nepravilne, s ili bez materijala ispune, za koje se pokazalo da postojeći modeli ne mogu dati zadovoljavajuće rezultate. Karakteristični primjer takvih vapnenaca predstavlja ležište arhitektonsko-građevnog kamena Kanfanar-jug koje se nalazi na Istarskom poluotoku u Hrvatskoj. Za potrebe razvoja modela za procjenu posmične čvrstoće diskontinuiteta, provedena su terenska istraživanja tijekom kojih su pripremljeni veliki uzorci blokova s prirodnim diskontinuitetima kao i uzorci materijala ispune u graničnim stanjima, na kojima su zatim provedena detaljna laboratorijska ispitivanja posmičnih čvrstoća. Posebna pažnja posvećena je određivanju koeficijenta hrapavosti pukotina JRC, stvarnoj kontaktnoj površini između stjenki diskontinuiteta, baznom, odnosno rezidualnom kutu trenja te kutu trenja ugrađenog materijala ispune između ploha diskontinuiteta. Razvoj modela za procjenu posmične čvrstoće diskontinuiteta temeljio se na Bartonovom JRC-JCS empirijskom modelu, s obzirom na činjenicu da je on jedan od najčešće primjenjivanih modela u inženjerskoj praksi. Na temelju rezultata provedenih ispitivanja provedena je modifikacija Bartonovog JRC-JCS modela na način da je umjesto baznog ili rezidualnog kuta trenja primijenjen kut trenja ugrađenog materijala ispune za slučaj diskontinuiteta s ispunom. Uz navedeno, za ispravno vrednovanje hrapavosti stjenki diskontinuiteta u masivnim i okršenim vapnencima utvrđena je nužnost povećanja koeficijenta hrapavosti pukotina JRC10 na veće vrijednosti od 20, koliko su do sada one bile predložene kao maksimalno moguće. Evaluacija predloženog modela pokazala je zadovoljavajuću točnost prilikom procjene posmične čvrstoće diskontinuiteta s materijalom ispune različitog stanja konzistencije.

Abstract (english)

In this study the problem of estimating the shear strength of discontinuity is presented, which especially occurs in massive limestones, where discontinuity walls can be extremely rough and irregular, with or without filling material, and for which the current models have proved to be unsatisfactory. A characteristic example of such limestones is the deposit of dimension stone Kanfanar-jug, located on the Istrian peninsula in Croatia. For the purpose of developing a model for estimating the shear strength of discontinuity, field research was conducted in which large samples of blocks with natural discontinuities were prepared, as well as samples of filling material in limit conditions, on which detailed laboratory tests of shear strength were performed. Special attention was paid to determining the joint roughness coefficient JRC, the actual contact area between the discontinuity walls, the basic or residual friction angle and the friction angle of the built-in filling material between the discontinuity surfaces. The development of the model for estimating the shear strength of discontinuity was based on Barton’s JRC-JCS empirical model, given the fact that it is one of the most commonly applied models in engineering practice. Based on the results of the tests, a modification of Barton's JRC-JCS model was made, in such a way that the friction angle of the built-in filling material in the case of discontinuity with a filling was applied instead of the basic or residual friction angle. In addition, for the correct evaluation of the roughness of the discontinuity walls in massive and karstified limestones it was found that it is necessary to increase the roughness coefficient to values larger than 20, which has been proposed as the maximum so far. The evaluation of the proposed model showed that it is satisfactory accurate in estimating the shear strength of discontinuity with filling material of different states of consistency.

• Keywords: diskontinuitet; posmična čvrstoća; koeficijent hrapavosti pukotine; ispuna
• Keywords (english): discontinuity; shear strength; joint roughness coefficient; filling
• Language: croatian
• URN:NBN: urn:nbn:hr:169:351915
• Study programme: Title: Applied Geosciences, Mining and Petroleum Engineering; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor znanosti/doktorica znanosti (doktor znanosti/doktorica znanosti)
• Catalog URL: http://katalog.nsk.hr/F/?func=direct&CON_LNG=ZAG&local_base=ZAG01_WEB&doc_number=000689263
• Type of resource: Text
• Extent: 1 sv. (razl. pag) ; 30 cm
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2022-03-31
• Created on: 2021-04-14 08:39:22