Time-dependent behaviour of some types of rocks is of the “creep” type, in particular in underground works, mining works, and in measuring procedures of rock properties. Tests used for defining material parameters or parameters relevant to defining a failure or behaviour of a material in the plastic state are usually of significantly shorter duration than the creep test. The duration of creep tests may vary from several hours to several years depending on the material being tested and the phenomenon that is the subject of the research. The required duration of the creep test, which provides reliable definition of the time-dependent material parameters of the rheological model, is a theoretical but also practical issue. The theoretical issue relates to establishing criteria for defining the required duration of the creep test. The practical issue relates to minimizing the duration of the creep test from which the necessary material parameters of the rock mass are obtained for correct numerical calculations. This paper proposes criteria for defining the required duration of a rock creep test, based on analysis of the results of unconfined uniaxial compression tests performed on marly rock samples.
Test puzanja, po definiciji, karakteriše konstantno optere enje pod kojim se materijal s vremenom deformiše. Uobi ajeno je da se testovi puzanja sprovode pove anjem ili smanjenjem optere enja na uzorak u inkrementima. Nakon svakog inkrementa, zadržava se konstantno optere enje u toku odabranog intervala. Optere ivanje ili rastere enje uzorka do odre enog naponskog nivoa i održavanje konstantnog optere enja u toku ovako dugog intervala, zahtijeva posebne ure aje prilago ene vrsti materijala koji se ispituje, veli ini uzoraka i naponskom stanju (jednoaksijalno, biaksijalno ili triaksijalno) koje se održava na uzorku. Za sprovo enje testa jednoaksijalnog puzanja, odnosno za održavanje konstantnog optere enja -napona na uzorcima, u toku relativno kratke istorije ovog testa, koriš eno je više razli itih ure aja baziranih na polugama i oka enom teretu. U poslednje dvije decenije, konstruisani su i servo-ure aji za konvencionalne triaksijalne testove puzanja na standardnim cilindri nim uzorcima stijene.Dug period testiranja i zahtjev da se naponsko stanje održi konstantnim, uz relativno mala odstupanja u toku dugog perioda koji se nekada mjeri i godinama, veoma komplikuje ure aje koji treba da odgovore tom zadatku. Pored navedenog, potrebno je obezbijediti pouzdano mjerenje relativno malih deformacija -sve od trenutka optere ivanja, pa do završetka testa. Pritom, treba imati u vidu da ukupna deformacija meke stijene može biti uzrokovana promjenom napona, vremenski zavisnim deformacijama (puzanje), promjenom temperature, promjenom vlage u stijeni, promjenom vlažnosti u vazduhu i sli no.Prof. dr Zvonko Tomanovi , Gra evinski fakultet, Univerzitet Crne Gore, Cetinjski put bb,
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.