Vol.8, No 1, 2010 pp. 79 - 97
UDC
691.212:531.47+539.211+539.42(045)=111
DOI: 10.2298/FUACE1001079K
INFLUENCE OF PRINCIPAL STRESS DIRECTION ON
THE STRESS-STRAIN-STRENGTH BEHAVIOUR OF
COMPLETELY DECOMPOSED GRANITE
Md. Kumruzzaman1, Jian-Hua Yin2
1Department of Civil Engineering, Rajshahi University of Engineering & Technology,
Bangladesh,
2Department of Civil and Structural Engineering, The Hong Kong Polytechnic University,
Hung Hom, Kowloon, Hong Kong.
E-mail:
kzzaman2001@hotmail.com, cejhyin@polyu.edu.hk
The measurement and study of the stress-strain-strength behavior of soils in
general stress states involving principal stress rotation are necessary and valuable. To
investigate the strength behavior under principal stress rotation, a series of undrained
tests on compacted hollow cylinder specimens of completely decomposed granite
(CDG) was carried in hollow cylinder apparatus. Tests were conducted using constant
inside and outside pressures and maintained a fixed angle of rotation of principal
stress with the vertical (α). Seven different angles of major principal stress orientations
were used to cover the entire range of major principal stress directions from vertical to
the horizontal. Two different confining stresses were used to find out the variations of
the experimental results. It is observed that the deviator stresses as well as excess pore
pressures decrease with the angle α. It is also observed that specimens were getting
softer with the increase of α. The results also show a significant influence of principal
stress direction angle on the strength parameters. It is found that the angle α is related
to the occurrence of cross-anisotropy and the localization which resulted in a
pronounced influence on the strength parameters of the CDG specimens.
Key words:
Hollow cylinder, principal stress rotation, friction angle, failure surface,
cross anisotropy.
UTICAJ PRAVCA GLAVNIH NAPONA NA PONAŠANJE
ČVRSTOĆE NAPON-DILATACIJU- KOD POTPUNO
RASPADNUTOG GRANITA
Merenja i proučavanja napona-dilatacije čvrstoće tla u opštim stanjima napona uključujući
glavni napon rotacije su neophodna i dragocena. Da bi se istražilo ponašanje čvrstoće pod glavnim
naponom rotacije, sproveden je niz opita na uzorcima raspadnutog granita (CDG) sabijenim u
šupljem cilindru. Opiti su sprovedeni uz stalne unutrađnje i spoljne pritiske uz održavanje fiksnog
ugla rotacije glavnih napona sa vertikalom (α). Korišćeni su sedam različitih uglova orjentacije
glavnih napona za da se pokrije opseg pravaca glavnih napona od vertikale do horizontale. Dva
različita ograničavajuća napona korišćena su za iznalaženje varijanti eksperimentalnih rezultata.
Primećeno je da devijator napona kao i prekoračenje pornog pritiska opada sa uglom α. Takođe je
primećeno da su uzorci sve mekši sa povećanjem ugla α. Rezultati takođe pokazuju značajan uticaj
ugla glavnih napona na parametre čvrstoće. Uočeno je da je ugao α vezan za pojavu poprečne
anizotropije i lokalizaciju koja je rezultirala izraženim uticajem na parameter čvrstoće CDG uzoraka.
Ključne reči:
šuplji cilindar, glavni napon rotacije, ugao trenja, površina loma, poprečna anizotropija
