Laboratory tests in borehole KFM01A, KFM08A, KFM11A, KFR102A and KFR104 : Uniaxial compression and indirect tensile strength tests of intact rock

• The density and mechanical properties were determined on water saturated specimens from boreholesKFM01A, KFM08A, KFM11A, KFR102A and KFR104 in the Forsmark site investigation area. Therock types in the selected sections were amphibolite (102017) and metavolcanic rock (103076). Somespecimens had a more or less foliated rock structure. The cores were sampled from a depth rangingbetween 196–901 m.The specimens were water saturated using tap water and all subsequent measurements wereconducted at this moisture condition. The density was determined on 30 specimens. The testingended with 20 indirect tensile tests yielding the indirect tensile strength and 10 uniaxial compressiontests including the post-peak response yielded the Young’s modulus, Poisson’s ratio and the uniaxialcompressive strength.Some variation of rock material along the short cores could be seen, which is reflected in themeasured data. The density at a water saturated condition was 2892–3067 kg/m3 for amphibolite, and2697–2763 kg/m3 for metavolcanic rock.The indirect tensile tests were conducted such that every specimen with visible foliation was testedwith the diametrical compression across the foliation planes, with higher values for the indirecttensile strength on the specimens. The strength variation in the amphibolite was large. The indirecttensile strength was 10.8–21.4 MPa for amphibolite and 16.9–20.7 MPa for metavolcanic rock. Twoof the amphibolite specimens had a deviating lower strength, indirect tensile strength 5.7 MParespectively 5.8 MPa, with a ductile failure. Those specimens had a high content of mica.The Young’s modulus obtained from the uniaxial compression tests was 88.6–114.5 GPa foramphibolite and 68.2–89.1 GPa for metavolcanic rock and the Poisson’s ratio was 0.339–0.386 foramphibolite and 0.236–0.313 for metavolcanic rock. The peak values of the axial compressive stresswere in the range 213.1–333.7 MPa for amphibolite and 104.1–283.1 MPa for metavolcanic rock.One of the amphibolite specimens had a deviating lower strength and a ductile failure with Young’smodulus 41.2 GPa, Poisson’s ratio 0.500 and peak axial compressive stress of 44.5 MPa. Thatspecimen had a high content of mica. 

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

Forsmark

elasticity parameters

post-failure behaviour

uniaxial compression test

indirect tensile test

AP SFK-22-032

Publikations- och innehållstyp

vet (ämneskategori)

rap (ämneskategori)