Flexural Strength of Laurentian Granite using Semi-Circular Bend Technique

Rock Engineering 2009 - Rock Engineering in Difficult Conditions
Feng Dai,
Abstract Due to difficulties associated with gripping in
direct tension, indirect methods are commonly
used to measure rock tensile strength. In this
work, we adopt an innovative indirect tensile
test method: Semi-Circular Bend (SCB) to measure
the tensile/flexural strength of Laurentian
granite (LG). The static tests are carried out
with a servo-controlled material testing machine
and the dynamic tests are conduced with a Split
Hopkinson Pressure Bar (SHPB) system. Pulse
shaping technique is adopted to achieve dynamic
force equilibrium in SHPB to facilitate data
regression. Finite element method is used to
relate the failure load to the tensile strength.
Strong rate dependence of the tensile strength is
observed. The flexural strength is higher than
the tensile strength measured using Brazilian
Disc (BD). This difference is rationalized using
the non-local theory. To further validate the
method, a coupled Finite element/Discrete element
method (Fem/Dem) in conjunction with the smeared
crack model is utilized to simulate the fracture
process during dynamic SCB tests. The resulting
fracture patterns are qualitatively consistent
with those from recovered samples. Both the
experimental and numerical methods have validated
the results and this new method is readily to be
used for other rocks and other brittle materials.
Full Access to Technical Paper
PDF version for $20.00
Other papers from Rock Engineering 2009 - Rock Engineering in Difficult Conditions