TY - JOUR
T1 - The New Scope of Frictionless Triaxial Apparatus—Disturbed Sand Testing
AU - Sabaliauskas, Tomas
AU - Ibsen, Lars Bo
PY - 2018
Y1 - 2018
N2 - Offshore wind turbine foundations episodically lose and recover stiffness as soil is disturbed during extreme events. Such sand behavior is not accounted for during standard testing procedures. Therefore, the following novel dynamic triaxial testing procedure is explored in this study: specimens are loaded past their peak strength and pulled back to initial length, where attempts to recover their initial stiffness are made by applying more loading cycles. This fundamentally changes how we view our specimens-they are no longer fragile and brittle. Instead, specimens can be axially compressed and pulled back to initial length many times as long as shear rupture and bulging are circumvented. Novel testing procedures were attempted using a frictionless triaxial apparatus. Frictionless triaxial is not itself a new concept, but the novel procedures revealed previously undocumented testing capabilities: (1) Multistage testing, wherein sand specimens can be liquefied (undrained), drained, and reliquefied (undrained again) many times, in one sequence, on one specimen; (2) Specimens can be compressed to large axial strain (15 % strain ormore) and pulled back to initial length more than once. In the process, peak yield strength can be measured more than once at more than one density, all while using one specimen.
AB - Offshore wind turbine foundations episodically lose and recover stiffness as soil is disturbed during extreme events. Such sand behavior is not accounted for during standard testing procedures. Therefore, the following novel dynamic triaxial testing procedure is explored in this study: specimens are loaded past their peak strength and pulled back to initial length, where attempts to recover their initial stiffness are made by applying more loading cycles. This fundamentally changes how we view our specimens-they are no longer fragile and brittle. Instead, specimens can be axially compressed and pulled back to initial length many times as long as shear rupture and bulging are circumvented. Novel testing procedures were attempted using a frictionless triaxial apparatus. Frictionless triaxial is not itself a new concept, but the novel procedures revealed previously undocumented testing capabilities: (1) Multistage testing, wherein sand specimens can be liquefied (undrained), drained, and reliquefied (undrained again) many times, in one sequence, on one specimen; (2) Specimens can be compressed to large axial strain (15 % strain ormore) and pulled back to initial length more than once. In the process, peak yield strength can be measured more than once at more than one density, all while using one specimen.
KW - Strength and compressibility of soils
KW - Cyclic and dynamic properties of soils
KW - Texture
KW - Plasticity and density characteristics of soils
KW - Strength and compressibility of soils
KW - Cyclic and dynamic properties of soils
KW - Texture
KW - Plasticity and density characteristics of soils
UR - http://www.scopus.com/inward/record.url?scp=85048722951&partnerID=8YFLogxK
U2 - 10.1520/GTJ20170223
DO - 10.1520/GTJ20170223
M3 - Journal article
SN - 0149-6115
VL - 41
SP - 1117
EP - 1130
JO - Geotechnical Testing Journal
JF - Geotechnical Testing Journal
IS - 6
M1 - GTJ-2017-0223
ER -