Kumlarin dinamik özelliklerini bender-extender elemanlar kullanilarak belirlenmesi

Geotechnical engineering required knowledge of the dynamic properties of the soil to analyze dynamic loadings such as machinery vibrations, earthquakes and ocean waves. Bender-extender elements can provide small strain dynamic soil properties by measuring body wave velocities (i.e. shear wave and compression wave velocities) and as a non-destructive method prevent detrimental effects of sample disturbance. In Soil Mechanics Laboratory of Yıldız Technical University, a bender-extender test apparatus was set up for this purpose. In this study, a series of bender-extender test were performed on uniformly graded (SP) coarse sand samples with varying initial void ratios. Test results show that (i) shear and compression wave velocities decrease as the initial void ratio increases (ii) shear and compression wave velocities increase as the confining effective stress (for both isotropic and anisotropic stress conditions) increases (iii) Poisson?s Ratio decreases as the confining effective stress (for both isotropic and anisotropic stress conditions) increases (iv) input frequency does not have a considerable effect on body wave velocity measurement (v) during drained shearing, body wave velocities increase until a threshold axial strain is reached and decrease thereafter (vi) during undrained shearing body wave velocities increase as axial strain increases, as expected. Keywords: Bender elements, Extender elements, small strains, dynamic behavior of sands, wave velocity, Poisson?s Ratio, maximum shear modulus, maximum constrained modulus, laboratory tests.