TY  - SER
AU  - Tamrakar,Surendra Bahadur
AU  - Kohgo,Yuji
AU  - Balasubramaniam,A.S.
AU  - Shibuya,Satoru
ED  - Government of Japan,
TI  - Shear behavior of unsaturated soils at constant suction
T2  - Thesis
PY  - 1997///
CY  - Bangkok
PB  - Asian Institute of Technology
KW  - Shear strength of soils
KW  - Testing
KW  - Strains and stresses
N1  - A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering; Thesis (M. Eng.) - Asian Institute of Technology
N2  - In order to investigate the unsaturated shear behavior of Khon Kaen loessial soil,  triaxial tests were carried out in a specially modified triaxial apparatus. Specimens were  statically compacted so that they had 1.2 kN/m3 initial density and 8 % initial water content  which were similar to the field conditions. Consolidated drained triaxial tests were performed  at three different confining pressures (50, I 00 and 200 kPa) with constant suction condition  of 0, 10, 50,100 and 200 kPa.  Axis translation technique was used for the making the initial suction condition  before starting the tests. The apparatus being specially designed, we could measure the  overall volume change of the sample more accurately than in conventional triaxial apparatus.  Hence the shear behavior could be observed more precisely. Also, pore-air and pore-water  pressures could be controlled separately in this test. The tests were performed in accordance  with the programming.  The test results showed that the amount of suction greatly influence the shear  behavior of the soils. Stress-strain relationship of test results showed that initial slope  (stiffness) of the curves are lower at the lower suction values, but the slope increases with the  increase in suction. It is also seen that suction effect; an increase in suction increases the  yield stress is dependent on the confining pressure. At lower confining pressure the effect of  suction is higher than at the higher confining pressure where it decreases.  From results of the volumetric strain and axial strain relationship, it is seen that with  the increase in suction there is a decrease in volume change of the specimens. This is due to  the increase in inhibition of plastic deformation of the sample with the increase in suction.  Also, from e - logp' lines during shearing, we can see the decrease in slopes of these lines as  the suction increases.  At higher suction values, the amount of drainage increases with the mcrease m  suction whereas at lower suction values, water goes into the sample.  All of the changes in shear behavior of the unsaturated soils are due to the effect of  suction which are explained by the Kohgo's elastoplastic model with two suction effects; (i)  an increase in suction increases the effective stress and (ii) an increase in suction increases  both the yield stress and stiffness against plastic deformation.
UR  - http://203.159.5.9/ait-thesis/detail.php?q=B13423
ER  -