• AIMAN SHABIR
• BRAHAMJEET SINGH

Unsaturated soils mechanics is new and emerging branch of soil mechanics in which shear strength and related parameters of partially saturated soils play significant role. There are various methods available to measure the shear strength of partially saturated soils like modified triaxial or modified direct shear test equipment with provisions for suction control, but they are usually difficult, expansive and slow moving. In this research an easy technique has been put to use to measure the shear strength of partially saturated soils. In this study combination of filter paper, simple direct shear test and unconfined compression test is used to determine the shear strength of partially saturated or unsaturated soils. In this study, soil water characteristic curve of the soil is generated by the filter paper technique, and then number of simple or conventional direct shear test and unconfined or axial compression tests are conducted to measure the shear strength and undrained shear strength of the soil respectively. To predict shear strength behavior of partially saturated soils with better consistency, the experimentally obtained tests results were compared the results obtained from semi-empirical procedures. In this study non-linear regression analysis were carried out to best fit the soil water characteristic curve established by using filter paper method into the models given by Fredlund & Xing (1996) and Van Genutchen (1980) by varying the curving fitting parameters. This study has reaffirmed that with rise in moisture content, suction values decrease. The test results have also shown that as the matric suction increases, the strength of partially saturated soils also increases. This variation of shear strength with matric suction (shear strength envelopes) for different net normal stress was observed to be non-linear. The shear strength parameters like apparent cohesion ‘c’ and apparent cohesion ‘ϕ’ also shows direct relation with the matric suction in the soil. The unconfined compressive values also shows the same direct trend with matric suction. Lastly, the experimentally determined test results were compared with the theoretically predicted test results. It was found that experimentally determined results were in agreement with the results obtained from semi-empirical procedures. This combined method is a very simple technique for analysing the shear strength of partially saturated soils as it can be utilized in almost every soil mechanics or geotechnical engineering laboratories.

"SHEAR STRENGTH BEHAVIOUR OF UNSATURATED FINE GRAINED SOILS USING CONVENTIONAL TEST", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.9, Issue 5, page no.c773-c778, May-2022, Available :http://www.jetir.org/papers/JETIR2205297.pdf

"SHEAR STRENGTH BEHAVIOUR OF UNSATURATED FINE GRAINED SOILS USING CONVENTIONAL TEST", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.9, Issue 5, page no. ppc773-c778, May-2022, Available at : http://www.jetir.org/papers/JETIR2205297.pdf