The effect of clay content on the liquefaction of the fine grained soils

This thesis has been prepared in partial fulfilment for the degree of Doctor of Philosophy in the Department of Civil Engineering of the Graduate School of Sakarya University.Adapazarı city soils have been studied at Sakarya University since 1998. The city is founded on alluvium with an estimated thickness of 1000 meters deposited by the River Sakarya. Adapazarı experienced most of ground failure problems such as liquefaction, strength decay, bearing capacity failure during the 1999 Kocaeli-Adapazarı earthquake. Investigations following the earthquake in Adapazarı have indicated that the dense sands mainly forming the ancient riverbeds traversing the city have rarely liquefied, whereas nonplastic silts exhibited liquefaction potential. Evaluating the liquefaction susceptibility of fine grained soils have generally been done using the so called Chinese Criteria. It was however seen that those criteria do not fully reflect the response of Adapazarı soils. It is thought that this disagreement is due to clay percentage in the ML silts. A laboratory investigation was accordingly undertaken using the cyclic triaxial test.It was thus concluded that clay content may be a decisive factor in judging the liquefaction potential of fine grained soils. It was observed that the increase clay percentage increased the liquefaction resistance of soils.