Investigation of lateral earth pressure in Ko condition for unsaturated fine grained soils

ABSTRACTPh. D. THESISINVESTIGATION of LATERAL EARTH PRESSURES IN K0CONDITION FOR UNSATURATED FINE GRAINED SOILSCafer KAYADELENDEPARTMENT OF CIVIL ENGINEERINGINSTITUTE OF NATURAL AND APPLIED SCIENCESUNIVERSITY OF ÇUKUROVASupervisor : Prof.Dr. M.Arslan TEK NSOYYear : 2005 Page : 156Jury : Prof. Dr. M. Arslan TEK NSOYProf. Dr. M. Yener ÖZKANProf. Dr. Orhan AKSOĞANAssoc. Prof. Dr. Mustafa LAMANAssoc. Prof. Dr. Hasan ÇET NIn this study, the lateral earth pressures at-rest of unsaturated fine grainedsoils were investigated in the laboratory. For this aim, a new test apparatus, allowingto perform the consolidation test in unsaturated conditions and to measure the lateralpressure, was designed and manufactured. The matric suction, an importantparameter of unsaturated soils, was controlled by using axis translation technique.The lateral pressures were measured by means of strain gauges embedded on theouter surface of the thin wall oedometer ring. The measurements of lateral pressurewere, also, performed in saturated conditions and compared with those results ofunsaturated counterparts. In the tests, reconstituted clayey and compacted siltyspecimens were used.In conclusion, it was deduced that matric suction has an effect on lateralpressures. When the vertical pressures are kept constant, Ko values of soil specimensdecrease under increasing matric suction. In other words, when the degree ofsaturation decreases, Ko values decrease.Keywords: Unsaturated soils, matric suction, axis translation technique, lateral earthpressure at-rest, Ko condition,II