Coefficient of earth pressure at rest of organic peat ground.

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In order to investigate the coefficient of earth pressure at rest of highly organic soil, two series KO-consolidated undrained triaxial compression shear test.Some samples were used this experimental studies were undisturbed samples. from paddy field on Sakata city in Yamagata prefecture. in which water content (W) was 591-861%, void ratio (e) was 12.55, ignition loss (lg) was 54.5-70.0%. The length of sample was 150mm. The diameter of sample was 75mm.The conclusions from this study are :1) In normal consolidation, KO value of organic peat soil was about 0.3.2) In over consolidation ratio 2.4.7.10, each KO value was 0.372,0.593,0.889,0.843.3) The relation KO value and KOR is KO value in swelling was expressed the following equation.KOR=KO (OCR) ^<alpha>where、KOR is KO value in swelling.KO is earth presume at restart normal consolidation.OCR is over consolidation ratio.alpha is constantThe KOR was able to expressed with the following equationKOR=0.445 (OCR)^<0.621>4) The coefficient of shear properties could not to obtained.According to esqueeze out water in pore, the effective stress in confining pressure (sigma_3') became 0 kgf/cm^2.So, highly organic soil could not be adapted the theory of shear properties to be connected with cohesive soil.