There are various kinds of causes of sample disturbance, some of which can not be avoided even with the best of sampling. This paper deals with disturbance in a soil sample taken with a thin-wall sampler, in the light of deformation of the sampler. In an experimental boring the punching load, inclination of a sampler and strains produced on the sampler were measured.

In medium to stiff clays the punching force exceeds the buckling load of the sampling rod. This causes the inclination of the sampler with penetration and therefore the deviation of the earth pressure acting around the sampler section.Under such a nonuniform pressure the sampler deforms and results disturbance to the soil in it. The amount of deformation increases with shear strength of the original soil and this kind of disturbance is most dominant in soils of shear strength over 0. 6kg/cm².

* Manuscript received on July 15, 1963