ABSTRACT
Generally, it is very difficult to make a specimen with an initial degree of saturation exactly controlled by a method for making specimen of unsaturated clay. Most of the specimens in laboratory tests are made by compacted dynamically or statistically method, but concrete methods for making a specimen were not explained in detail on many past papers. Moreover, they are not always guaranteed that the water contents and the dry densities in the parts of specimen become uniformity. Although it is sometimes tried that the specimen is approached to the fixed suction state by suction-controlled apparatuses from the initial state, it is indispensable for the long time applying suction to a specimen to balance state. On the other hand, if homogeneity is secured, consider the method that apply the fixed suction to a saturated specimen formed from a clay sample which was pre-consolidated at a slurry state, however, it takes a long time to balance up the fixed suction in this case. For example, the researches of water retention curve, Romero & Vaunat (2000), Karube & Kawai (2001), Gallipoli (2003), Tarantino & Tombolate (2005). A. Tarantino (2010) etc., the developments of elasto-plastic behavior of unsaturated soils, V. Sivakumar et al. (2010a, b), and experimental studies of effective stress of unsaturated soils, Alonso et al. (2010), Alonso E. E. & Romero E. (2011) use compacted specimen. The axis translation technique, namely a method for controlling suction by applying air pressure to a specimen is
2 PHYSICAL PROPERTIES OF SHIGARAKI CLAY
A sample used in this study is Shigaraki clay. Table 1 and Fig. 1 show physical properties and grain size accumulation respectively, therefore, it is classified as clay (CL) according to Japanese soil classification standard.
