The drying and shrinkage behavior of soil blocks(Department of Agricultural Engineering)

比較的密度の高い領域の作成供試土塊について乾燥・収縮特性を追求し, 次の結果を得た。(1)土塊の乾燥に伴なう含水比減少曲線の最大曲率の点は減率乾燥第1から第2段への転移点に相当する。(2)限界含水比や収縮限界はTable 3に示すとおり, コンシステンシー指数(Ic)や乾燥密度(γd)の影響をほとんど受けない。(3)土塊の収縮は限界点に達する相当以前に終了しており, 収縮限界と限界含水比は一致しない。(4)収縮率(Pc)とIcの間にはFig.5に示すような関係があり, 可塑性の大きな土程Pcが大きい。(5)体積変化係数CvcはIcやγdと無関係だが, 練返しの影響を多少受ける。各試料における。Cvc(W=0のCvc)の平均値はKinとYagajiで比較的大きく, Tomigusukuで小さい。(6)配列指数によって検討すると, 土粒子はIc=0.68∿1.15の範囲で等方配列を示し, 1.15以上では平行配列を示す。Experimental studies were made on the drying and shrinkage characteristics of soil blocks. The results obtained are as follows; 1. The water content at the maximum curvature of the water content-time curve corresponds to that in the boundary from the first stage of drying in decreasing rate to the second stage of drying in decreasing rate. 2. The critical water content and shrinkage limit are not affected very much by the consistency index (I_c) and dry density (γd) as showed in Table 3. 3. The shrinkage behavior of the soil blocks finishes considerably before reaching the critical water content. 4. The percentages of cubical contraction (P_c) are related to I_c as showed in Fig. 5,the more plasticity of a soil the larger Pc. 5. The coefficients of volumetric changes (C_) of the soil blocks have not to do with I_c and γd, but there is some difference in the shrinkage behavior due to remoulding, the averages of _oC_-values (C_ at w=0) of each of the samples are relatively large in Kin and Yagaji, and very small in Tomigusuku, Okinawa Island. 6. On the basis of the coefficient of particle orientation, the particle arrangement during shrinking of the soil block of I_c in the range of 0.68-1.15 has a isotropic arrangement and that above 1.15 is parallel