Rheological Investigation of Clay : On the Distribution Functions of the Stress Relaxation of Clays

Recently the rheological method is applied to the study of the mechanical characteristics of clay or clayey soil. It is because the time factor can not be ignored for the study of the relationship between stress and strain. The author have experimentally researched the distribution functions(τ) of stress relaxation of clay based on the model of linear visco-elastic body. The distribution functionФ(τ) can be shown as: E(t)=∫∞０Ф(τ)e-τ/t dt+E0 The experimental results are as follows: (1) The distribution functions are varied with given constant initial strain (ε0), and it means that the assumption of lineality is not proper. (2) The assumption of lineality is not proper but the distribution functionsФ (1nτ) show the difference of the yield phenomena between the state of dry of optimum and that of wet of optimum, (3) And it can also precisely express the ~mechanical phenomena in the range of plastisity

On the Operation Characteristics of a Bulldozer in the Land Consolidation Work : Studies on the Land Consolidation of Sloped Clayey Paddy Field(I)

The operation characteristics of a bulldozer in the land consolidation work of sloped clayey paddy fields, which are very common in Japan, were investigated. The operation consisted of 25-30% of cutting, 15-20% of banking, and 50-55% of pushing, scattering and leveling soils. The intermission taken by an operater was about 5-10% of the whole working hours. Cooperation of two bulldozers showed greater efficiency than one bulldozer. Operating distance of a bulldozer increased with the increment of its operation cycle, and there found were given parabolic equations between mean forward speed and its operating distance with highly significant correlation. The efficiency of a bulldozer in moving soils in this project was four or five times larger than in the common cases, and this fact points out the peculeatity of land consolidation work on sloped clayey fields. But when there were specially wetted places, which sometimes seen partially on such fields, the progression of work was significantly obstructed

On the Influences on a Mole Drain Hole in Paddy Field by the Operation of a Tractor : Investigation of the Physical and Mechanical Characteristics of Poldered Paddy Fields in Kojima Bay (II)

干拓地水田土壌に施工したモグラ暗渠は機械を導入することによってモグラの機能が阻害され,排水不良になるのでどのような機種が何回走行した場合にどの程度モグラ暗渠の渠孔に影響を及ぼすか,その実態を明らかにするためにまずFordson DEXTAを選定し,モグラ暗渠直上を種々の回数に走回させたその結果,次のような事柄を明らかにすることができた. 調査したモグラ暗渠は地表面下35cmの所に方金工しており,自然状態のモグラ渠孔断面は63.62cm2(約9cm径の渠孔)のものがトラクタ1回の走行で97%つぶされ,3回の走行で完全に渠孔は破壊されてしまうことが明らかとなった. 一方,一軸圧縮強度試験においては,表土については走行回数が2回で未攪乱土のquは0.71kg/cm2,3回で0.65kg/cm2,4回で0.54kg/cm2であった. また攪乱すると強度は低下し,2回で0.19kg/cm2,3回で0.22kg/cm2,4回で0.20kg/cm2であった. 一方,心土については1回走行で未攪乱土が0.4kg/cm2,攪乱土で0.05kg/cm2,2回走行で未攪乱土0.28kg/cm2,攪乱土が0.06kg/cm2,3回走行では,未攪乱土0.27kg/cm2のものが攪乱すると軟化が著しくテストすることができなかった. また鋭敏比を検討すると心土については走行回数3回目で∞となっていることから,トラクタが3回走行すればこの干拓地の心士地表面下35cmの所は極めて軟化が著しく生じることとなり,モグラがつぶれることが力学的試験によっても実証されたものと考える. 以上によって本研究においてはDEXTAの走行回数とモグラ暗渠孔の断面変形の状況を明らかにしたが,その結果からモグラの施工位置は浅くても軟化の小さい土の強度が大きい層にもっていくことが指摘されるが,これについては今後,種々な深さにモグラ暗渠を施工して,どの深さに施工するのが最も有効であるか,走行試験と排水試験を併行しながら実証したいと考えている. おわりにのぞみ,本調査研究にあたり,現地では三宅助手に多大の御配慮と御援助をいただいた. 記して深甚の謝意を表する

Investigation of the Physical and Mechanical Characteristics of Poldered Paddy Fields in Kojima Bay(I) : On the Behavior of the Foundation of the Poldered Paddy Fields caused by the Operation of a Combine Havester

In the poldered paddy fields in Kojima Bay the behavior of the cultivated surface soil is clearly distinct from that of subsoil, and in such fields the drainage of water and salt is generally not so easy. It is very difficult to work by the machinery, because the machines cause, such difficult problems as the drain disorder and other facilities' disorders. In order to solve these problems obstructing factors must be found. So the authors have experimentally investigated the behaviors of the soils before and after the operation of a combine havester. The results of the investigation are as follows: Concerning the consistency of the soils, either surface soil or subsoil is in the unstable condition, especially the disturbance gives it a tendency easily to flow and deform : the sensitivity ratio of the soils is･ very high (that of the surface soil is 2～3 and of the subsoil is infinity). These phenomena also clearly correspond with cone penetration resistance (qc), shearing resistance (τ), cohesive force (C) and unconfined compression strength (qU). Every value of the post-condition is lower than that of pre-condition. In other words they are the phenomena of the soil softening. The authors have proved in this paper that these phenomena are due mainly to the operation of a combine havester

Synthesis and physical properties of Ca1-xRExFeAs2 with RE = La ~ Gd

Synthesis of a series of layered iron arsenides Ca1-xRExFeAs2 (112) was attempted by heating at 1000 C under a high-pressure of 2 GPa. The 112 phase successfully forms with RE = La, Ce, Nd, Sm, Eu and Gd, while Tb, Dy and Ho substituted and RE free samples does not contain the 112 phase. The Ce, Nd, Sm, Eu and Gd doped Ca1-xRExFeAs2 are new compounds. All of them exhibit superconducting transition except for the Ce doped sample. The behaviour of the critical temperature, with the RE ionic radii have been investigated

Pressure effects on FeSe family superconductors

We investigated the pressure effects on the FeSe superconductor and the related compounds. Pressure dependence of superconducting transition temperature (Tc) for FeSe0.8S0.2 exhibits a dome-shaped behavior below 0.76 GPa. On the other hand, the Tc of FeSe0.25Te0.75 linearly increases up to 0.99 GPa. Here we discuss the relation between the physical pressure effects and the chemical pressure effects on the FeSe system.Comment: 8 pages, 5 figures, proceedings of the 2009 M2S conferenc