アニュラー試験機による土壌常数の動測定に関する基礎的研究 (第1報)

高速アニュラー土壌常数測定機KS-2型の試作とすべり速度を考慮した摩擦抵抗の式

抄録

The method and the most important conclusions of this investigation are as follows:
1. High-speed Annular Shear Device KS-2 for laboratory use was designed and built by which soil shearing stress, normal stress, annulus sinkage and horizontal displacement are measured simultaneously and continuously under the shearing speed of about 1 to 600cm/sec. Fly-wheel rotates the turn table on which cylindrical soil bin is placed immediately. Shear head permitted friction-free vertical movement is prevented from rotating by side arm. This configuration turned out to be profitable to measure soil-shearing stress in high-speed shearing.
2. Thirteen variables such as internal or external soil-shearing stress (S or F), cohesion or adhesion (c or a), bulk density of soil (ρ), coefficient of viscosity of soil (μ), mean diameter of soil particles (D), mean diameter of annulus (d), section width of annulus (b), grouser height (h), grouser span (λ), normal stress (σ), shearing speed (V), annulus sinkage (Z), and horizontal displacement (J) were assumed to be indispensable to soil-annulus shearing.
3. Buckingham's Pi Theorem led
f(π₁, π₂, …, π₁₀)…|π₁′, π₈′| (1)
in which π₁=S/ρV², π₁′=F/ρV², π₂=h/b, πn₃=b/d, π₄=λ/d, π₅=ρVd/μ, π₆=D/d, π₇=σ/ρV², π₈=c/ρV², π₈′=a/ρV², π₉=Z/J, and π₁₀=J/λ and the nomenculature |π₁′, π₈′| means both π₁′ and π₈′ are exchangeable with π₁ and π₈.
4. Component equation of Eg. (1)
π_1c=f_c(π₂, π₃, π₄, π₅, π₆, π₇, π₈, π₉, π₁₀)…|π_1c′, π₈′| (2)
in which π₉ was assumed to be negligible and the bar denotes constant values was considered. Let π₅ and π₇ be eliminated on dry sand and soft clay respectively, then
π₁ sand=Const⋅f₁(π₇)+π₈ sand…|π₁′sand, π₈′sand| (3)
and
π₁clay=const⋅f₂(π₅)+π₈clay.…|π₁′clay, π₈′ clay| (4)
5. In the experiment in which ρ and μ were held constant and the condition of Component Eq. (2) was satisfied, it was observed that the functions f₁ and f₂ were both exponential functions.
6. It was assumed that the component Eq. (2) could be obtained as the sum of Eqs. (3) and (4). Then
π_1c=k₁π₇^m+k₂π₅ⁿ+π₈…|π_1c′, π₈′| (5)
in which k₁, k₂, m, and n are dimensionless constants.
7. If both sides of Eq. (5) are multiplied by ρV², there results
S=c+Kσ⋅V^2(1-m)⋅σ^m+Kv⋅Vⁿ
|F, a| (6)
in which m, n, K_σ and Kv are new soil values. The equation would be a extended equation of soil-annulus shearing considering shearing speed.