This paper presents a new analysis method for designing rock-fill dams which are resistant to earthquakes; rock-fill dams mentioned in this paper are those consisting wholly of rock materials.When a rock-fill dam is subjected to a large earthquake force, it collapses, and the shape of the collapsing rock-fill dam approaches a circular arc in cross-section. The seismic coefficient circle method gives the relationship between the earthquake force, the cross-section of the circular arc and the stable cross-section formed in the circular arc at this moment.It is possible to obtain a seismic coefficient circle for any earthquake force (seismic coefficient) from theoretical considerations and thereby the cross-section of the dam required for any seismic coefficient can be designed.

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The upper bound theorem of the generalized theory of perfect plasticity is applied to obtain complete numerical solutions for the critical height of an embankment. A rotational discontinuity mechanism (logarithmic spiral) is assumed in the analysis. The analysis includes the existing solutions as a special case, so that it may be considered a generalization of previous solutions.

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At present earth pressures under seismic conditions are calculated assuming certain intensities of seismic force to act in the horizontal and vertical directions. In this paper, the seismic force is first assumed to act in a certain direction from the vertical, and this direction is optimized so that its effect is maximum on the earth pressures. Coefficients of active and passive earth pressure have been computed for a wide range of c, φ, N, δ, γ, and β-values. Typical results are presented and discussed. A particular advantage of this approach is that only the magnitude of the seismic force need be known at any place. Its direction has been optimized in the analysis.

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In this paper the effect of surface texture on the shear characteristics of granular materials is studied from the results of drained triaxial compression tests. The materials tested are uniform spheres of steel having different surface roughnesses. Test results indicate that for the granular materials the development of failure zone in the triaxial specimen is affected by surface roughness in the same manner as in Mogami's test results on one-layer assembly of uniform spheres, and that shearing strength and dilatancy increase correspondingly with an increase in surface roughness. The expression for the physical components of shear strength in granular materials is proposed, and the relationship between surface roughness and "k value" in Mogami's theory of mechanics of granular materials is also described concerning the test results.

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