土砂移動現象における土塊横断形状の地形学的意義

Abstract

Stability of the landslide block especially with an elongated plan shape and an arcuatecross profile is discussed theoretically at first by means of variation calculus. This kind oflandslide is treated as the transversal two-dimensional problem. The cross profile should beso that makes the slide block most unstable. The profile in homogeneous materials is thusthe arc or the ellipse which is the stationary curve obtained as the solution of iso-perimetricproblem in variation. This analysis introduces a new and reasonable method to evaluate thecohesive strength and the coefficient of friction of soil mass, based on the cross-profilemorphology of land slide block. Especially, the cohesive strength estimated in this way is ahalf as large as some value by the previous method applied to longitudinal profile. Applica-tion of this method to some actual cases is attempted and discussed.