Engineering Properties of Nuclear Craters, Report 4. The Formation and Initial Stability of Slopes on Cohesionless Materials

摘要

The purpose of the study of engineering properties of nuclear craters is to identify and describe the physical properties that will control the use of a nuclear crater for engineering purposes. One of the prime considerations in the engineering use of a nuclear crater is the stability of the crater slopes. The late time mechanism of explosion crater formation is a deposition phenomenon. The inclination of a slope formed by deposition of cohesionless material is termed the angle of deposition, and the maximum possible inclination of the slope is termed the angle of repose. This definition differs from some common definitions of angle of repose. The factor of safety of a slope formed by deposition is defined as the ratio of the tangent of the angle of repose to the tangent of the angle of deposition. Variations are recognized in the angle of deposition with the manner of deposition, and in the angle of repose with varying relative density and particle orientation. Such factors as particle size, shape, and angularity, structure of particle aggregations, manner of deposition, and geometry of slopes are discussed with regard to their relative influence on each of the aforementioned angles. A few simple analytical relations are given to aid in understanding the behavior of particles during deposition and their stability on an inclined surface. Empirical data from laboratory tests, stockpiles, rock-fill dams, natural slopes, explosion-produced craters, etc., are presented and compared. (Author)