Stress Propagation in Soils

Stress Propagation in Soils
Author: L. Seaman
Publisher:
Total Pages: 226
Release: 1963
Genre:
ISBN:

A knowledge of soil motions resulting from nuclear explosions is necessary for the design of underground structures which are to survive a nuclear attack. In this project the authors studied wave propagation in soil and developed methods for predicting wave propagation phenomena based on data from laboratory compression tests on soil samples. The study was restricted to one-dimensional wave propagation in a sand and a clay. Extensive wave propagation tests were made on 5-meter columns of Monterey sand of various densities subjected to transient loads of different intensities and duration. Stresses and particle velocities were measured at various locations in the column to test the validity of theoretical models representing sand. The main feature of stress wave propagation--stress attenuation--can be predicted for sand on the basis of a rate-independent model. In addition, wave front development, wave velocity, particle velocity attenuation, and duration of the stress wave are described qualitatively by this model in combination with a second rate-independent model. The parameters of the models can be determined from static or dynamic compression test data on small samples of sand. (Author).

Stress-strain-time Behavior of Soil in One Dimensional Compression

Stress-strain-time Behavior of Soil in One Dimensional Compression
Author: Robert V. Whitman
Publisher:
Total Pages: 564
Release: 1963
Genre: Soil mechanics
ISBN:

Ground motion prediction formulas based upon elastic wave propagation in one-dimension (no strain transverse to the propagation direction) have been used widely in protective construction work. Actual soil materials exhibit many deviations from elastic behavior. This report assesses the probable influence of these non-elastic effects upon the accuracy of the above-mentioned prediction formulas, and upon the question of stress attenuation with depth. Three different models of soil behavior are assumed: a standard 3-element visco-elastic model (spring in series with spring-dashpot combination); a compacting model (straight line loading and unloading curves); and an ''elastic'' model in which any arbitrary shape may be assigned to the loading stress-strain curve. This report deals primarily with the first of these three models; the possible significance and probable importance of the third model are discussed briefly. By combining the theoretical and experimental results, it is shown that the elastic ground motion prediction formulas are generally valid (for cases where it is appropriate to think of one-dimensional motion); i.e. the possible effects of viscosity and inelasticity are no greater than uncertainties as to the order of magnitude of the compressibility of an in situ soil mass. (Author).