LABORATORY STUDIES ON THE EFFECTS OF LABORATORY SIMULATED EARTHQUAKE LOADINGS ON COHESIVE SOIL STRENGTH, SAN LUIS DAM AND CANAL--SAN LUIS UNIT CENTRAL VALLEY PROJECT, CALIFORNIA,
Abstract
The laboratory method of testing cohesive soils to determine the effects of pulsating stresses, simulating the effects of earthquakes, provided adequate data for designing hydraulic structures made from these materials. The tests were performed on undisturbed finegrained clay soil from the San Luis Dam foundation and on undisturbed and remolded fine-grained clayey and sandy clay soils from the first 3 reaches of the canal to determine soil strength characteristics under dynamically applied stresses. The normal triaxial shear apparatus was used with modifications to apply vertical or deviator stress (sigma sub 1 - sigma sub 3) at a rate of 2 pulses per second. Results of the dynamic tests on individual soils are compared to the normal soil strengths at equivalent strains. The maximum normal soil strength is assigned a value of 100%, and soil strengths under pulsating stress may be expressed as a percentage of this. The studies show that confining pressure does not appreciably affect the relationship between normal and dynamic soil strength. Thus, the ratio of dynamic to normal soil strength may be applied directly to safety factors derived from normal strength test data. Results show the dynamic soil strength to be generally up to 15% greater than the normal strength for overconsolidated plastic clays. However, dynamic soil strength is less than the normal by about 10% for low density, wet of optimum water content, sandy clays, specially at low strains. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 26, 1965
- Accession Number
- AD0625443
Entities
People
- Willard Ellis
Organizations
- United States Bureau of Reclamation