NEHRP Clearinghouse
- Title
- Direct Simple Shear Behavior of Fine Grained Soils Subjected to Repeated Loads.
- File
- PB80212525.pdf
- Author(s)
- Floess, C. H. L.; Zimmie, T. F.
- Source
- National Science Foundation, Washington, DC. Engineering and Applied Science., December 1979, 199 p.
- Abstract
- Consolidated constant volume static and cyclic loading tests were performed using the Norwegian Geotechnical Institute (NGI) direct simple shear device. Emphasis was placed on high strain level repetitive loading, such as that caused by earthquakes and storm waves. Cyclic loading tests were performed using a square wave pulse shape with complete stress reversal on Gulf of Alaska and Blue Concord clays. Lateral stresses acting on soil samples were measured by means of calibrated, wire-reinforced rubber membranes. The membranes provided a convenient method of experimentally determining the coefficient of lateral stress at rest, K0. The measured value of K0 for Gulf of Alaska clay was 0.54. Lateral stress measurements also provided sufficient information to determine Mohr's circle of stress for an infinitesimal element of soil at the center of the sample. It was determined that the coefficient of lateral stress increases with greater shear strain, and that the horizontal plane of the sample is approximately the plane of maximum shear stress, not the plane of maximum obliquity. Cyclic loading failure does not occur if the cyclic shear stress is small. For both clays, the critical level of repeated loading is approximately 25 percent of the peak static undrained shear strength. For lightly overconsolidated Concord Blue Clay, the critical level of repeated loading is about 15 percent.
- Keywords
- Alaska Gulf; Soil tests; Shear properties; Dynamic response; Earthquake engineering; Concord blue clay; Liquefaction (Soils); Soil properties; Cycle loads; Soil mechanics; Earthquakes; Pervious soils