| Popis: |
Cyclic properties of 47 soils were tested in several investigations between 1994 and 2004 in the standard Norwegian Geotechnical Institute (NGI) direct simple shear (DSS) device and an NGI-type dual-specimen DSS (DSDSS) device for small strain testing. In each investigation many cycles of different amplitude, γc, and frequency, f, were applied at different levels of vertical stress, σv, and overconsolidation ratio, OCR. In DSDSS device many consecutive series of different small γc=0.0003-0.01% were applied on the same specimens without changing their structure, because at such small γc cyclic shearing is nondestructive. Consequently, the vast amounts of small-strain data were generated. This necessitated the development of new approach to data processing and analysis. New procedure for reading, checking, organizing, combining, comparing and analyzing the vast arrays of cyclic test data has been developed and structured into a database that has the cyclic loop as its elementary unit. Each cyclic loop in the database is characterized by the soils’ plasticity index, moisture content, void ratio, degree of saturation, σv, OCR, γc, f, secant shear modulus, damping ratio, and the shape of cyclic straining. Using the database very large number of cyclic loops can be compared to instantly obtain graphical presentation of different behavioral trends. The structure of the database and its application is summarized. |
