Assistant professor, University of California at Los Angeles, Los Angeles, CA
Professor, Civil Engineering Department, Rensselaer Polytechnic Institute, Troy, NY
Pages: 11 Published: Jan 1988
Two series of undrained cyclic triaxial strain-controlled tests were performed on two different Imperial Valley, California, silty sands which liquefied during an earthquake in 1981. Both intact and reconstituted specimens were tested, and the testing procedures are described. The experimental data confirm that cyclic shear strain is the fundamental parameter governing pore pressure buildup, because strain-controlled tests essentially eliminate the influence of specimen fabric and sample disturbance. Also, the results indicate that the cyclic triaxial test can be used to model cyclic simple shear (similar to seismic field conditions), if the cyclic simple shear strain, γcy, is related to the cyclic triaxial axial strain, εcy, by either of two similar analytical expressions: γcy = 1.5 εcy or γcy = √3 εcy. Consequently, a unique pore pressure model is developed and recommended to simulate the seismic pore pressure buildup at the site. This model is applicable to reconstituted and intact specimens of the two sands, despite their different void ratios and nonplastic silt contents, and is valid for both cyclic triaxial and cyclic simple shear strain-controlled conditions.
dynamic loading, liquefaction, model, pore pressure, repeated loading, sample disturbance, sand, simple shear test, triaxial test
Paper ID: STP29093S