This series includes technical reports prepared by faculty, students and staff who are associated with the John A. Blume Earthquake Engineering Center at Stanford University. While the primary focus of Blume Center is earthquake engineering, many of the reports in this series encompass broader topics in structural engineering and materials, computational mechanics, geomechanics, structural health monitoring, and engineering life-cycle risk assessment. Each report includes acknowledgments of the specific sponsors for the report and underlying research. In addition to providing research support, the Blume Center provides administrative support for maintaining and disseminating the technical reports. For more information about the Blume Center and its activities, see https://blume.stanford.edu.
The build-up of excess pore pressures in a layer of saturated cohesionless soil during an earthquake can lead to ground movements which damage structures and cause loss of life. This response is due to the application of cyclic shear stresses, which are generated primarily by the upward propagation of shear waves in the soil deposit. As a consequence of the applied cyclic stresses, the structure of the undrained cohesionless soil tends to become more compact, and this results in a transfer of stress to the pore water and a reduction in effective stress. If the sand is loose the pore pressure may increase rapidly to a value equal to the confining pressure and the soil layer will undergo large deformations. If the sand is dense, it may exhibit a zero effective stress condition at the end of a given cycle, but during subsequent cycles the soil will tend to dilate, the pore pressure will drop, and the soil may develop enough resistance to withstand the applied stress. The shear strain associated with this dilation will correspond to a limited degree of deformation. The extreme case of pore pressure increase up to the zero effective stress condition is often called liquefaction, and enormous damages have been attributed to this phenomenon. There are hundreds of recent cases of ground failures and damages to structures due to liquefaction during Earthquakes in China, Japan, Yugoslavia, Chile, Central America and in the United States.
Chameau, JL . (1981). Probabilistic and Hazard Analysis for Pore Pressure Increase in Soils Due to Seismic Loading. John A. Blume Earthquake Engineering Center Technical Report 51. Stanford Digital Repository. Available at: http://purl.stanford.edu/ky293sn3745
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