In Situ Pore-Pressure Generation Behavior of Liquefiable Sand

• Published in: Journal of geotechnical and geoenvironmental engineering Vol. 133; no. 8; pp. 921 - 931
• Main Authors: Chang, Wen-Jong, Rathje, Ellen M, Stokoe, Kenneth H, Hazirbaba, Kenan
• Format: Journal Article
• Language: English
• Published: New York, NY American Society of Civil Engineers 01.08.2007
• Subjects: Applied sciences; Buildings. Public works; Exact sciences and technology; Geotechnics; Soil investigations. Testing; Soil mechanics. Rocks mechanics; TECHNICAL PAPERS; Shear test; Stress analysis; Sand; Shear tests; Liquefaction; In situ tests; Soil test; Pore pressure; In situ test; Pore water pressure; Soil mechanics; Comparative study
• ISSN: 1090-0241; 1943-5606
• DOI: 10.1061/(ASCE)1090-0241(2007)133:8(921)

To overcome current limitations in predicting in situ pore-pressure generation, a new field testing technique is used to measure directly the coupled, local response between the induced shear strains and the generated excess pore pressure. The pore-pressure generation characteristics from two in situ liquefaction tests performed on field reconstituted specimens are presented, including the pore- pressure generation patterns at various strain levels, the observed stages of pore-pressure generation, and pore-pressure generation curves. Comparisons of the in situ pore-pressure generation curves with data in the literature and from laboratory strain-controlled, cyclic direct simple shear tests support the in situ testing results. In addition, the effects of effective confining stress on threshold shear strain and pore- pressure generation curves are discussed. Comparisons of the rate of pore-pressure generation among the in situ tests, laboratory strain-controlled tests, and a model based on stress-controlled tests reveal that in situ pore pressures generated in reconstituted soil specimens during dynamic loading develop more similarly to those from cyclic strain-controlled laboratory testing. This observation implies that the evaluation of induced strains rather than induced shear stresses may be more appropriate for the simulation of pore-pressure generation.