Postcyclic Reconsolidation Strains in Low-Plastic Fraser River Silt due to Dissipation of Excess Pore-Water Pressures

• Published in: Journal of geotechnical and geoenvironmental engineering Vol. 136; no. 10; pp. 1347 - 1357
• Main Authors: Wijewickreme, Dharma, Sanin, Maria V
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01.10.2010
• Subjects: Applied sciences; Buildings. Public works; Exact sciences and technology; Geotechnics; Soil mechanics. Rocks mechanics; Stabilization. Consolidation; TECHNICAL PAPERS; Canada; North America; America; Canada, British Columbia, Fraser R; Shear test; Water pressure; Cyclic loading; Deformation; Shear tests; Earthquake effect; Liquefaction; Earthquake response of silts; Cyclic loads; Direct simple shear testing; Postcyclic reconsolidation strains; Rivers; Experimental study; Soil liquefaction; Soil mechanics; Canada; Earthquakes; Pore pressure; Cyclic load; Silts; Test method; Silt; Pore water; Soil consolidation
• ISSN: 1090-0241; 1943-5606
• DOI: 10.1061/(ASCE)GT.1943-5606.0000349

The postcyclic reconsolidation response of low-plastic Fraser River silt was examined using laboratory direct simple shear testing. Specimens of undisturbed and reconstituted natural low-plastic Fraser River silt and reconstituted quartz powder, initially subjected to constant-volume cyclic loading under different cyclic stress ratios (CSRs) and then reconsolidated to their initial effective stresses ( σ vo ′ ) , were specifically investigated. The volumetric strains during postcyclic reconsolidation ( εv-ps ) were noted to generally increase with the maximum cyclic excess pore-water pressure ( Δ umax ) and maximum cyclic shear strain experienced by the specimens during cyclic loading. The values of εv-ps and maximum cyclic excess pore-water pressure ratio ( ru-max ) were observed to form a coherent relationship regardless of overconsolidation effects, particle fabric, and initial (precyclic) void ratio of the soil. The specimens with high ru-max suffered significantly higher postcyclic reconsolidation strains; εv-ps ranging between 1.5 and 5% were noted when ru-max >0.8 . The observed εv-ps versus ru-max relationship, when used in combination with the observed dependence of cyclic excess pore-water pressure on CSR and number of load cycles, seems to provide a reasonable approach to estimate postcyclic reconsolidation strains of low-plastic silt.