A case study of seismic response of an earth embankment foundation on liquefiable soils in Kansai area,western Japan was presented. Based on a calibrated cyclic elasto-plastic constitutive model for liquefiable sand a...A case study of seismic response of an earth embankment foundation on liquefiable soils in Kansai area,western Japan was presented. Based on a calibrated cyclic elasto-plastic constitutive model for liquefiable sand and Biot dynamic coupled theory,the seismic analysis was carried out by using a dynamic effective stress finite element method under plane strain condition. A recent design study was illustrated in detail for a river earth embankment subjected to seismic excitation on the saturated deposits with liquefiable sands. Simulated results of the embankment foundation during liquefaction were obtained for acceleration,displacement,and excess pore water pressures,which were considered to yield useful results for earthquake geotechnical design. The results show that the foundation soil reaches a fully liquefied state with high excess pore pressure ratios approaching to 1.0 due to the earthquake shaking. At the end of the earthquake,the extensive liquefaction causes about 1.0 m lateral spreading at the toe and 60 cm settlement at the crest of the earth embankment.展开更多
Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the ...Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage(permeable CFG pile bodies) and the later stage(impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors(including the replacement rate m, the treatment depth h1, the permeability coefficient Ks1, Kv2 and compression modulus Es1, Es2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.展开更多
基金Projects (40802070, 40841014) supported by the National Natural Science Foundation of ChinaProject (B308) supported by Shanghai Leading Academic Discipline Project, China
文摘A case study of seismic response of an earth embankment foundation on liquefiable soils in Kansai area,western Japan was presented. Based on a calibrated cyclic elasto-plastic constitutive model for liquefiable sand and Biot dynamic coupled theory,the seismic analysis was carried out by using a dynamic effective stress finite element method under plane strain condition. A recent design study was illustrated in detail for a river earth embankment subjected to seismic excitation on the saturated deposits with liquefiable sands. Simulated results of the embankment foundation during liquefaction were obtained for acceleration,displacement,and excess pore water pressures,which were considered to yield useful results for earthquake geotechnical design. The results show that the foundation soil reaches a fully liquefied state with high excess pore pressure ratios approaching to 1.0 due to the earthquake shaking. At the end of the earthquake,the extensive liquefaction causes about 1.0 m lateral spreading at the toe and 60 cm settlement at the crest of the earth embankment.
基金Project(51378197)supported by the National Natural Science Foundation of China
文摘Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage(permeable CFG pile bodies) and the later stage(impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors(including the replacement rate m, the treatment depth h1, the permeability coefficient Ks1, Kv2 and compression modulus Es1, Es2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.
