Prediction of Volumetric Strain for Sand under Cyclic Loading

In order to investigate volume change of sand due to cyclic loading, different tests were performed on hollow cylindrical specimens under drained cyclic simple shear condition. Correlation of accumulated plastic shear energy with volumetric strain and effects of different parameters such as initial confining pressure, initial anisotropic consolidation and strain amplitude on this correlation were studied. Test results showed that volumetric strain of sand under different initial confining pressures was almost same. Volume change of specimens with different initial anisotropic consolidations was also identical, except for initial stage of shearing. It was found that the correlation of volumetric strain and normalized energy was similar for different initial confining pressures and anisotropic consolidation. Test results showed that shear strain amplitude affected the volumetric strain-energy correlation. This effect was not significant when volume change was smaller. An average correlation of volumetric strain and energy can be used to predict volume change of sand under different strain amplitudes

The next-generation constitutive correlations for simulation of cyclic stress-strain behaviour of sand

This paper presents an innovate approach to simulate the stress-strain behaviour of sands subjected to large amplitude regular cyclic loading. New prediction correlations were derived for damping ratio (D) and shear modulus (G) of sand utilizing linear genetic programming (LGP) methodology. The correlations were developed using several cyclic torsional simple shear test results. In order to formulate D and G, new equations were developed to simulate hysteresis strain–stress curves and maximum shear stress (τmax) at different loading cycles. A genetic algorithm analysis was per­formed to optimize the parameters of the proposed formulation for stress-strain relationship. A total of 746 records were extracted from the simple shear test results to develop the τmax predictive model. Sensitivity and parametric analyses were conducted to verify the results. To investigate the applicability of the models, they were employed to simulate the stress-strain curves of portions of test results that were not included in the analysis. The LGP method precisely charac­terizes the complex hysteresis behaviour of sandy soils resulting in a very good prediction performance. The proposed design equations may be used by designers as efficient tools to determine D and G, specifically when laboratory testing is not possible

2003年バム地震におけるバム市内の地盤と基礎構造の挙動

Following the devastating earthquake disaster in Bam city, Iran, a reconnaissance team was sent to the site. The authors participated in its activities with special emphasis on geotechnical issues. A soil investigation in the city revealed that local soils have su$ciently good properties and cannot be the main source of heavy damage to houses. Because bridges and structures other than buildings experienced minor damage during the same earthquake, it seems that the structural weakness of houses made of masonry and adobe is a major problem. A possible mitigating measure may be to use light materials such as ESP, although consideration has to be given to the local climate and the landscape

Seismic Behavior of Local Soil and Foundations in Bam City During the 2003 Bam Earthquake in Iran

Following the devastating earthquake disaster in Bam city, Iran, a reconnaissance team was sent to the site. The authors participated in its activities with special emphasis on geotechnical issues. A soil investigation in the city revealed that local soils have su$ciently good properties and cannot be the main source of heavy damage to houses. Because bridges and structures other than buildings experienced minor damage during the same earthquake, it seems that the structural weakness of houses made of masonry and adobe is a major problem. A possible mitigating measure may be to use light materials such as ESP, although consideration has to be given to the local climate and the landscape