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Dynamic characteristics of natural kutch sandy soils
Abstract Kutch region has experienced widespread liquefaction and related damage during a series of past earthquakes; however, cyclic behavior of sandy soils of the region is yet to be explored. The current study is focused on the dynamic characteristics of natural soil deposits of the high seismicity Kutch region. In the previous studies, variations in fines content (FC) and the nature of fines (plastic, non-plastic) has been controlled and systematic and based on either non-plastic or plastic fines using mostly standard or river sands. However, the present study is different in the approach as the dynamic characteristics of natural sandy deposits with simultaneous presence, and random variations of both the plastic and non-plastic fines are explored. Results from cyclic triaxial tests indicated sandy soils of Kutch region are severe to moderately prone to liquefaction with a strong dependence on plasticity rather than FC. Pore pressure ratio (ru), mean effective pressure (p′) and cyclic stress ratio (CSR) for silty-sands signified effective stress failure, which was found to be coinciding with initial liquefaction. Clayey-sands exhibited strength degradation instead of liquefaction, and the plasticity index (PI) was found to control the magnitude of degradation. Large degradation in secant shear modulus and reduction in damping ratio with the number of cycles was observed in silty-sands whereas clayey-sands exhibited relatively lesser degradation in secant shear modulus and damping ratio.
Highlights Sandy soils of the Kutch region exhibited different dynamic behavior to be strongly dependent on the FC and nature of fines. While silty-sand specimens attained liquefaction within 31 cycles, clayey-sand specimens did not liquefy up to 50 cycles. Effective stress path analysis revealed that Kutch soil with non-plastic fines, irrespective of total FC, displayed effective stress failure (p¢ reaching zero, coincidental with initial liquefaction) within 31 cycles. Whereas in the presence of plastic fines, effective stress path of clayey-sand specimens ceased to reach to the stress origin indicating cyclic degradation. Evolution of cyclic stress ratio with the number of cycles was found to be strongly influenced by the FC, and the nature of fines.
Dynamic characteristics of natural kutch sandy soils
Abstract Kutch region has experienced widespread liquefaction and related damage during a series of past earthquakes; however, cyclic behavior of sandy soils of the region is yet to be explored. The current study is focused on the dynamic characteristics of natural soil deposits of the high seismicity Kutch region. In the previous studies, variations in fines content (FC) and the nature of fines (plastic, non-plastic) has been controlled and systematic and based on either non-plastic or plastic fines using mostly standard or river sands. However, the present study is different in the approach as the dynamic characteristics of natural sandy deposits with simultaneous presence, and random variations of both the plastic and non-plastic fines are explored. Results from cyclic triaxial tests indicated sandy soils of Kutch region are severe to moderately prone to liquefaction with a strong dependence on plasticity rather than FC. Pore pressure ratio (ru), mean effective pressure (p′) and cyclic stress ratio (CSR) for silty-sands signified effective stress failure, which was found to be coinciding with initial liquefaction. Clayey-sands exhibited strength degradation instead of liquefaction, and the plasticity index (PI) was found to control the magnitude of degradation. Large degradation in secant shear modulus and reduction in damping ratio with the number of cycles was observed in silty-sands whereas clayey-sands exhibited relatively lesser degradation in secant shear modulus and damping ratio.
Highlights Sandy soils of the Kutch region exhibited different dynamic behavior to be strongly dependent on the FC and nature of fines. While silty-sand specimens attained liquefaction within 31 cycles, clayey-sand specimens did not liquefy up to 50 cycles. Effective stress path analysis revealed that Kutch soil with non-plastic fines, irrespective of total FC, displayed effective stress failure (p¢ reaching zero, coincidental with initial liquefaction) within 31 cycles. Whereas in the presence of plastic fines, effective stress path of clayey-sand specimens ceased to reach to the stress origin indicating cyclic degradation. Evolution of cyclic stress ratio with the number of cycles was found to be strongly influenced by the FC, and the nature of fines.
Dynamic characteristics of natural kutch sandy soils
Hussain, Majid (author) / Sachan, Ajanta (author)
2019-06-06
Article (Journal)
Electronic Resource
English
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