Rock and Soil Mechanics ›› 2020, Vol. 41 ›› Issue (7): 2189-2198.doi: 10.16285/j.rsm.2019.6716

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Study on solid-liquid phase transition characteristics of saturated sand based on large shaking table test on free field

XU Cheng-shun1, DOU Peng-fei1, DU Xiu-li1, CHEN Su2, HAN Jun-yan1   

  1. 1. Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of Technology, Beijing 100124, China 2. Institute of Geophysics, China earthquake Administration, Beijing 100081, China
  • Online:2020-07-10 Published:2020-12-22
  • Contact: DU Xiu-li, male, 1962, PhD, Professor, major in geotechnical earthquake engineering and structural aseismic.
  • About author:XU Cheng-shun, female, 1977, PhD, Professor, major in soil dynamics and seismic research of underground structure.
  • Supported by:
    the National Natural Science Foundation of China (51427803, 51404240, 51479193).

Abstract: Based on the large shaking table test of saturated sand on the free field, the dynamic shear stress–strain response of the foundation soil model was obtained by using the linear interpolation method according to the data from accelerometer arrays. At the same time, the concepts of apparent viscosity and zero shear viscosity of non-Newtonian fluid based on the assumption of hydrodynamic theory were introduced to study the characteristics and behaviors of shear thinning after site liquefaction. The characteristics of solid-liquid phase transition of saturated sand under seismic load were studied. Results showed that when the saturated sand was stimulated by a large earthquake, excess pore water pressure accumulated rapidly, and sand liquefaction occurred as the pore water pressure ratio of the upper part of the saturated soil ran up to 1. According to the variation of dynamic shear stress–strain curve, the dynamic shear modulus of saturated sand decreased significantly after liquefaction, indicating that the soil softened gradually. The variation trend of shear stress-shear strain rate of saturated sand derived from the data of dynamic shear stress and dynamic shear strain was similar to the rheological curve of non-Newtonian fluid. The apparent viscosity of the liquefied soil in the upper part of saturated sand layer decreased significantly. After liquefaction, the sand showed the pseudoplastic fluid characteristics of "shear thinning".

Key words: liquefaction, free field, shaking table test, non-Newtonian fluid, shear-thinning