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The geotechnical earthquake engineering profession has struggled with the inherent complexity of the multiphase soil response to cyclic loading owing to the progressive nature of the generation of excess pore pressure (EPP) and degradation of soil stiffness and strength. One approach to improve understanding of the cyclic response and correlate the transition from a two-phase saturated soil to a single, fluid-phase liquefied soil is to treat the soil as a non-Newtonian viscous liquid. However, the work to date suggests that the viscous fluid model approach can only be implemented following the onset of sustained soil liquefaction. This paper presents a unified thixotropic fluid model and framework that effectively links the pre-shear soil fabric and its progressive cyclic response to the onset and maintained state of soil liquefaction. The framework treats the soil fabric as a fluid net-type structure proposed for use with thixotropic fluids, and presents the constitutive state and rate equations describing the deconstruction of the liquefiable soil fabric in response to cyclic loading. The unified framework uses physically meaningful soil parameters that can be obtained from common cyclic laboratory tests to seamlessly link the state-dependent and shear-strain-rate-dependent nature of soils to the generation of EPP, the latter of which is shown to increase in significance as EPP accumulates. The proposed thixotropic-induced excess pore pressure model should prove advantageous for use in forward modelling of the stress–strain rate response of liquefiable soil and generation of EPP. [ABSTRACT FROM AUTHOR]

To achieve recycled use of waste steel slag and waste tyres, it was proposed to incorporate waste tyre particles into waste steel slag and mix with sand to form a new geomaterial. Considering the effects of confining pressure, incorporation ratios of tyre particles and in corporation ratios of sand, the dynamic shear modulus and damping ratio of the new geomaterial were studied by a torsional shear vibration method based on resonance column tests. The specific control density of steel slag combined with different mixing ratios of tyre particles and sand were determined according to the relative density. The relationship between the dynamic shear modulus and the shear strain of the new geomaterial suited the hyperbolic model of Davidenkov. The maximum dynamic shear moduli of the new geomaterial with the tyre particle mixing ratio of 5% reached 166 MPa at the confining pressure of 200 kPa and were close to those of Fujian standard sand. The maximum dynamic shear modulus of the new geomaterial with the tyre particle mixing ratio of 15% was 103 MPa at the confining pressure of 200 kPa and was larger than those of Nanjing fine sand. The minimum damping ratio of the new geomaterial was in the range of 0·21–1·95% at the confining pressure of 200 kPa and was larger than that of the pure steel slag with 0·15–1·2%. These findings showed that the new geomaterial could be applied instead of sand. [ABSTRACT FROM AUTHOR]