Characteristics of dynamic shear modulus and damping ratio and the structural formula of EPS particles lightweight soil

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 166; p. 107768
• Main Authors: Hou, Tian-shun, Cui, Yi-xiang, Pan, Xing-ru, Luo, Ya-sheng, Liu, Qian
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2023
• Subjects: Damping ratio; Dynamic shear modulus; Dynamic triaxial test; Lightweight soil; Maximum damping ratio formula; Maximum dynamic shear modulus formula; Lightweight soil; Dynamic shear modulus; Maximum dynamic shear modulus formula; Maximum damping ratio formula; Dynamic triaxial test; Damping ratio
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2023.107768

Dynamic triaxial tests of lightweight soil were conducted to explore the dynamic characteristics of expanded polystyrene (EPS) particle lightweight soil under traffic load. The effects of different mixed ratios, confining pressure, frequency on the backbone curves, dynamic shear modulus, and damping ratio characteristics of lightweight soil were investigated. The maximum dynamic shear modulus formula and maximum damping ratio formula of lightweight soil were established. The results indicated that backbone curves of lightweight soil had typical nonlinear and strain-hardening characteristics. With an increase in dynamic shear strain, the dynamic shear modulus curves appeared as inverse “S-shaped”. The dynamic shear modulus in the initial stage varied under different confining pressures. For γd＞10−4, the attenuation rate of the dynamic shear modulus increased with an increase in the dynamic shear strain, and for γd＞10−2, the relationship curve between the dynamic shear modulus and dynamic shear strain coincided gradually, and the attenuation process then stabilized. Owing to the special structure of lightweight soil, the damping ratio curves were “Bell-shaped” and “S-shaped.” Both the confining pressure and compressive yield stress determined the change trends of the damping ratio curves of the lightweight soil. The specimens were in an over-consolidated state and the mixed soil was in the state of shear dilatancy under dynamic loads when the confining pressure was less than the compressive yield stress, resulting in “Bell-shaped” damping ratio curve. The specimens were in the normal consolidated state and the mixed soil was in the state of shear shrinkage under dynamic loads when the confining pressure was greater than the compressive yield stress, resulting in “S-shaped” damping ratio curves. The calculation methods of the relative structural degree k and generalized void ratio e' of lightweight soil were defined to express the structural damage laws of lightweight soil having different mixed ratios under complex stress conditions using a unified formula. Based on Hardin's empirical formulas, the maximum dynamic shear modulus and maximum damping ratio formulas of lightweight soil were established by introducing the relative structural degree k and generalized void ratio e'. The formulas can quantitatively describe the dynamic responses of the special structure of lightweight soil under complex stress conditions. [Display omitted] •The backbone curves of lightweight soil have typical nonlinear and strain-hardening characteristics.•The dynamic shear modulus curves of lightweight soil appear as inverse “S-shaped” with an increase in the dynamic shear strain.•Owing to the special structure of lightweight soil, the damping ratio curves are “Bell-shaped” and “S-shaped.”.•The maximum dynamic shear modulus and maximum damping ratio formulas of lightweight soil are established by introducing structural parameters.