Recent results of triaxial tests with granular materials

Over the last years rubber from scrap tyres has been reused in different civil works such as road embankments and railway platforms due to its resilient properties, low degradation and vibration attenuation. Unfortunately, this issue is still scarce. For instance, in Spain about 175.000 tonnes of scrap tyres were collected in 2014, of which only 0.6% were reused in civil works. Aiming to contribute to the reutilisation of large quantities of this waste material, this paper focuses on the analysis of unbound mixtures of granular materials with different percentages of rubber particles to be used as subballast layers. Mixtures are tested under cyclic triaxial tests so as to obtain their resilient modulus and evaluate their permanent deformations. It is found that as the rubber content increases, the resilient modulus decreases and the permanent deformation increases. Taking into account the usual loads transmitted to the subballast layer, the optimum rubber content that does not compromise the behaviour of the mixture is set in a range between 2.5% and 5% in terms of weight.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4231

Download Full-text

Resilient and permanent deformation of unsaturated unbound granular materials under cyclic loading by the large-scale triaxial tests

Acta Geotechnica ◽

10.1007/s11440-020-00966-0 ◽

2020 ◽

Vol 15 (12) ◽

pp. 3343-3356

Author(s):

Chuan Gu ◽

Yun Zhan ◽

Jun Wang ◽

Yuanqiang Cai ◽

Zhigang Cao ◽

...

Keyword(s):

Cyclic Loading ◽

Granular Materials ◽

Large Scale ◽

Permanent Deformation ◽

Triaxial Tests ◽

Unbound Granular Materials

Download Full-text

A numerical assessment of strain rate effects on the critical state of crushable granular materials

Géotechnique Letters ◽

10.1680/jgele.21.00097 ◽

2022 ◽

Vol 12 (1) ◽

pp. 1-19

Author(s):

S.K. Das ◽

S.K. Verma ◽

A. Das

Keyword(s):

Strain Rate ◽

Granular Materials ◽

Critical State ◽

Triaxial Tests ◽

Particle Crushing ◽

Confining Stress ◽

Stress Strain ◽

Strain Rate Effects ◽

Coral Sand ◽

Rate Effects

The present study highlights the effects of strain rate on the critical state response of crushable granular materials. A set of drained triaxial tests is simulated using the discrete element method (DEM) to understand the rate effects on the stress-strain and volumetric behaviour of the granular sample. The DEM parameters are obtained by comparing the stress-strain and particle crushing behaviour of in-house experimental analysis on crushable coral sand under a slow strain rate. In DEM, the particles are subjected to varied strain rates under different initial confining pressures and initial densities to capture the rate effects on the macroscopic responses until the critical state. It is seen that crushing increases with increasing confining stress. However, a higher strain rate induces relatively lower crushing and higher strength in terms of both peak stress and residual stress. It is observed that in pressure-volume space, the critical state line alters with the increasing strain rate of the crushable samples, especially at high confining conditions, whereas strain rate effect on critical state seems to be negligible at low confining conditions due to the absence of particle crushing.

Download Full-text