Geotechnics for Sustainable Development - Geotec Hanoi 2013, Phung (edt). Construction Publisher. ISBN 978-604-82-0013-8 Keyword: liquefied stabilized soil, fibred material, time-dependency, deformation property, curing day ABSTRACT: Recently, a comprehensive planning process for socioeconomic development at Hanoi City in Vietnam is taking initial steps to solve urban problems such as the concentration of industrial district and serious traffic jam caused by population growth. The construction of underground facilities like subway, underground stations and underground pedestrian roads will be included. However, the strength and deformation characteristics of the geomaterials for the construction are still many unclear. Therefore, it is required to understand a characteristic of geomaterials and to improve soft ground arising settlement due to consolidation in Hanoi. In Japan, the LSS whereby the soil is mixed with water (or muddy water) and cementing material and reused as backfilling material has been popular as a recycling method for excavated soil 1), 2) . However LSS is more brittle in strength behavior as higher strength by increasing cement content. To improve ductile characteristic of LSS, Kohata et al. 4)~8) have focused on a reinforcement method by mixing crushed newspaper as a fibred material into LSS, and carried out a series of unconfined compression tests and triaxial tests. The results indicated that after reinforcement with the crushed newspaper fiber, brittle property of LSS after the peak was improved. In this study, effect of time-dependency on strength and deformation characteristics of liquefied stabilized soil (LSS) reinforced with fibred material were investigated. A series of Consolidated– Undrained triaxial compression tests ( CU � � � � tests) under the various conditions at constant strain rates, constant deviator stress (creep), varying strain rates during monotonic loading have been carried out for LSS reinforced with different content of fiber (i.e. 0, 10, 20 kg/m 3 of LSS) at curing age of 28 & 56 days, respectively. The test results were discussed and the time-dependent shear deformation characteristics of fibred LSS were evaluated. It was found that the effect of time-dependency is not seen in stress-strain curve regardless addition amount of the fibered material to LSS. 1 INTRODUCTION There are two different components of the time effect 9) as shown in figure 1 and figure 2, respectively. Ageing effects are defined as time- dependent changes in the intrinsic stress-strain properties, including peak strength, elasticity, yielding and viscosity (such as cementation, weathering). The age effect can be expressed as a function of the time (t c ) having specially defined. Loading rate effects are defined as the rate-dependency of stress-strain behavior due to the viscous property, typically noted by creep deformation and strain rate effects on stress- strain behavior. The viscous property is a function of instantaneous irreversible (or visco- plastic) strain rate (̇ ) and other relevant parameter, not by time. In recent years, the researches on time-dependent shear deformation characteristics of geomaterials have been reported 9), 10) . However the characteristics of LSS reinforced with fibred material haven’t been known 11) . Therefore, this study aims to investigate the time-dependent shear Time-dependency on deformation property of Liquefied Stabilized Soil mixed with fibered material Yukihiro KOHATA Muroran Institute of Technology, Muroran, Japan. E-mail: kohata@news3.ce.muroran-it.ac.jp . DUONG Quang Hung Graduate student, Muroran Institute of Technology, Muroran, Japan. E-mail: 12091502@mmm.muroran-it.ac.jp .