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Centrifugal and numerical analysis of geosynthetic-reinforced soil embankments
Etude par centrifugeuse et analyse numérique des remblais renforcés par géotextile
Bo L., Linli J.
，
Ningyu Z., Sinong L.
School of Civil Engineering and Architecture, Chongqing Jiaotong University, Chongqing, China
ABSTRACT: Centrifuge models and numerical analysis of geosynthetic-reinforced and unreinforced soil embankments are presented.
The results obtained from the centrifuge tests were compared with those from the numerical analysis. It is found that the filamentous
fiber (polypropylene) is effective in constraining lateral displacement and reducing vertical settlement for the case of geosynthetic-
reinforced soil embankments. Also, the distribution of stress in the geosynthetic-reinforced soil embankment is significantly
ameliorated compared with the unreinforced. The presence of geosynthetic filamentous fibers in reticular structure provides the
reinforced soil embankments strength to resist crack.
RÉSUMÉ : Dans cet article, les résultats de modèles de centrifugeuse et les analyses numérique des remblais renforcés par géotextile
et non-renforcés sont présentés. Les résultats obtenus à l’aide de la centrifugeuse sont comparés avec ceux des analyses numériques.
Les fibres filamenteux (polypropylène) sont efficaces pour restreindre les déplacements latérales et réduire les tassements verticaux
dans le cas du remblais renforcé. De plus, la répartition des contraintes dans le remblai renforcé est améliorée de façon significative
comparé avec celle du remblai non-renforcé. La présence des fibres dans une structure réticulaire dans le remblai renforcé donne une
résistance contre la fissuration.
KEYWORDS: Embankment ; Geosynthetic-reinforcement ; Centrifuge test ; Numerical analysis
1 INTRODUCTION
The concept and design theory of reinforced soil were proposed
by the French engineer Henri Vidal from model tests in the
1960s. The reinforcement materials include metal strips,
concrete slabs, bamboo ribs and geosynthetic materials, etc.
Now-a-days, geosynthetics was commonly used in reinforcing
soil owing to its easy-controlled properties of structure type and
size, strength, impermeability, acid dissolution and durability.
“Cohesion” of filamentous fiber reinforced soil comes from
friction between soil and fibers, as well as the constraint force
of the fiber network. The magnitudes of CBR and unconfined
compressive strength(UCS) increase with augment of
filamentous fibers linearly(Xiong Youyan 1989). Soil
reinforced with continuous filamentous fibers is obviously
effective in reducing the vertical deformation of sand under the
vertical pressure; it is superior in reducing horizontal tension
than geogrids(A.F.L.Hyde and M.Ismail 1988). In recent years,
this technique has applied successfully by reinforcing the
embankment using filamentous fibers in embankment projects,
and datum are available from researches (Bao Chenggang and
Ding Jinhua 2012). However, the interaction micro-mechanism
of interface between soil and filamentous fibers is still unclear
(Tang Chaosheng, Shi Bin and Gu Kai 2011, Jie Yuxin and Li
Guangxin 1999).
In this paper, the behavior of geosynthetic-reinforced
embankments has been explored using centrifugal and finite
element modeling. The objectives of this paper include: (1) to
probe the mechanism of filamentous fibers in improving the
stability of the embankment, and (2) to examine the
effectiveness of filamentous fiber reinforcement.
2 CENTRIFUGE TESTS
Centrifuge model testing, because of its ability to reproduce
same stress levels, same deformation and same failure
mechanism in an 1/ n scale model as in a full-scale prototype, is
widely used in studying geotechnical problems. Jie Yuxin and
Guang-Xin Li studied the stability of cohesive soil slope and
fiber-reinforced soil slope with different densities through
centrifugal model tests; Yang Xiwu and Ouyang Zhongchun
obtained the deformation behavior of embankments which
reinforced with various fiber styles. It should be pointed out that
idealized conditions may be created in centrifuge models
carefully to avoid problems caused by stress errors, boundary
effects, particle scale effects and geometrical scale effects.
2.1
Centrifuge tests—Equipment and procedure
2.1.1
Equipment
In the present study, centrifuge model tests were performed
using the TLJ—60 centrifuge in Chongqing Jiaotong
University. The main parameters of the centrifuge are indicated
in Table 1.
Table 1. The main parameters of the centrifuge
Characteristic
Value
Maximum volume weight
60g·t
600kg(100g)
Maximum load
300kg(200g)
Effective radius
2.0m
Maximum acceleration
200g
Acceleration control accuracy
±0.5%F·S
Model box size
600mm×350mm
×500mm
2.1.2
Model scale
Due to the inherent symmetry of the embankment about its
centerline, only one half of it was modeled. In order to simulate
the actual project accurately and satisfy the boundary effects,
1:90 scale centrifuge model was constructed. Fig.1 shows the
details of test model and its full-scale prototype.
