Received in revised form 16 February 2012
Accepted 28 May 2012
Keywords:
Sliding zone
Unsaturated soils
Matric suction
Creep behavior
Burgers model
a b s t r a c t
The mechanical behavior of sliding zone soils plays a significant role in landslide. In general, the sliding
zone soils are basically in unsaturated state due to rainfall infiltration and reservoir water level fluctuation.
Meanwhile, a large number of examples show that the deformation processes of landslides always take a
long period of time, indicating that landslides exhibit a time-dependent property. Therefore, the deformation
of unsaturated soils of landslide involves creep behaviors. In this paper, the Burgers creep model for
unsaturated soils under triaxial stress state is considered based on the unsaturated soil mechanics. Then,
by curve fitting using the least squares method, creep parameters in different matric suction states are
obtained based on the creep test data of unsaturated soils in the sliding zones of Qianjiangping landslide.
Results show that the predicted results are in good agreement with the experimental data. Finally, to further
explore the creep characteristics of the unsaturated soils in sliding zones, the relationships between
parameters of the model and matric suction are analyzed and a revised Burgers creep model is developed
correspondingly. Simulations on another group of test data are performed by using the modified Burgers
creep model and reasonable results are observed.
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1. Introduction
Landslide is a major geological disaster, which poses a great
threat to human life and property in most parts of the world
(Yang and Lu, 1993). Sliding zone, one of the significant structural
elements of a landslide, records the detailed information
for physical changes and dynamic developments in the evolution
process of a landslide. In terms of sliding belt formed in
the development of a landslide, the creep behaviors of the soils
in sliding zone can reveal the mechanism of landslide formation,
and serves as an important index for the prediction and
evaluation of a landslide (He, 2005). On the one hand, soils in sliding
zone are basically

unsaturated due to rainfall infiltration or
water level fluctuation of reservoir (Riemer, 1992; Furuya et al.,
1999; Wang et al., 2008); on the other hand, a large number
of cases show that the deformation of landslides always takes a
long period of time, which means that time-dependent properties
of landslide soils are observed. According to this understanding,
 Supported by the National Natural Science Foundation of China (50879044)
and Master’s Degree Thesis Excellent Training Funds of Three Gorges University
(2011PY008).
∗ Corresponding author. Tel.: +86 717 6393044.
E-mail address: wwsm3044@yahoo.com.cn (S. Wang).
a series of triaxial creep tests on unsaturated sliding zone soils
were performed (Lai, 2010; Lai et al., 2010). To investigate and
describe the creep behaviors of the unsaturated soils, an appropriate
creep model needs to be constructed on the basis of creep
test data.
At present, creep models for the saturated soils can be roughly
classified into four categories: component model, integration
model, empirical model and semi-empirical model. Among these
models, component model, which is constructed on the basis of
linear visco-elastoplastic theorem, is featured with clear physical
meaning, visual concept and good reflection of rheological
properties of geotechnical materials (Sun, 1999). For this purpose,
numerous researches have been conducted using component
models (Liingaard et al., 2004; Wang et al., 2004; Sun, 2007; Yan