Deformation Mechanism and Trend
Research on a Creep Landslide in
Sichuan Province of China
Guo Yufei
Doctoral Student
School of engineering and technology, China University of GeoSciences, Beijing,
China; e-mail: [email protected]
Yao Leihua
Professor
School of engineering and technology, China University of GeoSciences, Beijing,
China; e-mail: [email protected]
Zhou Pinggen
Professor
China Institute of Geo-Environment Monitoring, Beijing, China
e-mail: [email protected]
Han Bing
Engineer
China Institute of Geo-Environment Monitoring, Beijing, China
e-mail: [email protected]
ABSTRACT
The Xiakou landslide is located north of Ya’an City in the Sichuan province of China, at the
transitional belt of the Sichuan Basin and the Tibetan Plateau, and 120 km from Yingxiu
Town (the epicenter of the Wenchuan earthquake measuring 8.0 on the Richter scale). The
Xiakou landslide is one of the most common and destructive landslides in the Ya’an area.
This landslide was formed in a layer of colluvium and can be classified as a creep landslide.
Monitoring data from 2006 to 2010 were used to analyze the deformation characteristics of
the different parts of the landslide. The limit equilibrium method was employed to identify the
influence of the water table to slope stability during different seasons. The deformation trend
of the landslide was predicted by analyzing incline displacements before and after the
Wenchuan earthquake. Based on these analyses, suggestions for the monitoring and early
warning of the Xiakou landslide are proposed.
KEYWORDS:
Creep landslide; Landslide monitoring; Wenchuan earthquake;
Deformation mechanism and trend
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INTRODUCTION
As a mountainous country, landslides occur in China each year during the rainy season,
causing heavy casualties and serious economic and property loss. To reduce the impact of
landslides, the Chinese government has been improving landslide prediction and prevention since
the end of the 20th century. Several typical landslides were monitored for the purpose of
demonstration. One of which is the Xiakou landslide from the Ya’an area of Sichuan province.
This landslide belongs to a typical creep landslide in colluvium found in the Sichuan area. Since
2002, the Xiakou landslide has been monitored by the China Institute of Geo-environment
Monitoring (CIGEM).
Landslides found in colluviums are common. Lansford [1] described colluviums as loose
deposits that accumulate slowly in long slopes. This sliding mass has high moisture contents,
large boulders, and significant proportions of organic materials. Karikari-Yeboah [2] defined
colluviums as non-homogeneous deposits that are composed of soil, cobbles, and boulders and
formed by gravitational forces; the slope of colluviums is mostly moderate compared with steep
grades. Moreover, these deposits usually have distinct zones of weakness and hardness that cause
the upper mass to slide along the surface of the harder, underlying residual soil or bedrock.
Sliding colluviums have complex deformation processes because of their strong anisotropy.
Several Chinese researchers have studied landslides in colluviums in China. He [3] studied the
displacement variation of several landslides in the area of the Three Gorges Reservoir. Zhao [4]
analyzed the stress pattern, state of the slope structure, and profile of the Xiakou landslide. Zhang
[5]
studied the creep behavior of the Xiakou landslide based on monitoring data from 2002 to
2004. He [6] used the Monte Carlo method and the residual thrust method to analyze the impact of
groundwater and seismic forces on the consistency of the Xiakou landslide. Although these
researchers obtained results, an analysis of the deformation characteristics and trends of the
Xiakou landslide before and after the Wenchuan earthquake in 2008 has not yet been conducted.
A devastating earthquake with a magnitude of 8.0 occurred in the Wenchuan area on 12 May
2008. The initial earthquake was accompanied by numerous secondary earthquakes that directly
induced a large number of landslides as well as several adverse geological impacts, such as
mountain destruction, rock pulverization, and landscape aberration. These elements triggered an
increase in the risk of geological disasters in the earthquake-stricken area. After the Wenchuan
earthquake, the area was divided into the extreme heavy loss, heavy loss, and loss areas based on
the damage incurred. The Xiakou landslide is categorized in the heavy loss area [7], and is located
about 120 km from the epicenter of the Wenchuan earthquake (M = 8.0) of Yingxiu Town.
Monitoring data from 2006 to 2010 were collected to study the deformation mechanisms,
characteristics, and trends of the slope as well as to lay the foundation for the construction of an
early warning system.
CHARACTERISTICS OF THE XIAKOU LANDSLIDE
Location, Geology, Regional Tectonic and Climate
The Xiakou landslide is located in the western slope of the Wujia Mountain, 10 km north of
Ya’an in the Sichuan province. The leading edge and forepart of the landslide is close to the
Longxi River and Yabi Road, respectively. Chengdu is situated in the northeast of the Xiakou
landslide with the same straight-line distance from the landslide as Yingxiu (approximately 120
km; Fig. 1).
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The Xiakou landslide was formed in colluvium derived from weathered bedrock units of the
Tianmashan Formation. The bedrock has an occurrence range of 315°–334° to 30°–35°, and is
composed of sandstone interbeded with mudstone. Thus, the Tianmashan Formation produces
stony, clay colluviums. This structure, where the upper layer contains loose deposits and the
lower layer is composed of harder bedrock, provides a favorable condition for the formation of
potential sliding across the interface of both layers.
The Xiakou landslide is located in the southeast edge of the transition zone between the
Tibetan Plateau and the Sichuan Basin, and is close to the southern section of the Longmen
Mountains tectonic belt (Fig. 2). The seismic activity of the Longmen Mountains tectonic belt
after the Wenchuan earthquake is less active than the northern section. This tectonic belt has a
straight-line distance of about 18 km from the main boundary fault of the Longmen Mountains
foreland. The Xiakou landslide is also located in the northwest wing of the Wujia Mountain
anticline near the anticline core. The geological structures in the nearby area are mainly folds, the
fracture in the area is not developed, and the seismic activity is weak. The new tectonic
movement in this region is strong, mainly moves in an intermittent upward motion, and displays a
V-shaped valley in the landscape.
Figure 1: Regional tectonic and seismic activity during the Wenchuan earthquake [8]. F1
is the main boundary fault of the Longmen Mountains foreland. F2 and F3 are the central
fault and the back fault of the Longmen Mountains, respectively.
The climate of the landslide in the Ya’an area has the following characteristics: rare snowfall,
abundant rainfall with an average of 218 rainy days a year for several years, and average
precipitation of 1732 mm. The maximum annual rainfall is 2367.3 mm (1966), and the minimum
annual rainfall is 1204.2 mm (1974). The abundant rainfall in Ya’an City has given the city the
moniker “Rainy City” and “Nature’s Funnel”. Rainfall in the summer season commonly accounts
for approximately 50% of annual precipitation, whereas rainfall in autumn accounts for
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approximately 20%. The precipitation peak, which may reach 450 mm or more, can be observed
mostly in August [9]. These data are from the Ya’an area records collected from 1986 to 2000.
Geomorphology and History Activity
The Xiakou landslide is located in the left corner of the Longxi River Valley on a wide and
gentle slope with a gradient of about 20°, which is smaller than the dip angle of the underlying
rock (Figs. 2 and 3).
Figure 2: Morphological map of the Xiakou landslide containing distributed monitoring
instruments.
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Figure 3: Typical geology and monitoring cross section “A-A”. The number one denotes
the stony clay colluvial cover, two is the bedrock composed of sandstone interbedded
with mudstone, three is the sliding surface, and four is the groundwater level.
The Longxi River lies at the bottom of the Xiakou landslide and changes direction in the
leading edge of the landslide, causing higher flow velocity and stronger lateral erosion as well as
aggravating the deformation at the landslide toe. The vegetation on the slope is very abundant.
The Xiakou landslide is composed of two parts: the old landslide and the new landslide. The
latter was reactivated in the former by a rainstorm during the summer of 1981. The main
morphometric characteristics of the old and new landslides are listed in Table. 1.
Table 1: Morphometric characteristics of the old landslide and new landslide
Characteristic
Volume
Depth
Maximum altitude at crown
Minimum altitude at foot
Difference of altitude
Maximum length
Maximum width
Length to width ratio
Average slope gradient
The old landslide
about 10 million m3
10-35 m
960 m
750 m
210 m
680 m
610 m
1.11
22°
The new landslide
about 4.5 million m3
10-35 m
920 m
750 m
170 m
520 m
350 m
1.49
20°
Table 1 shows that the volume of the old landslide is roughly twice of that of the new
landslide. The upper parts of the slope are steeper but thinner; thus, the average slope gradient of
the old landslide is somewhat bigger than that of the new one. The leading edge of the new
landslide, which is a scarp with a height of about 10 m to 20 m, is consistent with the old one.
The Yabi Road passes the upper parts of the scarp, whereas the Longxi River flows along the
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bottom of the scarp. The other side of the Longxi River is lined with cliffs. This type of terrain
sets the condition for slope toe instability.
The old landslide was formed many years ago by long-term deformation, which formed three
distinct platforms on the sliding body. The new landslide was formed in the old one roughly 30
years ago. According to the records, the slope toe began to deform when a large number of blast
quarrying was conducted on the bed of the Longxi River in 1978. In August 1981, the slope mass
within the old landslide was reactivated in a large scale because of heavy rainfall. Thereafter, the
newly formed landslide moved down and blocked the Longxi River [10]. Since the new landslide
emerged, the sliding mass has continued creeping and different levels of deformation and failure
in the local parts occur every rainy season. The deformations even led to the collapse of the Yabi
Road.
MONITORING WORK AND DATA ANALYSIS
Monitoring Work
In the early years, CIGEM used a variety of techniques to monitor the new landslide, such as
rainfall gauges, inclinometers, surface GPS, and stakes. However, considering economic factors
and other monitoring effects, the new landslide has been mainly monitored by two rainfall gauges
and four inclinometers since 2006. Groundwater depth and inclinometer displacement were
conducted artificially one to three times every month, and rainfall was recorded automatically
once per hour. Four inclinometers were installed in boreholes in the forepart (Bh3), the central
part (Bh2 and Bh6), and the posterior part (Bh1) of the new landslide. Bh1, Bh2, and Bh6 were
the original monitoring boreholes completed in 2002, whereas Bh3 was only completed in August
2006. Two data collection centers regularly send recorded data to the CIGEM monitoring center,
which is located several thousand kilometers away.
To make the different monitoring data coincide with time, a time unit was taken each month.
The rainfall data were collected from the lower rain gauge. The inclinometer displacement was
selected with the maximum monthly accumulative values, and the groundwater depth was
substituted with the minimum monthly data monitored.
Rainfall and Groundwater Depth
The monthly rainfall and groundwater depth data of the Xiakou landslide from 2006 to 2010
is plotted in Fig. 4. During these five years, the rainfall is shown to be focused mainly on the
months of June to September every year. The maximum monthly rainfall recorded is 830.3 mm in
August 2010. The minimum annual rainfall is 1254 mm in 2008, whereas the maximum annual
rainfall is 2088.6 mm in 2010.
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Figure 4: Records of the monthly rainfall and groundwater depth from 2006 to 2010
(Note: Bh3 started operations in August 2006; thus, monitoring data from January to May 2008 is
nonexistent. Bh1, Bh2, and Bh6 started operations in 2002; thus, the monitoring from February to July
2006 and January to May 2008 is missing. Bh2 became invalid in December 2009. Bh1, Bh3, and Bh6
were all invalid during the 2010 rainy season)
Fig. 4 also shows that the groundwater depth in Bh1 changes slightly; the groundwater depth
was always approximately 2.0 m with less than 0.5 m changes in amplitude during the whole
observation period. The groundwater depth in Bh2 fluctuates between 5 and 9 m, whereas the one
in Bh6 fluctuates between 7 and 10 m. Both Bh2 and Bh6 are located in the central part of the
new landslide and show obvious variations in the rainy season. In Bh3, the variation range of the
groundwater depth is 3 m to 9.5 m, which obviously shows the influence of seasonal rainfall.
Moreover, water levels in Bh2, Bh6, and Bh3 usually increase in July or August with the larger
rainfall of the year.
The reasons why the groundwater depth in Bh1 remained stable for a long period can be
explained as follows. First, Bh1 is located in the posterior part of the new landslide, and the
nearby zones in the upper part of the slope may have several good drainage channels. The
stability of the groundwater depth should not only be attributed to the new drainage completed in
2007 because the groundwater depth has changed little even before 2007. For this reason, no
matter how much rainfall occurs, rainwater can be discharged through the above channels; thus,
groundwater depth remains almost stable. Second, because of the large non-homogeneous
deposits in the colluvium, the sliding mass around Bh1 may have weaker permeability. The
lateral infiltration recharge on the slopes may also be greater than the osmotic excretion, thus
causing excess water to drain away from the upper channels.
Inclinometer Deformation
The inclinometer can easily identify the depth of the sliding surface and the changes in the
displacement of the different depths because of the distinct displacement near the sliding surface
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in the borehole. This technique is widely used in landslide monitoring [11–13]. In this paper, the
inclinometer displacement of the main deformation direction is selected (Fig. 5).
a. Bh1
c. Bh3
b. Bh2
d. Bh6
Figure 5: Inclinometer displacement of the main deformation direction in the four
monitoring boreholes from 2006 to 2010.
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Combining the data obtained from the six boreholes and the four deformations of the
inclinometer at different times, the following information can be observed:
Table 2: Bedrock depth and borehole deformation
Borehole
No.
Bh1
Bh2
Bh3
Bh4
Bh5
Bh6
Maximum
Maximum
Borehole Bedrock Deformation
deformation depth deformation depth
depth
depth
depth
near the slip surface in the borehole
(m)
(m)
(m)
(m)
(m)
24.34
14.32
14.5
12
12
35.45
27.71
27.5
25
0.5
50.14
29.06
26
24.5
24.5
20.3
9.8
—
—
28.2
21
—
—
40.69
32.6
31
29
5.5
Monitoring
period
200601–201006
200601–200911
200608–201006
—
—
200601–201006
Figure 5 and Table 2 show that the maximum displacement in Bh1 (Fig. 5a) is at a depth of
12 m; the displacement in the lower part of the sliding mass in Bh1 is obviously greater than the
surface part. The depth of the maximum displacement near the sliding surface in Bh2 is 25 m
(Fig. 5b.); the surface displacement is a little larger than the lower part in this borehole. In Bh3
(Fig. 5c), the maximum displacement is at a depth of 24.5 m; the displacement curve along this
depth represents a bulge in the lower part and a depression in the upper part because of the faster
movement in the lower part of the sliding mass. Bh6 (Fig. 5d) shows a similar condition as Bh2,
where the deformation in the lower part of the sliding mass is slightly smaller than that in the
upper part. In Bh6, the depth of the maximum displacement near the sliding surface is 29 m; the
distribution of the deformation along this depth is uneven, which may be caused by the nonhomogeneous structure of the sliding mass.
The deformation observed in the four boreholes shows that the displacement near the sliding
surface increases slowly and occasionally displays a small disturbance; however, the deformation
observed in the middle (Bh6) or upper (Bh3) borehole exhibits a larger disturbance. Therefore,
the maximum displacement near the sliding surface in inclinometer monitoring can be adopted
for the prediction of landslide deformation and construction of an early warning system.
To analyze the inclinometer deformation more directly, the maximum displacement near the
sliding surface of each borehole are plotted with time in Fig. 6. The collected data are shown in
Table 3.
Fig. 6 shows that from January 2006 to July 2007, the new landslide was on a stage of slow
deformation. In August 2007, however, accelerated deformation occurred. Thereafter, slope
deformation slowed down from September to December 2007. After the Wenchuan earthquake in
May 2008, the deformation of the central (Bh2 and Bh6) and posterior parts (Bh1) of the new
landslide was very slow. In time, the deformation gradually stabilized; hence, the two parts
affected by the Wenchuan earthquake are not significant. The deformation in the forepart (Bh3)
of the new landslide shows convex growth from June to December 2008, before slowing down.
Table 3 also shows that the whole deformation of the slope slowed down after 2008.
The new landslide had no significant overall sliding after the Wenchuan earthquake. This
phenomenon may be attributed to the following reasons. First, because of the larger increase in
displacement in August 2007, some energy was released from the slope. Additionally, the stress
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in the slope may also be attributed to the influence of the Wenchuan earthquake in 2008. Second,
the landslide is located near the south of the Longmen Mountains fault zone where the intensity
and activity of the Wenchuan earthquake was relatively weaker. Third, the Wenchuan earthquake
occurred in May 2008 when there had been a lower monthly rainfall (82.8 mm); thus, the
earthquake’s effect may not have been enough to induce large-scale deformation. Additionally,
the local department reinforced the leading edge of the slope, built a new drainage on the
posterior part (Fig. 3), and recovered vegetation as a response to several local collapses in the
leading edge of the new landslide because of the large rainfall in August 2007. These control
measures may have largely improved the stability of the new landslide, causing the deep
displacements in the central and posterior parts have changed little since December 2007. The
continued increase of the deep displacement in the forepart may be attributed to the impact of
other factors such as rainwater seepage, river erosion, and other human activities on road.
Figure 6: Cumulative displacement at the depth near the sliding surface with maximum
deformation as observed in different months.
Table 3: Increments of the yearly cumulative displacement at the depth near the sliding surface
with maximum deformation
Depth with max.
Borehole
cumulative
NO.
displacement near slip
surface (m)
Bh1
12
Bh2
25
Bh3
24.5
Bh6
29
Yearly increment of cumulative displacement (mm)
2006
2007
2008
2009
2010
Feb-Jun
Total
8.23
5.75
3.46
8.65
15.59
19.3
18.52
36.62
9.5
-2.86
19.59
-2.03
-3.48
2.73(Jan-Nov)
2.78
4.13
1.26
—
4.49
0.43
31.1
24.18
48.84
47.8
A comparison between Figs. 4 and 6 shows that the deformation in the forepart of the new
landslide is obviously affected by seasonal rainfall. The displacement curve of the new landslide
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shows a ladder-like increase (Fig. 6). A large displacement growth occurred in August 2007 when
the monthly rainfall was 570 mm, which is significantly greater than the average value in
previous years. In addition, three inclinometers (Bh1, Bh3, and Bh6) became invalid because of
the large deformation during the 2010 rainy season. The corresponding monthly rainfall in
August 2010 reached 830 mm, which is the maximum monthly rainfall observed in five years.
Therefore, we can speculate that a large rainfall induces larger deformation of the whole
landslide.
Stability of the New Landslide
The limit equilibrium method can effectively and efficiently assess the stability of a slope;
thus, this method is widely used in the long-term prediction of landslides. In the last decade,
several hydrological models have been combined with the limit equilibrium method to analyze
slope stability during rainfall with consideration to the impact of rainfall infiltration on the slope.
However, this combination will largely increase the complexity of the computation. Wilkinson
[14–15]
proposed a combined hydrology and stability model and later developed a procedure that
incorporated the Bishop and the Janbu methods in analyzing slope stability during rainfall. Yao
[16]
improved the Sarma method and considered the groundwater in a slope as a two-dimensional
steady phreatic water flow with uniform infiltration in his MSARMA V3.0.
For the new landslide, the structures and materials of the sliding mass have significant
anisotropy and non-homogeneity, and are affected by the drainages and the lush vegetation. The
groundwater level distribution in the slope is continuously affected by various factors that cause
complex hydrological conditions. To simplify the calculation of slope stability, the groundwater
is considered as a steady phreatic water flow without infiltration. Several hypotheses are made
concerning slope stability: (1) slope mass is homogeneous, made of isotropic material, and has no
infiltration; (2) groundwater flow is considered a two-dimensional flow; (3) groundwater flow
gradually varies and stabilizes; (4) sliding mass does not have a hydraulic connection with the
bedrock; and (5) groundwater evaporation is negligible. Thereafter, the groundwater level can be
calculated using the following formula:
h=
h12 −
h12 − h22
l
x
(1)
where h1 is the known higher groundwater level, h2 is the known lower groundwater level, l is the
horizontal distance between h1 and h2, and x is the horizontal distance from the unknown h to h1.
The stability of the new landslide with different groundwater levels was calculated by the
SLOPE/W mode in Geostudio. The Ordinary, Bishop, Janbu, and Sarma methods that belong to
the limit equilibrium method were adopted. Parameters were derived from laboratory tests and
inverse calculations (Table 4). Results of the slope stability factor F are shown in Fig. 7.
The slope stability factor F is significantly affected by groundwater levels in the forepart and
central part of the new landslide (Fig.7). Changes in the slope stability factor are consistent with
the fluctuations of seasonal groundwater levels. When the groundwater level in the forepart and
central part of the new landslide is high, F obtains a lower value. Based on the results of the four
methods, the value of F varies in a small range within 0.1 for each method. This value is caused
by the large scale of the new landslide, which makes the changes in groundwater levels seem
miniscule compared to the whole landslide scale. This observation shows that the Janbu method
can reflect well the fluctuations of the stability factor F above and below the safety line of 1.0
under these parameters. The fluctuations of F represent the critical state of the landslide for a
Vol. 17 [2012], Bund. X
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certain period of time. When heavy rainfall causes a rapid increase in groundwater levels in the
forepart and central part of the new landslide, the slope will become unstable. Therefore, based on
the historical monitoring data and results of the stability analysis, the Janbu method can be
combined with real-time groundwater level monitoring to predict the state of the new landslide.
Table 4: Parameters adopted in the calculation
Sliding Mass
Stony clay
Unit weight (kN/m3)
20.5
Cohesion (kPa)
22
Friction angle (°)
24 °
Figure 7: Stability factors of the new landslide in section “A-A” and the monitored
groundwater depth on different months.
New Landslide Deformation Mechanism and Trend Prediction
Zhao [4] divided the development of the new landslide into four stages: elastic deformation
stage, elastic-plastic stage, creep and extrusion stage, and sliding stage. He noted that although
the sliding mass has a large amount of accumulated energy because of the large difference in
altitude between the foot and the crown, the new landslide is more likely to cut from the riverbed
in the front of its leading edge as influenced by the topography of the narrow valley. The energy
of the slope is released in the form of compression deformation on its forepart; this energy is less
likely to induce fast overall sliding. He proposed that the deformation mode of the new landslide
is intermittent slide-stop-creep-slide.
According to the monitoring data collected between 2006 and 2010, the deformation of the
forepart shows ladder-like growth and that of the central and posterior parts shows long-term
stability since 2008 with a little increase in displacement. However, overall sliding occurred in
the rainy season of 2010 and rendered all monitoring inclinometers invalid. Therefore, the
deformation of the new landslide is more in line with the intermittent sliding mode proposed by
Zhao [4]; however, the intermittent cycles of deformation in the different parts of the new
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landslide are different. The deformation in the forepart of the landslide exhibits intermittent
growth every rainy season, whereas that in the central and posterior parts occurs unpredictably
and usually depends on the amount of rainfall in the rainy season.
These analyses show that the new landslide will be in a state of long-term creep-intermittent
sliding and may exhibit overall sliding or local failure in its forepart during the rainy season.
Deformation and failure are mainly affected by the amount of rainfall; however, providing an
accurate rainfall threshold for the occurrence of the overall sliding is very difficult because the
monitoring frequency of the inclinometer is very low and is not synchronized with rainfall
monitoring. We can only roughly speculate that overall sliding may occur when monthly
precipitation reaches more than 500 mm during the rainy season.
CONCLUSIONS
(1) The Wenchuan earthquake in 2008 has no significant effects on the deformation of the
Xiakou landslide.
(2) The new landslide is currently undergoing slow compression deformation in its front. The
deformation in the forepart is larger compared with that in the central and posterior parts.
Moreover, the deformation in the forepart has obvious intermittent increases that are consistent
with the rainy season every year. The new landslide will remain a creep in the long term;
however, the occurrence of sliding is still possible.
(3) The deformation development of the new landslide is largely influenced by rainfall. The
rapid increase in groundwater levels in the forepart and central part will largely reduce slope
stability. To predict the state of the new landslide, the Janbu method can be combined with the
real-time monitoring of groundwater level.
(4) The support structures in the front of the landslide and the surface drainage on slope can
effectively mitigate landslide deformation. Additionally, real-time monitoring of the forepart and
central part should be strengthened to improve research on the early warning of landslides.
ACKNOWLEDGEMENT
This study is part of the “research, development, and validation of sensor networks for the
monitoring and warning of geological hazards” (Project no. 2010ZX03006-007) supported by the
Ministry of Industry and Information Technology of the People's Republic of China.
REFERENCES
1. Lansford J. (1999) “Conquering the Mountains”, Civil Engineering, 69(10), 32-37.
2. Karikari-Yeboah O. and Gyasi-Agyei Y. (2000) “Stability of Slopes Characterised by
Colluvium: Investigation, Analysis and Stabilization”, International Conference on
Geotechnical and Geological Engineering, November, 2000, Melbourne, Australia.
3. He, Keqiang., Yang, Jibao. and Wang Sijing. (2007) “Landslide Displacement Dynamics
Theory and Its Applications – Several Typical Colluvium Landslide In Three Gorges
Reservoir Area” (in Chinese). Beijing: China Science Press.
Vol. 17 [2012], Bund. X
3428
4. Zhao, Yu. (2001) “Mechanical Analysis Of Sliding Process Of Ya'an Xiakou Landslide
And Prediction Of Its Hazard Model (in Chinese)”, Journal of Engineering Geology,
9(2), 188-192.
5. Zhang, Youyi. and Hu, Xiewen. (2007) “Creep Monitoring and EvolutionTrend Analysis
of Xiakou Landslide in Ya’an (in Chinese)”, Railway Engineering, 5, 69-72.
6. He, Pengpeng. (2010) “Reliability Analysis Of Xiakou Slope Under Multiple-StochasticFactor Conditions (in Chinese)”, Chinese Journal of Geotechnical Engineering. 32(6),
930-937.
7. China Government (2008) “The Assessment Report on the Area Range of Wenchuan
Earthquake Disaster (in Chinese)”
8. Yin, Yueping. (2009) “Wenchuan Earthquake Geohazards”, Beijing: Geological
Publishing House Press.
9. Li, Yi. and Wu, Shengpin. (2002) “Ya’an City Records (in Chinese)”, Chengdu: Sichuan
Science and Technology Press.
10. Liu, Mingman. (1998) “Introduction to the Comprehensive Treatment of Xiakou
Landslide (in Chinese)”, Sichuan hydraulic, 19(2), 33-34.
11. Fleming, R.W. and Johnson A.M. (1994) “Landslide in Colluvium”, U.S. Geological
Survey Bulletin 2059-B. Washington: United States Government Printing Office.
12. Ayalew, L., Yamagishi, H., Marui, H. and Kanno, T. (2005) “Landslides in Sado Island
of Japan: Part I. Case studies, monitoring techniques and environmental considerations”,
Engineering Geology. 81(4), 419-431.
13. Corsinia, A., Pasutob, A., Soldatia, M., Zannonib, A., (2005) “Field Monitoring of the
Corvara Landslide (Dolomites, Italy) and Its Relevance for Hazard Assessment”,
Engineering Geology. 66(4), 149-165.
14. Wilkinson, P.L., Brooks, S.M. and Anderson, M.G. (2000) “Design And Application Of
An Automated Non-Circular Slip Surface Search Within A Combined Hydrology And
Stability Model (CHASM)”, Hydrological Processes, 14, 2003-2017.
15. Wilkinson, P.L., Anderson, M.G. and Lloyd, D.M. (2002) “An Integrated Hydrological
Model For Slope Stability Earth Surface Processes”, Landforms, 27, 1267-1283.
16. Yao, Aijun. and Xue, Tinghe. (2008) “The Evaluation Methods Of Complex Slope
Stability And Engineering Practice (in Chinese)”, Beijing: China Science Press.
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