2182
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
which describe the severity degree, and landslide depth, which
reflects the spatial dimensions. The model is defined as:
I
def
= 1 – (1 –
I
d-def
)(1–
I
d-vel
)(1–
I
d-dep
)
(2)
where
I
d-def
,
I
d-vel
and
I
d-dep
are the parameters for deformation,
velocity and landslide depth at the location of the structure. The
deformations include settlement, horizontal movement and in-
clination (Bell 1978; Peng 1992; Zheng 2007). A basic relation-
ship (Eq. 3) seems to provide a good approximation:
W
s
= aW
g
+ bW
s
(3)
where
W
s
and
W
g
are the deformations of structure and ground,
a
is the slope and
b
is the intercept. Table 1 gives the range of
a
and
b
vs movement and structure types (Peng 1992; Zheng
2007). The deformation intensity depends on the ratio of defor-
mation to allowable threshold value as shown in Table 2.
Table 1.
a
and
b
as function of ground deformation and structure type
Brick masonry,
concrete structures
Reinforced (RC)
concrete structures
Structure
a
b
a
b
Settlement (mm)
0.87-0.99 0.50-1.27 0.96-1.03 1.19-3.57
Tension (mm/m)
0.74-0.89
—
0.68-0.71
—
Compression (mm/m) 0.28-0.32
—
0.24-0.27
—
Inclination (mm/m)
0.99-1.06 0.80-0.90 0.69-0.97 0.03-0.2
Table 2. Proposed value of intensity parameters for deformation
Ratio of deformation to allowable threshold
I
d-def
<0.2
0.1
0.2-0.4
0.2
0.4-0.6
0.4
0.6-0.8
0.6
0.8-1.0
0.8
1.0-1.2
0.9
≥1.2
1.0
According to the landside movement scale and response of
structures (Cruden and Varnes 1996), the intensity of the land-
slide velocity can be obtained by the model described in Eq. 4
(Li 2010).
v
is the velocity of landslide (mm/s).
For
≤5x
I
d-vel
=
For 5x
≤5 x
I
d-vel
=
log
10
For
≥5x
I
d-vel
= 1
For structures on a moving landslide, the degree of damage de-
pends mainly on the relative depth of the structure foundation to
the sliding surface. Ragozin (2000) quantified the vulnerability
of structures as a function of the foundation depth
h
(m) de-
pending on the depth of predicted landslide
d
(m).The model
described by Eq. 5 is proposed used.
For
d/h
<0.8
I
d-dep
= (1.25 ·
d/h
)
1/3
For 0.8<
d/h
≤1.2
I
d-dep
= 1
(5)
For
d/h
>1.2
I
d-dep
= 1.44 · (
d/h
)
-2
3.2
Failure stage
3.2.1
Landslide intensity for structures
The structures located within the release zone of a rapidly mov-
ing landslide are completely destroyed and have a vulnerability
of 1.0. For the structures within the run-out distance, the impact
mechanisms can be divided into two main categories: burial and
impact pressure. For structures, the intensity of the landslide is
defined as a function of its depth and impact pressure, where
I
pre
and
I
f-dep
are impact pressure and landslide depth parameters:
I
fai-s
= 1 – (1 –
I
pre
)(1 –
I
f-dep
)
(6)
(1) Impact pressure
After the landslide fails, the horizontal impact pressure is the
main cause of damage to structures (Glade 2004; Ulusay 2007).
Petrazzuoli (2004) analyzed the collapse limit load of regular
and irregular RC structures to horizontal pressure with the
strong beams and weak columns structural models. The pro-
posed vulnerability model uses the average value of each typol-
ogy to estimate the horizontal pressure limit
P
vs the number of
stories
n
, in which the values of coefficient α and β for each
structure type are listed in Table 3.
P = α
ln(
n
) +
β
(7)
Table 3. Coefficients α and β in Eq. 7 for different structure types.
Structure
Strongly
aseismic
Weakly
aseismic
Strongly
non-aseismic
Weakly
non-aseismic
Regular structure
Α
-4.384
-2.717
-2.157
-1.276
Β
19.125
13.164
10.568
7.693
Irregular structure
Α
-3.779
-2.467
-1.821
-1.343
Β
14.553
10.288
8.068
6.066
The ratio of landslide impact pressure on the building to
horizontal pressure limit is defined as the intensity parameter
I
pre
(Table 4). The horizontal pressure limit of RC frame can be
obtained according to Eq. 7, while the limit pressure of terra-
cotta panels in Table 5 can be used for masonry structure.
Table 4. Proposed values of impact pressure intensity parameter.
Landslide impact pressure/Structure horizontal pressure limit
I
pre
<0.1
0.05
0.1-0.2
0.20
0.2-0.4
0.40
0.4-0.7
0.70
0.7-1.0
0.90
≥1.0
1.00
Table 5. Estimated resistances of buildings and elements (Spence 2004)
Building elements
Failure pressure(kPa)
Terracotta tile infill panel with openings
7.6-8.9
Terracotta tile infill panel without openings
5.5
Tuff infill panel (length 4 m, thickness 40 cm)
6.8-9
Tuff infill panel (length 4 m, thickness 60 cm)
10-13
Weak non-aseismic RC buildings (1 to 3 storeys)
4.5-8
Strong non-aseismic RC buildings (4 to 7 storeys)
5-9
Weak aseismic RC buildings (multi-storeys)
5-10
Strong aseismic RC buildings (multi-storeys)
6-14
(2) Landslide depth
As inferred from the structural damage, the intensity parameter
for landslide depth should be defined as the ratio of landslide
depth to height of structure. When landslide depth is equal to or
greater than the structure, the structure loses completely lose its
functionality. The proposed values of I
f-dep
are found in Table 6.
Table 6. Proposed values of landslide depth intensity parameter
Ratio of landslide depth to height of structure
I
f-dep
<0.2
0.10
0.2-0.4
0.30
0.4-0.6
0.50
0.6-0.8
0.70
0.8-1.0
0.90
≥1.0
1.00
Depending on location, the persons within the affected area
can be divided into two categories: indoors and outdoors.
Land-
slide velocity, depth and width become the intensity parameters:
I
fai-p
= I – (I –
I
f-vel
)
(I –
I'
f-dep
)(I –
I
wid
)
(8)
where
I
f-vel
,
I'
f-dep
and
I
wid
are the parameters of landslide veloc-
ity, depth and width, respectively. A moving slide depth greater
than knee-height makes it difficult to escape. Using 1.6 m and
0.482 (Swami 2006) as average height and leg ratio, a threshold
value of 0.8m for critical landslide depth is obtained. The values
of
I'
f-dep
in Table 7 are proposed:
For landslide width, five degrees are identified to allow for
change in landslide activity conditions (Table 8). The landslide
velocity scale defined by Eq. 9 is identical to that proposed by
Li (2010). The value ν is the velocity of the landslide (mm/s).
For
≤5x
I
d-vel
=
For 5x
≤5 x
I
d-vel
=
log
10
For
≥5x
I
d-vel
= 1
