Introduction
Date | Trigger | Note |
---|---|---|
June 6, 1862 | Earthquake (M = 7.0) | Landslide; formation of a landslide dam |
December 17, 1941 | Earthquake (M = 7.1) | Landslide volume: 84 × 106 m3. Landslide dam (70–200 m in height) was formed. A dammed lake contained 12.8 × 106 m3 of water |
August 10, 1942 | Rainfall: 3 days’ cumulative precipitation of 770 mm | Landslide volume: 100 × 106 m3. Landslide dam (140–217 m in height) formed. A larger dammed lake containing 157 × 106 m3 of water, which falled on May 18, 1951, killing 147 people |
August 15, 1979 | Rainfall: 2 days’ cumulative precipitation of 327 mm | Landslide volume: 26 × 106 m3. A landslide dam (90 m in height) formed and a dammed lake contained 40 × 106 m3 of water |
September 21, 1999 | Chi–Chi Earthquake (M
L = 7.3) | Landslide volume: 125 × 106 m3. A debris dam formed with a height of 50 m at upstream and 150 m at downstream. Estimated storage capacity larger than 46 × 106 m3
|
The 1941 Tsaoling landslide
Slope stability
Geological framework
Geological setting of the Tsaoling area
The landslide geology in of Tsaoling
The role of groundwater
Earthquake | ML | Date | Longitude | Latitude | Distance To Tsaoling (km) |
---|---|---|---|---|---|
Chi–Chi earthquake | 7.3 | 1999/09/21 | 120.82 | 23.85 | 33.6 |
After shock of Chi–Chi earthquake | 6.6 | 1999/09/21 | 120.86 | 23.80 | 31.1 |
Chiayi earthquake | 7.1 | 1941/12/17 | 120.50 | 23.40 | 27.5 |
Ruali earthquake | 6.2 | 1998/07/17 | 120.66 | 23.52 | 6.5 |
Newmark method analysis and distinct element modeling
Newmark displacement method
Distinct element modeling and granular material simulation
Biaxial test
Stability of numerical experiments for the Tsaoling landslide
The PFC2D model
Item | Cholan formation | PFC model (Macroproperties) |
---|---|---|
Density | 2.500 kg/m3
| 2,650 kg/m3
|
Φ
r
| 18.9° (0.342) Lee et al. (1993) | 18.9° |
Young’s modulus (E) | 3.58 GPa Chen (2005) | 3.60 GPa |
UCS | 37.3 MPa Chen (2005) | 37.5 MPa |
Item | PFC model (Microproperties) |
---|---|
Minimum radius (R
min) | 1.52 m |
Ball radius ratio (R
max
/R
min) | 2 |
Ball-ball contact modulus (Ec) | 3.0 GPa |
Ball stiffness ratio (k
n/k
s) | 2 |
Ball friction coefficient (μ) | 0.5 |
Parallel bond radius multiplier (λ) | 0.8 |
Parallel bond modulus (\( \bar{E}_{\text{c}} \)) | 3.0 GPa |
Parallel bond stiffness ratio (\( \bar{k}_{\text{n}} /\bar{k}_{\text{s}} \)) | 2 |
Parallel bond normal strength (\( \bar{\sigma }_{\text{c}} \)) | 48 MPa |
Parallel bond shear strength (\( \bar{\tau }_{\text{c}} \)) | 24 MPa |
Station number | Distance to epicenter | Vertical of PGA (g) | N–S of PGA (g) | E–W of PGA (g) |
---|---|---|---|---|
(a) The 1999 Chi–Chi earthquake records | ||||
CHY028 | 32.1 | 0.342 | 0.765 | 0.637 |
CHY029 | 38.9 | 0.161 | 0.238 | 0.289 |
CHY080 | 31.7 |
0.731
|
0.859
|
0.809
|
CHY101 | 30.9 | 0.165 | 0.398 | 0.340 |
CHY074 | 38.8 | 0.100 | 0.160 | 0.234 |
(b) The records of M = 6.6 aftershock | ||||
CHY028 | 23.69 | 0.048 | 0.141 | 0.167 |
CHY029 | 40.27 | 0.030 | 0.071 | 0.070 |
CHY080 | 30.18 |
0.114
|
0.220
|
0.474
|
CHY101 | 33.31 | 0.220 | 0.122 | 0.146 |