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降雨誘發廣域山崩模型之力學參數逆分析實際案例

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降雨誘發廣域山崩模型之力學參數逆分析實際案例

報告者：陳麒任

指導教授：董家鈞

Classification of landslide assessment:

- Qualitative analysis
- Empirical method

- Quantitative analysis
- Statistic method
- Discriminant analysis
- Logistic regression
- Conditional Probability Approach

- Artificial intelligence
- Fuzzy Theory
- neural network

- Deterministic analysis
- Infinite –slope stability analysis

- Statistic method

Deterministic analysis of rain fall-induced landslides

Cohesion

Lab test

Lab test

Back calculate

Friction angle

Back analysis of strength has advantages over lab testing in that the scale is much larger. (Gilbert ,1998)

hydraulic conductivity

Deterministic analysis

hydraulic conductivity

Soil depth

Soil depth

DEM

DEM

unit weight of soil

unit weight of soil

Slope

Slope

Deterministic analysis

Predicted landslide inventory

Parameters

In situ test or Empirical methods

In situ test or Empirical methods

Rainfall intensity

Rainfall intensity

Godt et al. (2008)

Remote sensing

Remote sensing

Observed landslide inventory

Efficiency: (+)/(+++)

Sensitivity: /(+)

Specificity: /(+)

Observed

Predicted

Confusion matrix

Cohesion =1 to 50 kPa

Friction angle=1 ° to 50 °

Deterministic analysis

trial and error

Predicted landslide inventory

Observed landslide inventory

ROC

Criterion

Sensitivity: /(+)

Maximum Efficiency(林衍丞，2009) 。

Maximum AUC (林衍丞，2009) 。

Efficiency greater than 80%, Sensitivity greater than 60% and Specificity greater than 90%(中興工程顧問社，2004)。

FS=1

FS=1.5

FS=0.5

Sensitivity

Maximum Develop Sensitivity

Maximum the average of Efficiency, Sensitivity and Specificity

林衍承(2009)

Specificity

100%

Observed

Predicted

Observed

Predicted

Minimum distance between the corner(1,1,1) and the plane.

Compare results of each criterion

Back calculate the parameters (friction angle and cohesion)

- This research use TRIGRS, a Fortran program developed by USGS.
The Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability.

- Parameters: precipitation intensity, slope, soil depth, initial water-table depth, saturated vertical hydraulic conductivity, hydraulic diffusivity, cohesion for effective stress, angle of internal friction for effective stress, total unit weight of soil.

- Infinite-slope stability
- Landslide with planar failure surfaces.
- Slide depth is much smaller than length and width.
where c’ is soil cohesion for effective stress, Φ’ is the soil friction angle for effective stress, γw is unit weight of groundwater, and γs is soil unit weight, β is slope angle, ψ is pressure head.

Richards equation coordinate system

One-dimensional form

(linear diffusion equation)

(initial condition)

(boundary condition)

Cohesion=1,50

Friction angle=1,50

Observed landslide inventory

Criterion

Sensitivity

Efficiency

Specificity

Predicted landslide inventory

Cohesion

Friction angle

TRIGRS

Parameter

Discussion

Slope

Soil depth

Input parameters

Storm event

Iverson (2000)、吳佳郡(2006) 、中興工程顧問公司(2004) 、Paolo (2001)和Lancaster (2002)

2001/7/29 ~ 2001/7/30

Result of maximum AUC criterion

Five largest AUC parameters

Parameter number of maximum value within 1% is 1467. It’s hard to distinguish the most suitable parameter.

Landslide inventory

Five largest Efficiency parameters

Parameter number of maximum value within 1% is 489.

Cohesion=47 kPa Friction angle=39 degree

Efficiency greater than 80%, Sensitivity greater than 60% and Specificity greater than 90%

Parameter number of maximum value within 1% is 18

Five largest Develop Sensitivity parameters

Parameter number of maximum value within 1% is 7

Cohesion=23kPa Friction angle=32degree

The average of Efficiency, Sensitivity and Specificity criterion

Five largest value parameters

Parameter number of maximum value within 1% is 77.

Cohesion=20kPa Friction angle=29degree

Minimum distance between the (1,1,1) and the plane

Five largest value parameters

Parameter number of maximum value within 1% is 6.

C: Efficiency greater than 80%, Sensitivity greater than 60%

and Specificity greater than 90%

D: Develop Sensitivity

E: Average of Efficiency, Sensitivity and Specificity

F: Minimum distance between the corner and the plane

C: Efficiency greater than 80%, Sensitivity greater than 60%

and Specificity greater than 90%

D: Develop Sensitivity

E: Average of Efficiency, Sensitivity and Specificity

F: Minimum distance between the corner and the plane

C: Efficiency greater than 80%, Sensitivity greater than 60%

and Specificity greater than 90%

D: Develop Sensitivity

E: Average of Efficiency, Sensitivity and Specificity

F: Minimum distance between the corner and the plane

Using Bayesian inference to calculate the probability of parameters.

Thanks for your attention