1. Transformation models and their applications in geotechnical design
Jianye Ching (National Taiwan University)
Marcos Arroyo, Jieru Chen (contributor of SAND/7/2794), Celeste Jorge, Tim Länsivaara (contributor of F-CLAY/7/216), Dianqing Li, Paul Mayne, Kok-Kwang Phoon, Widjojo Prakoso, Marco Uzielli
June 5 Geo-Risk 2017
Transformation models and their applications in geotechnical design

2. Transformation models
Models that convert test results to design parameter
Mostly based on generic/global dataset
Kulhawy & Mayne (1990)
How do these models perform?
For a region
For a specific site

3. OCR versus su/v dataset
CLAY/10/7490 dataset
30 regions, 250+ studies
All su converted to su(mob)
Median estimate
95% confidence interval
Transformation uncertainty
Ching, J. and Phoon, K.K. (2014). Transformations and correlations among some clay parameters – the global database, Canadian Geotechnical Journal, 51(6),

4. OCR versus su/v model
How does it perform for a region?
Scandinavia dataset
Courtesy of Tim Länsivaara
22 sites, 168 data points
All su converted to su(mob)
Median estimate
Systematically biased
95% confidence interval
Not genuine 95%

5. OCR versus su/v model
What does it perform for specific site(s)?
Individual site can have its own local trend
Median estimate
Systematically biased
95% confidence interval
Typically too wide
Ensemble global sites
Unbiased
Genuine 95%

6. Global transformation models
Biased for a region or a specific site
Wide confidence interval (conservative)
Unbiased for ensemble global sites
Genuine 95% confidence interval

7. Future needs Intermediate transformation models
Site-specific models are good, but not enough data
Large statistical uncertainty
Global models can be biased and with wide CI
Large transformation uncertainty
Is there something in between that works well?
Fusion between limited site-specific data and global data?
Accumulate soil & rock databases
Make them available to the public
Web software & Apps
Sinotech cooperation

8. Thank you
(Some useful global transformation models are at the end of Chapter 1)