Browsing by Author "Ching, Jianye"

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Generic transformation models for some intact rock properties
(2018-12-01)
Ching, Jianye
;
Li, Kuang-Hao
;
Phoon, Kok-Kwang
;
Weng, Meng-Chia
;
土木工程學系
A global intact rock database of nine parameters, including uniaxial compressive strength and Young's modulus, is compiled from 184 studies. This database, labeled as "ROCK/9/4069", consists of 27.5% igneous rock, 59.4% sedimentary rock, and 13.1% metamorphic rock. The vast majority (>95%) of intact rocks in the database are in their natural moisture contents. About 14% of the data points are for weathered rocks and about 4% are foliated metamorphic rock. It is found that most existing transformation models are data-specific or site-specific in the sense that they fit well to their own calibration databases, but do not necessarily fit well to ROCK/9/4069. One can infer that transformation models for intact rocks are more data-site dependent than those for soils. It is evident that ROCK/9/4069 has coverage wider than most existing transformation models. The ROCK/9/4069 database is then adopted to calibrate the bias and variability of existing transformation models. Transformation models with relatively large application ranges and relatively small transformation uncertainties are selected as generic transformation models. These generic models can be valuable for scenarios where site-specific models are not available, e.g., construction projects with insufficient budget or the preliminary design stage of a project.
Multivariate probability distribution for some intact rock properties
(2019-08-01)
Ching, Jianye
;
Phoon, Kok-Kwang
;
Li, Kuang-Hao
;
Weng, Meng-Chia
;
土木工程學系
A multivariate probability distribution model for nine parameters of intact rocks, including unit weight (gamma), porosity (n), L-type Schmidt hammer hardness (R-L), Shore scleroscope hardness (S-h), Brazilian tensile strength (sigma(bt)), point load strength index (Is(50)), uniaxial compressive strength (sigma(c)), Young's modulus (E), and P-wave velocity (V-p), is constructed based on the ROCK/9/4069 database that was compiled by the authors. It is shown that the multivariate probability distribution captures the correlation behaviors in the database among the nine parameters. This multivariate distribution model serves as a prior distribution model in the Bayesian analysis and can be updated into the posterior distribution of the design intact rock parameter when multivariate site-specific information is available. In this paper, the parameters for the posterior distribution of the design intact rock parameter are summarized into user-friendly tables so that engineers do not need to conduct the actual Bayesian analysis. Caution should be taken in extrapolating the results of this paper to cases that are not covered by ROCK/9/4069, because the resulting posterior distribution can be misleading.