Browsing by Author "Lee, Jui-Ting"

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A Fiber Optic Sensored Triaxial Testing Device
(2011-03-01)
Lee, Jui-Ting
;
Tien, Kai-Cheng
;
Ho, Yen Te
;
Huang, An-Bin
;
土木工程學系
The physical quantities involved in a triaxial testing device have mostly been monitored with electric sensors. These sensors are currently subject to short circuit when submerged under water and electromagnetic interference (EMI). Waterproofing and EMI noise filtration have often been a challenge to the triaxial test set-up. These drawbacks can be substantially minimized when using optic fiber sensors. The optic fiber Bragg grating (FBG) sensors have the additional advantage of being partially distributive where multiple sensors can share the same signal transmission line. Taking advantage of these unique capabilities, the authors explored the possibility of converting all pressure/force and linear displacement transducers in a triaxial testing device into FBG based sensors. A series of shearing tests on unsaturated and saturated soil specimens were carried out using the new FBG sensored triaxial testing device. In most cases, the measurement of physical quantities was paired with electric sensors so that the results can be compared. This paper describes the principles of the individual FBG sensor designs and demonstrates their applications in triaxial testing.
Characterization of reservoir sediment under water with differential pressure-sensored flat dilatometer and piezo-penetrometer
(2013-08-01)
Lee, Jui-Ting
;
Wang, Chien-Chih
;
Ho, Yen-Te
;
Huang, An-Bin
;
土木工程學系
The unusually strong typhoons and heavy rainfalls occurred recently in Taiwan have caused major landslides in many reservoir catch basins. The debris from these landslides eventually settled in the reservoir and turned into mud. From soil mechanics point of view, the mud immediately in front of the dam where the reservoir is usually the deepest is a very young, normally consolidated or under-consolidated fine-grained soil. The engineering properties of the reservoir mud are important parameters in the planning and design of schemes to remove the mud. Yet, our knowledge in this regard is very limited. For some of the major reservoirs in Taiwan, the mud is often under more than 40 m of water. How to conduct effective geotechnical site characterization under these circumstances is a challenge. The authors developed techniques to incorporate differential pressure measurements in flat dilatometer (Delta DMT) and piezo-penetrometer (Delta Pu) tests to facilitate in situ measurements under water in a reservoir. A series of field Delta DMT and Delta Pu tests along with representative soil sampling were conducted at Tsengwen Reservoir in southern Taiwan. The paper describes the techniques of Delta DMT and Delta Pu tests, interpretation of available test data to obtain the engineering properties of the reservoir mud, and discusses implications in the future site characterization of reservoir mud.
Stability monitoring of rainfall-induced deep landslides through pore pressure profile measurements
(2012-08-01)
Huang, An-Bin
;
Lee, Jui-Ting
;
Ho, Yen-Te
;
Chiu, Yun-Fang
;
Cheng, Shyr-Yuan
It has long been recognized that field hydrological and geomechanical properties/conditions are the key elements controlling the stability of a slope under the influence of rainfall. Warning systems based on rainfall or ground displacement measurements are popular methods currently being used to minimize the hazards of landslides. When field hydrological monitoring is used, it usually involves a limited number of sensors for either positive or negative pore-water pressure measurements. The available numerical schemes that couple pore-water pressure with a geomechanical analysis are the most suitable for shallow slope failures. Due to the variable and transient nature of the hydrological conditions in earth slopes, field measurements that reflect the pore-water pressure profile on a realtime basis would be highly desirable. Thus, the authors have developed a piezometer system that is based on optical fiber Bragg grating (FBG) pressure sensors. With this system, an array of nine sensors was installed in a single, 60-m-deep borehole to monitor the pore-water pressure profile in a highway slope in Southern Taiwan. This paper describes the details of the FBG sensor array installation in the field and the data obtained throughout three typhoons from 2008 to 2010. The results demonstrate that the field readings can be readily incorporated into the existing mechanics-based analytical framework and can predict the potential of an upcoming slope failure. (C) 2012 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved.