Browsing by Author "Huang, A. B."

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Advanced calibration chambers for cone penetration testing in cohesionless soils
(2004)
Huang, A. B.
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Hsu, H. H.
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土木工程學系
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Department of Civil Engineering
The calibration chamber as it was first introduced had its main purpose to calibrate cone penetration test (CPT) in dry, uniformly graded clean sand. The use of an ingenious cavity-wall design enabled the soil specimen be subjected to either a constant stress or zero strain boundary condition. The calibration chamber allowed full scale CPT to be performed in a uniform specimen with known stress and density state. This unique capability was ideal for establishing correlations between CPT and soil design parameters. Empirical rules based on these correlations have routinely been used for the interpretation of CPT in cohesionless soils. The cavity-wall design, with its large but limited specimen, could not properly duplicate the field conditions where soil extends laterally to infinity. CPT performed in the cavity-wall chamber, regardless of the applied boundary conditions, could yield cone tip resistance values that were significantly lower than what would be expected in the field. Much of the calibration chamber related research in the last three decades has evolved around new techniques to either understand or overcome the boundary effects. Various forms of numerical simulations have been implemented and/or coupled into the physical model for CPT calibration. The test material has extended to silty sand under saturated conditions. Centrifuge has also been experimented as an alternative and may be more efficient way to calibrate CPT in coliesionless soils. The paper reviews these various techniques and discusses their implications in the use of calibration test data and future developments in CPT calibration techniques.
Assessment of liquefaction potential for a silty sand in Central Western Taiwan
(2005)
Huang, A. B.
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Huang, Y. T.
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Ho, F. J.
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土木工程學系
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Department of Civil Engineering
The Chi Chi earthquake of September 21, 1999 triggered extensive soil liquefaction in silty sand deposits in Central Western Taiwan. The post Chi Chi earthquake studies indicated that the fines content adjustments according to the simplified procedure could cause rather inconsistent results amongst various assessment methods. The authors performed a series of cone penetration chamber calibration tests and cyclic triaxial tests on remolded Mai Liao Sand (MLS) specimens, with various fines contents and densities. The triaxial cell was equipped with bender elements and shear wave velocity (V-s) was measured prior to the cyclic shearing test. With these data, the authors were able to calibrate the correlations among CRR, cone tip resistance (q(c)) and V-s for MLS. A test site was developed in Yuan Lin County where standard penetration test (SPT), seismic piezocone and field V-s measurements were performed and low disturbance silty sand samples using a Laval sampler were taken. A series of cyclic triaxial tests were conducted on the Laval samples with V-s measurements using bender elements. These field and laboratory test results were used to validate the correlations among CRR, q(c), and V-s from calibration tests and the simplified procedure typically used in liquefaction potential assessment. This paper describes the laboratory calibration tests on MLS, results from Yuan Lin test site studies and discusses their implications in the assessment of liquefaction potential for the silty sand in this region.
Geotechnical site characterization for reservoir sediment
(2013)
Wang, C. C.
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Huang, A. B.
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Ho, Y. T.
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Lee, J. T.
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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 in front of the dam is a very young, normally consolidated or under-consolidated soil. The engineering properties of the reservoir mud are important design parameters in the planning and design of schemes to remove the mud. Yet, our knowledge in this regard is very limited. For 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 a differential pressure flat dilatometer (Delta DMT) and a piezo-penetrometer (Delta Pu) to facilitate in situ tests 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 differential pressure DMT and piezo-penetrometer tests, interpretation of available test data to obtain the engineering properties of the reservoir mud, and discusses implications in future site characterization of reservoir mud.
Lessons learned from sampling and CPT in silt/sand soils
(2009)
Huang, A. B.
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交大名義發表
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National Chiao Tung University
Recent studies on the liquefaction behavior of sand and silt mixtures have covered a wide range of gradations. The term silt/sand or M/S is proposed as an inclusive abbreviation of soils that can span from clean sand, silty sand to pure silt. Earlier studies related to M/S soils have concentrated mostly on laboratory tests using reconstituted specimens. The author used Laval and gel-push sampler to retrieve high quality M/S samples at test sites in Central and Southern Taiwan. Piezo-cone penetration tests (CPTU) were conducted at the test sites concurrent with the field sampling. Results from natural undisturbed samples and field CPTU showed that the effects of fines are much less significant than what have been revealed from reconstituted soil specimens or field observations. CPTU in heterogeneous alluvial soil can be a drained test even with high fines contents. The age of natural soil deposit may reduce or nullify the effects of fines as we have learned from laboratory tests using freshly reconstituted specimens.
Recent trends in geotechnical earthquake engineering experimentation
(2010)
Elgamal, A.
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Huang, A. B.
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Okamura, M.
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土木工程學系
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Department of Civil Engineering
Experimental facilities and related research have been expanding dramatically, with efforts underway in small-scale centrifuge modeling, large-scale 1-g testing, and full-scale dynamic/seismic investigations. In parallel, the advances in instrumentation and Information Technologies (IT) are allowing for increased insights. Within this framework, researchers are able to increasingly focus on soil-structure system response, gleaning new outlooks that more effectively address current challenges. In view of the possibilities allowed by these current advances, this paper presents an overview of such current activities, findings, and future trends.
Session report: Seismic ground hazards
(2013)
Huang, A. B.
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土木工程學系
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Department of Civil Engineering
There are ten papers under the category of Seismic Ground Hazards in ISC'4. The papers can generally be divided into two groups. The first group deals with assessment or calibration of geophysical/geotechnical field testing methods. The second group relates to case histories in the applications of geophysical/geotechnical field testing methods for soil deposit profiling associated with seismic hazard analysis. This session report highlights the contents of these papers.
Static and cyclic behavior of a silty sand according to tests on undisturbed samples
(2006)
Huang, A. B.
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Huang, Y. T.
;
土木工程學系
;
Department of Civil Engineering
The effects of plastic or nonplastic fines on the static and cyclic strength of sand have been a subject of laboratory studies for many decades. These studies have not lead to a consensus as to how fines can affect the behavior of sand. Earlier studies have mostly been limited to tests on reconstituted specimens. Some of the controversies stem from the concerns that reconstituted specimens may not be able to duplicate the soil fabric in the field. The authors used Laval sampler to retrieve high quality samples in silty sand in Central Western Taiwan, following the procedures reported earlier. A test site was developed in Yuan Lin County where standard penetration test (SPT), seismic piezocone (SCPTU) and field V, measurements were performed in addition to Laval sampling. A series of monotonic and cyclic triaxial tests were conducted on natural and reconstituted Sand specimens. Laboratory V-s measurements were taken on the triaxial specimens using bender elements. With these data, the authors were able to evaluate the static and cyclic characteristics of YLS. This paper describes the results from Yuan Lin test site studies and discusses their implications in the assessment of liquefaction potential for the silty sand in this region.
Undisturbed sampling and laboratory shearing tests on a sand with various fines contents
(2007-08-01)
Huang, A. B.
;
Huang, Y. T.
;
土木工程學系
;
Department of Civil Engineering
The effects of plastic or non-plastic fines on the static and cyclic strength of sand have been a subject of laboratory studies for many decades. These studies have not lead to a concensus as to how fines can affect the behavior of sand. Earlier studies have mostly been limited to tests on reconstituted specimens. Some of the controversies stem from the concerns that reconstituted specimens may not be able to duplicate the soil fabric in the field. The authors used Laval sampler to retrieve high quality samples with a wide range of fines contents in Central Western Taiwan. A test site was developed in Yuan Lin Township where standard penetration test (SPT), seismic piezocone (SCPTU) and field shear wave velocity (V-s) measurements were performed in addition to Laval sampling. A series of monotonic and cyclic triaxial tests with V-s measurements were conducted on natural and reconstituted Yuan Lin Soil (YLS) specimens with fines contents ranging from 18 to 89%. While the study confirmed some of the earlier findings which indicated that fines tend to weaken the soil specimens, the results also showed that the effects of fines may be exaggerated according to tests on reconstituted specimens.