Consolidation Characteristics of Pusan Clays by Constant Rate of Strain and Conventional Oedometer Tests

E. Ninjgarav,Chung, S.G.,M. Suneel,Ganapathi Rao,Kim, G.J. 東亞大學校 建設技術硏究所 2005 硏究論文集 Vol.28 No.2

Large reclamation projects for a new Busan Port have been carried out in the western marginal area of the Nakdong River Estuary where are located at Busan city and its vicinity, south Korea, since the middle of 1990s. In the area studied clay deposits are usually thick, varying from 20m to 70m in thickness. The consolidation behaviour of Pusan clays in investigated by means of constant rate of strain consolidation tests with vertical and horizontal drainage conditions, comparing with those of conventional oedometer tests. For this, a sophisticated sampling technique was adopted for the site, as well as the preparation of specimens. As the results of tests, the sample quality was evaluated using the results of the consolidation testing. The effects of strain rate on consolidation properties such as apparent preconsolidation pressure, compression index and coefficient of consolidation are evaluated for the kinds of the tests. Moreover, the anisotropy of permeability and coefficients of consolidation were also compared with depth. Particularly the consolidation characteristics were presented with depositional environment at the site.

Pore Size Distribution of Pusan Clay Measured by Mercury Intrusion Porosimetry

Enebish Ninjgarav,Sung-Gyo Chung,Woo-Young Jang,Choon-Kil Ryu 대한토목학회 2007 KSCE JOURNAL OF CIVIL ENGINEERING Vol.11 No.3

Little atention was paid to the micro-structural investigation, although a number of geotechnical investigations have beenperformed on Pusan clay since early 1990s. Particularly, pore size distribution (PSD) which affects permeability, consolidation,and strength and so on has seldom been investigated on the clay. In order to examine the PSD during consolidation, mercuryintrusion porosimetry (MIP) investigation was carried out on intact clay and also the one-dimensional consolidated clays withthand also the change with the applied consolidation stress levels. It was recognized that the PSD are remarkably diferent for theuper and lower clays, but the compresion occurred during consolidation stress is dominantly resulted from a decrease in theinter-aggregate (large) pore spaces (larger than 2 m in diameter). Moreover, characteristics of the PSD were effectivelyrepresented by the mean pore size (Dp50).

Pore Size Distribution of Pusan Clay Measured by Mercury Intrusion Porosimetry

Enebish Ninjgarav,Sung-Gyo Chung,Woo-Young Jang,Choon-Kil Ryu 대한토목학회 2007 KSCE journal of civil engineering Vol.11 No.3

Little attention was paid to the micro-structural investigation, although a number of geotechnical investigations have been performed on Pusan clay since early 1990s. Particularly, pore size distribution (PSD) which affects permeability, consolidation, and strength and so on has seldom been investigated on the clay. In order to examine the PSD during consolidation, mercury intrusion porosimetry (MlP) investigation was carried out on intact clay and also the one-dimensional consolidated clays with various stress levels, as well as scanning electron microscope (SEM). As the result, the PSD of intact clay was observed in depth and also the change with the applied consolidation stress levels. It was recognized that the PSD are remarkably different for the upper and lower clays, but the compression occurred during consolidation stress is dominantly resulted from a decrease in the inter-aggregate (large) pore spaces (larger than 2 urn in diameter). Moreover, characteristics of the PSD were effectively represented by the mean pore size (Dp50).

Geological and Geotechnical Characteristics of Marine Clay in Busan New Port

Chung, S.G,E. Ninjgarav,M. Suneel,K.Ganapathi Rao,Kim, G.J. 東亞大學校 建設技術硏究所 2005 硏究論文集 Vol.28 No.2

Since early 1990s reclamation projects for Busan and its vicinity in Nakdong River plain have been performed for industrial and residential complexes. As well it has started to build a new port (Busan Newport) with increase in overloads of Busan port since late 1990s. In the area the sedimentary deposit is composed of soft clay of about 30m thick, thin sand layer of 3-4m thick, hard clayey soil, and then basal conglomerates and sandy sediments, total thickness of which is about 70m at maximum under seawater. For the huge project many contract companies have simultaneously performed geotechnical investigations to get design parameters. Based on the harmful experiences gained by the previous projects, it was also required to pay careful attention to sampling and laboratory and field tests for theproject. Nevertheless the results of laboratory tests were so scattered and then resulted in difficulty to evaluate the design parameters. Existing data has been reviewed to evaluate the validity or cause of their variation. In addition geological study, sampling and soil tests have been carefully carried out at a few locations. Using the results the clay would be effectively characterized for depositional environment and its relation to soil properties.

실내실험에 의한 부산점토의 투수특성

정성교,장우영,E. Ninjgarav,김성렬 한국지반공학회 2006 한국지반공학회논문집 Vol.22 No.11

Pusan clay, which is distributed in the Nakdong River estuary, is unusually soft and thick compared with other clays in the world. Because the consolidation settlement of the clay was significantly underestimated in several recent reclamation projects, it has been emphasized particularly on the need of studying the permeability characteristics. This study carries out vertical and horizontal permeability tests on undisturbed and consolidated samples from two sites of the area. The results of the study show the peculiar permeability anisotropy and the relationships with other indexes on Pusan clay and also comparison with those of other world clays.

낙동강 하구지역 부산점토의 퇴적환경에 따른 압축특성

정성교,류춘길,장우영,E. Ninjgarav 한국지반공학회 2006 한국지반공학회논문집 Vol.22 No.12

In the Nakdong River estuary soft and thick clay, which called Pusan clay, are deposited. Despite a number of great reclaimed projects that have been performed in the area, the consolidation settlement and time have been significantly underestimated due dominantly to sample disturbance, since the last decade. In order to resolve the underestmation, it was necessary to examine the compressibility characteristics through a systematic geotechnical investigation on the clay. In this study an advanced sampling technique was adopted on two sites chosen along the coastline, and then oedometer testing and geological investigation were performed for the undisturbed and reconstituted samples. As the results, the compressibility parameters of the clay were representatively determined, as well as their correlation. Particularly the effects of depositional environment on the physical indexes, level of structure, sample disturbance and compressibility parameters were analyzed for the clay.

Geotechnical Characteristics of Marine Clay in Busan New Port

Chung, S.G.,Ryu, C.K.,Beak, S.H.,Huh, D.Y.,Jo, K.Y.,Lee, N.K.,Ninjgarav 東亞大學校建設技術硏究所 2004 硏究論文集 Vol.28 No.1

Since early 1990s reclamation projects in Busan and its vicinity in Nakdong River plain have been performed for industrial and residential complexes. As well it has started to build a new port (Busan Newport) due to increase in overloads of Busan port since late 1990s. In the area the sedimentary deposit is composed of soft clay of about 30m thick, thin sand layer of 3-4m thick, hard clayey soil, and then basal conglomerates and sandy sediments, total thickness of which is about 70m at the maximum under seawater. For the huge project many contract companies have simultaneously performed geotechnical investigations to get design parameters. Based on the harmful experiences gained by the previous projects, it was also required to pay careful attention to sampling and laboratory and field tests for the project. Nevertheless the results of laboratory tests were so scattered and then resulted in difficulty to evaluate the design parameters. Existing data has been reviewed to evaluate the validity or cause of their variation. In addition geological study, sampling and soil tests have been carefully carried out at a few locations. Using the results the clay would be effectively characterized for depositional environment and its relation to soil properties.