• 한국지반신소재학회논문집
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• 제17권4호
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• pp.21-28
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• 2018

대심도 연약지반을 개량하여 상부에 개설되는 도로 등 각종 시설물의 안전을 확보하기 위해서는 공용개시 후 잔류 침하량에 대한 명확한 이해를 바탕으로 한 합리적인 설계관리기준의 설정과 예측 값 산정이 매우 중요하다. 그러나 지난 수십 년 동안 낙동강 하구 일원 등 대심도 연약지반상의 지반개량을 통해 조성된 부지에서는 설계단계에서 예측한 잔류 침하량을 크게 상회하는 침하가 발생하여 많은 시설물의 파손과 아울러 사회적인 논란을 야기되고 있음에도 이에 대한 연구는 거의 전무한 실정이다. 본 논문에서는 공용하중 개시 이후 장기간에 걸쳐 발생하는 잔류 침하에 대한 기초적이며 실무적인 연구를 위해, 대심도 연약지반개량을 통해 조성된 부지에서 약 10년에 걸쳐 측정한 침하계측결과를 이용하여 장기 침하거동 양상을 분석하였다. 그 결과 계측된 잔류침하량은 점성토층의 두께의 차이로 지점별로 차이가 있으나 침하양상은 모든 계측결과가 유사하였으며, 쌍곡선 함수식을 이용한 장래 잔류침하 예측결과와는 매우 좋은 일치를 보였다. 또한, 하부 미개량층에서 발생한 침하량이 전체침하량의 대부분(62-76%)을 차지하는 것으로 확인되어 개량층을 대상으로 허용침하량을 규정하고 있는 국내의 현실에 좀 더 신중한 고민이 필요한 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1110-1116
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• 2010

Void ratios are one of the key parameters for exact calculation of settlement of soft groundse. In the study, shear wave velocities of a soft ground were used to measure the field void ratio using bender elements sensors. The bender-element probes were installed in situ at the depths of 3, 5 and 8m on a pre-loading site near Incheon, Korea. During 90 days after installation, the changes of shear wave velocity and ground surface settlement were measured. The field void ratio was estimated from measured shear wave velocities. The void ratio estimated by the shear wave velocity measured by bender elements agrees well with the measured values in the field.

• 한국농공학회논문집
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• 제54권1호
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• pp.39-45
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• 2012

In this study, field test on utilization of recycled aggregates and crushed stone as horizontal drains to use an alternative material of sand in soft ground is practiced. The settlement with time showed similarly ranged from 28.4-30.3 cm in the all horizontal materials. The excess pore water pressure of the recycled aggregates and crushed stone showed smaller than sand. The small the excess pore water pressure becomes faster the consolidation period and it can reduces the amount of residual settlement. Therefore, it was verified as having enough to an alternative materials that the field applicability is excellent. The distribution of earth pressure with time showed similarly in the all horizontal materials. The recycled aggregates and crushed stone was very applicable to practice because there is no mat resistance in the horizontal drains layer. The penetration rate in the SCP and PVD improvement sections did not show large differences as the grain size and the horizontal drainage height increases.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1256-1263
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• 2010

Suction Drain Method is soft ground improvement technique, in which a vacuum pressure can be directly applied to the Vertical Drain Board to promote consolidation and strengthening the soft ground. This method does not require a surcharge load, different to embankment or Preloading Method. In this study, ground improvement efficiency of suction drain method was estimated when duplex loading pressure with vacuum and pressure. During suction drain method process, surface settlement and pore pressure were monitored, and cone resistance test as well as water content were also measured after the completion of Suction Drain Method treatment.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.272-279
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• 2005

This paper introduces a new method of improvement for marine soft ground, MLPP(Marine Large Pack Pile). The MLPP is a reinforcement technique for the conventional SCP or GCP piles by confining with geotextile pack. A pilot project at Busan New Port site and laboratory model tests were carried out to investigate the settlement reduction and bearing capacity enhancement effect of pack pile. The results of field and laboratory tests show that MLPP method can be a safe and economic alternative method for SCP and GCP.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 준설 및 환경매립에 관한 학술세미나
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• pp.35-48
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• 1999

낙동강은 그 하구 근처에서 김해평야하고 부르는 델타지역을 형성하였다. 김해평야에 퇴적된 점성토는 다른 나라의 점토층에 비해 유달리 두껍다 (최대 60m). 이 지역의 일부는 새로운 공업단지의 개발을 위해 연직 배수재를 설치한 후 평균 5-7m의 높이로 매립하였다. 연약 지반 위에 매립작업을 수행하면서 침하량을 측정하였는데, 실측침하량은 이론적으로 예측한 침하량보다 현저히 크다는 것을 알게 되었다. 이 논문은 김해점토의 퇴적환경의 관점에서 과다침하가 발생되는 이유를 기술하고 있다.

• Coupled systems mechanics
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• 제3권2호
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• pp.233-245
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• 2014

Coupled finite element analysis is carried out to study the effect of degree of saturation on the vertical displacements and pore water pressures simultaneously by developing a FORTRAN90 code. The finite element formulation adopted in the present study is based upon Biot's consolidation theory to include partially saturated soils. Numerical methods are applied to a two-dimensional plane strain strip footing (flexible) problem and the effect of variable degree of saturation on the response of excess pore water pressure dissipation and settlement of the footing is studied. The immediate settlement in the case of partly saturated soils is larger than that of a fully saturated soil, the reason being the presence of pore air in partially saturated soils. On the other hand, the excess pore water pressure for partially saturated soil are smaller than those for fully saturated soil.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 지반환경 및 준설매립에관한 학술세미나
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• pp.96-109
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• 2001

Land was reclaimed at the waterfront in the Pluit area of Jakarta for a 90ha residential-cum-recreational development. The reclamation works involve construction of permanent and temporary dykes, fill placement, soil improvement, dredging of internal canals and marina, and construction of canal revetment. The site lies on 16m to 18m thick soft seabed deposits. Settlement of the reclaimed areas will result as a consequence of consolidation of the soft underlying sediments. In order to reduce post-construction settlement to within acceptable levels, a system of vertical drains and preloading was adopted. This paper describes the use of Fibredrain, a prefabricated vertical drain made of jute and coir fibres developed at the National University of Singapore, in the soil improvement works and a secondary use in the construction of perimeter dykes for the reclamation works. The construction of the perimeter dyke must be carried out in such a way that slope stability is on ensured. Bamboo rafts and bamboo clusters with Fibredrain inserted, and stage construction were employed to improve stability during the dyke formation for the Pantai Mutiara project.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1007-1013
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• 2004

A three-arch NATM tunnel with a total length of 53.5m has been constructed for a metropolitan subway station in Daejon, Korea. The tunnel, whose crown is located 22m below the ground, crosses the old Daejon station underneath. Since the tunnel comprises a very large section (10${\times}$28 m; largest in Korea), it shows complicated mechanical behaviors, especially near portal, due to its short length relative to width. As far as its construction step is concerned, the center tunnel is excavated with pre-excavated pilot tunnel, which is a unique feature of this tunnel (first in Korea) to secure safety during construction and prevent excessive settlements. The both side tunnels are then excavated along with the center tunnel. Since significant amount of settlement was predictable from the design stage, extensive monitoring was performed during construction. During excavation of the side tunnels, unexpected large settlements up to ${\~}$140mm (estimated 41.8 mm at design stage) was measured at the center tunnel. In this paper, we study the causes of this unusually large ground settlement. We believe that the extra-wide tunnel excavation increases the stress influence zone of portal in longitudinal direction and consequently add more settlements to the existing due to excavation and consolidation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.905-917
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• 2008

Road or Railway construction over soft ground is needed to be considered on secondary consolidation which will be caused differential settlement, lack of transport serviceability, higher maintenance cost. Especially for the railway construction in the second phase of Gyung-Bu or Ho-Nam high speed railway, concrete slab track has been adapted as a safe and cost effective geotechnical solution. In this case controlling the total settlement under the tolerance is essential. And pile supported geogrid reinforced construction method is suggested as a solution for the problem of the traditional method on soft soil treatments. Pile supported geogrid reinforced construction method consists of piles that are designed to transfer the load of the embankment through the compressible soil layer to a firm foundation. The load from the embankment must be effectively transferred to the piles to prevent punching of the piles through the embankment fill creating differential settlement at the surface of the embankment. The arrangement of the piles can create soil arching to carry the load of embankment to the piles. In order to minimize the number of piles geogrid reinforced pile supported construction method is being used on a regular basis. This method consists of one or more layers of geogrid reinforcement placed between the top of the piles and the bottom of the embankment. This paper presents several methods of pile supported geogrid reinforced construction and calculation results from the several methods and comparison of them.