• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.25-32
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• 2001

Doosan Construction & Engineering Co., Ltd is building a railway tunnel beneath the Soo-Young River connecting MinLak Station and Centum City Station, a section 230, subway line 2, Pusan City, Korea. When completed the tunnel will have a finished inner diameter of 6.5m(21.311) throughout its total length of 840m(420m = 0.52 miles, Two Single Track Tunnel : 420m＋420m). The ground profile of the face toward shield machine is composed of multi layers, silty clay, clayey gravel, soft rock etc. This research paper is to predict ground deformation and variation of stresses around tunnel using Hyperbolic model, and to reflect the works on the next shield tunneling project. And this research paper is analyzed data of measuring instrument (such as settlement gauge, inclinometer, Multiple extensometer, etc.) which is installed along tunnel line for safety of tunnel. For calculations, the finite difference Method is applied. Backfill grouting material is supposed to have instantly strength of 10kg/$\textrm{cm}^2$ above, although its strength is available after 24 hours passed.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.277-289
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• 2019

In this study, an innovative anchoring approach has been developed dealing with all relevant aspects in consideration of previous works. An ultimate pulling force calculation of anchor is presented from a geotechnical point of view. The proposed umbrella anchor focuses not only on the friction resistance capacity, but also on the axial capacity of the composite end structure and the friction capacity occurring around the wedge. Even though the theoretical background is proposed, in-situ application requires high-level mechanical design. Hence, the required parts have been carefully improved and are composed of anchor body, anchor cap, connection brackets, cutter vanes, open-close ring, support elements and grouting system. Besides, stretcher element made of aramid fabric, interior grouting system, guide tube and cable-locking apparatus are the unique parts of this design. The production and placement steps of real sized anchors are explained in detail. Experimental results of 52 pullout tests on the weak dry soils and 12 in-situ tests inside natural soil indicate that the proposed approach is conservative and its peak pullout value is directly limited by a maximum strength of anchored soil layer if other failure possibilities are eliminated. Umbrella anchor is an alternative to conventional anchor applications used in all types of soils. It not only provides time and workmanship benefits, but also a high level of economic gain and safe design.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.75-82
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• 2014

Recently, public works becoming bigger in Jeju are implemented various kinds of ground reinforcement method including the chemical grouting method. In this study, we have been investigated on the proper material and the injection condition for the excellent injection effect and the excellent strength of injection material and the permanent waterproof and reinforcement through the experiment. The kind of injection material has been selected through the uniaxial compression test and the endurance test of injection material as the chamber test. An experiment was performed with model ground made of scoria, the injection performance of selected material has been identified through the evaluation test of injection range using the decision test of injection amount and the calibration chamber test. As a result of test, it has been analyzed that MSG appeared to have the excellent strength, durability and injection performance all compared with the ordinary cement, this result is judged to be possible as the ancillary data of design at time of design and construction with the chemical grouting method in the future.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.325-334
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• 2003

It is very difficult to rehabilitate the damaged earth dam core to manage it stably against development of flow path and increase of leakage by hydraulic fracture. In this study, application of CGS (Compaction Grouting System) to damaged earth dam core was noticed by analyzing and comparing the results of the in-situ data and FEM. Results of in-situ data showed that according as progress of rehabilitation works tip pressures increased and volume of injection decreased, voids of damaged dam core were filled with materials similar to origin dam core. Rehabilitations caused turbidity and volume of leakage to decrease at the same water level. Also, results of FEM analysis indicated that permeability decreased by rehabilitation. Through this study, it is proved that CGS is able to decrease permeability coefficient, volume of leakage and turbidity on damaged earth dam core.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1838-1844
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• 2007

The Wonhyo Tunnel on KTX railroad line is a section of latest concerns from domestic environmental NGOs, which focus on potential destruction of ecosystem or the like due to ever-depleted swamp water at about 300m upward from the tunnel under construction. As a result of study, out of all swamps in the vicinity of the tunnel, it was found that Mujechi 1st and 2nd swamps have been getting smaller in their area little by little since 50 years ago primarily under the influence of eroded streams around lower swamp and even ever-increasing annual mean temperature. As the result of monitoring about swamp before work, it was found that swamp water depends absolutely on amount of rainfall. Besides, the results of monitoring during work also didn't show any leakage generated in the tunnel during and after excavation works with regard to a wheat field swamp in the most vicinity of the tunnel (80m away). On the other hand, it was found that the range affected by ground water sink in tunnel section without grouting process amounted to about 100m around the tunnel, which indicates that such ground water sink has no significant impact upon most of swamps near the tunnel. As the result of testing by two well tracer test around swamps, it was noted that swamp water didn't run out from the bottom of swamp even with adjacent ground water level sunk in factitious ways. And the results of physical survey showed that swamp kept saturated even in dry season when ground water level becomes lower than the bottom of swamp. Therefore, even supposing that ground water level becomes sunk due to tunnel works, it is estimated that the water level of swamps would be still kept owing to impervious layer(peat beds).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2425-2433
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• 2011

DSM (Deep Soil Mixing) is to establish soil-cement column by injecting of cement slurry and blending it in soft ground and have been introduced to Singapore in 1980s and now a days quite popular and considered as alternative method to the jet grouting for temporary earth retaining works and foundations. Herein this paper, the results of lab mixing test based on comparison of characteristics between OPC (Original Portland Cement) and PBFC (Portland Blast Furnace Slag Cement), DSM field trial test and main installation results including monitoring, was presented and it would be referred to similar site later.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.829-834
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• 2009

Alluvial soil is one of the most difficult grounds for tunneling works due to the insufficient ground strength and excessive ground water inflow. Dduk island in Seoul has a wide alluvium developed by two rivers, Han and Jung-Ryang. Subway tunnel of $\bigcirc\bigcirc$ line planed across Dduk island has highly poor ground conditions due to small cover and deeply developed alluvium. Moreover, much part of this tunnel is located parallel to the bridge foundations of another railway with a small horizontal distance. Original design was done in 2002 and construction has been in progress. During the construction, tunnel design has been partly changed and adjusted for the complex ground condition and the demand from related organizations. This paper intend to introduce the urban tunnel design and construction in alluvial soils. This line could be divided three sections(A, B, C) according to ground and adjacent conditions. Section A is featured by mixed tunnel faces consisted with alluvial soils and weathered or weak rocks. The feature of section B is that tunnel underpasses near the bridge foundations of another subway. Lastly, section C with a very short length is the most difficult construction conditions due to the small cover, poor ground, obstacles on and underneath ground surface.

• Magazine of korean Tunnelling and Underground Space Association
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• v.1 no.2
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• pp.59-71
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• 1999

Recently, many deformations in tunnel such as crack and leakage were occulted. Specially, the defects of tunnel lining have been a serious problem in safety and stability many repair works for maintenance in tunnel have been carried out. Therefore, it is necessary to estimate the structural cracking for countermeasure in deformed tunnel and to investigate on the characteristics of lining system and the soundness of tunnel. In this study model tests for tunnel lining were carried out using test apparatus and centrifuge, In the direct loading test, the prototype was Kyungbu high-speed railway tunnel and the scale is 1/10, and lining models were made of concrete. Test conditions included load conditions such as direction, shape and type, lining conditions such as single and double lining, thickness, and reinforcement. In centrifuge model test, the prototype was Seoul subway tunnel and the scale is 1/100, and lining models were made of aluminum and hydrostone. Test conditions included tunnel defects such as thickness shortage. behind cavity and longitudinal cracks, reinforcement methods such as epoxy, grouting and carbon sheet. From these model tests , the characteristics of deformation and failure for tunnel lining were estimated, and the structural behaviors of deformed lining and the effects of repair and reinforcement for tunnel lining were researched.

• Journal of the Korean GEO-environmental Society
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• v.18 no.12
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• pp.13-23
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• 2017

This paper discusses about the reinforcement materials and construction method in order to cope with roadbed settlement in operating railway. In Korea, concrete tracks have been introduced to urban railways, high-speed railways, and general railways, but some recently constructed concrete tracks have experienced roadbed settlements. Reinforcement of the railway roadbed is urgent task for safe operation of railway, but it is difficult to reinforce the roadbed and there are no case history of reinforcing railway roadbed under an operating railroad track. Therefore, in this study, the target performance level for roadbed reinforcement was determined, and infiltration and solidity injection efficiency were investigated for selected reinforcement materials. As a result of the study, it was found that the generally used reinforcement materials and methods for geotechnical works need to be improved for applying in railway roadbed reinforcement.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.121-129
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• 2017

There have been a number of water and sewer pipe breakdown reports followed by ground subsidence. Also, the excavating works for construction due to overcrowding of city have been common. Particularly, in urban areas ground becomes unstable because of the lowered lifeline sinkage followed excavation and backfilling. In order to solve the problem, some reinforcement works for ground by rod tamping or grouting have been applied. However, it is hard to predict when the buried utilities in underground will be damaged. Also, there is a limit for the underground exploration and investigation methods. Therefore, in this study, the estimated about the water soluble polymer pouch including poor mixed admixture which is designed to eliminate the dangerous factors. The reinforcement strength of this method was confirmed by verifying three points: meltiness in a certain period, water solubility in the ground water level, and characteristics of the pouch, which can be stored in daily conditions. It is also proved that this method allows to keep the ground from getting weakened in the installation of water and sewer pipe along with back filling materials.