• Journal of the Korean GEO-environmental Society
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• v.23 no.4
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• pp.29-39
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• 2022

In order to solve the serious traffic congestion in seoul metropolitan city, large-scale underground space development such as underpasses, deep underground roads, and GTX (Great Train eXpress) is being carried out. In order to minimize the impact of the adjacent seoul metro line A pier foundation and stability due to the construction of the underground road in Seoul, earth retaining structures were reinforced and the foundation was reinforced as well. In this study, three-dimensional finite element mehtod analysis was performed to evaluate the effect on adjacent construction and to review the stability of the underpass excavation work. The reinforcement effect was quantitatively analyzed through numerical analysis. As a result of the analysis, compared to the result of performing the existing reinforcement when overlapping CIP and ground reinforcement grouting were performed, the displacement of the earth retaining structures was reduced by more than 50%, and stress of the foundation piles were also reduced by more than 45%. Based on the analysis of the numerical analysis results, it was confirmed that the displacement of the walls of earth retaining structures during adjacent construction should be strictly controlled.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.312-331
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• 1991

Top-down Method of basement construction technique has been applied for building of the deep basement car park the close proximity of priceless historic buildings in LONDON. Numerical analysis for the prediction of ground movement of the surrounding buildings was performed in order to compare the field data at the various stages of excavation and support. The predicted results from the elasto-plastic analytical method were compared with the observed data and the agreement is very satisfactory. It may be concluded that the system of diaphragm wall supported by the permanent base slabs (Top-Down Method) was proved to be the most effective technique in terms of reducing any critical damage to the surrounding buildings.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.201-208
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• 1999

The NATM(New Austrian Tunnelling Method) has been used for tunnelling since 1980's. But Collapses of tunnel under construction take place frequently, especially at urban areas because of adjacent buildings, underground conduits and traffic loads. This paper is a case study on the reinforcement method of subway tunnel at urban areas. In this study, ground inspection, geological investigation, laboratory test and numerical analysis by means of FDM program were carried out. The tunnel excavation was stopped because of over excessive brake of tunnel crown and shotcrete was installed to prevent deformation of adjacent ground as the temporary method. From the result of field survey and geological investigation, it is found that the soft weathered soil was distributed to the ground of tunnel invert unlike original investigation. The results of the analysis and the study show that the SGR(Space Grouting Rocket) method and Umbrella method can be applied for the stability of tunnel excavation and in addition the reinforcement of concrete lining is required for long-term stability of tunnel.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1206-1211
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• 2010

Soil-cement, a hardened mixture of Portland cement, soil, and water that contain sufficient durability, has been widely utilised in Seoul urban construction sites to retain lateral earth pressures or reinforce grounds. However, little information has been reported about the strength characteristics of soil-cement constructed in Seoul urban area. In this study, we performed a number of unconfined test to the soil-cements mixed from soils sampled in 3 sites in Seoul urban area. Results indicate that unconfined strengths and optimum cement amounts of soil-cements are highly dependent on the proportion of coarse-grain particles of mixed soils. Furthermore, changes of unconfined strengths with curing time are diverse with respect to mixing conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.485-492
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• 2000

Current design practice for the prediction of tunnelling-induced ground movements depends on empirical methods, which are based on many assumptions and simplification of the modeling. Some discrepancies between the predictions and the measurements of ground movements regarding adjacent structures are inevitable. In order to investigate tunnel-induced ground movements affect on the settlement of existing structures as well as existing structures affect tunnel-induced ground movement, 2-D elasto-plastic finite element analysis are performed. The following influencing factors such as load of the structures, the width of structures, its bending and axial stiffness, its position relative to the tunnel are considered in the numerical analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.902-911
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• 2009

There appeared many difficulties due to various construction factors during the recent construction adjacent to the housing for the aging. In particular, the study is going to summarize and overview the selection procedure and construction details of the excavation engineering of this site, which could ensure workability and economic efficiency through the construction of a shorter anchor than the length of the existing anchor with a minimal marginal space without invading the nearby private land.

• Tunnel and Underground Space
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• v.11 no.1
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• pp.20-29
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• 2001

Final convergence of tunnel crown due to excavation have been well predicted by regression analysis which is expressed as a function of convergence curve on a time and distance dependent. In this study, the validity of the equations for shallow, wide tunnel was investigated by measurement and numerical analysis. Studied tunnel(Sansoo Tunnel) is located at the boundary of downtown and mountain park. Exponential predictions equation was better coincided with measured data than fractional equation for studied tunnel, although the ground was expected to be elasto-plastic. This is because weathered rock ground is changed elasto-plastic ground into elastic ground by multi-steel grouting and forepoling.

• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.89-99
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• 2009

Compared to standard piling methods, micropile construction can be used in downtown areas since it generates less vibration and noise. Since it only causes less soil disturbance, it is commonly used as reinforcement to existing structures. In this study, a field wherein the bearing capacity and settlement of soil can not support the weight of the superstructure was selected and micropiles were implemented instead of ordinary piles. The deformation modulus of the micropile reinforced ground was determined and was directly reflected in the design. Loading testing was used to check whether or not the allowable bearing capacity satisfies the condition of the designed bearing capacity. The computed deformation modulus based from the test was used in the numerical analysis of soil to investigate the stability of the foundation and analysis method. And a method for controlling the bearing capacity and settlement was recommended.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.1-24
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• 2018

The use of TBM (tunnel boring machine) gradually increases in worldwide tunneling projects. TBM machine are often applied to more difficult and complex geological conditions in urban area, and many problems and difficulties have been reported due to these geological conditions. However, in Korea, there is a lack of research on difficult grounds so far. This paper discussed general aspects of investigation method, and problems of TBM tunneling in difficult grounds. Construction cases that passed through the difficult grounds in worldwide were analyzed and the typical difficult grounds were classified into 11 cases. For each case, the definition and general problems were summarized. Particularly, for mixed ground and boulder ground, and fault zone, which are frequent geological conditions in urban area with shallow depth, classification system, investigation methods and major considerations were discussed, and proposed the direction of future research. This paper is a basic study for the development of TBM construction technology in difficult ground, and it is expected that it will be useful for related research and construction of TBM in difficult ground in the future.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.203-210
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• 2000

Recently, environmental vibration by train operation has been getting such an attention that the ISO puts it into the environmental vibration regulation. However, the reasonable and efficient countermeasures against such a kind of vibration is not well established, especially in residential areas near the railroad. Therefore, it is very important to estimate the ground vibration induced by the train operation for the design and construction of track supporting structures as well as structures near the track. In this study a model estimating dynamic load on track due to train operation and analysis technique of propagation of ground vibration were developed. Futhermore, the estimated vibration from this model was compared with the actual measurement data in the field and found to be reasonably acceptable.