• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.11-23
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• 2020

In this paper development artificial neural networks (ANN) for preliminary design and prediction of urban tunnelling and deep excavation-induced ground settlement was presented. In order to form training and validation data sets for the ANN development, field design and measured data were collected for various tunnelling and deep-excavation sites. The field data were then used as a database for the ANN training. The developed ANN was validated against a testing set and the unused field data in terms of statistical parameters such as R², RMSE, and MAE. The practical use of ANN was demonstrated by applying the developed ANN to hypothetical conditions. It was shown that the developed ANN can be effectively used as a tool for preliminary excavation design and ground settlement prediction for urban excavation problems.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.561-568
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• 2003

The protection of adjacent structures in urban excavation has been an important issue. But the research on the interaction between ground movements and adjacent structure has been scarce, therefore this study was necessitated. Current design practice for the prediction of excavation-induced ground movements heavily rely on empirical method. In this study, damage levels of brick building are examined closely by means of angular distortion, deflection ratio, horizontal strain. The results of numerical analysis indicated that the movement of actual building was 60∼65% of the ground movement, while angular distortion was 45∼65%. Also numerical analysis for the assessment of brick building can be applied to the building protection at various construction stages.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.585-594
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• 2007

This paper presents the methods which estimate the influence of ground subsidence and the stability of buildings by tunnel excavation in urban area. First, we study the behaviour of ground subsidence using neural network and numerical method. And we analyze the characteristic of both methods. Using the both methods, we evaluate the stability of buildings by subway tunnel excavation and we compare the results of the neural network and numerical analysis.

• Journal of the Korea Institute of Building Construction
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• v.7 no.3
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• pp.131-137
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• 2007

To predict deep excavation wall movements is important in the urban areas considering the cost and the safety in construction. Failing to estimate deep excavation wall movements in advance causes too many problems in the projects. The purpose of this study is to propose the forecast model of deep excavation wall movements using artificial neural networks. The data of the Deep Excavation Wall Movements which were done form Long research is used of Artificial neural networks training and apply the real construction work measured data to the Artificial neural networks model. Applying the artificial neural networks to forecast the deep excavation wall movements can significantly contribute to identifying and preventing the accident in the overall construction work.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.03a
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• pp.81-88
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• 1997

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.271-278
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• 2002

Recently, deep excavation for high-rise buildings occurs frequently to accommodate the rapidly increasing population in urban area. The stability of the earth retaining structures for deep excavation becomes more critical. The behavior of the earth retaining structures should be accurately predicted in a design stage, but the predicted behavior is different from the measured data due to uncertain soil properties and problems in construction. In this study the back-analysis using Powell's optimization theory was performed to match the measured deflection and results obtained from back-analysis were presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1324-1329
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• 2009

Needs for underground space development and utilization have been increasing in urban area. The conventional strutting method in excavation is effective to restrain the ground movements and displacements of earth structures but inefficient for workers because of small working space. The conventional earth reinforcement methods such as earth-anchor and soil-nailing also have limitation to apply in urban area due to threats to stability of adjacent buildings around excavation boundaries. Recently, many types of earth retaining structures are being developed to overcome disadvantages of conventional excavation methods in urban area. In this study, a series of numerical analyses were performed with MIDAS GTS, geotechnical analysis program and MIDAS Civil, structural analysis design program to evaluate behavior and stability of the new type of non-supporting earth retaining structure, called Temporary Tower System (TTS), consisting of tower truss structures with much economical and spatial advantage.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.573-584
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• 2022

Water inrush may occur during seaside urban tunnel excavation. Various factors affect the water inrush, and the water inrush mechanism is complex. In this study, nine evaluation indices having potential effects on water inrush were analysed. Specifically, the geographic and geomorphic conditions, unfavourable geology, distance from the tunnel to sea, strength of the surrounding rock, groundwater level, tidal action, cyclical footage, grouting pressure, and grouting reinforced region were analysed. Furthermore, a two-step interval risk assessment method for water inrush management during seaside urban tunnel excavation was developed by a multi-index system and interval risk assessment comprised of an interval analytic hierarchy process, fuzzy comprehensive evaluation, and relative superiority analysis. The novel assessment method was applied to the Haicang Tunnel successfully. A preliminary interval risk assessment method for water inrush was performed based on engineering geological conditions. As a result, the risk level fell into a risk level IV, which represents a section with high risk. Subsequently, a secondary interval risk assessment method was performed based on engineering geological conditions and construction conditions. The risk level of water inrush is reduced to a risk level II. The results agreed with the current tunnel situation, which verified the reliability of this approach.

• Geomechanics and Engineering
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• v.32 no.1
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• pp.111-123
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• 2023

The slope of an open cut tunnel is located above the exit of the Leijia tunnel on the Changgan high-speed railway. During the excavation of the open cut tunnel foundation pit, the slope slipped twice, a large landslide of 92500 m³ formed. The landslide body and unstable slope body not only caused the foundation pit of the open cut tunnel to be buried and the anchor piles to be damaged but also directly threatened the operational safety of the later high-speed railway. Therefore, to study the stability change in the slope of the open cut tunnel under heavy rain and excavation conditions, a 3D numerical calculation model of the slope is carried out by Midas GTS software, the deformation mechanism is analyzed, anti-sliding measures are proposed, and the effectiveness of the anti-sliding measures is analyzed according to the field monitoring results. The results show that when rainfall occurs, rainwater collects in the open cut tunnel area, resulting in a transient saturation zone on the slope on the right side of the open cut tunnel, which reduces the shear strength of the slope soil; the excavation at the slope toe reduces the anti-sliding capacity of the slope toe. Under the combined action of excavation and rainfall, when the soil above the top of the anchor pile is excavated, two potential sliding surfaces are bounded by the top of the excavation area, and the shear outlet is located at the top of the anchor pile. After the excavation of the open cut tunnel, the potential sliding surface is mainly concentrated at the lower part of the downhill area, and the shear outlet moves down to the bottom of the open cut tunnel. Based on the deformation characteristics and the failure mechanism of the landslides, comprehensive control measures, including interim emergency mitigation measures and long-term mitigation measures, are proposed. The field monitoring results further verify the accuracy of the anti-sliding mechanism analysis and the effectiveness of anti-sliding measures.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1251-1258
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• 2008

The purpose of this research is to introduce the new temporary earth retaining wall system using landslide stabilizing piles. This system is a self-supported retaining wall(SSR) without installing supports such as tiebacks, struts and rakers. The SSR is a kind of gravity structures consisting of twin parallel lines of piles driven below dredge level, tied together at head of soldier piles and landslide stabilizing piles by beams. There are three types of excavation wall structures: standard method for medium retained heights(<8.0m), internal excavation method and slope excavation method for deep-excavation applications(>8.0m). In the present study, the measured data from seven different sites which the SSR was used for excavation were collected and analyzed to investigate the characteristic behavior lateral wall movements associated with urban excavations in Korea.