• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4C
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• pp.153-162
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• 2009

This paper investigates the effects of excavation-induced ground movements on nearby structures, considering soil-structure interactions of different soil and structural characteristics. The response of four and two-story block structures, which are subjected to excavation-induced advancing ground movements, are investigated in different soil conditions using numerical analysis. The structures for numerical analysis are modelled to have cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The response of four and two-story block structures are investigated with advancing ground movement phases and compared with the response of structures which are subjected to excavation-induced total ground movement. The response of structures is compared among others in terms of the magnitude and shape of deformations and cracks in structures for different structure and ground conditions. The results of the comparison provide a background for better understandings for controlling and minimizing building damage on nearby structures due to excavation-induced ground movements.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.127-132
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• 2004

The third double-track construction part of work, called Chung Ang Railroad line(Deok-So$\∼$Won-Ju) is in progress and the personal museum located 330m from the starting point of Pal-Dang Tunnel(length=4,470m) line in the canyon is to be effected by rock blasting during the tunnel excavation work, especially museum articles and building itself. This paper is the example of application suitable tunnel rock blasting pattern for excavation after the case study about the investigation and analysis of rock blasting noise pollution during tunnel excavation work. The museum is a three-story building, RC concrete structure and is located 17m from the top of the tunnel, in the center of the double-track line. Comparing estimate vibration frequency with site vibration one, it can be verified the reasonable rock blasting noise pollution as improving the application of tunnel excavation rock blasting pattern. The above pattern has been selected economically and effectively and applied to our construction field.

• The Journal of Engineering Geology
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• v.30 no.1
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• pp.1-15
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• 2020

The Mohr-Coulomb model is mainly used in evaluating the behavior of the ground in numerical analyses of domestic ground excavation. This study analyzes its limitations and compares its numerical results with the hyperbolic model, a model that closely follows actual ground behavior during excavation. Recent applications of the Mohr-Coulomb model in Korea have tended to impose arbitrary special boundary conditions to control the problem of excessive heaving of the ground excavation surface. This adjustment only controls the size of the heaving of the excavation surface, implying that the ground behavior is distorted from the actual behavior. This study compares results from the hyperbolic model (hardening soil model) and the Mohr-Coulomb model, and confirms that the hyperbolic model provides both a more-suitable solution to the problem of heaving during excavation and the actual stress-strain behavior. In numerical analyses of ground excavation, the hyperbolic model is expected to give results consistent with the actual ground behavior.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.4
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• pp.731-742
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• 2018

Recently, the construction of the urban area has been rapidly increasing, and the excavation work of the ground has been frequently performed at the upper part of the existing underground structure. Especially, when the structure is constructed after the excavation of the ground, the loading and unloading process is repeated in the lower ground of the excavation so that it can affect existing underground structures. Therefore, in order to maintain the stability of the existing underground structure due to the excavation of the ground, it is necessary to accurately grasp the influence of the excavation and the structure load in the adjoining part. In this study, the effects of the ground excavation and the new structure load on the existing tunnel were investigated by large - scale experiment and numerical analysis. For this purpose, a large model tester with a size reduced to 1/5 of the actual size was constructed, and model tests and numerical analyzes were carried out to investigate the effects of the excavation of the body ground by maintaining the distance between the excavation floor and the tunnel ceiling constant, The impacts were identified. As a result of the study, it was confirmed that the deeper the excavation depth, the larger the influence on the existing tunnel. At the same distance, it was confirmed that the tunnel displacement increased with the increase of the building load, and the ground stress increased up to 2.4 times. From this result, it was confirmed that the effect of the increase of the underground stress on the existing tunnel is affected by the increase of the building load, and the influence of the underground stress is decreased from the new load width above 3.0D.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.685-693
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• 2015

There have been high demands for urban underground structures. However, they should be rapidly constructed while maintaining the functions of adjacent structures and road systems especially in urban areas. In this respect, trenchless excavation methods are considered to very effective in minimizing ground displacements during excavation works. A variety of field conditions such as economic, technical and environmental aspects should be taken into consideration when an optimum trechless excavation method is to be chosen in a given condition. Therefore, this study aims to carry out a fundamental study to select an optimum trenchless excavation method by the decision making technique. Especially, AHP (Analytic Hierarchy Process) which is a kind of a multiple attribute decision making process is adopted to consider the opinions of experts and to derive reliable decision criteria. As a result, the weights of key factors and the most effective trenchless methods for different ground conditions were proposed in this study.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.6
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• pp.511-524
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• 2016

Since a room-and-pillar underground structure is characterized by its grid-type array of room and pillar, its economical efficiency can be governed by excavation sequence. In this study, the construction period by the drill-and-blast method as a excavation method for a room-and-pillar underground structure was examined. In addition, the parallel excavation sequence was considered as the main sequence of a room-and-pillar underground structure. Sequences of mucking and support installation were derived to estimate the total excavation cycle by taking the case of a road tunnel into consideration. From the excavation cycle of room-and-pillar underground structure, the relationship between available maximum and minimum numbers of jumbo drill machines depending on the number of faces in operation was suggested.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.456-467
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• 2019

In this study, the discrete element method was used to simulate the excavation of spoke-type shield TBM. The horizontal stress coefficient was used for the ground to simulate the increase of the horizontal stress according to the depth, and the driving conditions were set based on the torque generated from the cutterhead of the TBM to excavate within the operating range. That is, when the value of the torque generated at the cutterhead exceeds the given operating condition, the speed of excavation is constantly reduced, and conversely, the method of increasing the speed of excavation is considered. The change speed of the excavation was given the minimum change requirement in consideration of the driver's review time, and the change was possible according to the excavation conditions. In order to use these conditions, the user-subroutine was considered separately, and the results show that the DEM model were able to analyze the excavation within the considered operating range.

• Journal of the Korean Geotechnical Society
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• v.37 no.12
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• pp.89-105
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• 2021

In this paper, feasibility study was carried out to evaluate necessity of seismic design of earth retaining structures in a deep excavation. Dynamic behavior of retaining system was analyzed using FLAC, a finite difference analysis program. It was shown that maximum bending moments of retaining walls and axial forces of supports were increased up to 98% and 87% during earthquake, respectively, compared to final excavation step, which indicates that dynamic earth pressure has a large effect on a retaining system. The stability of retaining system designed according to current design specifications was evaluated using structural forces obtained by numerical analysis, and effect of earthquake loading on structural design was analyzed.

• Geomechanics and Engineering
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• v.31 no.1
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• pp.1-14
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• 2022

Urban deep excavation will affect greatly on the deformation of adjacent existing buildings, especially those with shallow foundations. Isolation piles has been widely used in engineering to control the deformation of buildings adjacent to the excavation, but its applicability is still controversial. Based on a typical engineering, numerical calculation models were established and verified through monitoring data to study the influence characteristics of isolation piles on the deformation of existing shallow foundation buildings. Results reveal that adjacent buildings will increase building settlement δ_v and the deformation of diaphragm walls δ_h, while the isolation piles can effectively decrease these. The surface settlement curve is changed from "groove" type to "double groove" type. Sufficiently long isolation pile can effectively decrease δ_v, while short isolation piles will lead to a negative effect. When the building is within the range of the maximum settlement location P, maximum building rotation θ_m will increase with the pile length L and the relative position between isolation pile and building d/D increase (d is the distance between piles and diaphragm walls, D is the distance between buildings and diaphragm walls), instead, θ_m will decrease for buildings outside the location P, and the optimum was obtained when d/D=0.7.

• Journal of the Korea Institute of Building Construction
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• v.6 no.4 s.22
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• pp.45-52
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• 2006

Top Down method is more widely used in downtown construction, recently. As underground construction constitutes a significant portion of the total construction cost and time in Top Down construction, it is important to develop a construction method to reduce the time required in underground works. The purpose of this study is to analyze load carrying capacity of Top Down prefounded columns on different excavation schedule. When several floors are excavated, the valid buckling length of prefounded column is increased and allowable buckling stress is decreased. The result shows that all columns are safe in buckling down to B3 story whether 2 or 3 stories are excavated. However, several columns are not safe from B4 story when 2 or 3 stories are excavated straightly. With these results, a process can be designed that the first three stories in the basement are excavated, and then excavate B4 story after placing concrete on B1 and B2 floor.