• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.268-275
• /
• 2006

Excavation works of cylindrical shafts and tunnels for the construction of a variety of infrastructures have been frequently going on in the urban areas. When ground excavations of cylindrical shafts and shallow tunnels proceed in the ground condition of high water level and silt particle component, ground water drawdown involving soil particle migration causes loosening of ground around tunnels and shafts, causes settlement and deformation of ground. Damages due to ground sinking and differential settlement can occur in the adjacent ground and structures. The extent and possibility of damage relevant to ground water drawdown and soil particle migration can't be so precisely expected in advance that we will face terrible damages in case of minor carefulness. This paper introduces two examples of construction management where using incremental deformation graph of inclinometer, we noticed the possibility of soil migration due to ground water drawdown in the excavation process of vertical shaft and shallow tunnel, analysed a series of measurement data in coupled connection, properly prepared countermeasures, so came into safe and successful completion of excavation work without terrible damages. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• International Journal of High-Rise Buildings
• /
• v.7 no.1
• /
• pp.85-93
• /
• 2018

The design of a supertall building poses many challenges to the architect and engineer. Using Jeddah Tower as a case study; this paper intends to discuss a few of those challenges specifically related to the arrangement of programmed spaces in the tower, their functional connection by means of the vertical transportation system and physical connection with shafts which introduces the potential for stack effect in the building. The measures applied in response to and mitigation of these issues are discussed.

• Geomechanics and Engineering
• /
• v.13 no.1
• /
• pp.173-194
• /
• 2017

Access shaft is of critical importance to the construction and operation of underground rock caverns. It usually has a relatively large cross-section and penetrates through fill materials, soil layers, and weathered rocks before reaching the caverns excavated in solid bedrock. In this paper, the design and construction of vertical shafts are reviewed in terms of diameter, depth, geological conditions, and support structure. Three shaft alternatives, namely alternative I: vertical shaft with spiral roads, alternative II: upper shaft with spiral roads & lower tunnels, alternative III: plain shaft, are proposed based on a simplified geological profile of the Jurong formation, Singapore. The advantages and limitations of the three types of shafts are discussed. The key issues relating to shaft design and construction, such as the shaft sinking, water control, support structure, are also discussed with a series of solutions provided, such as the sequential excavation, pre-grouting and diaphragm walls.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.880-885
• /
• 2004

When a fire takes place, the escape tunnel which could prevent passengers and the crew from disasters would be most important facility among railway tunnel facilities for prevention of disaster. A shorter space between the escape tunnels is much better for safety because of short escape time. The establishment of short space escape tunnels(driftways) in the single track parallel tunnel is much easier. The establishment of long space escape tunnels(inclined shafts, vertical shafts) in the double track is much more advantageous economically. We, therefore, compared the movement time of smog originated from fire with the escape time of the crew and passengers for setting up the best space between the escape tunnels in the double track tunnel. We could calculate the best space between the escape tunnels in the double track tunnel properly by computer simulation.

• KEPCO Journal on Electric Power and Energy
• /
• v.7 no.2
• /
• pp.285-293
• /
• 2021

The construction of underground structures such as power supply lines, communication lines, utility tunnels has significantly increased worldwide for improving urban aesthetics ensuring citizen safety, and efficient use of underground space. Those underground structures are usually constructed along with vertical cylindrical shafts to facilitate their construction and maintenance. When constructing a vertical shaft through the open-cut method, the walls are mostly designed to be flexible, allowing a certain level of displacement. The earth pressure applied to the flexible walls acts as an external force and its accurate estimation is essential for reasonable and economical structure design. The earth pressure applied to the flexible wall is closely interrelated to the displacement of the surrounding ground. This study simulated stepwise excavation for constructing a cylindrical vertical shaft through a centrifugal model experiment. One quadrant of the axisymmetric vertical shaft and the ground were modeled, and ground excavation was simulated by shrinking the vertical shaft. The deformation occurring on the entire ground during the excavation was continuously evaluated through digital image analysis. The digital image analysis evaluated complex ground deformation which varied with wall displacement, distance from the wall, and ground depth. When the ground deformation data accumulate through the method used in this study, they can be used for developing shaft wall models in future for analyzing the earth pressure acting on them.

• Geomechanics and Engineering
• /
• v.21 no.3
• /
• pp.269-277
• /
• 2020

In this study, numerical analyses were conducted to investigate the load transfer mechanisms and dynamic responses between the vertical shaft and the surrounding soil using a dynamic analysis method and a pseudo-static method (called response displacement method, RDM). Numerical solutions were verified against data from the literature. A series of parametric studies was performed with three different transient motions and various surrounding soils. The results showed that the soil stratigraphy and excitation motions significantly influenced the dynamic behavior of the vertical shaft. Maximum values of the shear force and bending moment occurred near an interface between the soil layers. In addition, deformations and load distributions of the vertical shaft were highly influenced by the amplified seismic waves on the vertical shaft constructed in multi-layered soils. Throughout the comparison results between the dynamic analysis method and the RDM, the results from the dynamic analyses showed good agreement with those from the RDM calculated by a double-cosine method.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.09a
• /
• pp.1073-1080
• /
• 2010

In this paper, the centrifuge model tests were conducted for the sake of measuring three dimensional arching earth pressure while two step excavation of the vertical shaft. The results of the centrifuge model tests were compared to newly suggested arching earth pressure equation proposed by Kim et al(2009) and two dimension earth pressure(Rankine). As the results, Measured arching earth pressure revealed about 35 percentages of two dimension earth pressure(Rankine) and almost same as that of newly suggested arching earth pressure equation.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.23 no.4
• /
• pp.77-84
• /
• 2017

Purpose: In terms of the flexibility in hospital architecture, there are fixed elements of hospital architecture: mechanical, electrical, aeration rooms and shafts, which are the main utility spaces. Thus, it is necessary to recognize the utility space as a system that helps internal functions and flexible internal changes. This study analyzes the notion of the main utility space in hospital architecture and the architectural planning features of the main utility spaces as the system in the design process of the recently built hospitals. Methods: The design factors are extracted comparing two hospitals' plans in each stage and the systematic characteristics of utility spaces are analyzed accordingly. The opinions gathered from interviews of practitioners, architects and facility planning experts directly involved in the architecture design process are analyzed and reflected in the results. Results: Planning for utility spaces should be accompanied by the architectural plan from the basic design process, and proceeded with recognizing utility spaces as a system, which is a fixed element. Utility spaces are highly organically connected. Horizontal and vertical distribution of air chambers can reduce the length and number of ducts, and thus save story height, and reduce the number of shafts, the vertical connection passage. This is advantageous in securing the variable area, which is the ultimate objective of the system-centered hospital architecture plan. Implications: Thereby aims to provide fundamental data on systematic utility space planning in the hospital architecture planning.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.4
• /
• pp.295-304
• /
• 2005

The smoke propagating distances are measured in case that a fire occurs within the subway railroad tunnel. The tunnel is 800m long and the dimension of the cross-section is. Three vertical shafts exist for smoke ventilation. The experiments are performed using the 1/50 reduced-scale model. The smoke propagating distances are measured by thermocouples and by visualization for the accuracy. In order to understand the effect of a fire size and ventilation capacity of the shafts on the smoke propagating distance, 9 test scenarios are chosen. Based on the results, the smoke propagating distance is shown to be important criteria for the ventilation design of the tunnel.

• Geomechanics and Engineering
• /
• v.11 no.6
• /
• pp.879-896
• /
• 2016

A new earth pressure equation considering the arching effect in $c-{\phi}$ soils was proposed for the accurate calculation of earth pressure on circular vertical shafts. The arching effect and the subsequent load recovery phenomenon occurring due to multi-step excavation were quantitatively investigated through laboratory tests. The new earth pressure equation was verified by comparing the test results with the earth pressures predicted by new equation in various soil conditions. Resulting from testing by using multi-step excavation, the arching effect and load recovery were clearly observed. The test results in $c-{\phi}$ soil showed that even a small amount of cohesion can cause the earth pressure to decrease significantly. Therefore, predicting earth pressure without considering such cohesion can lead to overestimation of earth pressure. The test results in various ground conditions demonstrated that the newly proposed equation, which enables consideration of cohesion as appropriate, is the most reliable equation for predicting earth pressure in both ${\phi}$ soil and $c-{\phi}$ soil. The comparison of the theoretical equations with the field data measured on a real construction site also highlighted the best-fitness of the theoretical equation in predicting earth pressure.