• Geomechanics and Engineering
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• 제34권2호
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• pp.115-124
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• 2023

By conducting three-dimensional simulation with consideration of small-strain characteristics of soil stiffness, the effects of excavation geometry and tunnel cover to diameter ratio on deformation mechanisms of an existing tunnel located either at a side of basement or directly underneath the basement were systematically studied. Field measurements were used to verify the numerical model and model parameters. For basement excavated at a side of an existing tunnel, the maximum settlement and horizontal displacement of the tunnel are always observed at the tunnel springline closer to basement and tunnel crown, respectively, regardless of basement geometry. By increasing basement length and width by five times, the maximum movements of tunnel located at the side of basement and directly underneath the basement increase by 450% and 186%, respectively. Obviously, tunnel movements are more sensitive to basement length rather than basement width. For basement excavated at a side of an existing tunnel, tunnel movements at basement centerline become stable when basement length reaches 10 H_e (i.e., final excavation depth). Moreover, tunnel heaves due to overlying basement excavation become stable when the normalized basement length (L/H_e) is larger than 8.0. As tunnel cover to diameter ratio varies from 2.5 to 3.0, the maximum heave and tensile strain of tunnel due to overlying basement excavation decrease by up to 41.0% and 44.5%, respectively. If basement length is less than 8 H_e, the assumption of plane strain condition of basement-tunnel interaction grossly overestimates tunnel movements, and ignores tensile strain of tunnel along its longitudinal direction. Thus, three-dimensional numerical analyses are required to obtain a reasonable estimation of tunnel responses due to adjacent and overlying basement excavations in clay.

• Geomechanics and Engineering
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• 제36권6호
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• pp.563-573
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• 2024

In this study, various countermeasures used to mitigate tunnel deformations due to nearby multi-propped basement excavation in soft clay are explored by three-dimensional numerical analyses. Field measurements are used to calibrate the numerical model and model parameters. Since concrete slabs can constrain soil and retaining wall movements, tunnel movements reach the maximum value when soils are excavated to the formation level of basement. Deformation shapes of an existing tunnel due to adjacent basement excavation are greatly affected by relative position between tunnel and basement. When the tunnel is located above or far below the formation level of basement, it elongates downward-toward or upward-toward the basement, respectively. It is found that tunnel movements concentrate in a triangular zone with a width of 2 H_e (i.e., final excavation depth) and a depth of 1 D (i.e., tunnel diameter) above or 1 D below the formation level of basement. By increasing retaining wall thickness from 0.4 m to 0.9 m, tunnel movements decrease by up to 56.7%. Moreover, tunnel movements are reduced by up to 80.7% and 61.3%, respectively, when the entire depth and width of soil within basement are reinforced. Installation of isolation wall can greatly reduce tunnel movements due to adjacent basement excavation, especially for tunnel with a shallow burial depth. The effectiveness of isolation wall to reduce tunnel movement is negligible unless the wall reaches the level of tunnel invert.

• 한국태양에너지학회 논문집
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• 제22권1호
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• pp.73-80
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• 2002

This is study of the planning of thermal insulation to prevent heat loss in a basement, is aimed at investigating the heat loss from the basement space and basement structures. The results analyzed in these researches are as follows; To analyze the heat loss from basement structures, this study experimented on the heat flow phenomenon of a non-insulation structure and two insulation structure models. From the result, the interior surface temperature of two insulation structures(B, C, model) showed an equal temperature, but the interior surface temperature of a non-insulation structure (A model) is different from the two models, Therefore, we understand that the insulator constructed in the basement structure makes a role of preventing the heat loss from the basement. In addition, the exterior surface temperature of two insulation structure models showed an equal temperature. Specially, judging from the temperature difference of C model. we understand that the performance of insulator is low under the definite depth of underground. The thermal insulation design should be constructed under the definite depth of underground considering outdoor and building conditions.

• BMB Reports
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• 제46권4호
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• pp.195-200
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• 2013

To understand the corneal regeneration induced by bevacizumab, we investigated the structure changes of stroma and basement membrane regeneration. A Stick soaked in 0.5 N NaOH onto the mouse cornea and 2.5 mg/ml of bevacizumab was delivered into an alkali-burned cornea (2 ${\mu}l$) by subconjunctival injections at 1 hour and 4 days after injury. At 7 days after injury, basement membrane regeneration was observed by transmission electron microscope. Uneven and thin epithelial basement membrane, light density of hemidesmosomes, and edematous collagen fibril bundles are shown in the alkali-burned cornea. Injured epithelial basement membrane and hemidesmosomes and edematous collagen fibril bundles resulting from alkali-burned mouse cornea was repaired by bevacizumab treatment. This study demonstrates that bevacizumab can play an important role in wound healing in the cornea by accelerating the reestablishment of basement membrane integrity that leads to barriers for scar formation.

• 설비공학논문집
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• 제15권11호
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• pp.918-927
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• 2003

This study is to analyze thermal characteristics of the basement structures with a non-thermal insulation and various thermal insulations. From the results through the field experiments and computer simulations, the thermal bridges and heat loss is found in non-insulation structure of the basement under the definite depth of ground level. Therefore, the thermal insulation structure should be installed for preventing the heat loss in the basement.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.9-13
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• 2009

Recently, construction in downtown is often done closely at the adjacent building. In this case, underground construction need to Basement Composite Wall(BCW) construction. However, generally, during the construction process of BCW form works have many problems that are narrow working space and inefficient time consuming. Despite of these problems, there was no quantitative research for the work time of BCM assembly. Therefore, in this study, work time of CBW form assembly in underground construction is identified by the work analysis. The results of this study reveal that buttress work of basement form take lots of time in the entire work process of Basement Composite Wall form assembly.

• 한국지진공학회논문집
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• 제20권4호
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• pp.223-234
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• 2016

To investigate earthquake responses of structures with basements affected by soil deposits, centrifuge tests were performed using an in-flight earthquake simulator. The test specimen was composed of a single-degree-of-freedom structure model, a basement and sub-soil deposits in a centrifuge container. The test parameters were the dynamic period of the structure model, boundary conditions of the basement, existence of soil deposits, centrifugal acceleration level, and type and level of input earthquake accelerations. When soil deposits did not exist, the earthquake responses of the structures with fixed basement were significantly greater than those of the structure without basement. Also, the earthquake responses of the structures with the fixed basement surrounded by soil deposits were amplified, but the amplifications were smaller than those of the structures without basement. The earthquake responses of the structures with the half-embedded basement in the soil deposits were greater than those estimated by the fixed base model using the measured free-field ground motion. The test showed that the basement and the soil deposit should be simultaneously considered in the numerical analysis model, and the stiffness of the half-embedded was not effective.

• Geomechanics and Engineering
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• 제30권6호
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• pp.565-577
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• 2022

In this study, a series of three-dimensional numerical parametric study was conducted to investigate deformation mechanisms of an existing box culvert due to an adjacent multi-propped basement excavation in clays. Field measurements from an excavation case history are first used to calibrate a baseline Hardening Soil Small Strain (HS-small) model, which is subsequently adopted for parametric study. Results indicate that the basement-box culvert interaction along the basement centerline can be considered as a plane strain condition when the length of excavation (L) reaches 14 H_e (i.e., final excavation depth). If a plane strain condition (i.e., L/H_e=12.0) is assumed for analyzing the basement-box culvert interaction of a short excavation (i.e., L/H_e=2.0), the maximum settlement and horizontal movement of the box culvert are overestimated significantly by up to 15.7 and 5.1 times, respectively. It is also found that the deformation of box culvert can be greatly affected by the basement excavation if the distance between the box culvert and retaining wall is less than 1.5 H_e. The induced deformation in the box culvert can be dramatically reduced by improving the ground inside the excavation or implementing other precautionary measures. For example, by adding jet grouting columns within the basement and installing an isolation wall behind the retaining structures, the maximum settlements of box culvert are shown to reduce by 37.2% and 13.4%, respectively.

• 한국주거학회논문집
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• 제16권4호
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• pp.1-7
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• 2005

In this study aim at searching for the basement residential planning of considering outdoor spaces. It look after research results, there should be necessary for the inflow of outdoor environment factors. This basement planning is core's area expending, or installing expended dry areas and acquiring side open spaces, installing arcades, installing atrium or court yard, utilizing maisonette spaces, activating pilotis on ground floors, openning main hall, earth sheltering method, etc. These should be improvement for easy step to change basement floors easily through underground floor extend, major repair, use change of present buildings and needs to the idea through architectural design competition.

• 한국구조물진단유지관리공학회 논문집
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• 제6권3호
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• pp.159-165
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• 2002

Currently structural design of basement exterior wall is based on the assumption of boundary condition of plate, which may lead to erroneous results. In this study, the behavior of basement exterior wall subject to earth pressure and hydraulic pressure is investigated using linear finite element analysis. Parametric studies are conducted to investigate the variation of moment and shear force according to column-to-wall stiffness and aspect ratios. Using these numerical results, modification factors applicable to the design of basement exterior wall are presented. Design example is illustrated, showing satisfactory results.