• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.1
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• pp.55-70
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• 2003

Ammunition magazine, which is installed on the ground, has difficulty in protecting from the external attack, and accidental explosion should cause great damage to the life and property. For these reasons, it is needed to develop underground magazine that it has the advantages of safety, security and maintenance. This paper introduce the design case for blasting facilities, which should resist blasting pressure, as well as layout of underground magazine, which takes a safety for explosion and a working space of loading/unloading machine into consideration. On the layout, in case of ${\bigcirc}{\bigcirc}$ underground magazine, put three storage chambers in position almost parallel with principle stress direction, where less effected on discontinuity and hard rock area. Also, secured safe distance according to safety criteria of the Defense Ministry, and verified suitable layout by trace simulation for loading/unloading machine on working stage. Blasting design was performed on evaluation of maximum blast pressure between donar and acceptor chambers, and design condition for blast door, valve, etc. Diminution facilities against explosion, such as thrust block or debris trap, determined its size after plan in accordance with blasting criteria and calculation by structural analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.5
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• pp.523-536
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• 2013

In order to ensure the safety of the subsea tunnel during its construction and operation, unlike the underground structures on land, the special monitoring system is essential which considers the characteristics of subsea tunnels in addition to conventional stress and displacement measurements applied to existing land tunnels. Therefore, the concept applied to NATM is reorganized to evaluate the stability of subsea tunnels. And the observation system for making a monitoring plan, the critical strain theory for tunnel safety management and MS monitoring methods for detecting the local failure and crack initiation of rock and supports, are introduced. Finally, the scheme of monitoring and management for subsea tunnels by using these methods is suggested.

• Tunnel and Underground Space
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• v.14 no.5
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• pp.339-344
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• 2004

Variation of horizontal to vertical stress ratio of transversely isotropic rock caused by erosion was studied by numerical analysis. Influence of transversely isotropic was less than 5% for isotropic case. Difference between stresses obtained by numerical analysis and theoretical solution was small when initial stress ratio was small and the difference increased as erosion depth increased. Stress ratios diverged from initial ones as depth increased. An equation to determine stress ratio considering erosion according to the analyses was suggested.

• Tunnel and Underground Space
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• v.1 no.2
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• pp.218-228
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• 1991

Natural stress measurements have been made at two sites at the depth of 280m from surface by means of stress relief overcoring methods using three directonal deformation gage. Attempts have been made to determine the state of natural stress in the rock and provide useful basic data to investigate the stress distribution and the determination of yield zone around powerhouse cavern. The magnitude and the direction of the miximum principal stress obstained from in-situ stress measurements is -96.1kgf/$\textrm{cm}^2$ and N38$^{\circ}$W, N35$^{\circ}$W respectively. Vertical stresses are in approximately agreement with the theoretical value. The ratio of measured to theoretical stresses are 85% at two sites. The ratio of average horizontal to vertical stresses(k=($\sigma$h)ave/$\sigma$v is 1.07.

• Journal of the Korean Geotechnical Society
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• v.31 no.6
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• pp.71-82
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• 2015

Recently, due to the expansion of urban infrastructure for the citizen convenience, the shield tunnel construction has increased considering the civil complaints minimization and construction stability. Most shield tunnels are designed based on the assumption of the undrained condition that underground water does not inflow, but they are operated in the field as drained tunnels with drainage facility to drain underground water. Therefore, the drained condition needs to be considered in the shield tunnel design. It is also necessary to consider the weathered granite soil that is widely distributed throughout the country and consequently is encountered in most of construction sites. In this paper, the model test which can control total stress and pore water pressure and simulate the underground tunnel located in the weathered granite soil below ground water level is conducted. Total stress, pore water pressure and an inflow water into an inner pipe were measured using the testing device. Test results showed that the total stress in a drained condition was lower than in an undrained condition because pore water pressure decreased in a drained condition and an inflow water into an inner pipe was proportional to the loading stress in a drained condition. As a result, if a drained condition is considered in the shield tunnel design, the more economical design can be expected because of the stress reduction of the lining.

• Geomechanics and Engineering
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• v.22 no.2
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• pp.187-196
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• 2020

The changeable stress environment directly affect the propagation law of a stress wave. Stress wave propagation tests in sandstone with different axial stresses were carried using a modified split Hopkinson Pressure bar (SHPB) assuming the sandstone has a uniform pore distribution. Then the waveform and stress wave energy dissipation were analyzed. The results show that the stress wave exhibits the double peak phenomenon. With increasing axial stress, the intensity difference decreases exponentially and experiences first a dramatic decrease and then gentle development. The demarcation stress is σ/σ_c=30%, indicating that the closer to the incident end, the faster the intensity difference attenuates. Under the same axial stress, the intensity difference decreases linearly with propagation distance and its attenuation intensity factor displays a quadratic function with axial stress. With increasing propagation distance, the time difference decays linearly and its delay coefficient reflects the damage degree. The stress wave energy attenuates exponentially with propagation distance, and the relations between attenuation rate, attenuation coefficient and axial stress can be represented by the quadratic function.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.315-326
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• 2004

This study performed model tunnel tests in order to investigate the influence of discontinuity condition of rock mass to the stress and deformation of tunnel lining. Tests were carried out changing the direction of main joint and lateral earth pressure condition of rock mass. Test results revealed that the axial force in tunnel lining showed a tendency of decrease with the presence of joints. It decreased much with the increase of lateral earth pressure coefficient. And, it also showed that the location or maximum displacement and maximum stress in lining were changed by the direction of main joint of rock mass. The tangential stress and normal stress showed the difference above the maximum twenty times as lateral earth pressure coefficient due to effect of joints increased. Also, these tendencies of concentration of tensile stress in tunnel lining were confirmed by elastic theory.

• Steel and Composite Structures
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• v.22 no.1
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• pp.63-77
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• 2016

Top-down construction is a construction technique in which pit excavation and structure construction are conducted simultaneously. Reducing construction time and minimizing noise and vibration which affect neighboring structures, the technique is widely employed in constructing downtown structures. While H-steel columns have been commonly used as core columns, concrete filled steel tube (CFT) columns are at the center of attention because the latter have less axial directionality and greater cross-sectional efficiency than the former. When compared with circular CFT columns, square CFT columns are more easily connected to the floor structure and the area of percussion rotary drilling (PRD) is smaller. For this reason, square CFT columns are used as core columns of concrete encased and filled square (CET) columns in underground floors. However, studies on the structural behavior and concrete stress transfer of CET columns have not been conducted. Since concrete is cast according to construction sequence, checking the stress of concrete inside the core columns and the stress of covering concrete is essential. This paper presents the results of structural tests and analyses conducted to evaluate the usability and safety of CET columns in top-down construction where CFT columns are used as core columns. Parameters in the tests are loading condition, concrete strength and covering depth. The compressive load capacity and failure behavior of specimens are evaluated. In addition, 2 cases of field application of CET columns in underground floors are analyzed.

• Tunnel and Underground Space
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• v.18 no.2
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• pp.149-161
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• 2008

It is nearly impossible to estimate the exact state of the current rock stress of interest site by the theoretical and physical approaches except some specific geological situations. This means that in-situ stress measurement is a unique way to obtain reliable information on rock stress especially for civil and mining engineering related problems. Since late in the 90's, in-situ rock stress tests have been widely conducted to provide the quantitative information on the stress state of engineering site at the design stage of an underground rock structure in the Kyungsang Basin, Korea. The study area is the near surface regions at the depth less than 300 m in the Kyungsang Basin. It includes Yeosoo to the west and Busan to the east. Totally, 270 in-situ stress measurements were conducted in the surface test boreholes at the depth from 14 m to 300 m by hydraulic fracturing method. In this paper, based on the measurement data set, the overall characteristics of the current in-situ rock stress fields in the study area are briefly described. And also the investigation results on the difference between the stress distributions for the granitoid and the andesitic rock region are also introduced. Finally, the distributions of the regional horizontal stress directions in Busan and the Yangsan faults area are shown.

• Tunnel and Underground Space
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• v.31 no.3
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• pp.145-166
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• 2021

Korea Stress Map database is built by integrating actual data of 1,400 in-situ stress measurements using hydraulic fracturing and overcoring method in South Korea. Korea Stress Map 2020 is presented based on the guideline proposed by World Stress Map Project. As detailed data, stress ratio and maximum horizontal stress direction distribution for each region are also presented. The dominant maximum horizontal stress direction in the Korean Peninsula is from northeast to southeast, and the magnitude of the in-situ stress is relatively distributed. There is some stress heterogeneity caused by local characteristics such as topographical and geological properties. We investigated case studies in which the in-situ stress was affected by mountainous topography, difference in rock quality of fracture zone, presence of mine or underground cavities, and geological structure of fault zone.