• Journal of Korean Tunnelling and Underground Space Association
• /
• v.10 no.1
• /
• pp.25-36
• /
• 2008

When constructing subsea underground structures, the influence of high water and seepage pressure acting on the structures can not be neglected. Thus hydro-mechanical coupled analysis should be performed to estimate the behavior of the structures precisely In practice, relaxed rock load is generally used for the design of tunnel concrete lining. A method based on the distribution of local safety factor around a tunnel was proposed for the estimation of a height of relaxed rock mass ($H_{relaxed}$). In this study, the validation of the suggested method is investigated in the framework of hydro-mechanical coupled analyses. It was suggested that inducing inflow by pumping through a drainage well gave more reliable results than inducing inflow with shotcrete hydraulic characteristics in case of rock condition of Class III. In this study, therefore, inducing inflow by pumping through a drainage well are adopted in estimating $H_{relaxed}$ due to a tunnel excavation with the rock condition of Class I, III, and V. Also the estimated $H_{relaxed}$ results are compared with those of the existing suggested methods. As the result of this study, it is confirmed that estimating $H_{relaxed}$ based on the distribution of local safety factor around a tunnel can be effectively used even for the case of hydro-mechanical coupled analysis. It is also found that inducing inflow pumping through a drainage well gives more precise and consistent Hrelaxed of a subsea structure.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1532-1548
• /
• 2008

The tunnel type spillways is under construction to increasing water reservoir capacity in Dae-am dam. The tunnel outlet was planned to be made after installing slope stabilization system on natural slope there. Generally, the tunnel outlet is made perpendicularly to the slope, but in this case, it had to be made obliquely to the slope for not interrupting flow of river. Because of excavation in condition of natural slope caused to deflecting earth pressure, the outlet couldn't be made. So, artificial ground made with concrete that it was constructed in the outside of tunnel for producing the arching effect which enables to make a outlet. We were planned tunnel excavation was carried out after artificial ground made. Artificial ground made by poor mix concrete of which it was planned that the thickness was at least 3.0m height from outside of tunnel lining and 30cm of height per pouring. Spreading and compaction was planned utilized weight of 15 ton roller machine. In order to access of working truck, slope of artificial ground was designed 1:1.0 and applied 2% slope in upper pert of it for easily drainage of water. In addition to, upper pert of artificial ground was covered with soil, because of impaction of rock fall from upper slope was made minimum. The tunnel excavation of the artificial ground was designed application with special blasting method that it was Super Wedge and control blasting utilized with pre-percussion hole.

• Journal of the Korean GEO-environmental Society
• /
• v.14 no.2
• /
• pp.13-17
• /
• 2013

Clogging phenomenon in drainage system is one of the important problems and this phenomenon would be bad effect to structure of tunnel, so it needs a remedy urgently. Recently, scale in drainage pipe is removed by water jet cleaning and other treatment. But these treatments need much cost and regular management. In this study, magnetic device was used to solve this problem and an effect of prohibiting scale in accordance with array of magnetic device was investigated. Analysis method was visual analysis and measuring weight of each pipes. As a result, interior top and out-bottom (CASE II) was the most effective array to prohibit scale. and interior left and right (CASE III), interior top and bottom (CASE I) was effective for prohibiting scale in order.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.21 no.4
• /
• pp.573-585
• /
• 2019

The objective of this study is to propose the drainage system that has been improved the workability, waterproofing and drainage performance to treat the leakage from the cement concrete structures in underground. It is improved that the pipe for conveying ground leak in the existing drainage system had the problem in workability and waterproof. The drainage systems with the improved pipe for conveying ground leak were constructed in conventional concrete lining tunnels to evaluate the workability, waterproofing and drainage. The waterproof and the drainage performance of the drainage system was evaluated by injecting 1,000 ml of red water in the back of the drainage system at 3 weeks, 6 weeks, 9 weeks, 11 weeks, 14 weeks, 17 weeks and 23 weeks. During 6 months of field performance test, the average daily temperature of the tunnel site was measured from $-12.4^{\circ}C$ to $19.7^{\circ}C$. The daily minimum temperature was $-17.2^{\circ}C$ and the daily maximum temperature was $26.7^{\circ}C$. There was no problem in waterproof and drainage performance on the pipe for conveying ground leak and the drainage system during 6 months for field performance test. It is concluded that the improved drainage system can be applied to various cement concrete underground structures where leakage occurs, and has little seasonal effect.

• The Journal of Engineering Geology
• /
• v.17 no.3
• /
• pp.339-350
• /
• 2007

Content, swelling, concentration, drainage of clay are critical factors that could control rock failures as well as discontinuous geological structures like faults and joints. Especially, the proportional components of clay minerals can be one of few direct indicators to a rock failure caused well by rainfall. Criticality of the role of clay mineral contents gets bigger in the slope and tunnel design. This study, using a horizontal boring core of pelitic/psammitic phyllite from the OO tunnel construction site, aims to investigate mineral composition changes related to fault distribution and their mechanical effects to the activity of these discontinuous layers (i.e., clay-filled fault layers), and eventually to define correlation among rock compositions, weathering products and rock instabilities. Field survey and lab tests were carried out for the composition and strength index of fault clay minerals within the core samples and microscopic analysis of fresh and weathered rock samples.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.15 no.2
• /
• pp.123-134
• /
• 2013

Urban underground structures at low ground elevations (i.e. shallow substructures) unlike typical tunnel structures are subjected to low overburden and high water pressures. This often causes the underground structures to become damaged. Various conventional methods for the urban underpass structures such as dead weight increasement, round anchors, and tension piles, are significantly conservative and provok concerns about the costly, time-consuming installation process. Recently, permanent drainage system becomes to widely use for supplementing the conventional method's shortcomings, but, it is applied without the considerations for ground conditions and water table. In this study, therefore, numerical analyses are performed with various parameters such as groundwater level, wall height, and ground conditions in order to establish design guidelines for induced drainage system which is a kind of the permanent drainage method constructed at the Y-area. According to the numerical results, the induced drainage system is very effective in reducing the uplift pressure that acts on the base of underpass structures.

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

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.195.1-195.1
• /
• 2011

This paper presents an experimental study on a new potential geothermal energy source obtained from tunnel structures. An "energy textile", which is a textile-type ground heat exchanger, was fabricated between a shotcrete layer and a guided drainage geotextile in the tunnel lining system. To examine the long-term thermal behavior of the energy textile, the difference in temperatures of the inlet and outlet fluid circulating through the heat exchange pipe within the energy textile was monitored using a constant-temperature water bath. Daily heat exchange rate of the energy textile during cooling operation was estimated from the measured temperatures of the inlet and outlet fluid through the energy textile. The air and ground temperature was also continuously monitored. The operation of the energy textile as a ground heat exchanger was simulated using a 3D numerical CFD model (Fluent). The thermal conductivity of shotcrete and concrete lining components and temperature variation of air in the tunnel were incorporated in the model. The numerical analysis shows a good agreement with the long-term monitoring result.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.3
• /
• pp.533-549
• /
• 2017

In this study, drainage systems were proposed to drain the leakage of groundwater in the existing underground concrete structures. The system consists of drainage board, wire mesh, fixed nail, and mortar with mineral. In order to increase constructability, the drainage board and wire mesh were attached on the surface of cement concrete using the air nailer and fixed nail. The mortar with 30% of blast furnace slag was sprayed on the drainage board and wire mesh using the spray mortar equipment. The field test construction was carried out in a conventional concrete lining tunnel and concrete retaining wall for performance verification of the drainage system in the field. There was no problem with performance degradation in the drainage system for three years after construction. The bond strength tests were performed on the sprayed mortar at 14 days and about 3 years after field test construction. In case of attaching the wire mesh on the drainage board, the bond strengths of the sprayed mortar were 1.04 MPa at 14 days and 1.46 MPa about 3 years. In case of the drainage board without the wire mesh, the bond strengths of the sprayed mortar were 1.13 MPa at 14 days and 0.89 MPa, less than 1 MPa of bond strength criteria, about 3 years.

• Journal of Environmental Science International
• /
• v.20 no.12
• /
• pp.1553-1560
• /
• 2011

The study analyzes groundwater balance with regard to the water recharge and discharge which contain urbanization components in Suyeong-gu, Busan. It also verifies the reliability and accuracy improvement on the analysis of the balance. The result of the study is viewed as preliminary data which are useful to develop, utilize and manage groundwater. The average quantity of groundwater recharge is 6,014.1 $m^3$/day in the research area during the last ten year period(from 1998 to 2007). The outflow from drainage areas to rivers and coasts is 149.3 $m^3$/day, the inflow from rivers and coasts to drainage area is 439.9 $m^3$/day. The use of the water is 4,243.0 $m^3$/day. The outflow caused by subway in line No.2 and No.3 through Suyeong-gu and the one by building an underground electric complex is 1,500.0 $m^3$/day. The leakage of water works is 6514.9 $m^3$/day. The inflow and outflow of sewerage is 5082.2 $m^3$/day from groundwater to sewer. The amount of groundwater recharge, the inflow from rivers and coasts to drainage area, and the leakage of water works belong to the amount of groundwater inflow and the total amount is 12,968.9 $m^3$/day. The amount of outflow from drainage area to rivers and coasts, the use of groundwater, outflow by subway and underground electric complex tunnel and the amount of inflow of the water to sewerage belong to the amount of outflow of groundwater and the sum amount is 13,031.5 $m^3$/day. The gap between the amount of inflow and outflow of groundwater is 62.6 $m^3$/day, which is considered to reflect the trend that the short term drop in the amount of rainfall results in the amount of groundwater recharge and that the amount of outflow from drainage area to rivers and coasts decreases.