• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.361-369
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• 2008

Control of ground water is one of the most important factors for long-term operation of tunnel because most of tunnel is located in the ground. In case of leakage tunnel, there is no pore water pressure on the lining when the drainage system is properly working. After long-term operation, however, the pore water pressure can be developed on the lining due to the deterioration of the drainage system. The increased pore water pressure on the lining is termed here as 'residual pore water pressure'. Residual pore water pressure can be measured by piezometer, but it is generally not allowed because of damages of drainage system. Therefore, an indirect and nondestructive method is required for evaluating the residual pore water pressure. Moreover, understanding of pore water pressure is needed during healthy operation of the lining. In this study, a new method for evaluation of pore water pressure on the lining during operation is proposed using theoretical and numerical analysis. It is shown that the method is particularly useful for stability investigation of pore water pressure on the lining during operation using theoretical analysis with normalized pore water pressure curve.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.463-499
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• 2011

Control of ground water is one of the most important factors for long-term operation of tunnel because most tunnels are located under the ground water level. In case of a drainage tunnel, there is no pore water pressure on the lining when the drainage system is properly working. After long-term operation, however, residual pore water pressure can be developed on the lining due to the deterioration of the drainage system. In this study, the water pressure distribution under obstruction condition of drainage material and conduit on the tunnel is numerically investigated using the ICFEP program and compared with the current value being applied to the residual water pressure for rational application plan of residual water pressure on the tunnel linings.

• Tunnel and Underground Space
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• v.5 no.4
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• pp.323-335
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• 1995

지열에너지 개발의 기본적 개념은 지하 심부의 고온건조암체에 시추공을 이용한 수압파쇄를 실시하여 고온건조암체내에 인공파쇄대를 형성함으로써 유체의 유동회로를 구축하여 지열에너지의 회수를 도모하는 것이다. 본 논문에서는 수압파쇄균열의 발전방향 조절문제와 관련하여, 초고압수 절삭장치를 이용, 수압파쇄공 내에 인공슬롯을 형성하여 수압파쇄를 실시함으로써 균열의 발전방향을 조사하였으며, 수압파쇄에 의한 파쇄대내로의 유체순환실험을 통해 지열수의 유동특성을 규명하였다. 이를 위해 모델에 종균열과 횡균열을 형성시키고 균열내에 주입되는 물의 주입률, 정상류압력, 흐름저항을 조사하고, 이 결과를 이용하여 전산모델링을 수행하였다. 인공절리면에 대한 투수시험에서는 10$0^{\circ}C$까지의 온도변화에 따라 투수계수가 증가하였으며, 봉압 증가에 따라 증가율이 현저히 감소하였다.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.21-29
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• 2011

Recently, typhoons or heavy rainfalls frequently occurred because of the effect of global warming, which caused serious damage such as landslide of mountain road, debris flow and uplift seepage pressure. Uplift seepage pressure induced on the pavement of mountain roads may cause serious pavement damage. It was known that subsurface drainage method is very effective to reduce uplift seepage pressure. Suitable permeability and stiffness of drainable base is very important to have the effectiveness of subsurface drainage. In this study, optimum particle size distribution of drainable base is investigate to meet the required permeability and bearing capacity of drainable base.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.275-278
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• 2003

지하터널과 같은 대규모 지하구조물 건설시 구조물의 안정성을 확보하고 시공성 등의 실시 설계를 위해서는 그 지역의 수리적 매개변수를 파악하는 것이 필수적이다. 부산광역시 북서부에 위치한 금정산 화강암지역의 수리상수를 산출하기 위하여 야외시험과 실내시험을 수행하였으며, 각각의 결과를 서로 비교 분석하였다. 야외에서는 6개의 시추공에서 수압시험을 수행하여 심도 구간별 수리전도도를 구하였고, 실내시험에서는 시추코아를 이용하여 절리투수시험을 실시하여 수리전도를 산출하였다. 수압시험에 의해 산정된 수리전도도는 2.28E-10 m/sec∼1.49E-06 m/sec 이며, 절리투수시험에 의해 산정된 수리전도도는 1.16E-11 m/sec∼3.26E-05 m/sec이다.

• The Journal of Engineering Geology
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• v.14 no.1
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• pp.93-104
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• 2004

This paper intended to assess the hydro-structure characteristics of volcanic rocks based on the hydrogeological data obtained from the underground storage cavern during construction. The variation of groundwater levels was periodically measured from the 28 surface monitoring holes(NX size) and the hydraulic pressures and injection rates were daily monitored from the water curtain holes(95 horizontal holes and 63 vertical holes). The hydraulic interference tests were performed in whole water curtain holes. The distribution patterns of hydraulic pressure are closely related to the dip angles of fracture intersected to the water curtain holes. Three domains can be grouped by the distribution of hydraulic pressures in the horizontal water curtain holes. The initial hydraulic pressures measured immediately after drilling of water crutain holes are high in ascending order of the cavern C-2, C-1, and C-3. The priliminary hydrochemical data also indicate that the portions of the deep groundwater composition is relatively great in the cavern C-3 area. Some of the horizontal water curtain holes in the cavern C-3 show a steady higher groundwater pressure with the composition of shallow groundwater indicating the outer boundary as constant hydraulic boundary. The water curtain holes in the cavern C-2 is characterized as low initial hydraulic pressure and less injection rates, suggesting poor hydraulic connectivity to a shallow groundwater system. The results of the study can help to understand a hydraulic compartment concept in a fracture hydro-geology and be utilized during the surface investigation for a groundwater system.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.1-8
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• 2010

Construction of road closed to mountains is inevitable in Korea because the mountainous region in Korea is more than 70% in area. Recently, due to global warming, typhoons or heavy rainfalls frequently occur, and accordingly, mountain roads are seriously damaged by landslides, debris flows, and uplift pressure below pavement. in this study, damage on pavement by uplift pressure was investigated. Various influencing factors such as slope angle, reinforcement of slope surface, thickness of soil cover underlain by rock, and types of drainage system were considered to evaluate uplift pressure acting on the bottom of pavement. Raising of water table up to the surface of slope may depend on the duration and intensity of rainfall. It shows that the installation of subdrain can reduce the uplift water pressure. Therefore, It is concluded that the use of subdrain system is effective to decrease uplift pressure and cement treated base is more endurable than typical crushed-stone base.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.3
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• pp.161-167
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• 1997

A numerical model (SK-EST) for estimating hydraulic conductivity using monitoring data of underground LPG storage cavern was developed. The model calculates hydraulic conductivity from matrix equation which is established from the distribution of hydraulic potential. To verify the applicability of this model, an inverse analysis was performed using the monitoring data of pressure cell of an operating underground LPG storage cavern. And also using the water pressure parker test data which were obtained to look over the operation capability of pressure cell, conductivity variation with depth was estimated using the developed numerical model (SK-EST) and was compared with in situ results.

• Proceedings of the Korean Geotechical Society Conference
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• 1989.10a
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• pp.1.1-10
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• 1989

본 연구에서는 유효응력 개념에 기초를 둔 응력-변형을 관계식을 이용하여 비배수 지하굴착 거등을 모댈하기 위한 수치해석적 방법이 개발된다. 비배수 조건 시 적용되는 체적불변형 조건은 조건방정식(Penalty formulation)의 혁태로 공극수압 변수를 이용하여 주어지며 결과되는 유한요소 방정식에 상닻히 른 물외 체적변형 개수를 부여함으로서 이루어진다. 이러한 형태와 조건식은 지하굴착 과정에서 발생되는 비배수 공극수압의 계산을 가능케 한다. 체적불변형 조건 부여 시 발생되는 mesh locking은 그 결과에 상당한 영향을 미치므로 이러한 mesh locking 문제는 T-방법에 근거를 둔 salective 적분방법월 적용함으로서 해결될 수 있다. 또한 흙의 거등을 모델하기 위하여 사용 된 Cam-Clay모텔과 Drucker-prager모텔에 새로운 implicit 웅력적분 방법을 적용함으로서 효율적인 방법으로 비선형거동을 해석할 수 있다. 개발된 지하 굴착 해석방법의 적용성을 검증하기 위하여 실재 현장에서 측정된 지하굴착 거동을 예제로 이용하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.1
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• pp.63-72
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• 2005

The influence of internal water pressure under the Probable Maximum Flood (PMF) on tunnel spillway is analysed using 3D FDM analysis. HEC-RAS program including 1-D hydrologic numerical model was also implemented to estimate the maximum pressure on the lining under the PMF, thereafter determined rational internal water pressure. Tunnel spillway was designed as twin tunnel and excavation and supporting stage are fully considered. Analysis was classified into the 3 cases; pressure is applied only to the left tunnel, only to right tunnel, and to both tunnels. The maximum tensile stress and axial force in supporting materials induced by water flow were compared with the critical values to assess the stablilty of the tunnel and the locations of stress concentration parts were also examined.