• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.309_310
• /
• 2009

본 연구에서는 가공배전선로의 상하단 단락고장을 예방하기 위하여 현행 관련 기준의 적정성 여부를 검토하고자 한다. 이를 위하여 기준이도, 완철의 최소 이격거리, 미국 NESC(National Electric Safety Code)의 수직선간이격거리에 대하여 문헌적 고찰을 한 후, 이를 토대로 국내에 적용할 수직선간이격거리 및 지상고 검토 조건을 도출하였고, 기준이도 적용 시 가공배전선 종류별 75^{\circ}C$이도를 계산하여 그 결과들을 비교 검토하였다. 그 결과 상하단 선간단락 고장을 예방하기 위하여 나전선의 기준이도를 특고압전선과 동일하게 적용하여야 하며, 특고압 완철 간의 최소이격거리는 경간 100m 이상에서 수직이격거리가 부족하므로 0.1m 정도 증가 시키는 것이 바람직하다는 것을 발견하였다.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.2
• /
• pp.199-211
• /
• 2009

Development of underground space is actively performed globally for better life in the surface, and the scale of the space is increasing. Extreme care should be taken in the construction of the underground space in urban areas in order to avoid damage of adjacent structures and interference with existing underground space. In case of shallow tunnels, reinforcement of ground and structures is necessary to minimize the damage to structures due to excavation but any standard for optimum range of the reinforcement has not been established yet. In this paper, a series of numerical analyses have been performed for a 20 m diameter tunnel excavated underneath a structure to investigate the degree of damage of the structure according to vertical and horizontal spacing between the tunnel and structure. In addition to that, optimum range of reinforcement is presented for each case where reinforcement is required. It has been observed that the reinforcement is necessary for the ground condition adapted in the analyses as follows: (1) if horizontal spacing ($S_{H}$) approaches to 0D (D: equivalent diameter of tunnel) for vertical spacing (Sv) of 0.5D, and (2) if tunnel exists underneath the structure for vertical spacing (Sv) of 0.75D. The reinforcement is not necessary for Sv of 10 regardless of $S_{H}$. It also has been obtained that the optimum ranges of the reinforcement around structure foundation are 7 m in depth and whole width of the structure and 5 m beyond tunnel sidewall. These reinforcememt ranges have been confirmed to be enough for stability of the structure if types of reinforcement method is appropriately selected.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.3
• /
• pp.355-373
• /
• 2017

Tunnelling in urban areas, it is essential to understand existing structure-tunnel interactive behavior. Serviced structures in the city are supported by pile foundation, since they are certainly effected due to tunnelling. In this research, thus, pile load distribution and ground behavior due to tunnelling below grouped pile were investigated using laboratory model test. Grouped pile foundations were considered as 2, 3 row pile and offsets (between pile tip and tunnel crown: 0.5D, 1.0D and 1.5D for generalization to tunnel diameter, D means tunnel diameter). Soil in the tank for laboratory model test was formed by loose sand (relative density: Dr = 30%) and strain gauges were attached to the pile inner shaft to estimate distribution of axial force. Also, settlements of grouped pile and adjacent ground surface depending on the offsets were measured by LVDT and dial gauge, respectively. Tunnelling-induced deformation of underground was measured by close range photogrammetric technique. Numerical analysis was conducted to analyze and compare with results from laboratory model test and close range photogrammetry. For expression of tunnel excavation, the concept of volume loss was applied in this study, it was 1.5%. As a result from this study, far offset, the smaller reduction of pile axial load and was appeared trend of settlement was similar among them. Particulary, ratio of pile load and settlement reduction were larger when the offset is from 0.5D to 1.0D than from 1.0D to 1.5D.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.5
• /
• pp.685-703
• /
• 2017

Recently, as the number of high-rise building and earthquake occurrence are increasing, it is more important to consider horizontal load such as wind and seismic loads, earth pressure, for the pile foundation. Also, development of underground space in urban areas is more demanded to meet various problem induced by growing population. Many studies on pile subjected to horizontal load have been conducted by many researchers. However, research regarding interactive behavior on pile subjected to horizontal load with tunnel are rare, so far. In this study, therefore, study on the behaviors of ground and horizontal and vertical loads applied to single pile was carried out using laboratory model test and numerical analysis. The pile axial force and ground deformation were investigated according to offset between pile and tunnel (0.0D, 1.0D, 2.0D: D = tunnel diameter). At the same time, close range photogrammetry was used to measure displacement of underground due to tunnelling during laboratory model test. The results from numerical analysis were compared to that from laboratory model test.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.4
• /
• pp.509-517
• /
• 2022

The demand for underground infrastructures such as tunnels is expanding due to rapid urbanization. Tunnels in urban areas are usually constructed adjacent to structures supported by piles. Therefore, a proper understanding of pile-tunnel interaction due to tunnel excavation activities is vital. Thus, in this study, a numerical analysis is conducted to analyze pile settlements, ground surface settlements and shear deformations above an existing tunnel subject to the presence of an adjacent tunnelling, with vertical offsets, the number of piles and the pile spacing considered as variables in the analysis. The results show that the vertical offsets between the tunnel crown and the pile tip generatelarger settlement than the pile spacing. In addition, the vertical offset shows an inversely proportional relationship to the shear deformation due to new tunnelling.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2019.05a
• /
• pp.42-44
• /
• 2019

금회 연구대상지인 진도 해역은 WQI지수 II, III등급 해역으로, 비교적 양호한 수질상태를 유지하고 있다. 최근 대명리조트는 이곳에 대규모 휴양시설을 계획 중에 있으며, 이에 따른 오수의 해양방류는 불가피할 것으로 보인다. 따라서, 오수의 해양방류로 인하여 대상해역의 오염이 우려됨에 따라 최적의 배수시설을 건설하여 수질악화를 방지하고자 한다. 배수시설에 따른 수질영향 예측을 수행하기 위하여 Delft3D-WAQ 모듈을 이용하여 당 해역의 수질특성을 재현 및 예측하였다. 또한, 상기 모델에 의한 모의결과의 정확도를 확인하고 보완하기 위하여 수직 와확산계수의 민감도 분석을 수행하였으며, 이를 통해 신뢰도를 확보하였다. 배수시설의 방류구 이격 거리 및 수층별 방류에 따른 수질변화를 검토한 결과, 해안에서의 이격거리가 멀고 중층에 방류할 경우 가장 효과적인 희석률을 보이는 것으로 나타났다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.3D
• /
• pp.453-459
• /
• 2006

This paper presents an experimental evaluation of wandering effect on asphalt concrete pavement responses. A laser-based wandering system has been developed and its performance is verified under various field conditions. The portable wandering system composed of two laser sensors with Position Sensitive Devices can allow one to measure the distance between laser sensors and tire edges of moving vehicle. Therefore, lateral position of each wheel on the pavement can be determined in a real time manner. Pavement responses due to different loading paths are investigated using a roll over test which is carried out on one of asphalt surfaced pavements in the Korea Highway Corporation test road. The pavement section (A5) consists of 5 cm thick surface course; 7 cm intermediate course; and 18 mm base course, and is heavily instrumented with strain gauges, vertical soil pressure cells and thermo-couples. From the center of wheel paths, seven equally-spaced lateral loading paths are carefully selected over an 140 cm wandering zone. Test results show that lateral horizontal strains in both surface and intermediate courses are mostly compressive right under the loading path and tensile strains start to develop as the loading offset becomes 40 cm from the wheel path. The development of the vertical stresses in the top layers of subbase and anti-frost is found to be minimal once the loading offset becomes 50 cm.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.14 no.3
• /
• pp.231-246
• /
• 2012

Recently, the construction of tunnel frequently involves neighboring weak ground conditions. In this case, the stabilized ground could be relaxed by the excavation of tunnel. This will create issues in terms of stability of tunnel. Major factors determining the stability of tunnel can be the direction (angle) of weak zone, the distance between tunnel and boundary of weak zone and so on. In this study, by quantifying the displacement and crack propagation during the excavation of tunnel constructed neighboring weak zone, the influence of the direction of weak zone and the distance between tunnel and boundary of weak zone on the mechanical behavior of tunnel is investigated. A series of experimental scaled model tests by changing the direction of weak zone and the distance between tunnel and boundary of weak zone, are performed and analyzed under the condition of homogeneous material. The results show that as the angle between ground surface and boundary of weak zone moves from horizontal to perpendicular plane, displacement near tunnel increases. An increased distance between tunnel and boundary of weak zone induces displacements near tunnel to decrease and stabilizes beyond a certain level of distance. These findings verify and extend the earlier studies quantitatively. Finally, an appropriate distance between tunnel and boundary of weak zone according to the angle of weak zone is justified. This fundamental insight provides the basis for a more rational design of tunnel neighboring weak ground conditions.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.2
• /
• pp.119-131
• /
• 2005

The two dimensional behaviors of the existing upper tunnel and the ground at crossed area due to the excavation of a lower tunnel were studied experimentally, The model tests were conducted by changing the relative location of the existing upper tunnel and the lower tunnel. The results of the study show that a vertical earth pressure outside the loosened area was increased due to longitudinal arching effect same as a single tunnel. In case vertical distance between the upper and lower tunnel is 0.7 H and 1.0 H respectively (H is a height of the lower tunnel), vertical earth pressure increased in the loosened area behind the tunnel face. But when a vertical distance is 1, 3 H, ground behaviors appeared similarly to a single tunnel.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.26 no.1
• /
• pp.59-78
• /
• 2024

In tunnel construction, the stability is evaluated by the settlement of adjacent structures and ground, but the shear strain of the ground is the main factor that determines the failure mechanism of the ground due to the tunnel excavation and the change of the operating load, and can be used to review the stability of the tunnel excavation and to calculate the reinforcement area. In this study, a twin tunnel excavation was simulated on a soft ground in an urban area through a laboratory model test to analyze the behavior of the twin tunnel excavation on the adjacent pile grouped foundation and adjacent ground. Both the displacement and the shear strain of ground were obtained using a close-range photogrammetry during laboratory model test. In addition, two-dimensional finite element numerical analysis was performed based on the model test. The results of a back-analysis showed that the maximum shear strain rate tends to decrease as the horizontal distance between the pillars of the twin tunnel and the vertical distance between the toe of the pile group and the crown of the tunnel were decreased. The impact of the second tunnel on the first tunnel and pile group was decreased as the horizontal distance between the pillars of the twin tunnel was increased. In addition, the vertical distance between the toe of the pile group and the crown of the tunnel had a relatively greater impact on the shear strain results than the horizontal distance of the pillars between the twin tunnels. According to the results of the close-range photogrammetry and numerical analysis, the settlement of adjacent pile group and adjacent ground was measured within the design criteria, but the shear strain of the ground was judged to be outside the range of small strain in all cases and required reinforcement.