• Land and Housing Review
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• v.7 no.4
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• pp.261-269
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• 2016

Pipe-roof method is one of the mostly used method to prevent the ground subsidence during the tunnel construction. As pipe-roof method has made technical advancement and performance improvement, it suggested to utilize pipe-roof to a permanent support system rather than a temporal pre-reinforcing method. Therefore, in this study, pipe-roof method is numerically simulated using finite element method to evaluate effects of pipe-roof on behavior of ground and structure. Analyses are performed considering two major conditions that are with and without the application of pipe-roof and the shape of tunnel cross section. The results are presented with respect to variation of settlement and vertical stress distribution. Based on this results, it is found that ground settlement above the shallow tunnel can be considerably reduced by application of pipe-roof system. Also, the shape of tunnel cross section can influence on the mechanical behavior of ground and structure.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1995.03a
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• pp.27-40
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• 1995

한강하저의 지질은 수많은 대ㆍ소 단층들로 인해 심하게 교란되어 있어 지질상황의 변화가 매우 심하며, 터널을 굴착함에 있어 지하수의 유입을 차단하는 것이 안전시공을 위한 필수 과제로 직면한다. 본 고에서는 기 시공실적을 바탕으로 암반상태에 따른 차수그라우딩의 패턴을 비교ㆍ검토하였다. 본 구간에서는 암반상태에 따라 5가지 패턴이 적용되었으며, 경암 암반일 경우는 상부반단면만을 주입범위(주입범위 : 3.5m, 28공)로 하고 암반의 전단강도증진을 위해 강관보강을 시행하였다. 연암 암반 내지 파쇄대가 부분적으로 협재된 경우는 상부반단면만을 주입하되 주입범위 및 그라우팅 공수를 늘리는 방식(주입범위 : 5∼7, 42∼56공)으로 보강하였다. 풍화암 암반의 경우는 전단면을 주입범위로 하여 그라우팅 공수를 늘림(주입범위 : 7m, 81공)으로서 차수효과를 증진시켰다. 또한 본 공사구간 중 가장 난제였던 연약지반대(잔류토 내지 풍화토) 85m 구간은 자문회의 등을 거쳐 주입범위, 주입길이 및 주입공수, bulk head 구간을 늘려 시공하고, 굴착하면서 차수효과를 확인하는 방식을 취하였다.

• Explosives and Blasting
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• v.21 no.3
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• pp.61-71
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• 2003

최근 도심지 굴착공법 선정시 주변환경에 대한 관심이 높아지면서 민원발생을 감안하여, 발파공법이 아닌 기계굴착공법(TBM, SHIELD 등) 등이 부분적으로 적용되고 있다. 그러나 이들 굴착공법들은 굴착조건의 변화에 따라 적용 한계성이 있고, 한계구간이 직면할시 시공성이 극히 떨어지거나 적용 자체가 불가능하게 된다. 이에 따라, 공사기간의 연장, 공사비의 증가 및 적용자체가 불가 할 경우는 공사중단에 이르게 되어 시공과정에서 다른 굴착공법으로 전환되는 사례가 빈번히 발생되고 있다. 따라서 본 사례는 도심지 터널구간으로 당초 할암공법으로 설계되었으나 암반의 강도가 높고 굴착단면적이 협소하여 할암공법이 적용될 수 없었다. 이에 대한 대안공법으로 TBM이나 기타 장비에 의한 기계굴착공법을 검토하였으나, 터널연장이 짧고 터널노선의 곡선부 반경이 작아 대형장비의 투입이 어려운 굴착조건 때문에 최종적으로 폭약을 이용한 발파굴착 공법을 선정하였다. 그러나 발파공법은 진동 및 소음이 필연적으로 수반되기 때문에, 주변 환경공해가 허용하는 범위 내에서 최대한의 시공성과 안전성 여부를 판단하기 위하여 발파진동 및 소음의 허용수준을 설정한 후 시험발파를 실시하였으며, 그 결과에 따라 진동제어발파공법을 적용하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.3
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• pp.315-325
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• 2009

The thickness of the material can be thinned because arch cut-and-cover tunnel has the support mechanism by the axial force, and the ground reaction force due moderate deformation can be expected thereby making it be dynamically advantageous, therefore the arch cut-and-cover tunnel has become more widely used. An important characteristic of the arch cut-and-cover tunnel is that the thickness of the material can be thinned because precast arch type has the support mechanism by the axial force. However, there is a different stress state surrounding the structures between normally excavated tunnels and cut-and-cover tunnels, it should be considered at designing. Therefore, finite element method was carried out to examine the mechanical behavior of the precast arch cut-and-cover tunnel considering construction procedure.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.633-639
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• 2005

We studied three dimension numerical analysis in the case that a train stops in tunnels by fire. And the 'Fluent 6.1' which is CFD(Computational Fluid Dynamics) program was used in this study. We compare the smog diffusion in single/double track ordinary railway tunnels with that in double track high speed railway tunnels in this study.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.223-237
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• 2010

The initial heating rate is well known as one of the most influencing factors on the occurrence of spalling and the loss of strength in concrete after fire initiation. In this study, a series of fire tests were carried out at different initial heating rates to find out its effects on the deterioration of tunnel structural members. Heat transfer analyses combined with an element elimination model were also carried out to verify its applicability in the same conditions as the fire tests. Moreover, the convection heat transfer coefficients compatible with fire test results were derived from parametric studies. In this course, their time-dependent variations were also analyzed at different initial heating rates. Finally, a numerical formula to estimate the heat transfer coefficients at the various initial heating rates was proposed by the interpolation of the results of numerical analyses.

• Explosives and Blasting
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• v.34 no.3
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• pp.17-20
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• 2016

This paper introduce a multistage parallel non-vibration electronic tunnel blasting cases which adapts Electronic Blasting System(EBS) and the center-cut blasting method to excavating a single line railway tunnel close to residential area. As a result, it was revealed that the vibration and noise showed a reduction of 23.5% and 75% of compared with the allowable standard. We successfully completed the tunnel excavation with decreasing construction time and construction cost and without civil compliant.

• Explosives and Blasting
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• v.31 no.1
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• pp.33-40
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• 2013

Carinthian cut and cover tunnelling method which combines cut & cover and NATM tunnel excavation method has increased the interest. Design and construction of arch concrete have been increased, but there is no applicable standards for arch concrete. Therefore, in this study numerical analysis was performed to propose standards for the Carinthian tunnelling method considering a variety of conditions such as ground conditions, tunnel overburden thickness, thickness of backfill, and overburden surface slope angle changes, linear regression equations derived to classify and organize a rational, economical, and safe Carinthian cut and cover tunneling method based proposed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.273-287
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• 2006

This study investigates the failure mechanism and load-carrying capacity of a single-shell lining which has no disturbance in transfer of shear force, with respect to a conventional double-shell lining which has separation between layers of shotcrete lining and secondary concrete lining by water-proof membrane. In order to evaluate the capacity, a 2-D numerical investigation is preliminarily carried out and then real-scale loading tests with tunnel lining section specimens are performed on the condition given by the numerical investigation. In the test, a concentrated load is applied for considering a released ground load or rock wedge load. Through this study, it appears that the single-shell lining takes the load-bearing capacity 20% higher than in case of the double-shell lining. In addition, a possibility of a composite single-shell shotcrete layer composed by multiple bonded layers partly involving different contents of high-capacity additives is shown thereby leading to use of less amount of the high-capacity additives on the condition of taking a similar load-bearing capacity.

• Tunnel and Underground Space
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• v.14 no.4
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• pp.269-274
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• 2004

In this study reduced-scale experiments were conducted to determine the backlayering distance in tunnel fires. The 1/20 scale experiments were carried out under the Froude scaling using ethanol square pool fire ranging from 8 to 1km in each side with total heat release rate from 2.47 to 12.30 ㎾. It has been found that ventilation velocity increases with aspect ratio(tunnel height/tunnel width). At L$\_$B/$\^$*/ ＜5 the ventilation velocity increases proportional to the backlayering distance from 0.25 power of the heat release rate. However at L$\_$B/$\^$*/ $\geq$5 the ventilation velocity varies as the 0.3 power of the heat release rate.