Earticle

도시 과밀화로 지하철, 지하도, 지하 공용 공간 등 도심지 내 지하시설물은 날로 증가되고 있으며, 노후화와 지하수위 저하에 따라 붕괴 위험이 점점 증가되고 있다. 또한, 도심지 지하시설물의 심부화로 인하여 재래식 중 장비를 이용한 기존의 구호방식으로는 고립된 인명의 신속하고 안전한 구호에 한계가 있다. 본 연구에서 도심지 내 시설물의 붕괴 및 매몰사고 발생 시 인명과 재산피해를 최소화하기 위하여 수평굴착 기술을 바탕으로 한 긴급 구호 방안을 제안하였다.

The overcrowding of the city has increased the number of underground faculties, such as subway, underpass, underground public spaces, and so forth. Morever, a growing risk of collapse has been observed due to deterioration of the facilities. The deeper urban underground faculties were installed, the more limitations the traditional method using only traditional heavy equipments faced in rescuing isolated victims rapidly and safely. In this study, a rapid rescue technology based on horizontal drilling techniques was proposed to minimize the loss of human lives and properties resulting from collapse and burial accidents.

산업화 및 도시 과밀화로 인하여 시설물이 점점 대형⋅고층화되고 있으며 대심도 굴착기술의 발전을 통해 지하철, 지하도, 터널 등 지하 공용 공간이 증가되고 있어 붕괴사고 시 엄청난 피해가 발생할 수 있다. 붕괴사고 발생 시 매몰 공동을 지지하는 부재는 초기 붕괴로 인하여 필연적으로 손상을 받게 되며 건전한 상태에 비해 불안정한 거동을 보이게 된다. 붕괴 지역에 고립되어 있는 인명을 구조하기 위해서는 구조전문가의 투입이 필요하며, 이 때 구조전문가의 안정성이 담보되어야 한다. 따라서 초기 손상을 고려한 공동의 지지구조 안전성 평가가 반드시 필요하다. 본 연구에서는 붕괴 원인에 따른 매몰지역 공동의 지지 유형을 분석하였으며, 유한요소 해석기법과 다양한 하중 하에서의 재료 및 구조물의 손상을 예측함과 동시에 손상을 고려한 파괴현상을 예측할 수 있는 연속체 손상역학을 이용하여 매몰지역 공동의 안전성을 평가할 수 있는 새로운 비선형 연속체 손상역학 모델을 개발하였다.

Due to the industrialization and overpopulation of cities, the facilities become bigger and taller and underground common use spaces such as subway, underground passages and tunnels are gradually expanding through the development of deep excavation technology. In the event of a collapse accident, huge damage may occur. When a collapse accident occurs, the member of framework supporting the buried void will be damaged as a result of initial collapse, showing unstable movements in comparison to their stable conditions. Therefore, the safety assessment of the support structure for void is essential in order to rescue a person isolated in the collapsed area. This study develops a numerical model that analyzes the support type for void in the buried area depending on cause of collapse and performs safety assessment of void in the buried area against a vibration that may occur at the time of excavation.

This paper is to investigate the failure surface and modes in a soil mass by a excavation of the model ground. To study the failure surface for the excavated slope, centrifugal model tests were performed by changing the angle of the excavated slope(50, 75, $90^{\circ}$) and the ground condition($D_r$=60, 90%, dry and submerged ground). Excavation was simulated during the centrifuge tests by operating a valve that allowed the zinc chloride solvent to drain from the excavation. Results of model tests were compared with those obtained with theoretical solutions using limit equilibrium analysis method. The results of model tests show that, there is a failure to create a straight line in the low angle of excavated surface and a create a circle as the angle increases. Also, as the angle of excavated surface is increasing, the angle of the failure surface increases. The failure length in the submerged ground increases approximately 1.10~1.34 times more than that of the dry ground.

Neighboring construction becomes mainstream of Ground excavation in downtown area. This causes the displacement, deformation, stress condition, etc of the ground surroundings. Therefore Neighboring construction have an effect on Neighboring structure. All these years a lot of Neighboring construction carried out, and the accumulation of technology also get accomplished. But earth retaining structure collapse happens yet. Types of earth retaining structure collapse are 12. 1. Failure of anchor or strut system, 2. Insufficiency of penetration, 3. H-pile Failure on excessive bending moment, 4. Slope sliding failure, 5. Excessive settlement of the back, 6. Deflection of H-pile, 7. Joint failure of coupled H-pile, 8. Rock failure when H-pile penetration is rock mass, 9. Plane arrangement of support systems are mechanically weak, 10. Boiling, 11. Heaving, 12. Over excavation. But field collapses are difficult for classification according to the type, because collapse process are complex with various types. When we consider the 12 collapse field, insufficient recognition of ground condition is 4 case. Thorough construction management prevents from fault construction. For limitations of soil survey, It is difficult to estimate ground condition exactly. Therefore, it should estimate the safety of earth retaining system, plan for necessary reinforcement, according to measurement and observation continuously.

To figure out the decay characteristics of naturally occurring radionuclides, eight sampled groundwaters from a monitoring borehole having high levels of uranium and radon concentrations in a two mica granitic area have analyzed by liquid scintillation counters (LSC) for over 1 year. In December 2011, three groundwater samples (DJ1, DJ2, DJ3) were obtained from each aquifer system located at -20 m, -40 m, -60 m of the monitoring borehole below the ground surface, respectively. Five samples (DJ4, DJ5, DJ6, DJ7, DJ8) were additionally gained from each aquifer positioned -20 m, -40 m, -60 m, -100 m, -105 m of the borehole in February 2012, respectively. Temporal variation characteristics of uranium and radon concentrations have showed over maximum 2.1 times and 1.4 times fluctuations of the values in the same sampling intervals over time, respectively. The intervals of -40 m and -105 m in the borehole have the highest values of uranium and radon concentrations, respectively. This may imply that the concentrations of naturally occurring radionuclides such as uranium and radon in groundwater have been changed over time and indicate that the qualities of groundwaters from the aquifers developed at each interval in the borehole are different each other. This discrepancy, moreover, could be caused by behaviour differences between uranium which is in ionic status having a half life of 4.6 billion years and is transported along with the flowing groundwater, and radon which is in gaseous status having a 3.82 day's half life in the aquifer systems. Physicochemical characteristics of groundwaters from the aquifer systems could be identified by the results of the on-situ measuring items such as pH and Eh, and the major ionic contents. The CPM values of eight groundwater samples analysed by LSC over one year have shown not to follow the theoretical decay curve of the radon. The CPM values of the samples have ranged from 2 to 7.5 after it had passed two months when the theoretical CPM values of the radon started zero since the initial analysis. Alpha and beta particle spectrums have shown the peaks of radium-226, however they have not revealed any peaks of radon and it's daughter products such as polonium-218 and 214, bismuth-214 for the late stage of the analysis. This implies that the groundwater from the borehole may contain radium-226 having a half life of 1,600 years which decays continuously.

국내에서는 매년 집중호우에 의하여 사면 붕괴 및 산사태가 발생하고 있다. 특히, 최근의 집중강우는 국지성 및 게릴라성 강우가 대부분이다. 본 연구에서는 집중호우에 의하여 붕괴된 현장의 특성을 분석하고, 토층의 심도와 지하수면의 변화에 따른 사면의 안정성을 해석한다. 본 연구에 사용된 자료는 집중호우시 붕괴된 절토사면 조사 자료와 일반 국도변 1,372개의 현장 조사자료이다. 토층의 붕괴 심도와 지하수 변동이 사면의 안정성에 미치는 영향에 대해서는 FLAC-SLOPE(ITASCA사)을 이용하여 분석을 실시하였다. 연구결과에 의하면 국내 사면붕괴의 주요 형태는 표층유실 및 표층붕괴 등 천부 파괴가 주를 이루고 있으며, 지하수면과 토층 심도 변화에 따라 사면의 안정성이 변화하는 것으로 나타났다.

The failure of cut slope and landslide sometimes come from a local downpour within a short duration in Korea. Especially, most of recent downpour converged upon a limited region and seemed the characteristics of guerilla. Characteristics of slopes failed due to local downpour are analyzed. failure mode is also analyzed with respect to the depth of soil layers and the change of groundwater level. To blow the influence factors of the slope stability during local downpour, the authors conducted field survey for failed slopes and tried to make a comparative study of 1,372 cut slope data distributed in the national road. FLAC-SLOPE(ITASCA Co.) is used to analyze slope stability with changing depth of soil layers and groundwater level. The result shows that the failed types of domestic slopes during local downpour are mainly shallow collapse and landslide. The change of soil depth and groundwater level have influenced on the stability of slopes.