• Geomechanics and Engineering
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• 제23권5호
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• pp.441-454
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• 2020

The tunnel collapse, large deformation of surrounding rock, water and mud inrush are the major geological disasters in soft rock tunnel construction. Among them, tunnel collapse has the most serious impact on tunnel construction. Current research backed theories have certain limitations in identifying the collapse risk of soft rock tunnels. Examining the Zhengwan high-speed railway tunnel, eight soft rock tunnel collapse influencing factors were selected, and the combination of indicator weights based on the analytic hierarchy process and entropy weighting methods was obtained. The results show that the groundwater condition and the integrity of the rock mass are the main influencing factors leading to a soft rock tunnel collapse. A comprehensive fuzzy evaluation model for the collapse risk of soft rock tunnels is being proposed, and the real-time collapse risk assessment of the Zhengwan tunnel is being carried out. The results obtained via the fuzzy evaluation model agree well with the actual situation. A tunnel section evaluated to have an extremely high collapse risk and experienced a local collapse during excavation, verifying the feasibility of the collapse risk evaluation model. The collapse risk evaluation model proposed in this paper has been demonstrated to be a promising and innovative method for the evaluation of the collapse risk of soft rock tunnels, leading to safer construction.

• 한국터널지하공간학회 논문집
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• 제26권5호
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• pp.421-433
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• 2024

지하 공간 활용이 증가하면서 터널 시공 중 발생하는 붕괴 사고의 예방이 중요한 과제가 되고 있다. 본 연구는 터널 시공 중 붕괴 위험을 정량적으로 평가하기 위해 다양한 영향인자를 분석하고, 이를 바탕으로 터널 붕괴 위험도 지수를 제안하였다. 터널 붕괴에 영향을 미치는 14개의 주요 영향 인자에 대해 AHP (analytic hierarchy process)를 통해 가중치를 산정하였다. 27개의 붕괴 사례 데이터를 수집하여 몬테카를로 시뮬레이션을 활용해 각 영향 인자의 등급 점수를 산정하고, 이를 종합하여 터널 붕괴 위험도 지수를 도출하였다. 터널 붕괴 위험도 지수의 평균값은 49.359점으로 분석되었으며, 향후 터널 붕괴 위험도에 대한 막장별 평가결과와 비교를 통해 해당 막장의 붕괴 위험도가 낮은지 높은지 평가할 수 있다. 본 연구는 터널 붕괴 위험도의 주요 인자들을 정량적으로 평가할 수 있는 체계적인 기법을 제시함으로써, 터널 시공 중 발생할 수 있는 붕괴 사고를 사전에 예방하고, 적절한 대책을 수립하는 데 기여할 수 있다. 향후 연구에서는 더 많은 현장 자료를 통해 터널 붕괴 위험도 지수의 신뢰성을 높이고, 이를 바탕으로 한 터널 붕괴 위험도 평가의 신뢰성을 향상시킬 수 있을 것으로 판단된다.

• International Journal of Advanced Culture Technology
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• 제6권4호
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• pp.255-261
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• 2018

In the field of excavation, it is important to recognize and analyze the factors that cause the ground collapse in order to predict and cope with the ground subsidence. However, it is difficult for field engineers to predict ground collapse due to insufficient knowledge of ground subsidence influence factors. Although there are many cases and studies related to the ground subsidence, there is no manual to help practitioners. In this study, we present the criteria for describing and quantifying the influential factors to help the practitioners understand the existing ground collapse cases and classification of the ground subsidence factors revealed through the research. This study aims to improve the understanding of the factors affecting the ground collapse and to provide a GSRp for the ground subsidence risk assessment which can be applied quickly in the field.

• Journal of Korean Neurosurgical Society
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• 제62권4호
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• pp.450-457
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• 2019

Objective : Anterior cervical discectomy and fusion (ACDF) is commonly used surgical procedure for cervical degenerative disease. Among the various intervertebral spacers, the use of allografts is increasing due to its advantages such as no harvest site complications and low rate of subsidence. Although subsidence is a rare complication, graft collapse is often observed in the follow-up period. Graft collapse is defined as a significant graft height loss without subsidence, which can lead to clinical deterioration due to foraminal re-stenosis or segmental kyphosis. However, studies about the collapse of allografts are very limited. In this study, we evaluated risk factors associated with graft collapse. Methods : We retrospectively reviewed 33 patients who underwent two level ACDF with anterior plating using allogenous bone graft from January 2013 to June 2017. Various factors related to cervical sagittal alignment were measured preoperatively (PRE), postoperatively (POST), and last follow-up. The collapse was defined as the ratio of decrement from POST disc height to follow-up disc height. We also defined significant collapses as disc heights that were decreased by 30% or more after surgery. The intraoperative distraction was defined as the ratio of increment from PRE disc height to POST disc height. Results : The subsidence rate was 4.5% and graft collapse rate was 28.8%. The pseudarthrosis rate was 16.7% and there was no association between pseudarthrosis and graft collapse. Among the collapse-related risk factors, pre-operative segmental angle (p=0.047) and intra-operative distraction (p=0.003) were significantly related to allograft collapse. The cut-off value of intraoperative distraction ${\geq}37.3%$ was significantly associated with collapse (p=0.009; odds ratio, 4.622; 95% confidence interval, 1.470-14.531). The average time of events were as follows: collapse, $5.8{\pm}5.7months$; subsidence, $0.99{\pm}0.50months$; and instrument failure, $9.13{\pm}0.50months$. Conclusion : We experienced a higher frequency rate of collapse than subsidence in ACDF using an allograft. Of the various preoperative factors, intra-operative distraction was the most predictable factor of the allograft collapse. This was especially true when the intraoperative distraction was more than 37%, in which case the occurrence of graft collapse increased 4.6 times. We also found that instrument failure occurs only after the allograft collapse.

• 터널과지하공간
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• 제21권5호
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• pp.333-340
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• 2011

RMR은 국내터널의 지보재 설계를 위해 가장 빈번하게 사용되는 암반분류 방법이다. 그러나 설계당시의 검토된 지반조사를 통한 RMR값은 지반을 정확하게 대변할 수 없다. 터널 시공시 발생하는 붕괴 및 낙반사고를 사전에 예방하고 효율적인 지보 설계를 위해 붕괴위험도에 따라 기존 RMR 점수에 가중치를 적용한 Weighted-RMR(W-RMR)을 제안하고 터널에 적용하였다. 비재터널 현장에 W-RMR을 적용한 결과 막장 붕괴의 위험도에 따라 지보 설계를 탄력적으로 변경할 수 있었다.

• Earthquakes and Structures
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• 제18권3호
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• pp.367-377
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• 2020

Incremental dynamic analysis (IDA) widely uses for the collapse risk assessment procedures of buildings. In this study, an IDA-based collapse risk assessment methodology is proposed, which employs a novel approach for detecting the near-collapse (NC) limit state. The proposed approach uses the modal pushover analysis results to calculate the maximum inter-story drift ratio of the structure. This value, which is used as the upper-bound limit in the IDA process, depends on the structural characteristics and global seismic responses of the structure. In this paper, steel midrise intermediate moment resisting frames (IMRFs) have selected as case studies, and their collapse risk parameters are evaluated by the suggested methodology. The composite action of a concrete floor slab and steel beams, and the interaction between the infill walls and the frames could change the collapse mechanism of the structure. In this study, the influences of the metal deck floor and autoclaved aerated concrete (AAC) masonry infill walls with uniform distribution are investigated on the seismic collapse risk of the IMRFs using the proposed methodology. The results demonstrate that the suggested modified IDA method can accurately discover the near-collapse limit state. Also, this method leads to much fewer steps and lower calculation costs rather than the current IDA method. Moreover, the results show that the concrete slab and the AAC infill walls can change the collapse parameters of the structure and should be considered in the analytical modeling and the collapse assessment process of the steel mid-rise intermediate moment resisting frames.

• Geomechanics and Engineering
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• 제18권5호
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• pp.515-525
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• 2019

A karst collapse, as a natural hazard, is totally different to a normal collapse. In recent years, karst collapses have caused substantial economic losses and even threatened human safety. A risk assessment model for karst collapse was developed based on the fuzzy analytic hierarchy process (FAHP) and grey relational analysis (GRA), which is a simple and effective mathematical algorithm. An evaluation index played an important role in the process of completing the risk assessment model. In this study, the proposed model was applied to Jiaobai village in southwest China. First, the main controlling factors were summarized as an evaluation index of the model based on an investigation and statistical analysis of the natural formation law of karst collapse. Second, the FAHP was used to determine the relative weights and GRA was used to calculate the grey relational coefficient among the indices. Finally, the relational sequence of evaluation objects was established by calculating the grey weighted relational degree. According to the maximum relational rule, the greater the relational degree the better the relational degree with the hierarchy set. The results showed that the model accurately simulated the field condition. It is also demonstrated the contribution of various control factors to the process of karst collapse and the degree of collapse in the study area.

• Journal of Korean Neurosurgical Society
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• 제61권1호
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• pp.1-9
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• 2018

Posttraumatic delayed vertebral collapse, known as Kummell's disease, is increasing in number of patients. This disease is already progressive kyphosis due to vertebral collapse at the time of diagnosis and it causes intractable pain or neurologic deficit due to intravertebral instability. Treatment is very difficult after progression of the disease, and the range of treatment, in hospital day, and cost of treatment are both increased. Clinical features, pathogenesis and radiologic findings of these disease groups were reviewed to determine risk factors for delayed vertebral collapse. The purpose of this article is to suggest appropriate treatment before vertebral collapse for patients with osteoporotic vertebral compression fracture who have risk factors for posttraumatic delayed vertebral collapse.

• 지질공학
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• 제30권4호
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• pp.663-671
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• 2020

최근 국내에서는 산림지역 뿐만 아니라 대도시지역에서도 자연재해가 많이 발생하고 있으며, 이에 대한 국가적인 요구사항은 증가하고 있다. 특히 국도 비탈면 붕괴에 대하여 체계적으로 관리할 수 있는 사전 재해정보 시스템은 전무한 실정이다. 본 연구에서는 CSMS(Cut Slope Management System)에서 관리하는 강원도와 경상도 지역의 국도 비탈면 붕괴 정밀조사 보고서와 비탈면 기초조사를 토대로 비탈면 붕괴 유발 인자에 대한 빅데이터 분석을 실시하였다. 분석 결과를 바탕으로 붕괴 비탈면 위치와 기상정보를 반영하여 분류 기반 머신러닝 모형인 Adaboost를 통한 비탈면 붕괴 위험도 예측모형을 구축하였다. 또한 시각화 프로그램인 비탈면 붕괴 위험도 시각화 지도를 개발하여 기상여건 변화에 따른 비탈면 위험도 파악을 통한 선제적 재해재난 예방대책에 활용할 수 있음을 보여주고 있다.

• 대한공간정보학회지
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• 제13권3호
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• pp.41-52
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• 2005

오늘날 도시지역은 인구밀집과 건축물의 고밀화로 인하여 자연재해나 인위적 재난이 발생할 경우 대형사고로 확산될 가능성이 매우 높다. 본 논문에서는 지형공간정보체계를 이용하여 도시지역의 종합적인 재해위험도를 평가하였으며, 이를 위해 도시지역 재해위험도를 침수위험도, 화재위험도, 건물붕괴위험도, 대피위험도 등 4가지로 세분하고 재해위험도를 평가하였다. 이러한 재해위험도 평가결과는 각종 도시관리계획을 수립할 때 재해를 최소화 시킬 수 있는 유효한 자료로 활용될 수 있다. 향 후 본 연구의 체계화와 전문성을 위하여 보다 많은 재해요소를 포함하고 관련분야의 전문가가 참여하는 공동연구 수행이 필요하다고 생각된다.