지반의 강성변화에 따른 지반-터널 동적 상호작용 연구

김대상(Dae-Sang Kim) 한국암반공학회 2001 터널과지하공간 Vol.11 No.4

열차하중 주파수 변화에 따른 자갈궤도의 동적거동 평가

김대상(Dae Sang Kim) 한국도시철도학회 2021 한국도시철도학회논문집 Vol.9 No.4

유지보수작업 후 도상층을 안정화시키기 위해 철도현장에서는 다양한 안정화 작업을 실시한다. 이와 같은 노력에도 불구하고 열차 운행 초기단계에서 자갈궤도는 큰 소성침하가 발생한다. 본 논문에서는 개별요소법(DEM)을 활용하여 침목과 도상층을 모델링하고, 가진 하중의 진폭 및 주파수 변화에 따른 소성침하 발생량을 정량적으로 평가하였다. 특정 가진주파수 이상에서는 초기 소성침하가 크게 발생한 후 침하가 더 이상 증가하지 않은 것을 알 수 있었다. 또한, 실험으로는 파악하기 어려운 도상층 내에서의 자갈의 이동량과 파괴양상에 대하여 검토한 결과 상대적으로 높은 주파수 영역에서 도상층내에서의 얕은 활동파괴가 발생됨을 알 수 있었다. After maintenance works various measures are performed to stabilize ballast layer in the railway. Nonetheless big plastic settlement that occurred at ballasted track in the railways opening. Sleeper and ballast laye are rmodeled with DEM. Plastic settlement is quantitatively evaluated depending on the change of amplitude and frequency of applied loading. Big plastic settlement were occurred at the initial loading stage over specific loading frequency since then without increased. Gravel movement and failure mechanism not easy to understand in the ballast layer are checked. The shallow sliding failure in the ballast layer is occurred at relatively high frequency regions.

철도분야 보강토옹벽 적용성 향상을 위한 고찰

김대상(Dae-Sang Kim),정영훈(Young-Hoon Jung),최찬용(Chan -Yong Choi) 한국토목섬유학회 2007 한국지반신소재학회 학술발표회 Vol.2007 No.11

This paper addressed the issue on the reason why the retaining walls have not been chosen in the railway industry. The residual settlement at the railhead surface during operation is the main issue for track maintenance. Currently, track engineers should decide the necessity of the track maintenance when the residual settlement of the railway exceeds a threshold level of 7㎜. To minimize the residual settlement, an alternative type of the retaining wall including a rigid facing wall was proposed. The dynamic behavior of the retaining wall subjected to the train load was numerically assessed. Based on the numerical results, a possible way to enhance the application of the retaining walJ in the railway industry is suggested.

고품질 철도보강노반에 관한 연구

김대상(Kim Dae-Sang),김기환(Kim Ki-Hwan),황성호(Hwang Seong-Ho),윤경민(Yun Kyung-Min) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월

Concrete track requires high quality of performance at not only the track structure, but also roadbed supporting the track. In the viewpoints of design specification, materials being used, and quality control during construction, the roadbed for the concrete track requires high quality and performance than the one for the ballasted track. With the recent trends of speeding up railroad lines, these are closely related with the riding comfort in the aspects of serviceability, the easiness for maintenance works. In this paper, a type of reinforced roadbed with high performance which can be applied to the high speed railroad was suggested, and half scale tests to evaluate the performance of the suggested roadbed were performed to validate the function of vertical(elastic and plastic settlements) and horizontal displacement under static and dynamic train loading. From the test results, it can be found that the reinforced roadbed have the excellent performance to satisfy the displacement limit.

자갈궤도 뜬침목 간이 평가 방법

김대상(Kim Dae Sang),김현기(Kim Hyun Ki),이태균(Lee Tae Gyun),김석동(Kim Seok Dong),김성중(Kim Sung Jung) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-

Hanging sleepers, which are not fully supported between the sleepers and the ballast, could cause large dynamic forces especially on high speed ballasted track. The dynamic forces resulting from insufficient supporting forces may badly affect the running stability and safety of train. These also accelerate track irregularities and deteriorate track components rapidly. Consequently, thehanging sleepers will lead to sharp increases in track maintenance cost. This paper introduces a rapid and easy method to detect hanging sleepers with portable light falling weight deflectometer (LFWD) and summarizes the results of experiments performed at the high speed ballasted track.

오대산지진 시 경부고속철도 지진감시시스템 거동

김대상,김성일,최수현,유원희,Kim. Dae-Sang,Kim. Sung-Il,Choi. Su-Hyun,You. Won-Hee 한국방재학회 2008 한국방재학회 학술발표대회논문집 Vol.2008 No.1

This paper reviews the operation standards and manuals of earthquake monitoring system for Gyungbu high speed railroad. The domestic earthquake monitoring system detects the acceleration data at the locations of lower part of pier and deck of viaducts and bridges, not like foreign system to do the surface ground accelerations. For the purpose of evaluating the behaviors of the domestic earthquake monitoring system, measured acceleration data on the Odaesan earthquake at Iwon viaduct were analysed. The values of maximum acceleration level of the viaduct were increased from 0.0089g(EW component) of the lower part of pier to 0.014g(EW component) on the deck of the viaduct. And also the predominant periods and frequencies were analysed by the frequency domain analysis.

일체형 교대의 완충구간 강성 변화에 따른 수평 지반반력계수 평가

김대상(Dae Sang Kim),김웅진(Ungjin Kim) 한국방재학회 2022 한국방재학회논문집 Vol.22 No.3

교대에 작용하는 수평토압 저감 및 접속부 잔류침하 저감이 가능한 일체형 교대(Integral Abutment, IA)에 대하여 뒤채움 재료의 강성을 조절할 수 있는 완충구간을 적용하였다. 수치해석을 통하여 완충구간의 강성변화에 따른 IA의 수평 지반반력계수를 평가하였다. 교대 배면으로부터 폭 1 m의 구간을 완충구간으로 설정하고 사용 재료를 사질토, 일반자갈, 시멘트 처리된 자갈로 다르게 적용하였다. 완충구간의 적용으로 인하여 수동은 최대 28%, 주동은 최대 31%의 수평 지반반력계수의 감소를 보였다. 이를 통하여 완충구간의 강성 변화를 통한 IA의 수평 지반반력에 대한 조절 가능성을 확인할 수 있었다. The buffering zone, which can control the stiffness of the backfill material, is applied at the integral abutment (IA) to reduce the horizontal earth pressure on the abutment and decrease the residual settlement at the transition zone. Numerical analyses are performed to evaluate the horizontal subgrade reaction modulus based on the stiffness change in the buffering zone. A 1 m section from the back of the abutment is set as the buffering zone, and materials such as sandy soil, gravel, and cement-mixed gravel are applied differently. By implementing the buffering zone, the passive and active coefficients of the horizontal subgrade reaction decrease by 28% and 31% at the height of 6.8 m. respectively. Hence, the possibility of adjusting the horizontal subgrade reaction of the IA by changing the stiffness of the buffering zone is confirmed.

Dynamic Friction Behavior of Interfaces Between Granular Materials and Steel

김대상(Dae Sang Kim) 한국지반공학회 2001 한국지반공학회논문집 Vol.17 No.3

짧은 보강재를 적용한 철도노반 설계 및 시공

김대상(Dae Sang Kim),박성용(Seong-Yong Park),최승선(Seung sun Choi),조성태(Seong Tae Cho) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10

단선 철도 노반과 기존 선로 법면에 짧은 보강재를 적용한 강성벽 일체형 철도노반을 설계 및 시공하였다. 국내에서 사용되고 있는 보강노반이 높이의 70%(0.7H) 수준의 보강재 길이를 적용하는데 비교하여, 본 설계 및 시공에서는 벽체높이의 30~40%(0.3~0.4H) 수준의 보강재를 사용하여 보강노반을 설계하고 시공하였다. 우선 짧은 보강재 적용에 대한 이론적 고찰을 실시하였다. 설계는 한국철도기술연구원에서 개발한 RSR(Reinforced Subgrade for Railways)를 사용하였으며, 연구원 부지내에 높이*폭*길이 (5m*6m*20m)의 실물 단선용 철도노반과 장항선 주포역 인근에 철도법면을 활용한 높이*폭*길이(7m*11m*40m)의 노반 2개소를 시공하고 안정성을 확인하였다. The reinforced subgrades with short geogrid were designed and constructed. This design and construction methods use 30~40% of wall height as a reinforcement length, while the domestic standard apply with 0.7H reinforcement length. First of all, an analytical approach using short geogrids was introduced considering construction loading states. The design was performed with RSR(Reinforced Subgrade for Railways) program developed by KRRI. Two full-scale railroad subgrades were constructed to evaluate the safety of the reinforced subgrades. One was back-to-back type with 5m*6m*20m(H*W*L), the other with 7m*11m*40m(H*W*L) was the type constructed on an existing railway slope. We found that the reinforced subgrades with short geogrids have an enough safety.

수치해석을 통한 철도보강교대의 응답 특성 연구

김대상(Kim, Dae-Sang),정락교(Jeong, Rag-Gyo) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.11

본 논문에서는 뒤채움을 선 시공하고, 교대를 후 시공하여 침하와 교대 수평 토압 및 변위를 저감할 수 있는 경제적인 교대 구조인 RAR(Reinforced Abutment for Railroads)을 제시하고 수치해석으로 성능을 확인하였다. 먼저 유한요소 해석 프 로그램을 이용하여 기존교대에서 발생하는 접속부의 침하와 교대 수평변위를 다양한 높이와 원지반 조건에 대하여 해석하였 다. 이 후 보다 경제적인 설계를 위하여 교대 단면과 말뚝 기초수를 저감시킨 RAR에 대해 동일한 조건으로 해석을 수행하고 그 결과를 비교, 분석하였다. 분석 결과 RAR에서 발생하는 접속부 침하와 교대 수평변위는 기존교대의 20%와 34% 수준이 며, 이는 뒤채움 안정화의 효과에 의한 것으로 나타났다. RAR은 침하와 수평변위 제어 및 토압 재분배 효과를 통하여 교대 저판, 교대벽체, 교대 기초 말뚝 수 저감으로 기존 교대 보다 경제적인 시공이 가능할 것으로 예상된다. This paper introduced the RAR(Reinforced Abutment for Railroads) to reduce settlement of transitional zone and horizontal displacement of abutment by constructing backfill before abutment. We expect that it has more economical and better performance which was validated by numerical analyses. First, transitional zone settlements and horizontal displacements of existing abutment were evaluated for various heights and ground conditions by using finite element analysis program. Then, numerical analyses of it under the same conditions were performed and its results were compared with existing abutment’s ones. From the numerical analysis, we found that the responses(settlement and horizontal displacement) of transitional zone of the RAR is about 20% and 34% of one of existing abutment due to the effect of backfill stabilizing. We expected that the RAR having small foundations could be economic way to construct abutment with the control of responses such as, settlement, horizontal displacement, and earth pressure.