중진지역에서 케이슨 안벽의 동적수평변위 특성에 관한 연구

박근보,차승훈,김수일,심재욱 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.8

In this study, 28 earthquake records with magnitudes from 5.3 to 7.9 are selected for dynamic analysis in order to assess applicability of the earthquakes for domestic seismic design. The assessment is performed using the seismic spectrum analysis of energy and acceleration. Based on results of the analysis, four acceleration time histories, which satisfy the Korean design standard response spectrum, are proposed. From the dynamic analysis using earthquake magnitudes from 6.4 to 7.9, it is found that horizontal displacements corresponding to earthquake magnitudes greater than 7 are two times larger than those with magnitude 6.5. Therefore, it can be stated that use of strong earthquakes, such as Miyagiken-ken-oki earthquake (Ofunato, MJMA=7.4) and Tokachi-oki earthquake (Hachinohe, MJMA=7.9), for the seismic design in Korea is not applicable, and may prove to be excessively conservative due to overestimated seismic force. From the dynamic analyses using the proposed acceleration time histories, effects of caisson quay wall dimension and the subsoil condition are investigated as well. The simplified design charts to evaluate horizontal displacements of caisson quay wall are also proposed based on earthquake magnitude 6.5 that is appropriate in Korea.

Assessment of Liquefaction Potential Based on Modified Disturbed State Concept

박근보,최재순,박인준 대한토목학회 2012 KSCE JOURNAL OF CIVIL ENGINEERING Vol.16 No.1

In this paper, the application of the disturbed state concept model for the assessment of liquefaction potential is examined through experimental and analytical investigation. In order to achieve a more realistic description of the dynamic responses of saturated sands, the disturbed state concept model was modified based on the dynamic effective stress path and excess pore pressure development. Static and cyclic undrained triaxial tests were performed for sands with different relative densities and confining stresses. Based on test results, a classification of liquefaction phases was proposed, in terms of the dynamic effective stress path and the excess pore pressure development. This was adopted into the modified disturbed state concept model. The liquefaction assessment method is also proposed, using the disturbed state concept model based on the deviatoric plastic strain trajectory. Factors of safety, calculated from the equivalent cyclic stress concept, were compared with the proposed method using the original and modified disturbed state concept models. This was proposed by using examples with different soil and earthquake conditions.

Development of Modified Disturbed State Concept Model for Liquefaction Analysis

박근보,최재순,박인준,김기풍,김수일 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.3

In this paper, the application of the DSC model to the analysis of liquefaction potential is examined through experimental and analytical investigations. For more realistic description of dynamic responses of saturated sands, the DSC model was modified based on the dynamic effective stress path and excess pore pressure development. Both static and cyclic undrained triaxial tests were performed for sands with different relative densities and confining stresses. Based on test results, a classification of liquefaction phases in terms of the dynamic effective stress path and the excess pore pressure development was proposed and adopted into the modified DSC model. The proposed methods using the original and modified DSC models were compared with examples with different relative densities and confining stresses. Based on the comparisons between the predicted results using the original and modified DSC models and experimental data, the parameters required to define the model were simplified. It was also found that modified model more accurately simulate initial liquefaction and dynamic responses of soil under cyclic undrained triaxial tests.

접목묘의 필요성 및 만들기

박근보 충남대학교 농업생명과학대학 2004 논문집 Vol.- No.11

손상 잠재력을 이용한 에너지 개념의 액상화 평가

박근보 한국지반공학회 2009 지반 : 한국지반공학회지 Vol.25 No.2

A Study on Magnitude Scaling Factors and Screening Limits of Liquefaction Potential Assessment in Moderate Earthquake Regions

박근보,박영근,최재순,김수일,Park Keun-Bo,Park Young-Geun,Choi Jae-Soon,Kim Soo-Il Korean Geotechnical Society 2004 한국지반공학회논문집 Vol.20 No.7

기존의 액상화 평가법은 대부분 미국, 일본, 그리고 유럽과 같이 지진 발생빈도가 높고 그로 인한 액상화 피해가 빈번한 국가에서 주도적으로 연구되어왔다. 이런 지역적 특성을 토대로 개발된 액상화 평가방법들은 높은 지진규모(M=7.5)에 바탕을 두고 있다. 국내의 경우, 1997년 실제적인 내진 연구가 시작된 이래 액상화 평가의 구체적 규정은 항만시설의 내진설계 표준서(1999)에 언급된 바 있으나 이는 문헌연구를 통해 제시된 것으로 실제적이지 못하다. 그러므로, 국내 적합한 설계기준을 작성하기 위해서는 지진피해자료의 부족을 국내 지반을 대상으로 한 동적실내시험을 통하는 것이 바람직하며, 일반적인 정현하중 진동시험 보다 실제 지진하중 재하 시험이 훨씬 효과적일 수 있다. 본 연구에서는 실제 지진파 고유의 특성을 적용한 진동삼축 시험을 통하여 상대밀도와 세립분함유량의 변화에 따른 액상화 저항강도를 산정하였다. 실험결과를 국내의 대표적인 항만지역의 지진응답 해석 결과와 비교 분석하고 중진지역에 적합한 액상화 평가의 생략기준을 제시하였다. 또한 실제 지진하중 삼축실험 결과를 이용하여 국내 여건에 적합한 지진규모 보정계수를 제안하였다. Conventional methods for the assessment of liquefaction potential were primarily for areas of severe earthquake zones (M=7.5) such as North America and Japan. Detailed earthquake related researches in Korea started in 1997, including development of the seismic design standards for port and harbour structures, which was later completed in 1999. Because most contents in the guidelines were quoted through literature reviews from North America and Japan, which are located in strong earthquake region, those are not proper in Korea, a moderate earthquake region. This requires further improvement of the present guidelines. Considering earthquake hazard data in Korea, use of laboratory tests based on irregular earthquake motion appears to be effective to reflect the dynamic characteristics of soil more realistically than those using simplified regular loading. In this study, cyclic triaxial tests using irregular earthquake motions are performed with different earthquake magnitudes, relative densities, and fines contents. Assessment of liquefaction potential in moderate earthquake regions is discussed based on various laboratory test results. Effects of these components on dynamic behavior of soils are discussed as well. From the test results, screening limits and magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were re-investigated and proposed using normalized maximum stress ratios under real irregular earthquake motions.

통계해석에 기초한 연속다짐평가기법 개발

박근보,김주형 한국지반공학회 2011 한국지반공학회논문집 Vol.27 No.8

The objective of this paper is to assess the potential use of the resilient force of the ground obtained from an accelerometer and to propose a new compaction control process. Several comprehensive field experimental programs were conducted to analyze the correlation of compaction results obtained from an accelerometer and conventional test methods (e.g. the plate load test and field density test). This study focused on comparing the compaction results obtained from an accelerometer with conventional test results statistically. Based on the statistical analysis results, impact and resilient force measured from an accelerometer, mounted on the drum of a roller are very useful factors for continuous compaction control. A new compaction criteria determination process using an accelerometer is also proposed in this study.

새로운 다짐도 평가기법의 적용성에 관한 연구

박근보,김주형 한국지반공학회 2012 한국지반공학회논문집 Vol.28 No.2

CMV(Compaction Meter Value) obtained from compaction results using an accelerometer, which measures the impact on the ground and the resilient force of the ground, is compared with the other degree of compaction through regression analysis. As a result, there is no correlation between results from conventional test methods (e.g., the plate load test and field density test) and the degree of compaction evaluated by either the Geogauge or the dyanamic cone penetrometer. To assess the possibility of replacing the conventional test methods with new test methods using CMV, several degrees of compaction tests were carried out. Those results show that the CMV obtained from compaction results using an accelerometer can be used as a substitute for conventional methods to evaluate the stiffness characteristics of compacted soil.

중진지역에 적합한 액상화 평가 생략기준 및 지진규모 보정계수에 관한 연구

박근보,박영근,최재순,김수일 한국지반공학회 2004 한국지반공학회논문집 Vol.20 No.7

Conventional methods for the assessment of liquefaction potential were primarily for areas of severe earthquake zones (M=7.5) such as North America and Japan. Detailed earthquake related researches in Korea started in 1997, including development of the seismic design standards for port and harbour structures, which was later completed in 1999. Because most contents in the guidelines were quoted through literature reviews from North America and Japan, which are located in strong earthquake region, those are not proper in Korea, a moderate earthquake region. This requires further improvement of the present guidelines. Considering earthquake hazard data in Korea, use of laboratory tests based on irregular earthquake motion appears to be effective to reflect the dynamic characteristics of soil more realistically than those using simplified regular loading. In this study, cyclic triaxial tests using irregular earthquake motions are performed with different earthquake magnitudes, relative densities, and fines contents. Assessment of liquefaction potential in moderate earthquake regions is discussed based on various laboratory test results. Effects of these components on dynamic behavior of soils are discussed as well. From the test results, screening limits and magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were re-investigated and proposed using normalized maximum stress ratios under real irregular earthquake motions.

극지환경을 고려한 남극 세종과학기지 계측시스템 적용성에 관한 연구

박근보(Keunbo Park),김영석(YoungSeok Kim) 한국지반신소재학회 2013 한국지반신소재학회 논문집 Vol.12 No.2

극한환경에서의 구조물 거동을 파악하기 위하여 남극 세종과학기지 부근의 기상환경을 분석(1988년-2007년 및 2010년)하고, 이에 적합한 상용화된 계측기를 선정하여 남극기지(생물해양연구동)에 설치하여 검토하였다. 남극 세종과학기지 기상환경 분석결과, -25.6℃ 이하의 온도 및 49.5m/s정도의 바람에도 견딜 수 있는 계측기를 설치해야 하며 설치위치도 지표면에서 225.0cm 이상이어야 한다. 또한, 남극에서 사용할 계측기 센서의 경우 온도, 폭설 및 강풍에 민감하고, 기상환경 이외에 남극의 동물이 침범할 수 있으므로 계측기 및 계측기용 데이터로거를 보호할 수 있는 시스템을 개발하여 적용하였다. 새롭게 개발된 보호시스템은 극한환경에서도 설치가 용이하고 경제적이다. 1년간의 계측결과를 바탕으로 보호시스템의 극지 적용가능성을 검토하였으며, 구조물 거동도 예측이 가능함을 확인하였다. Environmental monitoring analysis were analyzed for the period from 1988 to 2007 near King Sejong Station. Extreme environment structure behaviors(Marine Biology Lab.) were evaluated using monitoring sensors developed commercial sensors. Also when installing the sensors ambient environment of the King Sejong Station, to analyze the measured data and the comparative behavior of the structure were analyzed. As a environmental monitoring analysis result at King Sejong Station temperature, sensors were installed to withstand about -25.6℃ or less and 49.5m/s. They were needed that the height of 225.0cm or more to be installed during the installation. For several monitoring sensors used in Antarctic, temperature, snow and strong winds were very sensitive to the atmospheric environment. Quite often a camouflage(animals and humans) would make it necessary to provide housing for monitoring sensors. Therefore, protection system developed for these sensors were to protect the sensors and data logger. Protection system the newly developed, is economical, easy to install even in harsh environments. Based on the measurement result of the one year, consider electrode applicability of the protection system, it was confirmed that the behavior of the structure is also predictable.