상계해석을 이용한 보강토 사면의 해석

유남재,김종민,유남재 한국지반공학회 2004 한국지반공학회논문집 Vol.20 No.7

In this study, the upper bound theory is applied to a reinforced slope to develop an limit state analysis method. As processing of this upper bound theory in formulating finite element, the basic idea of numerical method can be obtained from a macroscopic point of view with an anisotropic homogeneous material. The reinforced soil strength reliability depends on properties of reinforcements which consist of the interaction of interfaces between back fill and reinforcements. Both soil's mechanical property and overall behaviour of reinforced soil can be controlled via arranging geometry and relative proportions of reinforced soil. Therefore, the upper bound theory can not only predict the particular limit state action of reinforced soil slope but also is efficiently able to estimate the local plastic failure.

원심모형시험에 의한 사석재의 내부마찰각 추정

유남재,박병수,정길수,이종호 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

This paper is an experimental work of estimating friction angle of very coarse grained soil such as rubble mound by performing laboratory experiments. Two crushed rocks of rubble mound were used for tests. Triaxial compression tests with drained conditions were performed to measure friction angles of soils prepared by mixing the crushed soil having an identical coefficient of uniformity with different maximum grain size distribution. Centrifuge model experiments with those soils were also performed to measure angle of repose and to estimate friction angle of soil from measuring the slope of slip line in the active stress state. Model tests were carried out by changing the G-levels of 1G and 50G. From triaxial compression tests, the measured value of friction angle of soil is in the range of 41∼57˚. The measured value of repose angle is in the range of 32∼35˚. The values of friction angle are found not so sensitive to the maximum grain size of soil as long as the coefficient of uniformity is identical. Estimated value of friction angle from measuring the slope of slip line in the active stress state is in the range of 30~46˚. Thus, the estimated angle of friction are found to be greater in the order of the measured angle of repose, the estimated value from the slope of active state, and triaxial compression test results. On the other hand, the measured values of friction angle from triaxial tests were compared with empirical equations, based on the relation between friction angle and void ratio. Equations proposed by Helenelund(1966) and Hansen(1967) found to be relatively reliable to estimate friction angles of soil.

2009년 발생한 제천시의 토석류 피해분석에 관한 연구

유남재 江原大學校 産業技術硏究所 2010 産業技術硏究 Vol.30 No.A

This paper is results of case study on characteristics of debris flow occurred at Jecheon during a heavy rainfall in 2009. The site studied is the mountain area located at Palsong-ri Bongyang-op in Jecheon-si where serious damages due to debris flow were occurred by heavy rainfall during July 7 to July 16 in 2009. Intensity and duration of rainfall causing debris flow were analyzed on the basis of AWS data. Characteristics of debris flow such as initiation, transportation and deposition were investigated through field reconnaissance. The geological and topographical characteristics of slope where debris flow was triggered were figured out and characteristics of erosion on the bottom and sides of valley during transportation of debris flow were also investigated. The slope and boundary of valley where the debris flow started to be deposited were studied.

강원도 토석류 산사태의 특성에 관한 연구

유남재,전상현,박남선 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

This paper is to investigate the characteristics of debris flow landslides in Gangwon Province through literature review, data collection and analyses and site investigation. As results of data analyses about landslides occurred currently in this province, the landslide in the form of debris flow is found to be 55 %. Therefore major loss and costs are caused by discharge of soil and rock fragments from landslide. From results of analyzing the geometrical characteristics of landslide, length of most of landslide is less than 200 m, their width is in the range of 10 - 40 m, most of them are know to be occurred in lower elevation than 400 m. Slope angle is in the range of 25 - 35 degrees. Compahng the period of rainfall intensity with the time of landslide being occurred, occurrence of landslide is quite related to duration of a heavy rainfall. For measures of controlling water flow discharge and debris flow, considering geological and topographical ground conditions, appropriate selection and building check dam, erosion control dam and ring net is very beneficial for reducing the loss and costs caused by the landslide of debris flow.

배수재의 직경과 형상변화가 수평진공배수에 미치는 영향

유남재,박병수,정길수,이병곤 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.A

This paper is experimental results of investigating the efficiency of horizontal vacuum drainage system. Effects of size and shape of drain on horizontal vacuum drainage were studied. Model tests in the laboratory with soft marine clay were carried out with drain pipe of having three different diameters and PBD (Plastic Board Drain) of strip shape so that consolidation settlement of soft clay due to applied vacuum pressure, amount of discharge, around settlement and distributions of pore pressure and undrained shear strength were measured during testing. From results of model test, amount of discharge due to vacuum pressure was increased with the diameter of pipe drain whereas the drain efficiency of pipe in per unit area of drain surface was decreased with diameter of pipe. The rate of discharge per unit time was reduced verb fast with diameter of pipe. Settlement of ground surface with time was increased with diameter of pipe as a result of increase of discharge to drain pipe.

준설토의 건조수축에 의한 강도증가 특성과 지지력에 관한 연구

유남재,이종호,이명욱,김현주 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.A

This research is results of experimental and numerical works on characteristic of strength increase and bearing capacity in dredged and reclaimed soil due to desiccation shrinkage. For a soil sampled from southern coastal area in Korea, basic soil property tests and standard consolidation test with falling head permeability tests were carried out to obtain consolidational characteristics of soil. Double cone penetration test. laboratory vane test and unconfined compression test were also performed to investigate the change of shear strength with degree of desiccation. Model tests were performed in 1G environment and 30G level artificially accelerated condition by using the centrifuge model test facilities to investigate the bearing capacity of desiccated ground. Test results were analyzed by using the bearing capacity of desiccated ground. Test results were analyzed by using the theoretical and load-settlement characteristics method proposed by Meyehof & Hanna(1978). On the other hands, the numerical technique, using the finite strain consolidation theory considering the effect of desiccation was used to estimate the appropriate time of using heavy construction equipments in field with respect to strength increase due to desiccation.

토사 절토사면 안정성 영향인자의 민감도 분석

유남재,박병수,전상현,조한기 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.B

A sensitivity analysis about effects of influencing factors on the stability of Soil cut slope was performed. Slope stability analyses were carried out under dry, rainy and seismic conditions. Dominant factors controlling the slope stability were chosen such as cohesion and internal friction angle, unit weight of soil, water table and seismic horizontal coefficient used for the slope stability during eurthquake. Parametric stability analysis with those factors was performed for sensitivity analysis. As results of analyzing the sensitivity of factors under dry and rainy conditions, effects of cohesion, internal friction angle and unit weight of soil on the stability of slope are more critical in the dry condition than in the rainy condition. Cohesion and internal friction angle are more dominant factors influencing the slope stability irrespective of dry or rainy conditions than unit weight of soil and the horizontal seismic coefficient. The unit weight and the horizontal seismic coefficient affects crucially the stability according to conditions of slope formation and dry or rainy seasons. For the effect of horizontal seismic coefficient on stability of slope, safety factor of slope is not affected significantly by dry or rainy conditions, However, increase of the horizontal seismic coefficient under the rainy condition does reduce the safety factor significantly rather than the dry condition. Therefore, it is needed that the location of the water table is assigned appropriately to satisfy the required safety factor of stability in the case of checking slope stability for the rainy and seismic conditions.

Column Test를 통한 연약점토의 자중압밀 특성에 관한 실험적 수치적연구

유남재,이영생,정윤화,이명옥 대한토목학회 1992 대한토목학회 학술발표회 논문집 Vol.1992 No.1

준설매립지반의 압밀침하에 대한 쌍곡선 침하예측기법의 적용성 연구

유남재,전상현,전진용 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

Applicability of hyperbolic settlement prediction method to consolidation settlement in the dredged and reclaimed ground was assessed by analyzing results of centrifuge tests modelling self-weight consolidation of soft marine clay. From literature review about self-weight consolidation of soft marine clays located in southern coast in Korea, constitutive relationships of void ratio - effective stress - permeability and typical self-weight consolidation curves with time were obtained by analyzing centrifuge model experiments. For the condition of surcharge loading, exact solution of consolidation settlement curve obtained by using Terzaghi's consolidation theory was compared with results predicted by the hyperbolic method. It was found to have its own inherent error to predict final consolidation settlement. From results of analyzing the self-weight consolidation with time by using this method, it predicted relatively well in error range of 0.04~18% for the case of showing the linearity in the relationship between T vs T/S in the stage of consolidation degree of 60~90 %. However, it overestimated the final settlement with large errors if those relation curves were nonlinear.

2006년 춘천지역 산사태 유발 강우와 사면의 기하 특성에 관한 연구

유남재,이용원,김호진 江原大學校 産業技術硏究所 2010 産業技術硏究 Vol.30 No.B

This paper is results of analyzing the characteristics of rainfall triggering landslides and geometry of slopes, caused by the heavy rainfall and antecedent precipitation by Typhoons Ewiniar and Bilis at Chuncheon area in Gangwondo around July in 2006. As results of analyzing the characteristics of rainfall, landslides in 131 sites were found to happen due to the heavy rainfall having the maximum intensity of rainfall in an hour during July 15 and antecedent precipitation during July 12 to 14 causing the ground to be weak by increasing the degree of saturation previously. From results of analyzing the geometrical characteristics of 131 slopes where landslides occurred, the slope width were in the range of 6~10m. The average slope length and angle were 46m and 51.8°, which was relatively steep slope, respectively. Landlises occurred in the elevation of 400 - 500 m with the most probable frequency.