• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.55-61
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• 2005

Mononobe-Okabe method is generally used to evaluate dynamic earth pressure for the seismic design of retaining walls. However, Mononobe-Okabe method does not consider the effects of dynamic interactions between backfill soil and walls. In this research, shaking table tests on retaining walls were performed to analyze the phase and magnitude of dynamic earth pressure. The unit weight of walls, the amplitude of input acceleration and the base friction coefficient of walls were varied to analyze the influence of these factors on the dynamic earth pressure. Test results showed that the dynamic earth pressure was 180 degrees out of phase with the wall inertia force for the low sliding velocity of the wall, whereas small peaks of the dynamic earth pressure, which are in phase with the wall inertia force, were developed for the high sliding velocity of the wall. The amplitude of dynamic earth pressure was proportional to that of wall acceleration and the unit weight of the wall. In addition, the dynamic earth forces calculated by the Mononobe-Okabe method were the upper limit of the dynamic earth pressures.

• Water for future
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• v.28 no.5
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• pp.205-217
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• 1995

The historical data from 3, 550 event storms during 11 years in Wi-stream basin have been used to investigate the statistical parameter of the time distribution for design storms by the method of Yen-Chow, Huff, Pilgrim-Cordery and Mononobe. The dimensionless value of triangular hyetograph, $a^0$, ranges from 0.44 to 0.50 and trapezoidal hyetograph, $h^0$, value increases as the duration time is getting longer in Yen-Chow method. In the Huff, the second-quartile storms occurred most frequently and third-quartile storms occurred most infrequently. In the Pilgrim-Cordery, the shapes for shorter than 6-hour durations are advanced tendency. However, for longer than 6-hour durations show delayed tendency. In the Mononobe, every one hour rainfall occured Centered Type. The application of these methods for each duration time was tested by using the observed rainfall-runoff data of Wi-stream basin. As a result, the reappearance of hydrographs of triangular hyetograph by Yen-Chow method showed promising, and it was approved to be used for prediction of the ungaged basins.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.235-244
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• 1993

The present study was made based on the zero extension line theory and the well-known Mononobe-Okabe's to determine the dynamic earth pressures acting on the retaining walls. The zero extension line theory, which was proposed by Roscoe et al., assumes the coincidence between the loci of failure and the zero extension lines in soil mass. ln order to compute the dynamic earth pressure developed by an earthquake, it was assumed that for the vertical retaining walls with no surcharge, the backfill materials are dense and cohesionless sandy soils, there are no changes in soil parameters during earthquake, and the horizontal earthquake intensity is considered. The effects of horizontal earthquake intensity, internal friction angle of soil, wall friction angle and dilation angle, on the earth pressure coefficients were analysed. Final1y, the presented theories were successfully compared with the Mononobe-Okabe's as well.

• Geomechanics and Engineering
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• v.3 no.4
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• pp.255-266
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• 2011

Knowledge of seismic earth pressure against rigid retaining wall is very important. Mononobe-Okabe method is commonly used, which considers pseudo-static approach. In this paper, the pseudo-dynamic method is used to compute the distribution of seismic earth pressure on a rigid cantilever retaining wall supporting dry cohesionless backfill. Planar rupture surface is considered in the analysis. Effect of various parameters like wall friction angle, soil friction angle, shear wave velocity, primary wave velocity, horizontal and vertical seismic accelerations on seismic earth pressure have been studied. Results are presented in terms of tabular and graphical non-dimensional form.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.75-82
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• 2002

The Mononobe-Okabe method is generally used to evaluate the dynamic earth force for the seismic design of retaining walls. However, the Mononobe-Okabe method does not consider the effects of the dynamic interactions between the backfill soil and the wall. In fact, a phase difference exists between the inertia force and the seismic earth pressure. In this study, shaking table tests were peformed on gravity walls retaining dry backfill sand to analyze the influence of several parameters (the unit weight of the wall, the input acceleration and base friction) on the development of the seismic earth pressure. The experiments revealed that the magnitude of the inertia force mobilized during seismic loading affected the seismic earth pressure. The difference in the phase angles between the inertia force and the seismic earth pressure was retained at 180 degrees before the wall failed but its magnitude changed significantly as the wall began to fail.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.1
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• pp.38-51
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• 1984

Mononobe-Okabe에 의해서 옹벽에 대한 동적 토압계산법이 개발된 이래 본론두중 옹벽의 과동에 의한 변위에 대해서는 많은 연구가 이루어졌으나 Mononobe-Okabe식이 원래 옹벽 자체의 관성을 고려치 아니하였고 또 동적 하중의 작용점을 제시하지 않으므로서 전도모멘트를 계산할 수 없게 하므로서 옹벽의 전도에 의한 변위에 대해서는 연구가 되지 아니하였다. 본 연구의 목적은 해석적 방법과 모형실험을 통해서 지진 및 폭파 등의 동적 하중에 의한 옹벽의 전도에 의한 변위를 고찰하고자 하는 바 그 결과를 요약하면 다음과 같다. 1. 활동에 대한 항복가속도가 있는 것과 마찬가지로 전도에 대한 항복가속도가 있다. 이 항복가속도는 옹벽의 안전율이 증가함에 따라 증가한다. 2. 이론치와 실험치는 경향으로 보아 일치한다. 실험치가 이론치보다 작은 것은 모형실험에서 옹벽측면과 컨테이너 사이의 마찰에 기인한 것으로 보아지며 마찰을 줄임으로써 이론치에 더 접근시킬 수 있을 것이다. 3. 옹벽의 회전각도의 크기는 지반가속도가 클수록, 옹벽저면이 작을수록 그리고 흙의 내부마찰각이 작을수록 크게 증가한다. 4. 실용적인 규격의 옹벽의 변위는 활동에 의한 것보다 전도에 의한 것이 훨씬 크며 전체 변위의 대부분을 차지한다. 5. 옹벽 상단의 횡적 변위는 옹벽 설계를 결정짓는 중요한 요소가 될 수 있다.

• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.35-43
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• 2016

The time distribution of rainfall is one of the most important considerations for evaluating soil slope stability. In order to study the rainfall-induced slope failure, the rainfall pattern has generally been assumed as uniform rainfall intensity for rainfall duration. However, it should be noted that the time distribution of the design rainfall method has a significant effect on the soil slope instability. The study implemented Mononobe, Huff, and uniform method as three types of time distribution method of the design rainfall to estimate the factor of safety of soil slopes by rainfall duration. As a result, the difference of soil suction and unsaturated hydraulic properties in a soil by rainfall pattern was found through the application of an appropriate time distribution method to numerical simulation for rainfall-induced slope stability.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1546-1550
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• 2009

최근 증가하고 있는 집중호우로 인해 피해 규모가 대형화 되어가고 있는 추세로 수공구조물 설계시 보다 정확한 수문분석을 요구 하고 있다. 강우의 시간분포는 정확한 수공구조물의 설계시 첨두홍수량 산정에 가장 중요한 영향을 미친다. 따라서 본 연구에서는 지역의 기상학적, 지형학적 특성에 맞는 적절한 강우분포형을 제시하고자 한다. 본 연구는 금호강권역의 단시간 강우에 대한 시간분포형을 결정하기 위하여 기존 강우의 시간분포방법 중에서 개념상 비교적 단순하면서도 물리적으로 의미를 갖는 Mononobe분포, Yen & Chow분포, Keifer & Chu분포의 방법을 이용하였다. 대상지점은 금호강권역의 가창으로 재현기간 50년의 6시간, 24시간 강우의 시간적 분포특성을 비교분석한 결과 6시간 확률강우량에서는 Mononobe 분포와 Keifer & Chu 분포의 첨두치가 비교적 크게 나타났고 24시간 확률강우량에서는 Keifer & Chu 분포의 첨두치가 가장 크게 나타났다. Yen & Chow 분포의 경우 6시간 강우의 첨두치에 비해 24시간 강우의 첨두치가 급격히 감소하는 것을 알 수 있다. 또한 확률강우를 이용해서 홍수유출량을 분석한 결과 6시간, 24시간의 첨두홍수량은 Keifer & Chu 분포가 가장 크게 나오는 것으로 나타났고 첨두시간 역시 Keifer & Chu 분포가 가장 빠른 것으로 나타났다. 최근 다양한 설계강우의 시간분포 방법들이 실제 강우분포의 특성을 표현하고 있지만 이러한 방법들 중에서 실제로 유역에 가장 적합한 시간분포 방법을 결정하기란 어렵다. 하지만, 첨두홍수량 결정을 위해서는 여러 가지 방법들 중 그 지역을 가장 대표할 수 있는 강우분포 방법을 선택해야만 한다. 따라서 분석지점 이외의 다양한 실제 지점에 대해 설계홍수량을 산정해 봄으로써 다른 설계강우의 시간분포 방법을 이용하여 산정한 결과의 비교 검토가 필요할 것으로 사료된다.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.35-45
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• 2012

Pseudo static analysis using the Mononobe-Okabe method and numerical analysis considering a small strain nonlinearity from the soil were performed to determine the bearing pressure changes of the inverted T-type retaining wall subjected to earthquake motions. In many cases, an inverted 'T' type retaining wall of more than 10 m shows bearing capacity failure under earthquake conditions, despite showing sufficient bearing capacity during normal conditions. The most important reason for this is the change of the effective base area during an earthquake. In this paper, the change of the effective base area of an inverted 'T' type wall is analyzed by using finite difference element code (FLAC). In addition, the effect of dynamic bearing capacity coefficients (which has been suggested by several researchers but not adopted in current design codes and procedures) was verified.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.2
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• pp.45-53
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• 2015

This paper reviews the current seismic design code and research for dynamic earth pressure on retaining structures. Domestic design codes do not clearly define the estimation of dynamic earth pressure and give different comments for seismic coefficient, wall inertia and distribution of dynamic earth pressure using Mononobe-Okabe method. AASHTO has been revised reflecting current research and aims for effective seismic design. Various design codes are analyzed to compare their performance and economic efficiency. The results are used to make improvement of current domestic seismic design code. Further, it is concluded that the experimental investigation is also needed to verify and improve domestic seismic code for dynamic earth pressure.