• 한국지반공학회논문집
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• 제24권4호
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• pp.23-36
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• 2008

본 연구는 측방변형을 일으키는 수평모래지반에 매설된 사각형 수동열말뚝의 모형실험에 대한 것이다. 말뚝의 형상, 열말뚝의 위치, 말뚝의 간격과 지반변형에 따른 열말뚝의 특성을 고찰하고자 하였다. 실험결과는 다음과 같다. 수평응력의 분포양상은 말뚝의 형상과 위치에 따라 삼각형, 사다리꼴, 사각형의 형태로 다양하게 나타났다. 휨모멘트는 B-type의 경우 outer pile이 inner pile보다 크게 나타났으나, H-type의 경우는 inner pile이 outer pile 보다 크게 나타났다. 수평저항력비$(R_f)$는 말뚝의 형상에 관계없이 열말뚝의 수평간격이 증가함에 따라 증가하는 경향으로 나타났다. 수평저항력의 작용점위치(Y/L)는 지반변위와 수평간격에 따라 큰 변화를 보이지 않으며, H-type이 B-type보다 조금 크게 나타났다.

• 건축역사연구
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• 제22권6호
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• pp.47-58
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• 2013

The purpose of this study is to analyze the cause of damage to the three storied stone pagoda of Bulguksa temple in GyeongJu. This report is attempted to making reinforcement and conservation plan through investigating and analyzing the cause of damage to that. The damage is caused by occurring of stress, degrading of stone strength, changing of underground soil structure, natural disasters and so on. Compressive stress, shear stress, bending stress and lateral pressure affected to the pagoda since built up. Ultrasonic examination data tells the strength of the stone. According to this result, strength of the stereobate stone materials is enough to support the weight of the upper ones. But we could found many other factors of the damage could consider, for example the problems occurred on building the pagoda construction and the weakness of the stone material(soft rock). And many environmental factors being changed in soil structure(subsidence of soil and degradation of bearing power of soil and freezing and melting of soil) can be seen as the cause of the damage. Natural disasters like earthquake, lightning and heavy rain were also thought to give direct impact to the damage. At last Concentration of compressive stress caused the crack and exfoliation on the stone materials and shear stress, bending stress and lateral pressure were main causes of the stereobate stone materials shearing.

• Geomechanics and Engineering
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• 제35권5호
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• pp.555-570
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• 2023

In the current study, a series of experimental and analytical evaluations were performed to introduce the horizontal pseudo static coefficient (kh) as a function of the wall configuration and the reinforcement type for analyzing reinforced soil walls. For this purpose, eight shaking table tests were performed on reduced-scale models of integrated and two-tiered walls reinforced by metal strip and geogrid to determine the distribution of dynamic lateral pressure in the walls. Then, the physical models were analyzed using Mononobe-Okabe method to estimate the value of kh required to establish the dynamic lateral pressures similar to those observed in shaking table tests. Based on the results, the horizontal pseudo static coefficient and the position of resultant lateral force (R) were introduced as a function of the horizontal peak ground acceleration (HPGA), the wall configuration, the reinforcement type as well as maximum wall displacement.

• 한국지반공학회지:지반
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• 제12권4호
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• pp.75-86
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• 1996

현재 옹벽해석에 사용되는 Rankine이나 Coulomb의 토압산정방법은 벽체 뒤의 토사가 파괴상태에 도달하였다는 가정조건에 근거하고 있으며, 이를 위해서는 충분한 횡방향 변위가 발생하여야 한다. 최근의 현장시험 등을 통한 많은 연구에서는 옹벽에 작용하는 수평주동토압이 Rankine이나 Coulomb의 토압보다 크게 나타나고 있음을 보여주고 있으며, 이는 발생 수평변위량과 밀접한 관계가 있는 것으로 판단된다. 본 연구에서는 Drucker Prayer의 지반구성모델을 이용한 유한요소해석을 통하여 캔틸레버식 옹벽의 벽체 지주와 가상배면에 작용하는 수평주동토압을 발생변위와 함께 분석하였으며, 아울러 경사진 뒤채움이 수평주동토압에 미치는 영향도 검토하였다. 그 결과 옹벽에 작용하는 수평주동 토압은 발생변위와 밀접한 관계가 있으며, Rankine과 Coulomb의 방법은 작용수평주동토압을 과소평가하고, 경사진 뒤채움의 수평주동토압증가효과도 과소평가함을 확인하였다. 그리고 본 해석결과를 토대로 수평주동토압을 간편하게 산출할 수 있는 새로운 방법을 제안하였다.

• Geomechanics and Engineering
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• 제20권5호
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• pp.433-445
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• 2020

A new code, called PRaFULL (Piled Raft Foundation Under Lateral Load), was developed for the analysis of laterally loaded Combined Pile Raft Foundation (CPRF). The proposed code considers the contribution offered by the raft-soil contact and the interactions between all the CPRF system components. The nonlinear behaviour of the reinforced concrete pile and the soil are accounted. As shallower soil layers are of great relevance in the lateral response of a pile foundation, PRaFULL includes the possibility to consider layered soil profiles with appropriate properties. The shadowing effect on the ultimate soil pressure is accounted, when dealing with pile groups, as proposed by the Strain Wedge Model. PRaFULL BEM code obviously requires less computational resources compared to FEM (Finite Element Method) or FDM (Finite Difference Method) codes. The proposed code was validated in the linear elastic range by comparisons with the code APRAF (Analysis of Piled Raft Foundations). The reliability of the procedure to predict piled raft performance was then verified in nonlinear range by comparisons with both centrifuge tests and computer code PRAB.

• 한국지반공학회지:지반
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• 제13권5호
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• pp.19-34
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• 1997

Classical earth pressure theories normally assume that ground condition remains uniform for considerable distance from the wall, and that the movement of the wall is enough to result in the development of an active pressure distribution. In the case of many low gravity walls in cut, constructed, for example, by using gabions or cribs, this is not commonly the case. In strong ground a steep temporary face will be excavated for reasons of economy, and a thin wedge of backfill will be placed behind the wall following its construetion. A designer then has the difficulty of selecting appropriate soil parameters and a reasonable method of calculating the earth pressure on the w리1. This paper starts by reviewing the existing solutions applicable to such geometry. A new silo and a wedge methods are developed for static and dynamic cases, and the results obtained from these are compared with two experimental results which more correctly mod el the geometry and strength of the wall, the fill, and the soil condition. Conclusions are drawn concerning both the magnitute and distribution of earth pressures to be supported by such walls.

• 한국농공학회지
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• 제34권2호
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• pp.60-72
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• 1992

This study aims at predicting the behavior of saturated soft clayey foundation subjected to earth structure loads such as tidal dike, embankment etc. by using Biot's consolidation equation coupled with elasto-viscoplastic constitutive model. To validate the computer program developed b author, a case study was performed for the site of Kwang-yang steel works improved by sand drain, where since the beginning of the works, field measurements(settlement, lateral displacement and excess pore water pressure) had been accurately achieved. Comparisons between numerical results and observation values were carried out. The main results obtained are summarized as follows : 1. Settlement and lateral displacement between numerical and observation values show satisfactory accordance. 2. As for the exess pre water pressure, numerical results appear to be larger than observation values, which may be due to the existence of sand seams which were not found during soil investigation. 3. Useful data available for failure prediction of soft foundation can be secured by examining lateral displacement, settlement, exess pore water pressure and stress paths.

• Geomechanics and Engineering
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• 제34권5호
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• pp.481-489
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• 2023

Drained cyclic triaxial tests were conducted on a saturated sand to examine its deformation characteristics under either axial or lateral cyclic loading condition. To apply lateral cyclic loading, the cell pressure was cycled while maintaining a constant vertical stress. The strain accumulations and flow direction in the soil were presented and discussed considering various initial stress ratios (η₀), cyclic stress amplitudes and cyclic stress paths. The results indicate that axial strain accumulation shows an exponential increase with the maximum stress ratio (η^max). The initial deviatoric stress has comparable effects with lateral cyclic stress amplitude on the accumulated axial strain. In contrast, the accumulated volumetric strain is directly proportional to the lateral cyclic stress amplitude but not much affected by η₀ values. Due to the anisotropy of the soil, the accumulated axial and lateral bulging strains are greater in lateral cyclic loading when compared to axial cyclic loading even though η^max is the same. It is also found that η^max affects soil's lateral deformation and increasing the ratio could change the lateral deformation from contraction to bulging. The flow direction depends on η^max in the sand under lateral cyclic loading, regardless of η₀ values and the cyclic stress amplitudes, and a large η^max could lead to great deviatoric strain but a little volumetric strain accumulation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1496-1503
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• 2005

The study on the lateral earth pressure is briskly preformed for various conditions such as type of retaining walls, ground condition, and type of supporting systems. It is not simple to determine the distribution of lateral earth pressure accurately, however, because the lateral earth pressure is affected by various factors. This study is performed to analyze the behavior of earth retaining walls for new excavation contacting with existing excavation by comparing with the site measuring values before and after new excavation. On the base of observation, the distribution of strut axial forces is similar to that of ganeral earth retaining walls, but strut axial forces is increased by removal of existing earth anchors. When new excavation is performed contacting with existing excavation, the axial force of strut is decreased because of soil exclusion in the behind walls, but that force is increased after new exeavation. The analysis result show that the installation of strut in middle part makes a effect to not only 1 adjacent strut, but 3-5 adjacent struts. Also during new excavation strut axial forces is decreased by relaxation of total earth retaining wall system.

• 한국지반공학회논문집
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• 제25권2호
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• pp.37-44
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• 2009

본 연구에서는 대표적인 원위치현장시험인 CPT의 콘관입치 $q_c$ 값을 이용하여 말뚝의 극한수평단위지지력과 극한수평지지력을 산정하는 예측식들을 제안하고, 검증하였다. 일반적으로 기존 극한수평단위지지력과 극한수평지지력은 사질토지반에서 중요한 요소인 상대밀도, 연직응력, 그리고 다양한 토압계수들에 대한 함수로 표현하여 왔다. 하지만 이들은 수평음력에 대한 영향을 고려하지 않았으며, 말뚝 주변지반이 단 일층으로 구성되어 있다고 가정하여 실제 현장에서의 영향을 고려하지 않았다. 따라서 본 연구에서는 이에 대한 영향을 고려할 수 있는 CPT 결과를 이용한 극한수평단위지지력 산정식과 극한수평지지력을 산정하는 방법을 제안하였다. 이는 순수사질토에 대상으로 하고 있으며, 그에 대한 해석을 위해 적합한 대상지반을 대상으로 제안된 산정식의 신뢰성을 확보하였다.