• Geomechanics and Engineering
• /
• 제29권6호
• /
• pp.599-614
• /
• 2022

In this study, the reliability analysis of internal and external stabilities of Reinforced Soil Walls (RSWs) under static and seismic loads are investigated so that it can help the geotechnical engineers to perform the design more realistically. The effect of various variables such as angle of internal soil friction, soil specific gravity, tensile strength of the reinforcements, base friction, surcharge load and finally horizontal earthquake acceleration are examined assuming the variables uncertainties. Also, the correlation coefficient impact between variables, sensitivity analysis, mean change, coefficient of variation and type of probability distribution function were evaluated. In this research, external stability (sliding, overturning and bearing capacity) and internal stability (tensile rupture and pull out) in both static and seismic conditions were investigated. Results of this study indicated sliding as the predominant failure mode in the external stability and reinforcing rupture in the internal stability. First-Order Reliability Method (FORM) are applied to estimate the reliability index (or failure probability) and results are validated using the Monte Carlo Simulation (MCS) method. The results showed among all variables, the internal friction angle and horizontal earthquake acceleration have dominant impact on the both reinforced soil wall internal and external stabilities limit states. Also, the type of probability distribution function affects the reliability index significantly and coefficient of variation of internal friction angle has the greatest influence in the static and seismic limits states compared to the other variables.

• 한국해안해양공학회지
• /
• 제14권2호
• /
• pp.95-107
• /
• 2002

신뢰성설계법의 적용성을 확대하기 위하여 혼성제 직립 케이슨의 활동에 대한 신뢰성 해석이 수행되었다. 충격쇄파 효과를 고려한 결정론적 설계법에 의하여 단면의 안전성이 자세히 해석되었으며, 특히 신뢰성 해석의 결과를 직접 결정론적 설계법의 결과와 연결시키기 위한 연구가 시도되었다. 해석 결과에 의하면 현재의 결정론적 설계 법에서 적용되고 있는 안전율은 약간 안전 측에 속한다. 또한 동일한 입사조건과 안전율에 대하여 수심이 증가함에 따라 신뢰지수는 감소하는 경향을 보이고 있다. 한편 방파제가 그 기능을 수행하는데 지장이 없을 것으로 예상되는 목표 파괴확률을 설정하고 그 목표 범위내에서 가장 최적의 파괴 확률을 산정하였는데, 입사조건에 따라 약간 씩 다른 최적의 안전율이 추정되었다. 마지막으로 혼성제 케이슨의 단면 결정에 영향을 주는 변수들의 변화에 따른 민감도 분석이 수행되었다. 해석 결과에 의하면 입사각, 주기의 영향이 크게 나타났으며 하상의 경사나 마운드의 두께에 대한 영향의 정도는 상대적으로 낮게 평가되었다.

• 한국수자원학회논문집
• /
• 제51권9호
• /
• pp.827-837
• /
• 2018

혼성제 케이슨에서 발생 가능한 활동, 전도 그리고 편심 경사하중에 의한 마운드 지지력에 대한 안정성을 다중 파괴모드 개념으로 해석하였다. 먼저 결정론적 해석에서는 활동 및 전도 그리고 마운드 지지력에 대한 한계 상태방정식을 이용하여 최소 안전율을 만족하는 혼성제 케이슨의 최소 단면을 산정할 수 있는 식을 유도하였다. 입사조건 및 마루높이 그리고 설치수심에 따른 결정론적 해석 결과에 의하면 활동 파괴모드와 마운드 지지력 파괴모드간 상충이 발생되었다. 따라서 혼성제 케이슨의 설계단면을 결정론적으로 산정하는 경우에도 활동뿐만 아니라 전도와 마운드 지지력에 대한 다중 파괴모드를 동시에 고려하여야 한다. 한편 확률론적 해석에서는 활동에 의하여 결정된 단면에 대하여 다중 파괴모드에 대한 시스템 신뢰성 해석을 수행하였다. 혼성제 케이슨의 다중 파괴모드에 의한 제체의 시스템 파괴확률이 입사조건에 따라 매우 다르게 거동하는 것을 알 수 있었다. 또한 마루높이와 설치수심이 증가하여도 제체의 시스템 파괴확률이 증가하는 경향이 나타났다. 특히 시스템 신뢰성 해석의 일차 해석모형과 이차 해석모형의 결과들은 본 연구에서 수행된 조건들에서는 일치되는 거동 특성을 나타냈다. 그러나 파괴모드 사이의 상관성을 올바로 고려할 수 있는 이차 해석모형의 결과가 더 높은 정도를 갖는다. 다만 파괴모드 사이에 파괴확률이 상대적으로 크게 차이나는 경우에는 일차 해석모형도 간편하게 사용할 수 있다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 가을 학술발표회 논문집
• /
• pp.449-456
• /
• 1999

The concrete wall is the most useful of retaining structure which can obtain the engineering stability, but has problems that is not friendly with nature environment in a fine view, such as poor rear drainage, and shrinkage crack by temperature difference, etc. Because of this problems, the research for a segmental crib retaining wall has been performed. A segmental crib retaining wall is quickly and easily erected because is possible to be erected as the individual members, and is not sensitive to differential settlement and earthquakes. Also, it shows effective drainage and has a friendly advantage with nature environment because of being able to be planted with vines and shrubs in retaining walls The design of crib retaining walls has traditionally been based on classical soil mechanics theories. These theories, originally derived by Rankine(1857) and Coulomb(1776), assume that the wall acts as a rigid body. This assumption results in failure being predicted by either monolithic overturning or base sliding mechanisms. However, the wall consists of individual members which have been created a three dimensional grid. This grid confines an fill mass which becomes part of the wall. The filled wall resists the earth pressure with the same mechanism of classical gravity walls. Because of the flexibility of the individual segment, it allows relative movement between the individual members within the wall. The three dimensional flexible grid leads to stress redistribution when the wall is subjected to external or fill loads. Due to the flexibility and the stress redistribution, the failure of segmental crib wall consists of not only overturing and base sliding but the local deformation and the failure between the segmental members. It has been researched in the field that due to this flexibility and load redistribution, serviceability failure of segmental crib walls is unlikely to be due to overturning or base sliding. Therefore, in this study, the relative displacement appearance of retaining wall due to variation of inclination is measured to examine this behavior characteristics. Also, the behavior characteristics of retaining walls by surcharge load, and location of acting point of retaining wall rear, and the displacement characteristics and deflections are estimated about the existence and nonexistence of Rear Stretcher performing an role in transmitting earth pressure of Header and Stretcher organizing retaining walls. This research focuses on the characteristics due to the behavior of retaining walls. This research focuses on the characteristics due to the behavior of retaining walls.

• 한국터널지하공간학회 논문집
• /
• 제2권3호
• /
• pp.13-24
• /
• 2000

본 논문에서는 고속도로터널의 붕락형태와 원인분석, 보강방법에 대하여 다루었다. 고속도로터널의 붕락형태를 분석해 보면 3가지 유형으로 분류된다. 지반풍화로 인해 터널붕락이 지표면까지 함몰된 경우 35%, 불리한 암반절리로 인한 터널내 국부적인 쐐기형 암반블럭 붕락의 경우 50%, 터널굴진방향과 미끄럼면의 교차로 인해 터널내 침하가 발생한 경우 15%의 비율로 조사되었고 터널붕락이 발생된 위치는 입출구 40m 이내와 입출구와 인접한 계곡부에서 85%, 비상주차대과 본선접속부에서 15% 발생되었다. 고속도로터널에서 발생한 붕락을 파괴개념으로 분석하면 활동파괴가 83%이상을 차지하는 것으로 분석되었다.

• Coupled systems mechanics
• /
• 제7권1호
• /
• pp.27-42
• /
• 2018

Behavior of soil is usually described with continuum type of failure models such as Mohr-Coulomb or Drucker-Prager model. The main advantage of these models is in a relatively simple and efficient way of predicting the main tendencies and overall behavior of soil in failure analysis of interest for engineering practice. However, the main shortcoming of these models is that they are not able to capture post-peak behavior of soil nor the corresponding failure modes under extreme loading. In this paper we will significantly improve on this state-of-the-art. In particular, we propose the use of a discrete beam lattice model to provide a sharp prediction of inelastic response and failure mechanisms in coupled soil-foundation systems. In the discrete beam lattice model used in this paper, soil is meshed with one-dimensional Timoshenko beam finite elements with embedded strong discontinuities in axial and transverse direction capable of representing crack propagation in mode I and mode II. Mode I relates to crack opening, and mode II relates to crack sliding. To take into account material heterogeneities, we determine fracture limits for each Timoshenko beam with Gaussian random distribution. We compare the results obtained using the discrete beam lattice model against those obtained using the modified three-surface elasto-plastic cap model.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.660-670
• /
• 2009

Neighboring construction becomes mainstream of Ground excavation in downtown area. This causes the displacement, deformation, stress condition, etc of the ground surroundings. Therefore Neighboring construction have an effect on Neighboring structure. All these years a lot of Neighboring construction carried out, and the accumulation of technology also get accomplished. But earth retaining structure collapse happens yet. Types of earth retaining structure collapse are 12. 1. Failure of anchor or strut system, 2. Insufficiency of penetration, 3. H-pile Failure on excessive bending moment, 4. Slope sliding failure, 5. Excessive settlement of the back, 6. Deflection of H-pile, 7. Joint failure of coupled H-pile, 8. Rock failure when H-pile penetration is rock mass, 9. Plane arrangement of support systems are mechanically weak, 10. Boiling, 11. Heaving, 12. Over excavation. But field collapses are difficult for classification according to the type, because collapse process are complex with various types. When we consider the 12 collapse field, insufficient recognition of ground condition is 4 case. Thorough construction management prevents from fault construction. For limitations of soil survey, It is difficult to estimate ground condition exactly. Therefore, it should estimate the safety of earth retaining system, plan for necessary reinforcement, according to measurement and observation continuously.

• Geomechanics and Engineering
• /
• 제6권6호
• /
• pp.561-575
• /
• 2014

Estimating seismic displacements has a great importance for foundations on or adjacent to slope surfaces. However, dynamic solution of the problem has received little attention by previous researchers. This paper presents a new analytical model to determine seismic displacements of the shallow foundations adjacent to slopes. For this purpose, a dynamic equilibrium equation is written for the foundation with failure wedge. Stiffness and damping at the sliding surface are considered variable and a simple method is proposed for its estimation. Finally, for different failure surfaces, the calculated dynamic displacement and the surfaces with maximum strain are selected as the critical failure surface. Analysis results are presented as curves for different slope angles and different foundation distances from edge of the slope and are then compared with the experimental studies and software results. The comparison shows that the proposed model is capable of estimating seismic displacement of the shallow foundations adjacent to slopes. Also, the results demonstrate that, with increased slope angle and decreased foundation distances from the slope edge, seismic displacement increases in a non-linear trend. With increasing the slope angle and failure wedge angle, maximum strain of failure wedge increases. In addition, effect of slope on foundation settlement could be neglected for the foundation distances over 3B to 5B.

• Geomechanics and Engineering
• /
• 제34권3호
• /
• pp.285-301
• /
• 2023

During the construction of E75 highway through Grdelica gorge in Serbia, a major failure occurred in the zone of reinforced rock slope. Excavation was performed in highly anisotropic Paleozoic schist rock formation. The reinforcement consisted of the two rows of micropile wall with pre-stressed anchors. Forces in anchors were monitored with load cells while benchmarks were installed for superficial displacement measurements. The aim of the study is to investigate possible causes of instability considering different probability distributions of the strength of discontinuities and anchor bond strength by applying different optimization techniques for finding the critical failure surface. Even though the deterministic safety factor value is close to unity, the probability of failure is governed by variability of shear strength of anisotropic planes and optimization method used for locating the critical sliding surface. The Cuckoo search technique produces higher failure probabilities compared to the others. Depending on the assigned statistical distribution of input parameters, various performance functions of the factor of safety are obtained. The probability of failure is insensitive to the variation of bond strength. Different sampling techniques should yield similar results considering that the sufficient number of safety factor evaluations is chosen to achieve converged solution.

• 터널과지하공간
• /
• 제29권5호
• /
• pp.332-345
• /
• 2019

평사투영도에서 불연속면을 대표하는 유일한 점으로 정의되는 최대경사벡터를 해당 면의 경사와 경사방향에 의거하여 형성하였다. 평사투영해석에서 평면의 극점이 대원과 역방향에 제도되는 것에 비해 최대경사벡터는 대원의 최대 경사지점에 위치하여 불연속면의 미끄러짐 방향을 직접 투영도 상에서 지시한다. 투영도 상에서 불연속면의 거동방향을 직접적으로 지시하는 최대경사벡터를 활용하여 평면 및 전도파괴 양상을 직관적으로 확인하였다. 특히 평면 파괴의 경우 블록의 옆면을 형성하는 고 경사 절리의 존재를 확인하여 실제 미끄러짐 블록의 형성가능성을 산정하였다. 또한 사면 방향과 반대방향을 갖는 고경사절리들의 존재를 확인하여 3각형 단면을 갖는 미끄러짐 블록의 형성여부를 판별하고 안전율을 도출하였으며, 4각형 단면을 갖는 가장 취약한 블록의 안전율과 비교분석하였다. 쐐기파괴 경우에는 절리면 교차에 의해 형성되는 쐐기의 기저선 방향이 최대경사벡터 속성을 지니고 있어 쐐기파괴 영역을 평면 및 전도파괴 영역이 제도된 투영도 상에 함께 도시하여 분석을 수행하였다. 특히 쐐기 상부 면을 형성하는 절리를 추출할 수 있어 전체 쐐기형상을 추정하고 역학적 거동분석을 수행하는데 요구되는 쐐기의 기하학적 특성자료를 도출하는 토대를 확립하였다.