• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.87-93
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• 1994

Factors which affect the capacity and the soil plug condition of an open-ended pile can be broadly divided into three categories:i.e., pile conditions, soil conditions and penetration methods. It has been found that the relative density and the horizontal stress have much effects on the soil plug behavior than other soil conditions. Also, it has been found that the pile diameter is the most important factor among pile conditions. However, a few investigations have been performed to account for both soil conditions and pile conditions. In this paper, a number of calibration chamber tests have been conducted with three different sized open-ended model piles. The model pile was driven into siliceous sand, with varying soil conditions, to clarify coupled effects of pile diameter and soil conditions on the plug behavior, the capacity, and the load trasfer mechanixm of soil plug. The model piles are composed of two stainless steel pipes so as to measure the plug capacity, the tip resistance, and the outside skin friction. separately.

• 한국지반환경공학회 논문집
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• 제2권2호
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• pp.23-32
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• 2001

본 연구에서는 매립토, 풍화토, 연암등으로 구성된 지반의 흙막이 가시설 시공에 쏘일네일링을 적용하였다. 굴착중 지반 및 네일의 거동특성을 분석하기 위하여 계측과 수치해석을 수행하였다. 계측은 경사계로부터 벽면의 변위를 측정하였고 변형률계를 네일에 설치하여 굴착중 발생하는 네일의 축력을 측정하였는데 네일에 작용하는 축력은 벽면의 변위와 비례하는 것으로 조사되었으며 네일에 작용하는 축력은 벽면가까이에서 최대로 측정되었다. 또한 수치해석과 실측치를 비교한 결과 벽체변위는 실측치와 일치하였으나 네일의 축력의 크기 및 축력이 발생하는 위치등은 계측치와 상당한 차이를 보이는 것으로 분석되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제13권6호통권58호
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• pp.183-191
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• 2009

본 연구에서는 지진시 nailed-soil 굴착벽체의 안전율과 거동특성에 대하여 제시하였다. 시간이력해석을 이용하여 정적하중과 지진하중을 받는 nailed-soil 굴착벽체 전면부의 수평변위, 축력, 전단력, 모멘트를 해석하였다. Dawson과 Roth가 제안한 전단강도 감소기법에 바탕을 둔 안전율을 지진시 nailed-soil 굴착벽체의 안전율 계산에 사용하였다. 제안된 방법에 의한 안전율을 기존의 연구에서 산정된 안전율과 비교하여 그 타당성을 확인하였다.

• Geomechanics and Engineering
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• 제38권3호
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• pp.275-284
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• 2024

This paper aims to explore the evolution of the pullout behavior of geocell reinforcement insights from three-dimensional numerical studies. Initially, a developed model was validated with the model test results. The horizontal displacement of geocells and infill sand and the passive resistance transmission in the geocell layer were analyzed deeply to explore the evolution of geocell pullout behavior. The results reveal that the pullout behavior of geocell reinforcement is the pattern of progressive deformation. The geocell pockets are gradually mobilized to resist the pullout force. The vertical walls provide passive pressure, which is the main contributor to the pullout force. Hence, even if the frontal displacement (FD) is up to 90m mm, only half of the pockets are mobilized. Furthermore, the parametric studies, orthogonal analysis, and the building of the predicted model were also carried out to quantitative the geocell pullout behavior. The weights of influencing factors were ranked. Ones can calculate the pullout force accurately by inputting the aspect ratio, geocell modulus, embedded length, frontal displacement, and normal stress.

• Geomechanics and Engineering
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• 제1권1호
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• pp.53-74
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• 2009

In recent years, several computer-aided pattern recognition and data mining techniques have been developed for modeling of soil behavior. The main idea behind a pattern recognition system is that it learns adaptively from experience and is able to provide predictions for new cases. Artificial neural networks are the most widely used pattern recognition methods that have been utilized to model soil behavior. Recently, the authors have pioneered the application of genetic programming (GP) and evolutionary polynomial regression (EPR) techniques for modeling of soils and a number of other geotechnical applications. The paper reviews applications of pattern recognition and data mining systems in geotechnical engineering with particular reference to constitutive modeling of soils. It covers applications of artificial neural network, genetic programming and evolutionary programming approaches for soil modeling. It is suggested that these systems could be developed as efficient tools for modeling of soils and analysis of geotechnical engineering problems, especially for cases where the behavior is too complex and conventional models are unable to effectively describe various aspects of the behavior. It is also recognized that these techniques are complementary to conventional soil models rather than a substitute to them.

• Geomechanics and Engineering
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• 제25권4호
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• pp.283-294
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• 2021

This paper presents a rigorous solution for spherical cavity expansion in unsaturated soils under constant suction condition. The hydraulic behavior that describes the saturation-suction relationship is modeled by a void ratio-dependent soil-water characteristic curve, which allows the hydraulic behavior to fully couple with the mechanical behavior that is described by an extended critical state soil model for unsaturated soil through the specific volume. Considering the boundary condition and introducing an auxiliary coordinate, the problem is formulated to a system of first-order differential equations with three principal stress components and suction as basic unknowns, which is solved as an initial value problem. Parameter analyses are conducted to investigate the effects of suction and the overconsolidation ratio on the overall expansion responses, including the pressure-expansion response, the distribution of the stress components around the cavity, and the stress path of the soil during cavity expansion. The results reveal that the expansion pressures and the distribution of the stress components in unsaturated soils are generally higher than those in saturated soils due to the existence of suction.

• 한국지반공학회논문집
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• 제19권5호
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• pp.199-210
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• 2003

흙이 변형하는 동안 전단지역 내에서 변형국지화가 자주 관찰된다. 사실상, 그 현상은 예외적이라기보다는 전형적으로 보인다. 개념적으로, 행해진 일의 증가가 음인 경우 변형국지화가 쉽게 발생한다. 이러한 현상을 검증하기 위해서, 본 연구에서는 배수상태의 조밀한 흙, 비배수상태의 느슨한 흙, 비배수전단하의 조밀한 흙에서의 공동화, 비균질한 흙, 판상형의 입자로 된 흙에서의 입자배열, 입자 깨짐을 가지는 흙, 그리고 낮은 함수비나 약한 시멘트결합이 된 흙 등 다양한 흙과 다양한 조건에 대하여 조사를 수행하였다. 이러한 경우들의 각각을 독립적으로 시험할 수 있도록 시료를 제작하였고 실험절차를 구상하였다. 실험결과에 의하면, 최고점후 변형연화거동을 가지는 흙은 변형국지화, 전단대형성, 그리고 점진적 파괴가 되기 쉽다. 응력상태, 흙밀도, 흙입자의 고유적인 역학적$.$지형학적인 특성, 저함수비, 그리고 비균질성이 변형국지화를 일으키는데 공헌을 하였다. 국지화가 가능한 모든 경우들을 고려해 볼 때, 실내시험으로부터 한계상태정수를 결정하는 최선의 방법은 배수전단하의 느슨하고 균일한 포화시료를 사용하는 것으로 나타났다.

• 한국지반공학회지:지반
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• 제12권6호
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• pp.21-36
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• 1996

흙과 Geogrid사이의 응력 전달은 마찰저항 및 수동저항으로 나눌 수 있는데 Geogrid의 횡방향 요소에 작용하는 수동저항은 그 메카니즘이 복잡하여 아직까지 거동이 명확하게 파악되지 못하고 있다. 이러한 수동저항의 메카니즘을 이해하기 위하여 돌기가 있는 보강재에 대한 직접 전단시험을 유한 요소 방법으로 해석하였다. 유한 요소해석으로 돌기의 간격에 따라 수동저항의 크기, 파괴형태, 응력 및 변형 분포 등을 분석하였으며 일 결과들을 실제 계측치와 비교 분석하여 Geogrid의 횡방향 요소에 작용하는 보강재의 수동저항의 거동을 파악하도록 하였다. 또한 흙의 종류에 따라 수동저항의 메카니즘을 파악하기 위해 점성토에 작용하는 수동저항의 거동을 예측하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.805-812
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• 2003

The purpose of this study is to evaluate the behavior of a reinforced earth wall by modeling the properties of the interface between soil and reinforced elements as well as the non-linear stress-strain characteristics of soil. The effect of lateral earth pressures induced during construction is also included in the analyses. The interface element used to evaluate the relative movement of the interface between soil/reinforcement and soil/wall- facing has a zero thickness and essentially consists of normal and shear springs. The behavior of soil element is calculated based on the hyperbolic model. The computer program SSCOMPPC which includes the interface element, hyperbolic model and bi-linear model is applied in this study. From the analyses, it is showed that the locus of maximum tension were closed to the hi-linear failure line of theoretical analyses. The lateral displacement of SSCOMPPC is larger than that of the FLAC which adopts the elastic model. This means the analysis which is adopted the hyperbolic model and interface element induced more larger displacement.

• Geomechanics and Engineering
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• 제3권1호
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• pp.29-43
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• 2011

In this paper a semi-analytical approach is proposed to study the lateral behavior of a piled footing under horizontal loading. As accurate computation of stresses is usually needed at the interface separating the footing (pile) and the soil, this important location should be appropriately modeled as zero-thickness joint element. The piled footing is embedded in elastic soil with either homogeneous modulus or modulus proportional to depth (Gibson's soil). As the pile is the principal element in the piled footing system, a limited parametric study is carried out in order to investigate the influence of footing dimensions and the interface conditions on the lateral behavior of the pile. Hence, the pile behavior is examined through its main governing parameters, namely, the lateral displacement profiles, the bending moments, the shear forces and the soil reactions. The numerical results are presented for Poisson's ratio of 0.2 to represent a large variety of sands and Poisson's ratio of 0.5 to represent undrained clays.