• 한국농공학회지
• /
• 제42권6호
• /
• pp.98-105
• /
• 2000

Recently, the construction method of high pressure jet-grouting is in wide-use, for the purpose of structure foundation ground, reinforcing of ground behind propped retaining walls and cut-off in order to perform safe construction of underground excavation work. This study was performed a serious of tests of field permeability and unconfined compressive strength upon ground improved established on the ground behind propped retaining walls and examined proper jet mechanism by changing the construction parameter value of high pressure jet-grouting. In addition, we got the conclusion like the followings as a result of inspecting the condition of earth pressure distribution and deformation, using elasto-plastic method and FEM. 1. In that characteristics of strength of ground improved, with the same condition of construction parameter, unconfined compressive strength of sand gravel is shown bigger than that of silty sand by about 1.6 times and cut-off effect is shown to have effect of reducing the permeability of original ground by about 10$^{-2}$ ~10$^{-3}$ cm/s. 2. As a result of analysis of figures of horizontal displacing quantity of propped retaining walls materials regarding before and after High pressure jet- grouting through FEM, the reducing quantity of 0.1~0.3mm in maximum horizontal displacement is shown.

• Structural Engineering and Mechanics
• /
• 제49권1호
• /
• pp.1-22
• /
• 2014

A seismic evaluation is made of the response to horizontal ground shaking of cantilever retaining walls using the finite element model in three dimensional space whose verification is provided analytically through the modal analysis technique in case of the assumptions of fixed base, complete bonding behavior at the wall-soil interface, and elastic behavior of soil. Thanks to the versatility of the finite element model, the retained medium is then idealized as a uniform, elastoplastic stratum of constant thickness and semi-infinite extent in the horizontal direction considering debonding behavior at the interface in order to perform comprehensive soil-structure interaction (SSI) analyses. The parameters varied include the flexibility of the wall, the properties of the soil medium, and the characteristics of the ground motion. Two different finite element models corresponding with flexible and rigid wall configurations are studied for six different soil types under the effects of two different ground motions. The response quantities examined incorporate the lateral displacements of the wall relative to the moving base and the stresses in the wall in all directions. The results show that the wall flexibility and soil properties have a major effect on seismic behavior of cantilever retaining walls and should be considered in design criteria of cantilever walls. Furthermore, the results of the numerical investigations are expected to be useful for the better understanding and the optimization of seismic design of this particular type of retaining structure.

• Geomechanics and Engineering
• /
• 제27권5호
• /
• pp.419-431
• /
• 2021

Construction of retaining walls with geocell has been gaining in popularity because of its easy and fast installation compared to conventional methods. In this study, model tests were conducted by constructing the geocell retaining wall (GRW) at a constant height (i.e., 90 cm) and using aggregate as an infill material at four different configurations and two different surface angles. In these tests, a circular footing was placed behind the walls at different lateral distances from the wall surface and loaded monotonically. Subsequent to this vertical loading being applied to the footing, horizontal displacements on the GRW surface were measured at three different points. The performance of Type 4 GRW exceeded the other three types of GRW, with the highest lateral displacement occurring in Type 4 GRW at approximately 0.67 % of wall height. In addition, the results of these tests were compared with theoretical approaches widely accepted in the literature. The stress levels reached beneath the footing were found to be compatible with theoretical results.

• 국제학술발표논문집
• /
• The 3th International Conference on Construction Engineering and Project Management
• /
• pp.218-223
• /
• 2009

During the process of excavation for substructures of buildings, precise and constant measurements of retaining wall displacement is crucial for construction to be complete and safe. Currently an inclinometer is used to measure displacement around the perimeter of an excavation site. The existing inclinometer system requires an instrument to be placed inside pre-bored holes for each measurement with an typical interval of two weeks. This makes it difficult to obtain continuous displacement data, especially during a critical time such as rainy season in summer. Also, the existing inclinometer is placed at certain distance away from the retaining wall system itself. Thus, exact measurement of retaining wall movement is compromised because of the distance between the retaining wall and the inclinometer. This paper presents the development of wireless inclinometer system for the displacement measurement of retaining walls by being attached directly to the retaining wall. The result of the application of the developed systems are provided with advanced ubiquitous sensor network (USN) system features. The USN technique incorporated into the system enables users to monitor movement data from wherever possible and convenient such as construction manager's office on site or any other places connected through internet. The research work presented in this paper will provide a basis to save construction time and cost by preventing safe-related unexpected delay of construction due to the failure or collapse of retaining walls.

• 국제학술발표논문집
• /
• The 5th International Conference on Construction Engineering and Project Management
• /
• pp.517-520
• /
• 2013

In construction operation, the temporary structure is used to support designed facilities or to provide work spaces for construction activities. Since the structure is used only during the construction operation, the operation may be given insufficient attention. The contractor is likely to try to save cost on the material and labor cost. This contractor's behavior frequently leads to construction accidents. In order to prevent accidents from the failure, the operation should be carefully monitored for identifying the effect of dynamics in the surrounding site area. Otherwise, any unexpected adversary effect could result in a very costly construction failure. This study presents the feasibility of the ubiquitous sensor network (USN) technology in collecting construction data during the construction operation of earth retaining walls. The study is based on the result at the Construction System Integration Laboratory (CSIL) at the Pusan National University. A USN-based system has been developed for monitoring the behavior of the temporary structure of earth retaining walls. The data collected from the sensors were used to understand the behavior of the temporary structure. The result of this study will be used in increasing the safety during the construction operation of retaining walls.

• 한국산학기술학회논문지
• /
• 제14권4호
• /
• pp.2006-2012
• /
• 2013

이 연구에서는 경기도에 위치한 ${\bigcirc}{\bigcirc}$대학교 캠퍼스 내 외곽도로 신설을 위해서 설치된 보강토옹벽의 붕괴사례를 통해 다양한 원인조사 및 분석에 대한 내용을 다루었다. 붕괴된 보강토옹벽에 대한 안정성 평가 및 설계도서 검토결과 다짐불량, 기초지반의 지지력 검토 누락, 보강재 설치 길이와 간격, 배수시설 문제 등의 시공과 관련한 문제들로 인해서 붕괴가 발생한 것으로 판단되었다. 설계 시 고려해야 할 전체 사면활동에 대한 안정성 검토, 2단 형태의 보강토옹벽에서 일반적으로 사용되는 FHWA 또는 NCMA 제안방법을 적용하지 않는 등의 여러 설계상의 문제점들도 확인하였다. 또한, 이러한 안정성 평가 내용을 바탕으로 재시공될 보강토옹벽의 안정을 위한 보강대책 및 시공방안 등을 제시하였다.

• 한국지반신소재학회논문집
• /
• 제1권1호
• /
• pp.31-41
• /
• 2002

보강토 옹벽이 장대화 됨에 따라 보다 다단식 옹벽의 시공사례가 늘어가고 있다. 현재 NCMA 혹은 FHWA 설계기준에서 제시하고 있는 다단식 옹벽의 설계기준에서는 옹벽의 내 외적 안정성 검토에 주안점을 두고 상 하단 옹벽의 포설 조건을 설정하도록 제안하고 있으나 우리나라의 설계사례를 검토할 경우 설계기준에 부합되지 않는 경우가 많은 것으로 보고되고 있다. 본 논문에서는 우리나라 보강토 옹벽의 설계에서 그 이해가 부족한 부분이라고 할 수 있는 다단식 보강토 옹벽의 설계개념을 알아보았으며 NCMA 및 FHWA 설계기준에 근거하여 네 개의 현장옹벽에 대한 내 외적 안정성 및 복합파괴에 대한 안정성을 검토하였다. 아울러서 그 결과를 토대로 현재 우리나라에서 적용되고 있는 다단식 보강토 옹벽 설계의 문제점 및 이에 대한 대책 등을 언급하였다.

• 한국지반공학회논문집
• /
• 제21권8호
• /
• pp.55-61
• /
• 2005

현재 옹벽의 배면 동적토압을 산정할 때 주로 등가정적해석법인 Mononobe-Okabe 식이 이용되고 있다. 하지만 이식은 벽체와 뒤채움 지반간의 동적상호작용을 고려하지 못한다는 단점이 있다. 본 연구에서는 벽체와 뒤채움 지반간의 동적상호작용을 분석하기 위하여 건조 사질토로 뒤채움한 옹벽에 대하여 진동대 시험을 수행하였다. 벽체 단위중량, 입력가속도의 진폭 그리고 벽체 바닥면 거칠기를 변화시키면서 이들 각 인자가 동적토압에 미치는 영향을 분석하였다. 그 결과 벽체의 활동속도가 작은 경우에는 동적토압과 관성력간은 180도 위상차를 가졌지만 활동속도가 큰 경우에는 동적토압에 관성력과 동일한 위상을 가지는 작은 정점이 발생하였다. 동적토압의 크기는 벽체가속도와 벽체단위중량의 크기에 비례하였다. 또한 Mononobe-Okabe 방법으로 계산된 동적토압은 측정된 동적토압의 상한값으로 나타났다.

• 한국지반신소재학회논문집
• /
• 제16권4호
• /
• pp.21-31
• /
• 2017

식생토낭 공법은 토목섬유 콘테이너 공법의 일종으로 옹벽건설시 시공환경에 따른 영향을 최소화할 수 있으며, 자연친화적 공법이다. 본 연구에서는 식생토낭 보강토벽 시공방법을 식생토낭 비다짐 옹벽, 식생토낭 다짐 옹벽, 중력및 일반쌓기 혼용 옹벽, 게비온과 일반쌓기 혼용 옹벽 등 4가지 시공방법 대하여 계측기를 매설하고, 식생토낭 보강토벽의 거동특성을 평가하였다. 시공계측 결과, 식생토낭 일반쌓기 비다짐 구간에서의 변위가 게비온과 식생토낭 혼용구간 보다 최대 30%이상 발생하였다. 또한, 뒤채움부 무보강 2m이상 식생토낭 보강토벽은 변위에 대해 불안정한 것으로 평가되었다. 한편, 토압의 분포는 시공직후 모든 구간 Rankine 및 Coulomb의 주동토압 이내에 분포하는 것으로 나타났다. 그러나 집중강우 이후 일반쌓기 구간은 토압의 증가폭이 크게 나타났으며, 게비온과 일반쌓기 혼용구간이 일반쌓기 구간과 비교하여 보다 안정한 것으로 평가되었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 가을 학술발표회 논문집
• /
• pp.109-116
• /
• 2000

This paper presents the results of investigation on the effects of surface loading on the performance of soil-reinforced segmental retaining walls using the finite element method of analysis. A parametric study was performed by varying location of surface loading. The results of the analyses indicate that the increment of the reinforcement tensile load due to the presence of surface load may be significantly over-estimated when using the conventional approach. Furthermore, the external stability should be carefully examined when a surface loading is present just outside the reinforced soil zone. The implications of the findings from this study to current design approaches are discussed in detail.