• Geomechanics and Engineering
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• 제17권5호
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• pp.413-420
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• 2019

The changes in earth pressure and ground settlement due to underground excavation near an existing retaining wall were studied experimentally according to the separation distance between the underground excavation and the retaining wall. In addition, this study attempted to experimentally prove that the arching phenomenon occurred during the construction of the underground space. A model tank having 120 cm in length, 160 cm in height, and 40 cm in width was manufactured to simulate underground excavation through the use of five separated base wall bodies. The variation of earth pressure on the retaining wall was measured according to the underground excavation phase through the use of 10 separated right wall bodies. The results showed that the earth pressure on the retaining wall was changed by the lowering of the first base bottom wall; however, the earth pressure was not changed significantly by the lowering of the third base bottom wall, since the third base wall had sufficient separation distance from the retaining wall. Lowering of the first base wall induced a decrease in the earth pressure in the lower part of the retaining wall; in contrast, lowering of the first base wall induced an increase in the earth pressure in the middle part of the retaining wall, proving the arching effect experimentally. It is necessary to consider the changes in earth pressure on the retaining wall in designing earth retaining structures for sections where the arching effect occurs.

• Geomechanics and Engineering
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• 제19권4호
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• pp.315-327
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• 2019

Deep excavations for development of subway systems in metropolitan regions surrounded by adjacent buildings is an important geotechnical problem, especialy in Tabriz city, where is mostly composed of young alluvial soils and weak marly layers. This study analyzes the wall displacement and ground surface settlement due to deep excavation in the Tabriz marls using two dimensional finite element method. The excavation of the station L2-S17 was selected as a case study for the modelling. The excavation is supported by the concrete diaphragm wall and one row of steel struts. The analyses investigate the effects of wall stiffness and excavation width on the excavation-induced deformations. The geotechnical parameters were selected based on the results of field and laboratory tests. The results indicate that the wall deflection and ground surface settlement increase with increasing excavation depth and width. The change in maximum wall deflection and ground settlement with considerable increase in wall stiffness is marginal, however the lower wall stiffness produces the larger wall and ground displacements. The maximum wall deflections induced by the excavation with a width of 8.2 m are 102.3, 69.4 and 44.3 mm, respectively for flexible, medium and stiff walls. The ratio of maximum ground settlement to maximum lateral wall deflection approaches to 1 with increasing wall stiffness. It was found that the wall stiffness affects the settlement influence zone. An increase in the wall stiffness results in a decrease in the settlements, an extension in the settlement influence zones and occurrence of the maximum settlements at a larger distance from the wall. The maximum of settlement for the excavation with a width of 14.7 m occurred at 6.1, 9.1 and 24.2 m away from the wall, respectively, for flexible, medium and stiff walls.

• Geomechanics and Engineering
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• 제33권5호
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• pp.507-518
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• 2023

The effects of various supporting arrangements have been investigated on an excavation support system using a numerical tool. The purpose of providing different supporting arrangements was to limit the pile wall deflection in the range of 0.5% to 1% of the excavation depth. Firstly, a deep excavation supported by sheet pile wall was modeled and the effects of sheet pile wall thickness, excavation depth and distance to adjacent footings from sheet pile wall face were explored on the soil deformation and wall deflection. Further analysis was performed considering six different arrangements of tieback anchors and struts in order to limit the wall deflections. Case-01 represents the basic excavation geometry supported by sheet pile wall only. In Case-02, sheet pile wall was supported by struts. Case-03 is a sheet pile wall supported by tieback anchors. Likewise, for the Cases 04, 05 and 06, different arrangements of struts and tieback anchors were used. Finally, the effects of different supporting arrangements on soil deformation, sheet pile wall deflection, bending moments and anchor forces have been presented.

• 한국건축시공학회지
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• 제7권3호
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• pp.131-137
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• 2007

To predict deep excavation wall movements is important in the urban areas considering the cost and the safety in construction. Failing to estimate deep excavation wall movements in advance causes too many problems in the projects. The purpose of this study is to propose the forecast model of deep excavation wall movements using artificial neural networks. The data of the Deep Excavation Wall Movements which were done form Long research is used of Artificial neural networks training and apply the real construction work measured data to the Artificial neural networks model. Applying the artificial neural networks to forecast the deep excavation wall movements can significantly contribute to identifying and preventing the accident in the overall construction work.

• 한국지반환경공학회 논문집
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• 제13권12호
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• pp.67-74
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• 2012

기존건물의 지하층과 인접하여 굴착 시 양단벽체 토사의 마찰로 발생하는 아칭효과는 굴착벽체에 작용하는 토압을 경감시키게 된다. 본 논문에서는 굴착깊이에 대한 배면폭의 비와 벽마찰각의 변화에 따른 아칭효과의 변화를 다양한 조건에서 수치해석을 통하여 살펴보았다. 수치해석 모델은 원심모형시험결과를 바탕으로 검증하여 적용하였으며, 아칭에 의한 토압경감 효과는 굴착깊이에 대한 배면폭의 비가 작고 벽마찰각이 커짐에 따라 증가함을 알 수 있었다. 이와 같은 아칭 현상은 기존의 아칭이론 중 Handy(1985)가 제안한 이론식을 통하여 가장 정확히 묘사 가능함을 알 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1251-1258
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• 2008

The purpose of this research is to introduce the new temporary earth retaining wall system using landslide stabilizing piles. This system is a self-supported retaining wall(SSR) without installing supports such as tiebacks, struts and rakers. The SSR is a kind of gravity structures consisting of twin parallel lines of piles driven below dredge level, tied together at head of soldier piles and landslide stabilizing piles by beams. There are three types of excavation wall structures: standard method for medium retained heights(<8.0m), internal excavation method and slope excavation method for deep-excavation applications(>8.0m). In the present study, the measured data from seven different sites which the SSR was used for excavation were collected and analyzed to investigate the characteristic behavior lateral wall movements associated with urban excavations in Korea.

• Geomechanics and Engineering
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• 제14권4호
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• pp.315-324
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• 2018

With rapid economic growth, numerous deep excavation projects for high-rise buildings and subway transportation networks have been constructed in the past two decades. Deep excavations particularly in thick deposits of soft clay may cause excessive ground movements and thus result in potential damage to adjacent buildings and supporting utilities. Extensive plane strain finite element analyses considering small strain effect have been carried out to examine the wall deflections for excavations in soft clay deposits supported by diaphragm walls and bracings. The excavation geometrical parameters, soil strength and stiffness properties, soil unit weight, the strut stiffness and wall stiffness were varied to study the wall deflection behaviour. Based on these results, a multivariate adaptive regression splines model was developed for estimating the maximum wall deflection. Parametric analyses were also performed to investigate the influence of the various design variables on wall deflections.

• 터널과지하공간
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• 제5권3호
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• pp.223-229
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• 1995

During excavation works for underground facilities, temporary tieback wall with earth anchor system was investigated for safety's sake. An excavation 9.7 meter deep was monitored by slope inclinometer in twelve measuring points. Instrumented lateral displacements of the wall during 177 days are represented. Especially, lateral displacements of the two positions under completely different condition are compared to investigate the effect of backfilling between soldier pile and the soil behind wall. The deformation behaviors of the wall according to both depth and elasped time are discussed. Finally, a numerical analysis by the program FLAC was performed, and calculated displacements are compared to measured ones.

• 한국지반신소재학회논문집
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• 제14권4호
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• pp.23-33
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• 2015

소단은 굴착 후 지지구조물이 설치되기 전 벽체의 강성과 더불어 가설벽체의 안정성을 좌우하는 역할을 한다. 특히 굴착지반이 느슨하거나 연약한 경우 소단의 역할은 매우 중요하다. 본 연구에서는 소단을 이용한 도심지 버팀굴착현장의 계측결과와 수치해석을 사용하여 가설벽체의 최대수평변위에 미치는 소단의 규모(폭과 경사) 및 굴착깊이, 지반물성의 영향을 분석하였다. 계측결과 소단 폭이 짧아질수록 벽체의 수평변위는 증가하는 경향을 보였다. 수치해석 결과 소단의 경사가 급해질수록, 소단폭이 짧아질수록 최대수평변위량은 크게 나타나 소단이 벽체의 변위를 억제하는데 효과가 있음을 알 수 있었다. 또한 굴착심도가 깊어질수록 소단폭과 경사의 영향을 크게 받는 것으로 나타났다. 동일한 소단 조건에서 지반물성이 높을수록 벽체의 최대수평변위를 억제하는 것으로 나타났다.

• 한국지반환경공학회 논문집
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• 제19권2호
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• pp.13-21
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• 2018

The magnitude and distribution of earth pressure on the excavation wall in jointed rock mass were examined by considering different wall permeability conditions as well as rock types and joint inclination angles. The study was numerically extended based on a physical model test (Son & Park, 2014), considering rock-structure interactions with the discrete element method, which can consider various characteristics of rock joints. This study focused on the effect of the permeability condition of excavation wall on the earth pressure in jointed rock masses under a groundwater condition, which is important but has not been studied previously. The study results showed that the earth pressure was highly influenced by wall permeability as well as rock type and joint condition. Earth pressure resulted from the study was also compared with Peck's earth pressure in soil ground, and the comparison clearly showed that the earth pressure in jointed rock mass can be greatly different from that in soil ground.