• 한국지반공학회논문집
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• 제23권10호
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• pp.85-96
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• 2007

쏘일 네일 공법은 기존의 지보공법에 비해 시공의 편리성과 경제성, 안정성이 우수하여 최근 현장에 적용되는 사례가 증가하고 있다. 하지만, 쏘일 네일 공법에 대한 공학적인 접근은 미흡하여 우리나라에서는 지금까지 체계적인 설계 공법이 확립되지 못한 실정이다. 기존의 쏘일 네일 공법 설계에는 네일에 작용하는 전단 저항 및 휨 저항을 고려하지 않았으나, 철근과 시멘트로 구성된 쏘일 네일은 전단 및 휨에 대한 저항을 가지고 있다. 따라서, 본 논문에서는 네일의 전단 및 휨 저항을 고려한 쏘일 네일 보강시 수치해석 프로그램인 $FLAC^{2D}$를 이용해 사면의 안정성을 분석하였다.

• 한국지반신소재학회논문집
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• 제5권3호
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• pp.1-7
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• 2006

1960년대 초 오스트리아에서 개발된 그린월(green wall) 공법은 독립식 콘크리트 보형식의 옹벽으로, 전, 후면 가로보와 세로방향으로 버팀보를 연속적으로 쌓아 올려 내부에 다짐성토를 시행, 구조체가 일체 거동하도록 강성벽체(rigid body)를 형성시키는 옹벽 구조물이다. 국내의 경우, 옹벽 전면 가로보 사이의 공간에 식생이 가능한 친환경적 장점이 있어, 1999년 이후 국내실정을 고려 원지반의 토공량을 최소화할 수 있도록, 쏘일네일 등으로 보강하여 절토 공사현장에 다양하게 적용되고 있는 추세이다. 그러나 그린월 옹벽과 배면에 보강된 쏘일네일이 합벽시공될 경우, 네일에서의 토압분담효과 등에 대한 영향을 고려하지 않고 일반적인 Rankine 토압으로 설계, 시공하여 이중으로 보강공사비용이 투입되고 있는 실정이다. 따라서 본 연구에서는 G$\ddot{a}$ssler(1988)가 제안한 'Two-Body Translation Mechanism(TBTM)'을 이용한 안정해석기법을 수정하여, 네일의 토압 분담효과를 반영할 수 있는 설계기법을 제시하였으며, 본 연구에서 제안한 설계기법을 적용하여 그린월의 보수, 보강공사 비용을 상당부분 감소한 현장설계 사례를 소개하고자 한다. 아울러 본 연구에서 제시한 설계기법을 토대로 계산된 토압을 수치해석 결과와 비교, 검토해 보았다.

• Archives of Plastic Surgery
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• 제41권6호
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• pp.768-772
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• 2014

Background To compare clinical and radiographic outcomes between intramedullary nail fixation and percutaneous K-wire fixation for fractures in the distal third portion of the metacarpal bone. Methods A single-institutional retrospective review identified 41 consecutive cases of metacarpal fractures between September 2009 and August 2013. Each of the cases met the inclusion criteria for closed, extra-articular fractures of the distal third of the metacarpal bone. The patients were divided by the method of fixation (intramedullary nailing or K-wire). Outcomes were compared for mean and median total active motion of the digit, radiographic parameters, and period until return to work. Complications and symptoms were determined by a questionnaire. Results During the period under review, 41 patients met the inclusion criteria, and the fractures were managed with either intramedullary nailing (n=19) or percutaneous K-wire fixation (n=22). The mean and median total active range of motion and radiographic healing showed no statistically significant difference between the two groups. No union failures were observed in either group. The mean operation time was shorter by an average of 14 minutes for the percutaneous K-wire fixation group. However, the intramedullary nailing group returned to work earlier by an average of 2.3 weeks. Complications were reported only in the K-wire fixation group. Conclusions Intramedullary nailing fixation is advisable for fractures in the distal third of the metacarpal bone. It provides early recovery of the range of motion, an earlier return to work, and lower complication rates, despite potentially requiring a wire removal procedure at the patient's request.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.320-329
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• 2005

The use of diverse methods for the retaining system has been continuously increased in order to maintain the stability during excavation. However, ground anchor system occasionally may have the restriction in urban excavation sites nearby the existing structures because of space limitation. In this case, soil nailing system with relatively short length of nails could be efficiently useful as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in excavating the zone of weak soils or nearby the existing structures. Therefore, applying the pretension force to the soil nails then could play important roles to reduce deformations mainly in an upper part of the nailed-soil excavation system as well as to improve the local slope stability. In this study, a newly modified soil nailing technology named as the PSN(Pretention Soil Nailing) is developed to reduce both facing displacements and ground surface settlements during top-down excavation process as well as to increase the global slope stability. Up to now, the PSN system has been investigated mainly focusing on an establishment of the design procedure. In the present study, the field tests including pull-out tests were fulfilled to investigate the behavior of characteristics for PSN system. All results of tests were also analyzed to provide a fundamental and efficient design.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.783-790
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• 2004

In this study, a newly modified soil nailing technology named as the PSN(pretensioned soil nailing) system, is developed to reduce both facing displacements and ground surface settlements in top-down excavation process as well as to increase the global stability. Up to now, the PSN system has been investigated mainly focusing on an establishment of the design procedure. In the present study, the analytical procedure and design technique are proposed to evaluate maximum pretension force and stability of the PSN system. Also proposed arc techniques to determine the required thickness of a shotcrete facing and to estimate probability of a failure against the punching shear. Based on the proposed procedure and technique, effects of the radius of a influence circle and dilatancy angle on the thickness of a shotcrete facing, bonded length and safety factors arc analyzed. In addition, effects of the reduction of deformations expected by pretensioning of the soil nails are examined in detail throughout an illustrative example and $FLAC^{2D}$ program analysis. And a numerical approach is further made to determine a postulated failure surface as well as a minimum safety factor of the proposed PSN system using the shear strength reduction technique with the $FLAC^{2D}$ program. Global minimum safety factors and local safety factors at various excavation stages computed in case of the PSN system arc analyzed throughout comparisons with the results expected in case of the general soil nailing system. The efficiency of the PSN system is also dealt with by analyzing the wall-facing deformations and the adjacent ground surface settlements.

• 한국지반신소재학회논문집
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• 제15권2호
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• pp.65-75
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• 2016

본 연구에서는 최근 적용사례가 급증하고 있는 가압식 그라우팅을 이용한 쏘일네일링의 현장인발시험 자료를 수집하여 데이터베이스를 구성하였으며, 기존의 도해법을 이용한 극한인발저항력 판정법의 문제점을 보완하기 위하여 비선형회귀분석을 이용하여 극한인발저항력을 판정하는 방법을 제안하였다. 비선형회귀분석에 의해 추정된 하중-변위곡선은 현장인발시험 자료와 매우 높은 상관성을 보였으며, 도해법에 의해 판정된 극한인발하중에 비해 평균 29% 정도 크게 판정되었다. 쏘일네일의 하중-변위곡선이 항복하중 이후에 급격한 변위를 보이는 경우에는 S자 성장곡선 회귀모형이 가장 적합하며, 인발하중과 변위의 증가량이 점진적으로 감소하는 파괴거동을 보이는 하중-변위곡선은 점근적 방법이 가장 적합한 회귀모형으로 평가되었다. 본 연구로부터 제안된 단위극한주면 마찰 저항력은 국내 지반특성과 가압식 그라우팅 공법의 특성이 반영된 것으로 해외 연구결과로부터 제시된 설계도표를 이용하던 문제점을 개선함으로써 독자적인 설계기준을 확보하는데 기여할 수 있을 것으로 기대된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.419-433
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• 2009

Pressure grouting is a common technique in geotechnical engineering to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressure grouting has been applied to a soil-nailing system which is widely used to improve slope stability. The soil-nailing design has been empirically performed in most geotechnical applications because the interaction between pressurized grouting paste and the adjacent ground mass is complicated and difficult to analyze. The purpose of this study is to analyze the increase of pullout resistance induced by pressurized grouting with the aid of performing laboratory model tests and field tests. In this paper, two main causes of pullout resistance increases induced by pressurized grouting were verified: the increase of residual stress; and the increase of coefficient of pullout friction. From the laboratory tests, it was found that residual stress in borehole increases by pressurized grouting and dilatancy angle could be estimated by cavity expansion theory using the measured wall displacements. From the field test results, the pullout resistance of soil-nailing with pressurized grouting was found to be 10% larger than that of soil-nailing with gravitational grouting, mainly caused by mean normal stress increase and dilatancy effect. So, the pullout resistance could be estimated by considering these two effects. The radial displacement increases with dilatancy angle increase and the dilatancy angle decreases with injection pressure increase. The measured pullout resistance obtained from field tests is in good agreement with the estimated one from the cavity expansion theory.

• Hip & pelvis
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• 제35권3호
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• pp.193-199
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• 2023

Purpose: Cephalomedullary (CM) nailing is widely performed in treatment of elderly patients with femoral intertrochanteric fractures. However, in cases of fixation failure, re-operation is usually necessary, thus determining factors that may contribute to fixation failure is important. In this study, we examined factors affecting the occurrence of fixation failure, such as age or fracture stability, after CM nailing in elderly patients. Materials and Methods: This study was conducted retrospectively using registered data. From April 2011 to December 2018, CM nailing was performed in 378 cases diagnosed with femoral intertrochanteric fractures, and 201 cases were finally registered. Cases involving patients who were bed-ridden before injury, who died from causes unrelated to surgery, and those with a follow-up period less than six months were excluded. Results: Fixation failure occurred in eight cases. Comparison of the surgical success and fixation failure group showed that the mean age was significantly higher in the fixation failure group compared with the control group (81.3±6.4 vs. 86.4±6.8; P=0.034). A significantly high proportion of unstable fractures was also observed (139/54 vs. 3/5; P=0.040), with a significantly high ratio of intramedullary reduction (176/17 vs. 5/3; P=0.034). A significantly higher ratio of unstable fractures compared with that of stable fractures was observed in the intramedullary reduction group (132/49 vs. 10/10; P=0.033). Conclusion: Fixation failure of CM nailing is likely to occur in patients who are elderly or have unstable fracture patterns. Thus, care should be taken in order to avoid intramedullary reduction.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.77-84
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• 2003

Deep excavations in the urban areas have been frequently going on in large scale. Soil-nailing and Earth-anchor supporting methods are generally used in deep excavation. These construction methods cause ground disturbances during drilling process, and damages of adjacent structures and ground due to the differential settlement throughout construction period, and unexpected behaviors of supporting system according to the characteristics of drilling machine and ground condition. This article introduces two actual examples of adjacent deep excavation for the construction of university buildings in granitic Seoul area. The important results of construction and measurements obtained using Crawler drilling machine for Soil-nailing and Earth-anchor supporting methods are summarized. And some suggestions are given to improve and develop the technique of design and construction in the deep excavation projects having similar ground condition and supporting method.

• 산업기술연구
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• 제19권
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• pp.115-125
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• 1999

Current design and analyzing methods about soil nailing structures, developed on the basis of results obtained from experiments in laboratory or in field and numerical analyses, have applied different interaction mechanisms between the reinforced nails and the surrounding ground, and this different safety factors against failure have been obtained. They might be proper approached if the assumptions about rigidity of nails and ground conditions are met with actual conditions occurred in field. Otherwise, they would result in designing on analyzing in inappropriate ways so that it is needed to evaluate the validity of them. Therefore, overall behavior and failure mechanism about soil nailing system were investigated by performing numerical method. Using a finite element analysis, parametric studies were made to examine the importance of the various parameters and their effects on the soil nailing system. The numerical technique of FEM, implemented with Hyperbolic constitutive model, was also used to analyze the test results.