• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.85-96
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• 2007

The application of soil nailing method has increased because it provides easier construction, economic efficiency, and stability than existing support methods. The mechanical comprehension of the soil-nailing system has not been established and the resisting shear force and bending moment of the soil-nail have been disregarded for the design of soil-nailing system. The soil nail consists of cement associated with rebar and resists shear force and bending moment mobilized by applied loading or soil-self weight. In this study, the slope analysis in the consideration of the resisting shear force and bending moment of the nail has been performed using $FLAC^{2D}$, which is programed by the finite difference method.

• Journal of the Korean Geosynthetics Society
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• v.5 no.3
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• pp.1-7
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• 2006

The Green Wall system, developed in Austria early 1960, is one of segmental concrete crib type earth retaining wall. Green wall is constructed as procedures that lay the front stretchers, rear stretchers and headers then making a rigid body through harden filled soil of interior cell. Green wall has pro-environmental advantages that able to grow grass in front space of stretchers and decrease cutting ground. In Europe, Green wall used without other reinforcement method. However, green wall used with other reinforcement method like a soil nailing because of environmental problem. This study was performed to introduce the design case by 'Two-Body Translation mechanism' to be able to consider distribution of earth pressure in the soil nailing when designing the green wall using soil nailing system. Also, this study attempts to evaluate the earth pressure change when advanced soil nailing system is constructed using $FLAC^{2D}$ ver. 3.30 program and 'Two-Body Translation mechanism'.

• Archives of Plastic Surgery
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• v.41 no.6
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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.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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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.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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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.

• Journal of the Korean Geosynthetics Society
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• v.15 no.2
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• pp.65-75
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• 2016

In this study, we constructed a database by collecting field pullout test data of the soil nailing using pressurized grouting, and suggested a method to estimate the ultimate pullout resistance using nonlinear regression analysis to overcome the problems of ultimate pullout resistance estimation using graphical methods. The load-displacement curve estimated by nonlinear regression showed a very high correlation with the field pullout test data. Estimated ultimate pullout load by nonlinear regression method was average 29% higher than estimated ultimate pullout load using previous graphical method. A sigmoidal growth model was found to be the best-fitting nonlinear regression model against rapid pullout failure. Further, an asymptotic regression model was found to be the best fit against progressive nail pullout. The unit ultimate skin friction suggested in this research reflected in the domestic geotechnical characteristics and the specifications of the pressurized grouting method. This research is expected to contribute towards establishing an independent design standard for the soil nailing by providing solutions to the problems that occur when using design charts based on foreign research.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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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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• v.35 no.3
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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.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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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.

• Journal of Industrial Technology
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• v.19
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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.