• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.183-191
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• 2009

In this study, the behavior and safety factor of a nailed-soil excavation wall during earthquake is presented. The horizontal displacement, axial force, shear force, and moment of facing of a nailed-soil excavation wall subjected to static and seismic load are analyzed using time history analysis. The safety factor based on the strength reduction technique proposed by Dawson and Roth is used to calculate the safety factor of a nailed-soil excavation wall during earthquake. The safety factor by the proposed method is verified by comparing with those by other methods.

• The Journal of Engineering Research
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• v.6 no.1
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• pp.83-96
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• 2004

A soil mailed wall is adapted as road widening measure and is constructed under a miniature abutment built on steel pipe piles. The soil nailed wall called for removal of the existing embankment slope to permanently retain the fill behind the abutment. The soil nailed wall is fully instrumented and is monitored. A 3D finite element analysis is used to study further the behavior of the soil nailed wall. The complete sequence of construction is simulated. The numerical model is calibrated against the instrumented nailed wall. Then a parametric study is conducted. The results provide valuable information related to the effect of the excavation and nailing on the following: axial load and bending moment in the piles, load in the nails, and wall deflections.

• Journal of the Korean Geotechnical Society
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• v.19 no.3
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• pp.5-13
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• 2003

The soil nailing is one of the useful support-system in urban excavation because of the presence of other structures in the vicinity Since the soil nailing system was introduced, model experiments and theoretical studies have been performed to investigate behavior of soil nailed wall. However, there are few data in the case of multi-layered soil strata just like Seoul Metropolitan area in Korea. The feed back analyses are carried out using the measured wall displacement data for soil nailing construction sites with multi-layered strata in order to analyze the distance and the coefficients of extension zone of ground behind soil nailed wall. As a result, the distance of extension zone increased with increasing of the final excavation depth and the ratio of the distance to the final excavation depth was shown to be about 94% of the final excavation depth. Also, the coefficients of extension zone increased with enlargement of soil layer thickness and converged into constant value of 1.05. On the other hand, the maximum vertical displacements by the feed back analysis and Caspe's method were shown to be approximately 80%, 150~280% of the maximum horizontal displacement respectively.

• Journal of the Korean GEO-environmental Society
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• v.2 no.2
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• pp.23-32
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• 2001

A soil wall reinforced by soil nailing is excavated in the typical soil conditions which are consisted of weathered soil, weathered rock and soft rock. The resulting nail loads computed are compared to loads measured by utilizing strain gauges during construction. The wall deflection at two locations are related to construction events and specific soil conditions, providing an understanding of the behavior of soil nailed walls. The load distribution along the nail indicated relatively high loads close to the wall. The mobilized load on the nail is proportional to the wall deflection showing the maximum value at the surface of the wall. The construction monitoring for this project provided valuable information in understanding the behavior of soil nailed walls.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.71-86
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• 1999

The displacements of soil nailed wall and the nail tensile force for 11 soil nailing sites were investigated by using measurements obtained from inclinometer and strain gauge. The maximum horizontal displacement which occurred between 5% and 15% of the final excavation depth was found to be below 0.3% and 0.2% of excavation depth for well and poorly constructed sites. It was also found that the maximum horizontal displacements for 0.4%, 0.3% and 0.2% of excavation depth occurred when the ratios of nail length to final excavation depth were 0.5, 0.5~0.6 and 0.6~0.7. But the maximum horizontal displacement increased by 0.3% of excavation depth when the ratio was above 0.7. This was probably due to the shallow excavation depth and the deep soil stratum. The non-dimensional maximum tensile force of nail, K, from ground surface to $(0.6H_f)$ of the final excavation depth was less than 0.8 and decreased linearly between $(0.6H_f)$ and the final excavation depth. Also, the maximum tensile force was found to reach up to 60% of the ultimate tensile force at final excavation.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.97-106
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• 1996

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.61-68
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• 2003

In this study, a newly modified soil nailing technology named as the pretension 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 pretension soil nailing system, has been investigated mainly focusing on an establishment of the design procedure. In the present study, laboratory model tests are carried out to investigate the failure mechanism and behavior characteristics of the pretension soil-nailed wall. Various results of model tests are also analyzed to provide a fundamental basis for the efficient design.

• Journal of the Korean GEO-environmental Society
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• v.16 no.3
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• pp.23-34
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• 2015

In this study, a newly modified soil nailing technology using bamboo is developed. And field tests were performed to confirm applicability of bamboo soil nailing system. For the practical use of bamboo soil nailing system, laboratory tests, field instrumentations and pullout tests were also performed to investigate the applicability. The results of field measurement through field tests were compared with the results of numerical analyses for verifying the field construction. As a result, the results of comparing with the field measurement and numerical analyses shows the similar behavior characteristics. Based on this study, applicability for bamboo soil nailing systems were confirmed for the case of comparatively low scale nailed-soil excavation wall. And it is expected that the bamboo soil nailing system can be used as satisfactory reinforcement technique taking the place of existing steel reinforcement soil nailing system. Hereafter, it needed the research for the applicability for the various types of excavation condition, also the active practical application of bamboo soil nailing system is needed.

• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.113-132
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• 1999

Recently in Korea, application of the soil nailing is gradually extended to the sites of excavations and slopes having various ground conditions and field characteristics. Design of the soil nailing is generally carried out in two steps, The First step is to examine the minimum safety factor against a sliding of the reinforced nailed-soil mass based on the limit equilibrium approach, and the second step is to check the maximum displacement expected to occur at facing using the numerical analysis technique. However, design parameters related to the soil nailing system are so various that a reliable design method considering interrelationships between these design parameters is continuously necessary. Additionally, taking into account the anisotropic characteristics of in-situ grounds, disturbances in collecting the soil samples and errors in measurements, a systematic analysis of the field measurement data as well as a rational technique of the optimum design is required to improve with respect to economical efficiency. As a part of these purposes, in the present study, a procedure for the optimum design of a soil nailing excavation wall system is proposed. Focusing on a minimization of the expenses in construction, the optimum design procedure is formulated based on the genetic algorithm. Neural network theory is further adopted in predicting the maximum horizontal displacement at a shotcrete facing. Using the proposed procedure, various effects of relevant design parameters are also analyzed. Finally, an optimized design section is compared with the existing design section at the excavation site being constructed, in order to verify a validity of the proposed procedure.