• Proceedings of the Korean Geotechical Society Conference
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• 1997.11a
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• pp.1-20
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• 1997

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.112-118
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• 2004

Recently, when being constructed the large structures, the deep excavations have performed to utilize the underground space. As the ground excavation is deeper, the damage of the adjacent structure and the ground is frequently occurred. the Analysis of the retaining structures is necessary to safety of the excavation works. There are many methods such as elasto-plastic theory, FEM, and FDM to analyze the displacement of the retaining structure. In this thesis, GEBA-1 program by the Nakamura-Nakajawa elasto-plastic method was developed. The lateral displacement of the wall was analyzed by the developed program GEBA-1, SUNEX, and EXCAD, and compared with the measured displacement bye the Inclinometer. The monitored fields were three excavation work site in S-I, S-II, and S-III area. Excavation method of each site is braced retaining wall using H-pile. Excavation depth is 14m, 14m, and 8.2m.

• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.23-30
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• 2000

The use of strut-preloading method is gradually increasing in braced excavations in Korea. And it is necessary to analyze the effects of strut preloading on the wall deflection, wall bending moment and strut axial force, etc. In this study, by using the analysis method of beams on elasto-plastic foundations, measured data and calculated results of 2 sites are compared and parametric studies of correlation between preloading and earth retaining structures in sandy soils are carried out in strut preloading application. As results, about 50%~75% of design strut load is effective as preloading force in considering the displacement and member forces of earth retaining structures. And the effective stiffiness of strut should be at least 25% of th ideal value in order to restrain the excessive increase of wall deflection and bending moments. As one of some methods to prevent excessive movements in braced excavation, to preload the strut is confirmed as more effective way than to increase the stiffiness of strut in braced wall, if the excessive axial force of strut due to preloading can be avoided.

• Geomechanics and Engineering
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• v.17 no.5
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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.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1324-1329
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• 2009

Needs for underground space development and utilization have been increasing in urban area. The conventional strutting method in excavation is effective to restrain the ground movements and displacements of earth structures but inefficient for workers because of small working space. The conventional earth reinforcement methods such as earth-anchor and soil-nailing also have limitation to apply in urban area due to threats to stability of adjacent buildings around excavation boundaries. Recently, many types of earth retaining structures are being developed to overcome disadvantages of conventional excavation methods in urban area. In this study, a series of numerical analyses were performed with MIDAS GTS, geotechnical analysis program and MIDAS Civil, structural analysis design program to evaluate behavior and stability of the new type of non-supporting earth retaining structure, called Temporary Tower System (TTS), consisting of tower truss structures with much economical and spatial advantage.

• Geomechanics and Engineering
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• v.7 no.3
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• pp.263-277
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• 2014

In the conventional design of retaining structures in a seismic zone, seismic inertia forces are commonly assumed to act upwards and towards the wall facing to cause a maximum active thrust or act upwards and towards the backfill to cause a minimum passive resistance. However, under certain circumstances this design approach might underestimate the dynamic active thrust or overestimate the dynamic passive resistance acting on a rigid retaining structure. In this study, a new analytical method for dynamic active and passive forces in c-${\phi}$ soils with an infinite slope was proposed based on the Rankine earth pressure theory and the Mohr-Coulomb yield criterion, to investigate the influence of seismic inertia force directions on the total active and passive forces. Four combinations of seismic acceleration with both vertical (upwards or downwards) and horizontal (towards the wall or backfill) directions, were considered. A series of dimensionless dynamic active and passive force charts were developed to evaluate the key influence factors, such as backfill inclination ${\beta}$, dimensionless cohesion $c/{\gamma}H$, friction angle ${\phi}$, horizontal and vertical seismic coefficients, $k _h$ and $k_v$. A comparative study shows that a combination of downward and towards-the-wall seismic inertia forces causes a maximum active thrust while a combination of upward and towards-the-wall seismic inertia forces causes a minimum passive resistance. This finding is recommended for use in the design of retaining structures in a seismic zone.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.167-174
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• 2002

Earth retaining structure is constructed structure in order to construct a multistoried building, the subway, a subterranean downtown for effective use and obtainments of the limited ground. Recently, many kinds of research have been actively developed for a standardization and a database on designing and constructing of bridge, tunnel, road. With the works of database construction of that, many kinds of data with respect to statistics is cumulated. However, Database work of designed and constructed earth retaining structure in the construction field is wholly lacking and lagged behind in the works of database construction. This paper suggested classification system on indication data in connection with designing and constructing earth retaining structures a hundred fields. On the basis of that, code work with classification system was practised and DB program of indication data in connection with designing and constructing earth retaining structures was developed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.6
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• pp.19-28
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• 2004

Segmental Retaining Wall(SRW) has been variously applying in Civil and Architecture construction. Recently, the application of environmental element in all type's structures came to essential requirement, and the construction cases of retaining wall using reinforced soil and block are more increased than the past. But, this trend more widely was spread environmental element as landscape work for the backside of reinforced retaining wall as well as block itself. New environmental block, Greenstone Block, developed to apply of this tendency. The retaining wall system using Greenstone can be environmental constructing at both block itself and backside of retaining wall. The material tests, the axial compressive strength test of block and bending test of fiber-pipe, exercised to design and construction of vertical SRW, which were satisfied NCMA standard. Through this procedure, Rewall (ver 1.0) was developed, which can be automation design of SRW including internal stability, external stability and local stability. And these can be considered setback of retaining wall, as well the examples of vertical retaining wall using block presented to satisfying the follows; strength of reinforced geotextile, height of retaining wall, surcharge, types of backfill and groundwater level etc. Many problems investigated on after or before of construction were due to local failure, insufficiency of bearing capacity and groundwater level. Especially, the local failure was many occurred to during compaction or after construction, and the cases of SRW construction is similar to the results of model test on vertical SRW.

• Geomechanics and Engineering
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• v.6 no.2
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• pp.99-115
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• 2014

Uncertainties in design variables and design equations have a significant impact on the safety of geotechnical structures like retaining walls and slopes. This paper presents a possible framework for obtaining the partial safety factors based on reliability approach for different random variables affecting the stability of a reinforced concrete cantilever retaining wall and a slope under static loading conditions. Reliability analysis is carried out by Mean First Order Second Moment Method, Point Estimate Method, Monte Carlo Simulation and Response Surface Methodology. A target reliability index ${\beta}$ = 3 is set and partial safety factors for each random variable are calculated based on different coefficient of variations of the random variables. The study shows that although deterministic analysis reveals a safety factor greater than 1.5 which is considered to be safe in conventional approach, reliability analysis indicates quite high failure probability due to variation of soil properties. The results also reveal that a higher factor of safety is required for internal friction angle ${\varphi}$, while almost negligible values of safety factors are required for soil unit weight ${\gamma}$ in case of cantilever retaining wall and soil unit weight ${\gamma}$ and cohesion c in case of slope. Importance of partial safety factors is shown by analyzing two simple geotechnical structures. However, it can be applied for any complex system to achieve economization.

• Structural Engineering and Mechanics
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• v.52 no.6
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• pp.1225-1256
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• 2014

Calculating the seismic displacement of retaining walls has an important role in the optimum design of these structures. Also, studying the effect of surcharge is important for the calculation of active pressure as well as permanent displacements of the wall. In this regard, some researchers have investigated active pressure; but, unfortunately, there are few investigations on the seismic displacement of retaining walls with surcharge. In this research, using limit analysis and upper bound theorem, permanent seismic displacement of retaining walls with surcharge was analyzed for sliding and overturning failure mechanisms. Thus, a new formulation was presented for calculating yield acceleration, critical angle of failure wedge, and permanent displacement of retaining walls with surcharge. Also, effects of surcharge, its location and other factors such as height of the wall and internal friction angle of soil on the amount of seismic displacements were investigated. Finally, designing charts were presented for calculating yield acceleration coefficient and angle of failure wedge.