• Geomechanics and Engineering
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• v.5 no.2
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• pp.87-97
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• 2013

In this paper, a novel fibrous material known as axially reinforced braided composite rods (BCRs) have been developed for reinforcement of soils. These innovative materials consist of an axial reinforcement system, comprised of longitudinally oriented core fibres, which is responsible for mechanical performance and, a braided cover, which gives a ribbed surface texture for better interfacial interactions with soils. BCRs were produced using both thermosetting (unsaturated polyester) and thermoplastic (polypropylene) matrices and synthetic (carbon, glass, HT polyethylene), as well as natural (sisal) core fibres. BCRs were characterized for tensile properties and the influence of core fibres was studied. Moreover, BCRs containing carbon fibre in the core composition were characterized for piezoresistivity and strain sensing properties under flexural deformation. According to the experimental results, the developed braided composites showed tailorable and wide range of mechanical properties, depending on the core fibres and exhibited very good strain sensing behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.193-200
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• 1999

Since Broms and Bennermark(1967) suggested the face stability criterion based on laboratory extrusion tests and field observations, the face stability of a tunnel driven in cohesive material has been studied by several authors. And recently, more general solution for the tunnel front is given by Leca and Panet(1988). They adopted a limit state design concept to evaluate the face stability of a shallow tunnel driven into cohesionless material and showed that the calculated upper bound solution represented the actual behavior reasonably well. In this study, two factors are simultaneously considered for assessing tunnel face stability: One is the effective stress acting on the tunnel front calculated by upper bound solution; and the other is the seepage force calculated by numerical analysis under the condition of steady state ground water flow. The model tests were performed to evaluate the seepage force acting on the tunnel front and these results were compared with results of numerical analysis. Consequently, the methodology to evaluate the stability of a tunnel face including limit analysis and seepage analysis is suggested under the condition of steady state ground water flow.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.489-496
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• 1999

The safety of a structure can be improved by applying the three dimensional passive earth pressure. Because the three dimensional passive earth pressure is much larger than the two dimensional passive earth pressure and it is determined by the size(width B and height H) and the wall frictional angle of the resistant wall. Therefore, the three dimensional passive resistance behavior was studied through the model tests in sandy ground, where the size of the resistant wall and the wall frictional angle were varied. The results show that three dimensional passive earth pressure is 1.1∼3.4 times larger than that of the two dimensional value depending on the wall size and the wall friction.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.207-214
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• 2000

Sand Compaction Pile method is one of the widely used ground improvement techniques at loose sand or soft clay ground in Asian countries. However, due to environmental and economical problems concerning shortage of sand resources alternative materials are needed to substitute sand for SCP. This study is on the applicability of slag as an alternative material SCP. Consolidation and direct shear test are performed for the slag-clay composite specimens to find out the positive effects of consolidation rate and shear resistance of slag reinforced ground. The result shows that slag has similar effects with sand in consolidation and shear resistance behavior in composite ground, which says slag can be used as alternative material of sand for SCP.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.265-272
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• 2000

This study introduces the current theory of the SWCC and tries to verify the theory by performing laboratory tests for the local soils of Korea. First, the SWCCs of Poi-dong soil and Shinnae-dong soil, the most typical weathered residual soils in Korea, were experimentally obtained and the results were compared among others. Second, a SWCC model for deformable soils was proposed. For deformable soils, which show huge volume change during desaturation, the volume change behavior should be considered, and the SWCC should be expressed as a function of void ratio as well as suction.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.281-288
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• 2000

In this study, we tried to determine failure criteria for joints of soft rock using ring shear test machine. The residual stress fellowing shear behavior was determined by the result of ring shear test and direct shear test. Ring shear test with the specimens which cover a large deformation range was adapted to measure a residual stress, and was possible to present the peak stress to present the peak stress to the residual stress at the same time. Residual stress is defined a minimal stress of specimens with a large displacement and the result of the peak residual stress is shown by a size of displacement volume. Therefore, the residual stress in soil was decided by shear stress of maximum shear stress - shear displacement(angle) based on the test result of a hyperbolic function ((equation omitted), a, b ＝ experimental constant). In this study, it was proved that the residual stress of rock joint can be determined by using of this method.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.379-386
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• 2000

This paper presents the results of finite element analysis on the seismic response of a soil-reinforced segmental retaining wall subjected to a prescribed earthquake record. The results of finite element analysis indicate that the maximum wall displacement occurs at the top, exhibiting a cantilever type of wall movement. Also revealed is that the increase in reinforcement force is more pronounced in the upper part of the reinforced zone, resulting in a more or less uniform distribution. None of the design guidelines appears to be able to correctly predict the dynamic force increase when compared with the results of finite element analysis. The calculation model adopted by the NCMA guideline, however, appears to compare better with the results of finite element analysis as well as field survey than the FHWA guideline. Based on the findings from this study, a number of implications to the current design methods are discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.631-638
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• 2000

Pioneering work by Terzaghi imparted scientific and mathematical bases to many aspects of this subject and many people use this theory to measure the consolidation settlement until now. In this paper, Finite Difference Methods for consolidation are considered. First, it is shown the stability criterion of Explicit scheme and the Crank-Nicolson scheme, although unconditionally stable in the mathematical sense, produces physically unrealistic solutions when the time step is large. it is also shown that The Fully Implicit scheme shows more satisfactory behavior, but is less accurate for small time steps. and then we need to decide what scheme is more proper to consolidation. The purpose of this paper is to suggest the pertinent scheme to consolidation.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.457-464
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• 2010

Ever since the introduction of high strength steel pipe strut(POSTRUT) in 2008, there has been over 50 applications domestically. The merits of construction period reduction and cost savings have been well reported abroad in countries such as America, Europe and China but ever in domestic projects or ground condidtions. 25 actual construction projects were investigated and statistically analyzed to evaluate the quantitative effects of POSTRUT. Also the construction projects along with the cautions that should be taken and the structural behavior differences between POSTRUT and H-section struts are briefly described in this paper.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.580-586
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• 2010

The purpose of this study is to analyze the behavior of the concrete pile under the horizontal loads by the model tests in laboratory. The rock ground was modeled by the concrete of about 30MPa, and a model pile was made of some mortar with the capacity of 24MPa. The diameter(D) and length(L) of a model pile was each 1200mm and 1800mm. The embedment depth into the concrete block was varied with 1.0D, 1.5D, and 2.0D in the model tests. The results of model tests showed that the lateral resistance of a pile with the embedment depth of 2.0D was more large than other cases, and the lateral displacement of yielding was similar.