• Journal of the Korean GEO-environmental Society
• /
• v.22 no.12
• /
• pp.71-77
• /
• 2021

As the number of using road in Korea increases, maintenance costs and traffic congestion costs also increase. In order to reduce maintenance cost and time of road, existing long - lived modular road system has been proposed. In this study, the design and performance evaluation of the adaptable support module, which is the substructure of the proposed system, was performed. Two adaptable (Cross-Beam type)support modules were designed and fabricated to determine the load and shape. A adaptable support module was constructed and a static load test was carried out to select the type with better performance. As a result of the load test, the maximum value of the measured earth pressure difference is about 158 kPa and the settlement amount is about 0.032 mm in the two types of adaptable support modules. Based on these results, it is concluded that the performance of the adaptable support module of the bottom curved cross-beam type is better.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.2
• /
• pp.25-30
• /
• 2023

The high-strength rockfall net developed in this study is to replace the fallout prevention net method using PVC coating net made of core wire thickness 3.2 mm and tensile strength 290-540 MPa class steel wire. General PVC coating net have low performance, and in the event of falling rocks or surface loss, they cannot withstand the load and are torn, which rather adds to the damage. Developed rockfall net was manufactured using steel wires with a core wire thickness of 2.8 to 3.2 mm and a tensile strength of 1,000 to 2,000 MPa. Test method was referred to the international standard Steel wire rope net panels and rolls-Definitions and specifications (ISO 17746:2016), and was conducted in accordance with the provisions of the punching test. Through indoor punching tests, the load-displacement curves of the general PVC coating network and the developed high-strength capture net (1,000 and 2,000 MPa) were compared, and the maximum Pull-out load was analyzed to be improved by 324.47% (2,000 MPa high-strength net).

• Journal of the Korean Geotechnical Society
• /
• v.22 no.8
• /
• pp.89-97
• /
• 2006

This study investigated the effect of relative density on the thickness of shear zone. Digital image processing was used to measure the thickness of shear zone under plane strain conditions. A suitable epoxy resin was injected into the sample and the thickness of the shear zone was investigated. Four independent condition samples were prepared and the thickness of the shear zone was measured. The results indicated that the thickness of shear zone increases as the initial density of sample increases, and during the shear, the void ratios of the shear zone were changed, but the thickness of shear zone was not changed. In addition, the result of measurement of the thickness showed that the thickness of shear zone was almost fixed before critical state, but beyond critical state, the thickness of shear zone sharply increases as relative density increases.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.8
• /
• pp.13-24
• /
• 2006

A site investigation has been performed for bridge abutments constructed on soft ground, which are deformed laterally by backfill. As the result from the evaluation of lateral movement in bridge abutment, the foundation piles were not considered as the passive pile at the design stage and the period for soft ground improvement was not proper. In order to prevent lateral movement of bridge abutment, the pile slab is proposed as a countermeasure. This method can effectively prevent the lateral flow of soft ground, since the overburden surcharge due to backfill on soft ground would be effectively delivered to bedrock through the piles in soft ground. The instrumentation system is designed and installed to investigate the behavior of bridge abutment on soft ground reinforced by pile slab. The instrumentation results show that pile slab effectively resists to the lateral movement of bridge abutment due to backfill. Also, the surcharge loads due to backfill are transmitted to the bedrock through piles. It confirms that the pile slab effectively resists to the lateral movement of bridge abutment due to backfill and the applied design method is reasonable.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.10
• /
• pp.121-129
• /
• 2006

Stone column is one of the ground improvement systems which is being used for accelerating consolidation and increasing bearing capacity for settlement sensitive structures like load embankments, bridge abutments, oil storage tanks etc. The effects of this method are enhancement of ground bearing capacity, reduction of settlement, prevention of liquefaction and prevention of lateral ground movement. Recently, geosynthetic reinforced (encased) stone column approach has been developed to improve its load carrying capacity through increasing confinement effect. Although such a concept has successfully been applied in practice, fundamentals of the method have not been fully explored. This paper presents the results of an investigation on the bearing capacity and failure mechanism of geogrid-encased stone column by model tests. The results of the analyses indicated improved bearing capacity of the geogrid reinforced stone column method over the conventional strone column method with no encasing.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.8
• /
• pp.107-116
• /
• 2007

Load and Resistance Factor Design (LRFD) method is being used increasingly in geotechnical design practice worldwide, and is expected to completely replace the current Allowable Stress Design (ASD) method in the near future. LRFD has advantages over ASD in that it allows the design of superstructures and substructures at a consistent reliable level by quantification of failure probability based on reliability analysis. At present, resistance factors for cast-in-place piles embedded in rocks are determined by AASHTO only for the intact rock conditions. In Korea, however, most of the bedrocks in which piles are embedded are heavily weathered. Thus, this study will try to determine the resistance factors of heavily weathered rocks (so-called intermediate goo-materials). To this aim, reliability analysis was carried out to evaluate the resistance factors of cast-in-place piles embedded in intermediate geo-materials in Korea. Pile load test data of 21 cast-in-place piles of 4 construction sites were used for the analysis. Depending on the method which calculates the pile capacities, the resulting resistance factors ranged between 0.1 and 0.6.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.2A
• /
• pp.155-162
• /
• 2009

This paper deals with the strongest beams with the solid regular polygon cross-section, whose volumes are always held constant. The differential equation of the elastic deflection curve of such beam subjected to the concentrated and trapezoidal distributed loads are derived and solved numerically. The Runge-Kutta method and shooting method are used to integrate the differential equation and to determine the unknown initial boundary condition of the given beam. In the numerical examples, the simple beams are considered as the end constraint and also, the linear, parabolic and sinusoidal tapers are considered as the shape function of cross sectional depth. As the numerical results, the configurations, i.e. section ratios, of the strongest beams are determined by reading the section ratios from the numerical data related with the static behaviors, under which static maximum behaviors become to be minimum.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.1D
• /
• pp.89-94
• /
• 2006

Premature failures in pavements are frequently reported due to rapid increasement in traffic volume, heavy vehicles, and high temperature in the summer. Based on this concept in mind, Korea Highway Corporation established the Test Road Operation Center to estimate the pavement performance. To evaluate the pavement performance effectively using the field data, wandering is an important topic in pavement analysis. In this study, portable wandering system was developed and analyzed to investigate the pavement responses due to the dynamic truck passes, and analyzed the wandering to dynamic load test. The test results revealed that the advantages of laser devices were noticeable compare to the other measuring ones. To understand the behavioral characteristics of pavements using the wandering measurement devices, dynamic truck tests were conducted in the field. Test results showed that the effects of wandering on asphalt pavement were significant. The data analysis using this wandering effect is considered as an important tool in performance analysis of asphalt concrete pavement.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.3A
• /
• pp.497-512
• /
• 2006

In this paper, a simple but effective analysis procedure to estimate seismic capacities of multi-span continuous bridge structures is proposed on the basis of modal pushover analysis considering all the dynamic modes of structure. Unlike previous studies, the proposed method eliminates the coupling effects induced from the direct application of modal decomposition by introducing an identical stiffness ratio and an approximate elastic deformed shape. Moreover, in addition to these two introductions, the use of an appropriate distributed load {P} makes it possible to predict the dynamic responses for all kinds of bridge structures through a simpler analysis procedure. Finally, in order to establish the validity and applicability of the proposed method, correlation studies between rigorous nonlinear time history analysis and the proposed method are conducted for multi-span continuous bridges.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.3
• /
• pp.255-264
• /
• 2009

This paper concerns the behavior of 2-Arch tunnel constructed under various conditions. A 2-Arch tunnel section adopted in a subway tunnel construction site is considered in this study. A calibrated 3D finite element model was adopted to conduct parametric studies on a variety of construction scenarios including lagged distance between left and right tunnels, overburden, and geological condition. The results of analyses were examined in terms of crown settlement, shotcrete lining stress, and load on center column in relation to the lagged distance, cover depth, and the ground condition. The results indicate that the shotcrete lining stress and the center pillar load are more influenced by the second tunnel excavation than the tunnel deformation. Also shown is that a greater lagged distance is required to minimize the interaction between two tunnels when the ground condition becomes weaker. Fundamental mechanisms of 2-arch tunnel were also discussed based on the results.