• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.1-8
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• 2021

In urban areas, structures are installed deep underground in the lower part of the structure to utilize space. Therefore, a retaining wall is used to prevent earth pressure from the ground when constructing a structure. Due to the development of construction technology, retaining wall applied to excavation work are used to prevent danger such as falling rocks and landslides in temporary facilities when construction or retaining walls are installed. In general, the application of a retaining wall to a temporary facility during the embankment construction is the case of expanding an existing roads or railways. Therefore, it is necessary to study the retaining wall applied to the embankment construction such as the double-track site of the high-speed railway. In this study, two types of common one row H-pile retaining wall and two types of IER retaining wall were analyzed, and the stability of the retaining wall applied to the construction of double-track of the high-speed railway was analyzed. The earth retaining wall is a construction method that combines forced pile applied to the stabilization of the slope with the wall of the earth retaining wall. As a result of the analysis, the IER retaining wall had maximum lateral displacement of 19.0% compared to the type with H-plie installed only in the front while dynamic load was applied. In addition, the slower the speed of high-speed railway, the more displacement occurred, and the results show that more caution is needed when designing the ground in low-speed sections.

• Journal of the Korean Geotechnical Society
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• v.24 no.7
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• pp.61-73
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• 2008

Piles of a bridge pier are connected with the column through the pile cap (footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. Connection methods between pile heads and the pile cap are divided into two groups : rigid connections and hinge connections. Domestic design code has been specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However, some specifications prescribe that conservative results through investigations of both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which has high-quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) is unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the large diameter drilled shaft and the pile cap for Incheon Bridge which will be the longest bridge of Korea were investigated through the full modeling for rigid connection conditions.

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.1-9
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• 2014

Expansion of a roadway on a soft ground can cause settlement of the existing road during embankment construction due to the consolidation characteristics of the soft soil. Many problems related to construction and maintenance, such as deterioration of the surface, decreased safety, and decreased structural stability, could affect the existing road. This scenario is especially true if the roadway foundation is a deep thick soft ground. Therefore, engineers should carefully select a proper design based on the characteristics of the soil layer. In this study, the expansion of the second branch of the Namhae Expressway was selected as the target site because this expressway has been constructing on a soft soil layer approximately 50 m thick. The original design was reviewed, problems were discussed and alternative was proposed through value engineering job plan phases: investigation, speculation, evaluation, development and presentation. In addition, the proposed alternative was evaluated on cost, function and value improvement. Compared to the original design, the proposed alternative saved cost and improved the function and overall value.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.2
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• pp.141-148
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• 2016

The long-span bridges such as Incheon Bridge and Seohae Grand Bridge are located on the coastal region effected frequently by strong wind of typhoons. In order to ensure the wind-resistant performance of the structure, estimation of the proper design wind speed is very important. In this study, stochastic estimation of design wind speed incurred by typhoons is carried out. For this purpose, we first established probability distribution of climatological parameters such as central pressure depth, distance of closest approach, translation speed and heading to build statistical model of typhoons, which are employed in Monte Carlo simulation for hypothetical typhoons. Once a typhoon is generated with statistically justified parameters, wind speeds are estimated along its path using wind field model. Thousands of typhoons are generated and their peak wind speeds are utilized to establish the extreme wind speeds for different return period. The results are compared with design basic wind speeds in Korean Highway Bridge Design Code, showing that the present results agree well with similar studies while the existing code suggests higher design wind speed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.60-68
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• 2017

Since the bridge is the main facility of the road that is the core of the civil infrastructure, the bridge is constructed to ensure stability and serviceability during the traffic use. In order to secure the safety of bridges, evaluating the integrity of bridges at present is an important task in the maintenance work of bridges. In general, to evaluate the load carrying capacity of bridges, it is possible to confirm the superimposed behavior and symmetric behavior of bridges by estimating the lateral load distribution factor of the bridges through vehicle loading tests. However, in order to measure the lateral load distribution factor of a commonly used bridge, a static loading test is performed. There is a difficulty in traffic control. Therefore, in this study, the static displacement component of the bridge measured in the dynamic loading test and the ambient vibration test was extracted by using empirical mode decomposition technique. The lateral load distribution was estimated using the extracted static displacement component and compared with the lateral load distribution factor measured in the static loading test.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.121-139
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• 2023

Various tunnels such as road, subway, and railway are under construction and operation. Various types of linings are used for structural stability of tunnel structures, and concrete segment linings are mainly installed in TBM tunnel construction. In this paper, when a fire occurs in a tunnel, the impact on the concrete segment lining, which is the structure in the tunnel, and related standards, fire resistance evaluation and fire resistance method are investigated through literature review and related contents are presented. Through this, it is intended to provide an information for practitioners to secure the safety of concrete segment linings against tunnel fires.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.255-262
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• 2021

In this study, a jointless bridge that integrates the superstructure and abutment without installing an expansion joint was analyzed. An example of a jointless bridge that has been introduced in Korea since 2009. Owing to the short period of use and lack of experience in design, construction, and maintenance, there is insufficient information regarding the long-term behavior of jointless bridges. When analyzing numerous bridges, the numerical analysis model must maintain the numerical values used and ensure the convenience of model construction. In this study, sensitivity analysis was performed to select a numerical model for various types of jointless bridges using commercial finite element programs, MIDAS Civil and ABAQUS 2018. According to a solid element-based model, we analyzed the mean and maximum relative errors between structural models. Consequently, it was found that the beam element-based model exhibits a significantly small relative error in comparison to the shell element, where a relatively large error was recorded. Therefore, the optimal numerical analysis model, a practical model that maintains the similarity and precision of the displacement shape cause by relative error, was judged to be the most suitable for jointless bridges based on the shell element.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.87-96
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• 2015

Geosynthetics are widely used in different ways such as reinforcement of structures in road, railway, harbor and dam engineering, drainage, separation and erosion prevention. They are especially applied to reinforced retaining wall and slope or ground reinforcement. Recently, geosynthetics reinforced pile supported (GRPS) embankment was developed to improve stability and construability of embankments in railway engineering. Extension strains are usually measured by strain gauges adhered to geosynthetics to evaluate the stability of geosynthetics. However, the measurements are influenced by manufacturing method and stiffness of geosynthetics and also adherence of strain gauge. In this study, wide-width tensile strength tests were performed on three types of geosynthetics including geogrid, woven geotextile and non-woven geotextile. During the test, strains of geosynthetics were measured by both video extensometer and strain gauges adhered to the geosynthetics and the measured results were compared. Results show that the measured results by strain gauges have high reliability in case of large stiffness geosythetics like geogrid and woven geotextile, whereas they have very low reliability for small stiffness geosythetics like non-woven geotextile.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.397-419
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• 2012

The pressurizing support tunneling method has been developed that overcomes shortcomings of conventional trenchless methods and applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies higher pressure than the pressure relaxed by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through 3D numerical analyses. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long ramp tunnel that passes under ${\bigcirc}{\bigcirc}$ Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months which decreases construction time to 35% compared to conventional methods, and ground displacement was almost negligible.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.469-484
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• 2012

This study aims to numerically investigate ground movement around a square steel pipe as well as a group of square steel pipes induced by its and their ground penetration for trenchless construction of a concrete box. From numerical results, ground movement induced by a square steel pipe is much more dominantly governed by vertical displacement rather than horizontal displacement. Ground settlement induced by pipe penetration is much larger as the overburden becomes lower. The settlement is also shown to be slightly dependent upon the sequence of pipe penetration. More careful construction management is highly in demand during the penetration of upper pipes since their induced settlement occupies approximately 75 percent of total ground settlement after the whole construction of steel pipes.