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저토피부 암거상부 포장의 동상피해 예방을 위한 단면설계
서영국 한국도로학회 2007 한국도로학회논문집 Vol.9 No.3
During the whole month of December in 2005, Korea experienced both heavy snowfall and freezing temperature in southeast regions, which had caused frost related damages to many pavements laid on top of box culverts. In-situ observation revealed that the formation of ice lenses in subgrade and subsequent unbound layers led to upward heaving and transverse cracks in concrete and asphalt pavements. This has affected the long-term performance of pavements, as well as has threatened drivers' safety for a while. Recently, Korea Expressway Corporation has proposed a design guide to better protect newly constructed unbound pavement layers over culverts from frost heave. A trench drainage system has been selected to effectively draw off water and to alleviate pore-water pressure in soils during the coldest season. This paper presents experimental and analytical backgrounds behind this new design guide. Soil specimens retrieved from the sites are tested to quantify clay content and to estimate the permeability of subgrade. A 2-D ground seepage analysis has been conducted to better understand the changes in pore water pressures as a function of grain size. Finally, an optimum size of trench drainage is determined based on numerical analysis and workability in the field.
서영국 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.3
For the acceptance of, and payment for, road pavements, a Percent within Limit (PWL) specification was developed and applied to highway asphalt overlays for the first time in Korea. This paper deals with this unprecedented attempt along with some practical concerns raised by both the contractors and the agencies. Specification development started with defining the size of a LOT that was divided into three to six sub-lots depending on the construction variables. Five Acceptance Quality Characteristics (AQCs) that are considered to affect pavement’s performance were chosen to implement the specification, and current highway QC/QA manuals were utilized to set the tolerances and allowable limits of AQCs. This study proposed three scenarios with different number of AQCs to calculate the composite pay factors, and their impacts on the payments were compared. As a result, it was found that a scenario with five AQCs was deemed the most advantageous to the contractor. However, if variances (standard deviations) of AQCs are large,the money penalties would be imposed on the contractors. Among test sites considered in this study, about 10% payment reductions were resulted primarily due to the scattering of AQCs. Finally, measured standard deviations were used to verify the tolerances of selected AQCs proposed in the PWL specification.
서영국,김성민,이재훈 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.5
This paper presents an operation scheme developed and implemented for Korea Expressway Corporation Test Road (KECTR), the first full scale road test facility in Korea. Several key elements such as field testing, data acquisition system, database, budget,schedule, and staff were identified as either technical or administrative aspect of operation. Some issues related to those elements were discussed based on operation at KECTR from 2002 to 2010. During this period, asphalt sections with thin layers were prematurely damaged under heavy highway traffic and high temperature, whereas most of data acquisition systems functioned properly. It was found that the lack of supporting staffs and a decreasing number of researchers have caused frequent delays during operation. Findings of this study may serve as practical guidelines for subsequent road test facilities.