• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.31-32
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• 2018

Lately, cement mixed siliceous powder waterproofing coating has been used as a waterproofing material in the wet environment condition of an underground concrete structure. Underground is exposed to environmental influences such as pressure of ground water, pressure of soil. However, the quality standard for pressure (water pressure, earth pressure) is not specified in the specification of the cement mixed siliceous powder waterproofing coating. Therefore, in this study, the permeability test was carried out based on the assumption that the durability should be verified in consideration of the environmental aspects of the material in actual field. As a result of the test, the permeability was generated from the inorganic single type material, but it was caused by the sealing failure and the test error, and the permeability was not generated in most of the materials. The results of this study will be analyzed by reviewing the physical properties of the material, and the research direction will be resumed.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1205-1210
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• 2004

Cracks in the underground structures are mainly observed due to internal ununiformity of thermal stresses or restraint of structural movement in associate with rapid temperature gradient. Especially, thermal cracks are known to occur easily in a massive structure, but possibility of these depend on the amount of cement applied and ratio of span to height of the structure even though the thickness is less than specification‘s. Thus, this study aims at how to control thermal cracks in a massive subway structure and figures out an optimized construction method and procedure. As results of parametric study for length, height and outer temperature for concrete placement, it is found that hydration heats were not affected by both length and height of concrete placement but thermal stresses were greatly dependent. Most effective ways of controling thermal cracks were to fit a proper ratio of length to height of concrete placement and to decrease temperature of concrete placement as much as possible.

• Advances in concrete construction
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• v.15 no.6
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• pp.377-389
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• 2023

In this study, an improved modular arch system with the lower arch space composed of a precast arch block and an outrigger was proposed as an underground culvert, and its applicability and structural behaviors were confirmed. This modular arch culvert structure with vertical walls was designed using precast blocks and by adjusting the placement spacing of concrete blocks to the upper part form an arch shape and the lower part form a vertical wall shape, based on previously researched modular arch systems. Owing to the vertical wall of the proposed modular arch system, it is possible to secure a load-carrying capacity and an arch space that can sufficiently resist the earth pressure generated from the backfill soil and loading on the arch system. To verify the structural characteristics, and applicability of the proposed modular precast arch culvert structure, a full-scale modular culvert specimen was fabricated, and a loading test was conducted. By examining its construction process and loading test results, the applicability and constructability of the proposed structure were analyzed along with its structural characteristics. In addition, its the structural predictability and safety for the applicability were evaluated by comparing the construction process and loading test results with the FE analysis results.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.87-98
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• 2007

For the quick rehabilitation of a fire-damaged tunnel structure, it is the most important procedure to investigate the fire-induced damaged zone rapidly. This study aims to propose a new drilling resistance testing method by which mechanical properties of tunnel concrete lining altered by high temperature can be estimated easily and continuously. Especially, it alms to derive the relationships to estimate mechanical properties of mortar and concrete materials from drilling parameters. To obtain the optimum testing condition, a series of drilling resistance tests were carried out for mortar specimens. When the rotation per minute of drill bit, tile penetration rate and the bit diameter were 1,300 rpm, 1.40 mm/sec, and 10 mm respectively, the deviation of measured drilling resistance forces was minimal. Under the optimum testing condition, the relationships between drilling resistance and mechanical properties of mortar specimens were shown to be very favorable. The concept of replacing a mean value of resistance farces measured during drilling with the resistance energy was proposed to consider the effects of randomly distributed aggregates inside a concrete material on drilling resistance. When the concept was applied to concrete materials, a favorable relationship between actual compressive strength and drilling resistance energy was also successfully derived.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.793-800
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• 2000

This is a double Composite Waterproofing Method of Mastic Asphalt Film ad Sheet(MAS) on concrete structure and its working method. MAS is characterized as having excellent strength and adhesion to concrete. To make a good waterproofing system, it is needed the information on the performance tests. The designer should choose a material that can be applied in almost all conditions. During their service life, Underground spaces have been keeping to dry enough for habitable or utilitarian used. This method is of use for waterproofness in various spaces.

• Magazine of the Korea Concrete Institute
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• v.20 no.4
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• pp.57-62
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• 2008

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.77-81
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• 2004

The massive structures are not free to move with vibration, differential settlement, thermal stresses because, construction and expansion joint, crack etc., can be large enough to cause leakage as deformation of waterproofing. It has been depended on the test method of tensile/tear strength which is waterproofing performance as behavior of concrete structure crack. However, not to practically confirm the creep applied to concrete surface, even waterproofing membrane have more performance than definite strength and elasticity. Therefore, in this study will focus on the test method to consider a resistance performance about loose adhesion and deformation of waterproofing and behavior of concrete structure as construction/expansion joint, crack. Performance test method on the influence as behavior of concrete structure crack is to choose waterproofing materials and construction method which possible to confront with behavior of 50mm crack in the atmosphere and low temperature. Examine the deformation of waterproofing membrane and loose adhesion which can occur to structure in general job site, suggest standard testing method to analyze correlation waterproofing membrane and structure with 5-types of materials used in this study, such as Adhesion membrane and sheet complex, sheet and urethane complex, self-adhesive sheet, spray poly-urea, spray membrane of rubberized Asphalt.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.49-56
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• 2001

The techniques to make assessment of the structural integrity of underground structures include Infrared thermagraphy, GPR using the reflection of the electromagnetic wave, ultrasonic test, seismic methods using the propagation of elastic wave, and etc These methods have pros and cons in the assessment of the structural integrity in the complex environment of the underground structure, so that a single method alone is not enough to evaluate parameters required for the assessment. In this study, a new seismic method was proposed to improve the existing methods and to provide an additional information like stiffness of concrete. The proposed method combines the advantages of the modified impact-echo test and the SASW method. To verify the validity of the proposed method, a large scale model of a tunnel concrete liner was built and the proposed method was applied to the center of the model and also to the corner of the model which has several distinct reflection boundaries.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.95-102
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• 2013

PURPOSES: The existing method evaluating the existence of the hollows in concrete pavement does not consider the stiffness of pavement. In addition, the method uses unreasonable logic judging the hollow existence by the deflection caused by zero loading. In this study, the deflection of slab corner due to heavy weight deflectometer (HWD) was measured in concrete pavement sections where underground structures are located causing the hollows around them. METHODS: The modulus of subgrade reaction obtained by comparing the actual deflection of slab to the result of finite element analysis was calibrated into the composite modulus of subgrade reaction. The radius of relative stiffness was calculated, and the relationship between the ratio of HWD load to the radius of relative stiffness and the slab deflection was expressed as the curve of secondary degree. RESULTS: The trends of the model coefficients showing width and maximum value of the curve of secondary degree were analyzed by categorizing the pavement sections into three groups : hollows exist, additional investigation is necessary, and hollows do not exist. CONCLUSIONS: The results analyzed by the method developed in this study was compared to the results analyzed by existing method. The model developed in this study will be verified by analyzing the data obtained in other sections with different pavement structure and materials.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.44-45
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• 2017

There are various national standards designed to test the physical properties of waterproofing materials for the respective countries based on each of their environmental parameters, variables and requirements. The problems of these standard systems can be outlined in the following: (1) there are too many test methods and criteria to satisfy in order assess one waterproofing membrane system, and (2) there is currently no known method to compile the separate testing results to provide a comprehensive report on waterproofing system durability. This paper outlines and compares the performance testing results of various types of asphalt waterproofing membrane systems and discusses the potentials of a complex environmental deterioration analysis method.