• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.93-105
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• 2021

In this study, we evaluated the effect of soil fine contents on the formation of underground cavities and ground cave-ins induced by damaged sewer pipes. Simulating the domestic rainfall conditions and ground conditions, model tests were performed under three different fine particle contents conditions (7.5%, 15%, and 25%). By repeating the groundwater supply and drainage twice, ground settlement and the amount of discharged soil were obtained. Also, digital images were taken at regular time intervals during the model tests, and internal displacement and deformation were measured using PIV technique. As the cycles were repeated, the soil with high fine content showed greater resistance to the formation of underground cavities. The ground cave-ins, identified by the collapse of the surface, occurred only when the fine particle content was 15%. It is presumed to be due to the suffusion phenomenon; further study was needed to investigate the effect of fine particle contents on the suffusion phenomenon and associated changes of soil strength.

• Journal of the speleological society of Korea
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• v.41 no.1
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• pp.27-33
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• 1994

Tourists visiting Korea's resort island of Cheju-do often hear the legend of how the founders of the island's three original clans emerged from holes in the ground. They can even visit the site where three depressions remain in the ground -- one each for the Ko, Yang and Pu families.(omitted)

• Journal of the Speleological Society of Korea
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• no.67
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• pp.11-20
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• 2005

The envirronment of Gosu cave and distribution of inhabitant were surveyed every month from 2002, April to 2003, march. in Gosu Cave, average temperature in summer was $16^{circ}C$ and in winter $14^{circ}C$. Average humidity in summer was $85\%$ and in winter $90\%$. At the entranceof cave in the site 1, trogloxenes:4 species were observed. Troglophiles: Diestrammena japanica was a large population. inside of cave in the site 2 and in the middle Part of the site 3, troglobites:4 species, troglophiles:2 species, trogoxenes: Rhinoiophus ferrumeqinum korai, skleroprotopus laticoxalis longus were observed. Galloisiana sp. were observed on the ground of the Sindong in the site 4, Pseudocrangonyx asiaticus were obserued in the water of yongsu valley. Troglobites have to be preserve as cave animals living in the darkness for a long time.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.399-406
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• 1999

Recently, the construction of the several highway bridges in the karst area have encountered severe problems associated with cavities and sinkholes. To solve this problems, it is important to understand the distribution characteristics of cavities in the construction site on limestone area. This paper briefly describes the different types, the distribution control factors and the infill sediment types of lime-cavities in the study area, bridge site in the karst area and propose the effective method of survey design. Cavity system may be divided into two main groups, 1)'slot and cave system'and 2)'sinkhole and cave system'. And the shape, the size and the distribution pattern of cavity are controlled by three main factors - rock type, geological structure and ground water condition. Additionally, infill sediment may be considered as one of the important design factors for foundation design and divided into four types by sediment properties. There are geophysical thechnics and geologic survey and drilling test, etc. by the survey method to interpretate characteristics of cavity system, and this methods are optimally designed at the site investigation stage.

• Tunnel and Underground Space
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• v.27 no.6
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• pp.387-392
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• 2017

Recently, road cave-ins, also referred to as ground sinking, have become a problem in urban environments. Public utility facilities such as sewage pipelines, communications pipes, gas pipes, power cables, and other types of underground structures are installed below the roads. It was reported that cave-ins are caused by the aging and lack of proper maintenance of underground facilities, as well as by construction problems. A road cave-in is first initiated by the formation of cavities typically induced by the breakage of underground pipelines. The cavities then grow and reach the base of the pavement. The traffic load applied at the surface of the roads causes an abrupt plastic deformation. This type of accident can be considered as a type of disaster. A road cave-in can threaten both human safety and the economy. It may even result in the loss of human life. In the city of Seoul, efforts to prevent damage before cave-ins occur have been prioritized, through a method of discovering and repairing joints through the 3D GPR survey.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.593-600
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• 2000

Most of ground investigations can be grasped geological distribution which like rock name, geological structure, soil condition, underwater condition, land slide, ground cave-in, ground collapse by geological survey. But geological survey is limited to part region geological structure, not wide region. Therefore, Image Processing Method must need to grasp wide region geological structure. The object of this research is presented analysis data of geotechnical engineering in first step investigation.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.59-68
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• 2017

PURPOSES : The objective of this study is to evaluate the potential risk level of road cave-ins due to subsurface cavities based on the deflection basin measured with falling weight deflectometer (FWD) tests. METHODS: Ground penetrating radar (GPR) tests were conducted to detect road cavities. Then FWD tests were conducted on 13 pavement test sections with and without a cavity. FWD deflections and a deflection ratio was used to evaluate the effect of geometry of the cavity and pavement for road cave-in potentials. RESULTS : FWD deflection of cavity sections measured at 60 cm or a closer offset distance to a loading center were 50% greater than more robust sections. The average deflection ratio of the cavity sections to robust sections were 1.78 for high risk level cavities, 1.51 for medium risk level cavities, and 1.16 for low risk level cavities. The relative remaining service life of pavement with a cavity evaluated with an surface curvature index (SCI) was 8.1% for the high level, 21.8% for the medium level, and 89.8% compared to pavement without a cavity. CONCLUSIONS : FWD tests can be applied to detect a subsurface cavity by comparing FWD deflections with and without a cavity measured at 60 cm or a closer offset distance to loading center. In addition, the relative remaining service life of cavity sections based on the SCI can used to evaluate road cave-in potentials.

• Journal of the Speleological Society of Korea
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• no.66
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• pp.45-57
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• 2005

This Paper is a study on the duality of speleothem that appeared in 'Hyeob Jae Cave' which is designated as the natural monumen. No.236. It is located at Hyeob Jae Ri, Hanrim Eub, Bug Je-ju Gun, Je-judo. The findings are as follows. 1. The distribution range of the shelly sand which has maximum thickness of $10m{\pm}$ and average of $3m{\pm}$ was $3.2m^2$. 2. The desert hollow acted to promote the speleothem deposits in the lava tunnel with lava mound formed by lavapilz and artificial breaksand wall. 3. The main component of the pseudo limestone cavern was carbonate Calcium from shelly sand. And the deposition of speleothem in the Cave was accelerated after the volcanic erupsion of Biyang island in 1002. A.D. 4. The secondary depositions of Calcite recognized as speleothem up to now it can be used for the pseudo karst in general. 5. It seems that the variety of the cave deposits is decided depending upon the geology, land form, climate, vegetations and the structural environmental factors. 6. It seems that the wondering development of accretionary deposits caused by encrusting has a close relation with intermittent seepage of ground water. 7. Finally, we can acknowledge the coexistent duality of speleothem by shelly sand along with the joint and the lava stalactites formed at the same time with the lava tunnel on the ceiling where there was no seepage.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.165-172
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• 2002

We presents an hazard zonation mapping technique in karst terrain and its assessment. From the detailed engineering geological mapping. Controlling factors of sink hole and limestone cave formation were discussed and 4 main hazard factors affecting hazard potential are identified as follows: prerequisite hazard factor(distributions of pre-existing sink holes and cavities), geomorphological hazard factors(slope gradient, vegetation, and drainage pattern etc.) geological hazard factors(lithology, fracture patterns and geological structures etc.) and hydraulic conditions(hydraulic head, annual fluctuation of ground water table and composition of g/w water). From the construction of hazard zonation map along the Jecheon-Maepo area, and vertical cross-sectional hazard zonations specific tunnel site we suggest hazard zonation rating systems.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.310-320
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• 1998

This study is aimed at identifying the socio-economic effects of storage of ginger in artificial caves. The gingers stored in artificial caves in Seochun, 12 sampled areas, were surveyed to get information on the socio-economic effects. The surveyed data were processed by TSP, Qbasic and B/C Ratio computer programs and analyzed the decision making criteria such as B/C ratio, NPV and IRR. The socio-economic effects of the storages of the gingers are as follows. 1. The storage benefits per ton was showed as 184,050won. 2. Considering 10% of the opportunity cost of capital, the uper limits of investments for the cave storages was analyzed as 6,784 thousand won for ginger. 3. The investment of the natural cave storages was revealed economically feasible considering the decision making criteria as B/C ratio = 1.33, NPV = 35.059 thousand won and IRR = more than 100%. The other socio-economic effects of the ginger storages was expected as ; 1. The cave storages will contribute to increase consumer's and producer's welfare through the control of supply and demand and price stability. 2. Long-term storage of ginger without damaging quality and grades will be made on account of the storage conditions as relatively low temperature, high humidity and indifferent affects from the outside climate. 3. Utilization of the underground space, the caves, for storage will maximize the land use and the sustainable environment considering the mountainous area, two third of the total national land area. 4. Construction costs of the underground storage facilities as caves are cheaper than the ground storage facilities by 15 to 20% in general. In conclusion, the underground space like natural and artificial caves are considered the most suitable for storage of ginger on account of the storage conditions as temperature, humidity and blocking the sun light. Accordingly a study on convenient utilization of new development of artificial caves should be made considering transportation and input-output of the farms. Financial support of the government should be institutionally rearranged for the successful implementation of storing farm products like ginger in natural and man-made caves.