• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.49-58
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• 2019

A study on the analysis of underground ground condition using 3D-GPR exploration was carried out in this paper. The test bed was constructed similar to the field, and the detection analysis was carried out for each depth of cavity and underground burial. Through this, we were able to know the permittivity of the ground by inversion, and we could confirm the depth of detection for the joint by accurate calculation. We confirmed the signal waveforms in the cavity under the road through 3D-GPR exploration, analyzed more quantitatively in subjective and empirical analysis. The subsidence and depth of the subsurface settlement can be observed through 3D-GPR survey, and ground condition change after the ground reinforcement can be confirmed through the exploration section.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.33-43
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• 2016

In order to analyze ground relaxation and cavity formation mechanism due to deteriorated sewer pipe, field test was carried out and a numerical assessments were compared with the field test results. An artificial underground cavity was intended using the ice block overlaying the buried pipe and confirmed that the cavity and relaxation of the surrounding ground were gradually formed as the ice block starts to melt down. Such mechanism was highly suspected to be involved with soil particle interlocking as a soil compaction was a typical process for the buried pipes. In exploring such mechanism numerically, commercially available DEM (Discrete Element Method) code PFC2D was used and the interlocking induced cavern behaviors were successfully simulated and compared with field test results by utilizing the clump logic imbedded in PFC code.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.104-110
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• 2016

To get the empirical data of GPR detection and to develop the image prosessing program of GPR detection data, GPR detection were proceed by the underground pipes and cavities buried in the Chamber. In the case of non pavement and asphalt pavement, water filled cavity that was buried in 0.7m depth was able to detection. But in the case of 1.0 m and 1.3 m buring depth, water filled cavity was not able to detection. In the case of non-reinforced and reinforced concrete pavement, it was difficult to detect the cavity caused by signal interference. GPRiPP programs was developed for image processing of the GPR detection data. The major processing algorithm were background removal, stacking and gain function. With proper image processing of gain function and background removal in GPRiPP program, it was showed that similar results can be obtained with conventional image processing program.

• Journal of the Society of Disaster Information
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• v.15 no.3
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• pp.391-401
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• 2019

Purpose: In this study, the location and history information of the cavity identified in the cavity exploration, such as repacking of the pavement, is not known. Therefore, it is to review the field applicability of RFID(Radio Frequency Identification) systems that enable anyone to accurately identify information. Method: Basic experiments were conducted for field applicability for cavity recognition distance, recognition and recognition rate, tag performance and tag type, reader interference, communication, underground burial impact, and duplicate recognition by RFID system. Results: As a result of the depth of tag and reader recognition, the electronic tag chips and readers applied in the basic experiment are judged to be effectively applicable in the field environment where the road cavity is located. Conclusion: The RFID tags for field application of the pavement management system store various information such as location and size of cavity, identification date, cause of occurrence, and surrounding underground facilities to maximize cavity management effect with a system that can be computerized and mobile utilization.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.2
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• pp.62-71
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• 2000

The abandoned mines causing settlement of the surface above and collapse of the cavities are the major influencing factor on the stability of the nearby underground structures. To prevent the harmful effect, the backfill methods are commonly applied to the cavities although the design criteria and the analysis method are not properly addressed in some cases. An approximate analytical method together with the numerical technique is considered in this study to simulate the gradual deterioration of the rock masses around the cavities and, therefore, the influential zone to the underground structures passing through the cavities. Also considered in this study is the backfill effect on the stability of the rock masses around the cavities. Specifically, the incomplete backfill effect is compared with that of the idealized backfill method by adopting elasto-plastic analysis involving a strain softening material law.

• Journal of the Korean earth science society
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• v.27 no.5
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• pp.539-547
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• 2006

The activity of the seismic wave propagation around the cavity is investigated for the exact inversion of the crosshole tomography data, in order to understand the possibility of the existence inside the underground cavity. It is found that the adequate frequency range for the tunnel investigation is about 2 kHz to 5 kHz, and the grid space should be set up to 1/10 of the wavelength. The propagation of the seismic wave near the cavity may go through or detour the cavity according to the seismic velocity inside the cavity. The detouring wave propagates with the seismic velocity of mother rock in spite of the velocity of inside of the cavity. The smaller the velocity difference is between the mother rock and cavity, the more frequent penetration of the seismic wave through the cavity appears.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.291-296
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• 2006

The aspect of wave propagation around cavity was investigated for the exact inversion of crosshole tomography data in order to understand the possibility of the existence of underground cavity. We found that the adequate frequency range for the tunnel investigation was about 2kHz to 5kHz, and the grid space was set up to 1/10 length of wavelength. The propagation of the seismic wave near the cavity may go through or detour the cavity according to the seismic velocity of inside of cavity. The detouring wave propagates with the seismic velocity of mother rock in spite of the velocity of inside of cavity. The smaller the velocity difference between the mother rock and cavity, the more frequent penetration of the seismic wave through the cavity was appeared.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.3
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• pp.195-205
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• 2002

Most tunnel damage such as cracks or leakage which exist in tunnel liner commonly, is caused by the cavities that exist behind the tunnel liner, through the tunnel safety inspections. These cavities were analysed to check if they affect the stability of tunnels. This study is on the development of the controlled low-strength and flowable filling material which an be applied to the cavity behind the tunnel lining. The backfilling material studied here is crushed sand and stone-dust which is in cake-state and is a by-product obtained in the producing process of aggregate. Varying the compound mixing ratio, laboratory tests of compression test and chemical analyses were carried out. In addition, the material was applied to an old tunnel for the performance assessment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.1013-1028
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• 2017

This paper presents key findings obtained from the numerical experiment investigating into the use of the cylindrical cavity for rock splitting operations. The stress and strain path analyses were carried out in order to provide a better insight into the crack formation. The principal stress analysis carried out along the crack line using the results obtained from these numerical analyses allowed the failure of the brittle material and the crack propagation to be investigated. This paper also suggested possible reasons for the change in crack direction observed during the rock splitting operations using the results obtained.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.334-343
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• 2023

Purpose: In this study, the cavity data found through ground cavity exploration was combined with underground facilities to derive a correlation, and the ground subsidence prediction map was verified based on the AI algorithm. Method: The study was conducted in three stages. The stage of data investigation and big data collection related to risk assessment. Data pre-processing steps for AI analysis. And it is the step of verifying the ground subsidence risk prediction map using the AI algorithm. Result: By analyzing the ground subsidence risk prediction map prepared, it was possible to confirm the distribution of risk grades in three stages of emergency, priority, and general for Busanjin-gu and Saha-gu. In addition, by arranging the predicted ground subsidence risk ratings for each section of the road route, it was confirmed that 3 out of 61 sections in Busanjin-gu and 7 out of 68 sections in Sahagu included roads with emergency ratings. Conclusion: Based on the verified ground subsidence risk prediction map, it is possible to provide citizens with a safe road environment by setting the exploration section according to the risk level and conducting investigation.