• Title/Summary/Keyword: the evaluation of tunnel safety

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Evaluation of Hydrogeological Characteristics of Deep-Depth Rock Aquifer in Volcanic Rock Area (화산암 지역 고심도 암반대수층 수리지질특성 평가)

  • Hangbok Lee;Chan Park;Junhyung Choi;Dae-Sung Cheon;Eui-Seob Park
    • Tunnel and Underground Space
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    • v.34 no.3
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    • pp.231-247
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    • 2024
  • In the field of high-level radioactive waste disposal targeting deep rock environments, hydraulic characteristic information serves as the most important key factor in selecting relevant disposal sites, detailed design of disposal facilities, derivation of optimal construction plans, and safety evaluation during operation. Since various rock types are mixed and distributed in a small area in Korea, it is important to conduct preliminary work to analyze the hydrogeological characteristics of rock aquifers for various rock types and compile the resulting data into a database. In this paper, we obtained hydraulic conductivity data, which is the most representative field hydraulic characteristic of a high-depth volcanic bedrock aquifer, and also analyzed and evaluated the field data. To acquire field data, we used a high-performance hydraulic testing system developed in-house and applied standardized test methods and investigation procedures. In the process of hydraulic characteristic data analysis, hydraulic conductivity values were obtained for each depth, and the pattern of groundwater flow through permeable rock joints located in the test section was also evaluated. It is expected that the series of data acquisition methods, procedures, and analysis results proposed in this report can be used to build a database of hydraulic characteristics data for high-depth rock aquifers in Korea. In addition, it is expected that it will play a role in improving technical know-how to be applied to research on hydraulic characteristic according to various bedrock types in the future.

Factor Analysis and LISREL Model Development for Landscape Estimation on The Road Cutting Slope Area (도로절토사면(절개면)의 경관평가를 위한 요인분석 및 LISREL 모형구축)

  • 지길용;박일동;임성빈;금기정
    • Journal of Korean Society of Transportation
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    • v.21 no.2
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    • pp.33-43
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    • 2003
  • In South Korea, about 74% of total area is mountainous terrain It is therefore inevitable to make tunnel or cutting slope for road construction. According to a related survey, approximately 2,400 sites of cutting slopes were found from 24 different routes of roadway which is overall 900 km long, implying 2.7 slopes per 1km of roadway on average. Even though safety matter such as the slope failure prevention would be the most important consideration for the construction of cutting slopeslandscape of sloped face is nowadays becoming another important factor due to the growing demand for the driver-friendly road environment Various construction methods which attain this goal should therefore be considered in the design stage of the roadway. The objective of this study is to identify important factors in landscape of sloped-cut roadway using factor analysis. For this, 10 main treatment methods of sloped-cut fact were analyzed. This study employed the LISREL(structural analysis of common variance) model in order to capture the qualitative characteristics of the slope-cut road and examine the relationship between the suey error and the variable(s). As a result, more reasonable landscape evaluation model for the road design and construction was proposed.

The Evaluation on Applicability of Leakage-prevented Sealing Packer Out of Grouted Rockbolt Hole (록볼트 그라우팅 시 역류방지용 밀봉 패커의 적용성 평가)

  • Yang, Taeseon;Kim, Jichang;Jeong, Jongki;Yoo, Dongho;Choi, HakYun;Baek, Seungcheol
    • Journal of the Korean GEO-environmental Society
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    • v.17 no.11
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    • pp.15-21
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    • 2016
  • Nowadays, some studies have been performed for rockbolt method widely used in Korea. To make large slopes, tunnels or rock structures stable, supporting systems, such as anchor bolt, rock bolt which are developed recently, are commonly used. In this study, laboratory pullout tests were carried out to compare the characteristics of rock bolt that is most widely used with ones of rock bolt by newly developed circular model testers. Re-pullout test for the rock bolt in which loading and unloading cycles are repeated several times showed that the maximum pullout load is almost constant irrespective of the number of loading cycles, which may be due to no failure between rock bolt and filler that is filled with soils and concrete as a substitute. A development of rock bolt fillers as supporters using to protect people in tunnels and slopes is reviewed as a probable man-made hazard after excavation works. The functions of the grouted rock bolts associated with reinforcement effects also should be assessed in this study, which develop the sealing apparatus preventing from overflowing mortar out of a rock bolt hole for securing safety in the tunnel and slopes in order to secure stability named the sealing packer.

Study on Moye's Method for Analysis of Constant-Head Tests Conducted in Crystalline Rock (결정질 암반에서 Moye 방법을 이용한 정압시험의 해석에 대한 고찰)

  • Kyung-Woo Park;Byeong-Hak Park;Sung-Hoon Ji;Kang-Kun Lee
    • The Journal of Engineering Geology
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    • v.33 no.4
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    • pp.519-530
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    • 2023
  • Moye's analytical solution was examined as a method for constant-head tests under steady-state conditions, and results were compared with transient-state analyses in in situ hydraulic tests. The sensitivity of hydraulic conductivities calculated using Moye's method increased with the length of the test section, which should be as large as possible under test conditions. Particularly in low-permeability media with less than 10-8 m/sec of hydraulic conductivity, hydraulic conductivity is lower than that under transient-state conditions and can be recalculated by adjusting the boundary between radial and spherical flow assumed in Moye's equation. Constant-head tests performed in the research borehole at the KAERI Underground Research Tunnel (KURT) indicated that transmissivities derived from the constant-head withdrawal test under transient-state conditions in low-permeability media were higher than those derived from steady-state tests, likely because the groundwater flow boundary was smaller than the "half of the test-section length"assumed by Moye's equation. When interpreting constant-head test results for crystalline rock, the hydrogeological properties of the medium may be better understood by considering assumed conditions accompanying analysis of the steady-state condition and comparing them with results for the transient-state analysis, rather than simply assuming properties based on steady-state analyses.

Estimation Method of Key Block Size on a Large Scale Rock Slope by Simulation of 3-D Rock Joint System (3차원 절리계 모사를 통한 대규모 암반비탈면 파괴블록크기 추정방법)

  • Kim, Dong-Hee;Jung, Hyuk-Il;Kim, Seok-Ki;Lee, Woo-Jin;Ryu, Dong-Woo
    • Journal of the Korean Geotechnical Society
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    • v.23 no.10
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    • pp.97-107
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    • 2007
  • Accurate evaluation of the slope stability by assuming failure block as the entire slope is considered to be apposite for the small scale slope, whereas it is not the case for the large scale slope. Hence, appropriate estimation of a failure block size is required since the safety factor and the joint strength parameters are the function of the failure block size. In this paper, the size of failure block was investigated by generating 3-dimensional rock joint system based on statistical data of joints obtained from research slope, such as joint orientation, spacing and 3-dimensional joint intensity. The result indicates that 33 potential failure blocks exist in research slope, as large as 1.4 meters at least and 38.7 meters at most, and average block height is 15.2 meters. In addition, the data obtained from 3 dimensional joint system were directly applicable to the probability analysis and 2 and 3 dimensional discontinuity analysis.

Stability Analysis of Open Pit Slopes in the Pasir Coal Field, Indonesia (인도네시아 Pasir 탄전에서의 노천채탄장 사면의 안정성 해석)

  • 정소걸;선우춘;한공창;신희순;박연준
    • Tunnel and Underground Space
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    • v.10 no.3
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    • pp.430-440
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    • 2000
  • A series of studies such as geological logging data analysis, detailed geological survey, rock mass evaluation, in-situ and laboratory tests, rock strength and mechanical properties of the rock were concerned. The stability of the slope were carried out inorder to design the pit slope and individual benches using the stereographic projection analysis and numerical methods in Roto Pit of Pasir coal field. The bedding plane was one of the major discontinuities in the Roto Pit and the dip of which is about 60$^{\circ}$ in the northern part and 83$^{\circ}$ in the southern part. The dip of bedding becomes steeper from north to south. The plane and toppling failures are presented in many slopes. In laboratory test the average uniaxial compressive strength of mudstone was 9MPa and that of weak sandstone was 10MPa. In-situ test showed that the rocks of Roto north mining area are mostly weak enough to be classified in grade from R2(weak) to R3(medium strong weak) and the coal is classified in grades from R1(Very weak) to R2(Weak). The detailed stability analysis were carried out on 4 areas of Roto north (east, west, south and north), and 2 areas of Roto south(east and west). In this paper, the minimum factor of safety was set to 1.2 which is a general criterion for open pit mines. Using the stereographic projection analysis and the limit equilibrium method, slope angles were calculated as 30∼36$^{\circ}$ for a factor of safety greater than 1.2. Then these results were re-evaluated by numerical analysis using FLAC. The final slope angles were determined by rational described above. A final slope of 34 degrees can guarantee the stability for the eastern part of the Roto north area, 33 degrees for the western part, 35 degrees for the northern part and 35 degrees for the southern part. For the Roto south area, 36 degrees was suggested for both sides of the pit. Once the pit slope is designed based on the stability analysis and the safety measures, the stability of slope should be checked periodically during the mining operations. Because the slope face will be exposed long time to the rain fall, a study such aspreventive measures against weathering and erosion is highly recommended to be implemented.

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Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.