• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.3
• /
• pp.543-560
• /
• 2018

With the increased development in downtown underground space facilities that vertically cross under a railway at a shallow depth, the demand for non-open cut method is increasing. However, most construction sites still adopt the pipe roof method, where medium and large diameter steel pipes are pressed in to form a roof, enabling excavation of the inside space. Among the many factors that influence the loosening region and loads that occur while pressing in steel pipes, the size of the pipe has the largest impact, and this factor may correspond to the magnitude of load applied to the underground structure inside the steel pipe roof. The super equilibrium method (SEM) has been developed to minimize ground disturbance and loosening load, and uses small diameter pipes of approximately 114 mm instead of conventional medium and large diameter pipes. This small diameter steel pipe is called an SEM pile. After SEM piles are pressed in and the grouting reinforcement is constructed, a crossing structure is pressed in by using a hydraulic jack without ground subsidence or heaving. The SEM pile, which plays the role of timbering, is a fore-poling pile of approximately 5 m length that prevents ground collapse and supports surface load during excavation of toe part. The loosening region should be adequately calculated to estimate the spacing and construction length of the piles and stiffness of members. In this paper, we conducted a comparative analysis of calculations of loosening load that occurs during the press-in of SEM pile to obtain an optimal design of SEM. We analyzed the influence of factors in main theoretical and empirical formulas applied for calculating loosening regions, and carried out FEM analysis to see an appropriate loosening load to the SEM pile. In order to estimate the soil loosening caused by actual SEM-pile indentation and excavation, a steel pipe indentation reduction model test was conducted. Soil subsidence and soil loosening were investigated quantitatively according to soil/steel pipe (H/D).

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.4
• /
• pp.255-263
• /
• 2009

This study assessed the facility volume distribution for artificial reefs (ARs) deployed at the sea bottom in fishing grounds in the Busan Sea region, and estimated the efficient use of volume in the initial AR group. Analysis of the volume of AR facilities in the Busan Sea region indicated that the quantity and surface areas of deployed facilities varied greatly between 1997 and 2004. However, a rapid decrease in AR facility volume after 2003 indicated an increased use of different kinds of ARs, such as steel or ceramic ARs. And the results revealed that a total of 2,777 AR facilities were deployed in the Gijang sea region with a founding ratio of 89%; corresponding numbers for the Heaundae and Namgu sea region were 7,691 and 84.9%, and 905 and 96% for the cubic type of AR in the Saha and Gangseo sea regions. The analysis indicated that ARs deployed in the Busan sea region maintained a good conservation ratio of more than 85%. The loss in AR volume (approximately 15%) was due to subsidence, breakaway, and incomplete deployment.

• Journal of Acupuncture Research
• /
• v.33 no.2
• /
• pp.21-34
• /
• 2016

Objectives : The aim of the present study is to examine the effect and mechanism of Erycibae Caulis and Corydalis Tuber Pharmacopuncture (ECP) on a mouse model with collagen induced rheumatoid arthritis (CIA). Methods : We evaluated the Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Creatinine, and the Blood urea nitrogen (BUN) of serum to examine the safety of this study. In vivo, we compared the results of the non-treated group, the normal saline pharmacopuncture treated control group, the indomethacin treated group and the ECP group. We evaluated rheumatoid arthritis manifestation and the Rheumatoid Arthritis Index (AI). Also, immune cells in blood affected by ECP were evaluated by calculating the level of white blood cells (WBC), neutrophil, lympocytes and monocytes. Next, the level of Immunoglobulin M (IgM), Immunoglobulin G (IgG), Interleukin (IL)-$1{\beta}$, IL-6, IL-17, Tumor Necrosis Factor (TNF)-${\alpha}$ and Granulocyte-macrophage Stimulating Factor (GM-CSF)in serum were measured. We examined the imaging of cartilage degeneration using micro CT-arthrography of the hind paw. Additionally, we examined the effects of reducing bone volume (BV) ratio and bone surface/bone volume (BS/BV) ratio with 3D Micro-CT. Finally, we did a histopathologic examination analysis. Results : The absence of liver and kidney toxicity was evident. In vivo, edema of the joints of the ECP group decreased greatly in macroscopic observation. AI measurement of the ECP group also decreased significantly compared to the control group. The level of WBC, neutrophil, lympocytes, and monocytes in the blood decreased but there was no statistical significance of this data. IgM of the ECP group decreased significantly compared to the control group. IL-$1{\beta}$, IL-6, TNF-${\alpha}$, and GM-CSF production of the ECP group decreased significantly compared to the control group. As a result of examining joint condition with 3D micro CT, deformation and destruction of the joint was shown to have decreased. Bone density of ECP group increased at a statistically significant level compared to the control group. Degree of joint inflammation of ECP group decreased significantly compared to the control group. After H&E and M-T staining, infiltration of immune cells, subsidence of the cartilage, damage to the synovial cells and joint erosion decreased. Conclusion : This study showed that ECP hindered the process of rheumatoid arthritis and protected joints and cartilage.

• Journal of the Society of Disaster Information
• /
• v.16 no.3
• /
• pp.449-457
• /
• 2020

Purpose: The Seoul Metropolitan Government classifies the cavity risks into emergency, priority, general, and observation grades in consideration of the cavity size, asphalt pavement thickness, and pavement depth based on the cavity management grade criteria of Seoul. In this study, the depth of cracking was measured at 17 cracks identified by checking the pavement condition of the cavity at 265 cavities found in the 2019 cavity investigation service. Method: In the first phase, crack width and depth were measured using a vernier caliper, taper gauge, and depth gauge to check the cracks of the identified cavities. In the second phase, the location of the largest crack in the upper road surface was confirmed, and A.C. was drilled to further measure the crack depth. Results: As a result, the cavity management level was raised in nine of the 17 test cavity identified. Therefore, in case of emergency and priority recovery, the grade should be adjusted according to the depth of pavement crack and the thickness of residual A.C. pavement. Conclusion: In the case of cracks in the upper part of the cavity, the crack progression must be determined through the perforation and the remaining asphalt concrete thickness must be determined to determine the cavity grade.

• The Journal of Engineering Geology
• /
• v.10 no.1
• /
• pp.1-12
• /
• 2000

Heaving of road and subsidence of slope took place at the Wiri region of the local highway 999 in Gyeongsangbukdo, Korea after heavy rain in the next year of construction. Although the state government had performed remedial treatments by reducing the angle and the height of the slope, deformation had never stopped. Therefore, we have preformed the analysis of deformation and stabilityof the slope. Study area consists of the Cretaceous shale, siltstone and sandstone and two faults are found. The major deformation occurred by sliding of rock mass along faults after heavy rain because not only thepore pressure at the fault plane and the unit weight of sliding mass increased, but did the shearstrength of saturated fault clay become very low. The decrease in shear strength of saturated fault clayis the major factor among the reasons for deformation. Numerical simulations using limit equilibriummodel, finite difference model and finite element model were performed for eight cross sections.Although safety factors are above 1.7 during the dry season, they become below 1.0 when groundwaterlevel raises to surface. The maximum displacement is about 15-3Ocm. However, safety factors increasedto above 2.4 and the maximum displacement is below 2.08cm after remedial treatment, Indicating thatthe slope becomes stable.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.5
• /
• pp.787-807
• /
• 2018

When conducting the underground safety impact assessment under the special law in Korea, it is essential to investigate the occurrence of underground cavities. When underground cavities were discovered, the underground safety was assessed through numerical analysis. The previous study has suggested the stability evaluation based on the factor of safety by changing the 2D shape of the small underground cavity. In this study, the effects of small underground cavities considering 3D shapes were examined using a continuum analysis program and compared with the 2D results presented in previous study. If the 3-Dimensional shape of the underground cavity is found close to the sphere type, it would be reasonable to evaluate the factor of safety by the shear strength reduction method regardless of the size and position of the cavity. If a high-aspect ratio underground cavity with a depth of 2 m or more from the ground surface and an aspect ratio (a/b) of 2.0 or more is in the vertical direction, not only the factor of safety but the failure mode shape should be cautions in the stability evaluation using the shear strength reduction method. The results of this study are expected to be basic data on underground safety impact assessment.

• The Journal of Engineering Geology
• /
• v.24 no.4
• /
• pp.525-534
• /
• 2014

Environmental problems typically occurring in abandoned mine lands (AML) include: contaminated and acidic surface water and groundwater; stockpiled waste rock and mill tailings; and ground subsidences due to mining operations. This study examines the effectiveness of various geophysical techniques for mapping potential hazard and contaminated zones. Four AML sites with sedimentation contamination problems, acid mine drainage (AMD) channels, ground subsidence, manmade liner leakage, and buried mine tailings, were selected to examine the applicability of various geophysical methods to the identification of the different types of mine hazards. Geophysical results were correlated to borehole data (core samples, well logs, tomographic profiles, etc.) and water sample data (pH, electrical conductivity (EC), and heavy metal contents). Zones of low electrical resistivity (ER) corresponded to areas contaminated by heavy metals, especially contamination by Cu, Pb, and Zn. The main pathways of AMD leachate were successfully mapped using ER methods (low anomaly peaks), self-potential (SP) curves (negative peaks), and ground penetrating radar (GPR) at shallow penetration depths. Mine cavities were well located based on composite interpretations of ER, seismic tomography, and well-log records; mine cavity locations were also observed in drill core data and using borehole image processing systems (BIPS). Damaged zones in buried manmade liners (used to block descending leachate) were precisely detected by ER mapping, and buried rock waste and tailings piles were characterized by low-velocity zones in seismic refraction data and high-resistivity zones in the ER data.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.3
• /
• pp.181-187
• /
• 2009

To estimate the status and volume of artificial reefs(ARs) deployed at the sea bottom in fishing grounds, this study assessed the initial volume of ARs, the cubic volume of AR groups, and the porosity of each AR using image data collected during a survey using a multi-beam echo sounder(MBES) and a side scan sonar(SSS). These results were compared with data collected during diver surveys and used to develop a new method and prediction formulas for countermeasures, facility volume, and efficient use of volume for deployed ARs(cubic concrete). The field survey results for nine ARs deployed in the Busan Sea region were calculated, and the average value of coefficient k(indicating the efficient use of volume ratio) among ARs was 0.753, and the correlation between coefficient k and year(Yr) of deployment was calculated as k=0.0023Yr+0.725. The relationship between these two factors was poor. In years following the deployment of artificial reefs, coefficient k and year of deployment were not correlated, in spite of the hardening ground due to subsidence and the reduced distance between ARs. Consequently, it is reasonable to suppose that coefficient k was defined by bottom surface conditions and initial deployment conditions.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.16 no.4
• /
• pp.403-415
• /
• 2014

Recently, the temperature rise in the summer due to climate change, power usage is increasing rapidly. As a result, power generation facilities have been newly completed and the need for ultra-high-voltage transmission line for power transmission of electricity to the urban area has increased. The mechanized tunnelling method using a shield TBM have an advantage that it can minimize vibrations transmitted to the ground and ground subsidence as compared with the conventional tunnelling method. Despite the popularity of shield TBM for cable tunnel construction, study on the mechanical behavior of cable tunnel driven by shield TBM is insufficient. Thus, in this study, the effect of fractured zone ahead of tunnel face on the mechanical behavior of the shield TBM cable tunnel is investigated. In addition, it is intended to compare the behavior characteristics of the fractured zone with continuous model and applying the interface elements. Tunnelling with shield TBM is simulated using 3D FEM. According to the change of the direction and magnitude of the fractured zone, Sectional forces such as axial force, shear force and bending moment are monitored and vertical displacement at the ground surface is measured. Based on the stability analysis with the results obtained from the numerical analysis, it is possible to predict fractured zone ahead of the shield TBM and ensure the stability of the tunnel structure.

• Journal of the Korean Geophysical Society
• /
• v.2 no.3
• /
• pp.179-190
• /
• 1999

The overall structural framework was studied using the regional 2D seismic data, followed by the sequence stratigraphic study on the 3D seismic and well- log data in the margin of the South Con Son basin of the South China Sea. This research contributes to delineate depositional stratigraphy, depositional environment and geologic history in the 3D seismic area of highly complicated faulting. Eight Miocene sequences were indicated on the 3D seismic and well-log data, in which the structural maps of each sequence boundary and the isochron maps for the corresponding sequence were made. The seismic facies were analyzed for each sequence volume and sequence boundary surface. The 3D seismic area is characterized by coal beds deposited in the transgression environment (transgression systems tract) and channel distributions just above the sequence boundaries. During the Early Miocene, the coals and thick shales deposited in the mangrove swamp representing the lower coastal plain environment. During the Mid to Late Miocene, thick clastic sediments deposited in the coastal to shallow shelf by regional subsidence and marine transgression. The isochron maps and structural patterns indicate that the sediments were transported from west to east or from northwest to southeast.