• Geomechanics and Engineering
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• v.16 no.4
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• pp.399-413
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• 2018

This paper addresses the issue of field measurement of excavation damage zone (EDZ) and its numerical simulation method considering both excavation unloading and blasting load effects. Firstly, a 2000 m-deep rock cavern in China is focused. A detailed analysis is conducted on the field measurement data regarding the mechanical response of rock masses subjected to excavation and blasting operation. The extent of EDZ is revealed 3.6 m-4.0 m, accounting for 28.6% of the cavern span, so it is significantly larger than rock caverns at conventional overburden depth. The rock mass mechanical response subjected to excavation and blasting is time-independent. Afterwards, based on findings of the field measurement data, a numerical evaluation method for EDZ determination considering both excavation unloading and blasting load effects is presented. The basic idea and general procedures are illustrated. It features a calibration operation of damage constant, which is defined in an elasto-plastic damage constitutive model, and a regression process of blasting load using field blasting vibration monitoring data. The numerical simulation results are basically consistent with the field measurement results. Further, some issues regarding the blasting loads, applicability of proposed numerical method, and some other factors are discussed. In conclusion, the field measurement data collected from the 2000 m-deep rock cavern and the corresponding findings will broaden the understanding of tunnel behavior subjected to excavation and blasting at great depth. Meanwhile, the presented numerical simulation method for EDZ determination considering both excavation unloading and blasting load effects can be used to evaluate rock caverns with similar characteristics.

• The Journal of Engineering Geology
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• v.13 no.2
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• pp.193-205
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• 2003

Fine grained granite, porphyritic granite and biotite granite together with intruded and extruded andesitic rocks are distributed in the study area which is bounded by the Yangsan and Dongrae faults. A new domestic road is being constructed along the area between the two major faults. The NNE trending Bupki fault and NE trending Myungkog fault are also developed within the area cross the road. The sheeting joints with dips of less than 30 degrees are only developed in the area of granite outcrop. High angle joints can be divided into 3 sets, such as, NE trending, NW trending and nearly EW trending joints. The joint space is mostly more than 20cm and the joint compressive strength is more than 100 MPa. These data show that even though the study area is situated between large faults, the ground condition is good because the damage zone of the Yangsan and Dongrae faults is relatively narrow.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.5-13
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• 2016

In this study, Coupled Eulerian-Lagrangian (CEL) analysis, which is one of the large deformation analyses, was incorporated to investigate excavation damage zone (EDZ) under TBM advancement. Considering the quasi-static condition, the dynamic analysis was performed to simulate the real TBM advancement and subsequently a case study on mesh and TBM excavation rate was carried out for satisfying a balance of accuracy and economic computational time. Based on this, a series of parametric studies were performed for different rock types and tunnel diameters. From the numerical analysis results, it is found that EDZ was taken to range within 0.4D(D=tunnel diameter) for most rocks. It is also found that the EDZ tends to increase as the tunnel diameter increases.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.237-247
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• 1993

Carbon fiber reinforced plastics(CFRP) have gained increased application in aerospace structures because of their specific strength and stiffness, but are sensitive to impact-induced damage. An experimental investigation was carried out to evaluate the impact resistance of CFRP according to the ply angle. The specimens of angle ply laminate composites were employed with [0.deg. $_{6}$/ .deg.$_{10}$/0.deg.$_{6}$], in which 6 kinds of ply angle such as .deg.=15.deg., 30.deg., 45.deg., 60.deg., 75.deg. and 90.deg. were selected. The impact tests were conducted using the air gun type impact testing machine by steel balls of diameter of 5 mm and 10 mm, and impact-induced damages were evaluated under same impact speed of V=60m/s. The impact damaged zones were observed through a scanning acoustic microscope (SAM). The obtained results were summarized as follows: (1) Delaminations on the interfacial boundaries showed th directional characteristics to the fiber directions. The delamination area on the impact side (interface A) was considerably smaller compared to that of the opposite side (interface B). (2) Cracks corresponding to other delaminations than those mentioned in SAM photographs were also seen on the impact damaged zone. (3) The delamination patterns were affected by the ply-angle, the dimensions of the specimen, and the boundary conditions. (4) The impact damaged zone showed zone showed the delamination on the interfacial boundaries, transverse shear cracks of the surface layer, and bending cracks of the bottom layer.r.r.r.

• Journal of Ocean Engineering and Technology
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• v.26 no.5
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• pp.5-10
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• 2012

In this study, carbon steel (A53) is used as the material for the pipes in a marine plant and ship industry. Welds are necessary to join the carbon steel, and the effect of this welding on the properties of the carbon steel has been studied by many researchers. In this study, the dynamic behavior of welded carbon steel was studied using an acoustic emission (AE) technique, which is a nondestructive test. There are numerous AE parameters that can be used to analyze the damage behavior of carbon steel by external loading. The AE parameters of energy, cumulative count, amplitude, and AE event were used, and each parameter was differentiated according to the degree of damage to the carbon steel. The energy showed a high level at the elastic range of the load curve, while the amplitude had the highest value at the hardening region. The cumulative count showed a growth tendency similar to the loading curve. In addition, an ultrasonic technique and hardness test were applied to evaluate the mechanical properties according to the base zone, HAZ region, and weld zone of the weld specimen. The velocity and attenuation ratio showed little change between zones, and an evaluation of the ultrasonic waves on each zone of the specimen was found to be a useful method to clarify the mechanical properties of the carbon steel.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.105-112
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• 2001

The purpose of this study is to assess the stability of tunnel for a high speed railway crossing the fault zone. The area where the tunnel crossed the fault zone can be unstable during construction and operation. Geotechnical investigations have been conducted to determine an optimum excavation method by obtaining the material properties around the fault zone and to check the stability of the tunnel. For the numerical analysis, the FLAC, numerical analysis code based on finite difference method, was utilized to analyze the behavior of the fault at three points having typical ground conditions. Based on the results of numerical analysis, the combinations of compaction grouting and LW grouting were determined as suitable methods for pre-excavation Improvement of the ground surrounding the tunnel opening. In conclusion, the stability of the tunnel construction for the high speed railway within the fault zone may be obtained by adopting the optimum excavation method and the reinforcement method. The numerical analysis based on FLAC program contains errors caused by assumptions used in numerical analysis, therefore constant monitoring with respect to the change of ground condition and groundwater is highly recommended to minimize the numerical error and the possibility of damage to tunnel.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.109-109
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• 2018

전 세계적인 기후변화로 인한 자연재해의 빈도가 급증하고 있으며, 대규모 재산피해가 빈번하게 발생하고 있다. 자연재해로 인한 피해를 효과적으로 저감시키기 위하여 지역적 특성과 재해 특징을 함께 고려한 적절한 대책 방안을 수립해야 한다. 본 연구에서는 지역적 특성(해안 지역, 산간 지역, 내륙 지역)에 따라 크게 3분류로 구분하였고, 지역별 호우피해 발생빈도를 함께 고려하여 피해 특석을 분석하고자 하였다. 호우피해 특징을 분석하기 위하여 지역별 피해액과 호우피해 발생빈도를 분석하였고, 지역별 피해액과 호우피해 발생빈도를 무차원화 하여 4가지 유형(Red Zone, Orange Zone, Yellow Zone, Green Zone)으로 분류하였다. 지역별로 평균 피해액 발생 빈도(I)와 최대 피해 발생빈도(II)로 피해유형을 구분하였다. 최종적으로 지역적 특징 3가지에 대하여 2가지 피해유형과 4가지 호우피해 발생빈도를 분석하였다. 본 연구를 통하여 대피해가 발생하는 Red Zone, Orange Zone의 경우 평균 피해액 발생빈도(I)는 30%이고, 최대 피해액 평균 발생빈도(II)는 23%로 분포하고 있음을 알 수 있다. 따라서 본 연구결과를 활용한다면, 지형에 따른 호우피해 특징 파악 및 효과적인 방재대책 수집에 활용 할 수 있을 것으로 판단된다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1824-1832
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• 1992

This study investigated the compressive Young's modulus and the impactinduced damage of CFRP angle-ply laminate under same impact energy condition. The specimens of angle-ply laminate composites [0.deg.$_{6}$/ .theta..deg.$_{10}$/ 0.deg.$_{6}$] with .theta..deg. =30.deg., 45.deg., 60.deg. and 90.deg. were employed, and damaged by steel balls of diameter of 5mm and 10mm propelled by air gun type impact testing machine. The impact damaged zones were observed through a scanning acoustic microscope(SAM), and their cross-sections were observed through a scanning electron microscope(SEM). The compressive Young's moduli before and after impact were measured, and compared with the theoretical values calculated. The results obtained were as follows: (1) The damage areas on the interfacial boundaries showed more severe change on the back side interface than on the impact side interface with increasing ply-angle. (2) The damage areas on the interfacial boundaries became larger with increasing impact velocity or ply-angle. (3) The impact damaged zone showed the delamination on the interfacial boundaries and transverse cracks inside laminas. (4) The impact damaged zone was affected by the impactor size and speed or ply-angle under same impact energy condition. (5) Compressive Young's moduli before and after impact were lower than theoretical value, but showed a similar change according to ply-angle. (6) Compressive Young's moduli after impact were higher than those before impact, but there was no remarkable change in apparent compressive modulus after impact.t.act.

• The Journal of Fisheries Business Administration
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• v.55 no.1
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• pp.21-35
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• 2024

In this study, we collected and analyzed the current status of licenses for the limited fishery business and divided the problems related to licenses for the limited fishery business into partial damage compensation and cancellation compensation areas. In the case of partial damage compensation areas due to existing public water use projects, it is suggested that the issuance of licenses for limited fishery businesses should be reconsidered. In the case of cancellation compensation areas, it is recommended that the disposition of communal fishery businesses that do not require capital investment should be the principle. If capital such as facilities are invested, compensation should be made by Article 52 of the Enforcement Decree of the Land Compensation Act if the licenses for limited fishery business are closed due to other development projects. In addition, we proposed an improvement plan to establish a rational management system for licenses for limited fishery businesses. In addition to these improvement measures, we hope that further investigation and research on licenses for limited fishery business, which have been insufficient so far, will be conducted to promote the comprehensive use of fisheries resources and waters and the sustainable development of fisheries that are the objectives of the Fisheries Act, and contribute to the improvement of the quality of life of the people and the balanced development of the national economy.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.1
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• pp.185-193
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• 2016

Purpose of this study is to classify damaged lands according to the cause of the damage and their influences based on characteristic of the damaged lands in DeMilitarized Zone(DMZ) area, and utilize this study as a fundamental study for establishment of ecosystem restoration system. Literature review and field survey have been conducted to review the damage status of DMZ area. For field survey, first year and second year have been conducted, in which type of the damage has been reviewed in this study. In the result, types of damage have been classified into 6 categories: 'alteration of initial landform', 'loss of surface layer', 'land pollution', 'alteration of soil chemical property', 'decline of vegetation', and 'invasion of foreign species'. Restoration for each damage type is as following. First, for alteration of initial landform, the land is restored to the original landform prior to the damage and connection to surrounding ecosystem is considered. Second, for loss of surface layer, lost surface layer is restored or further loss is prevented with stabilization. Third, for land pollution, source of the pollution is eradicated or self-circulation with purification of polluted land is encouraged. Fourth, for alteration of soil chemical property, soil is restored of its original property with eradication of the pollution source and improvement of soil. Fifth, for decline of vegetation, current vegetation and anticipated alteration in future are considered and number of wild species is to be increased based on structure and characteristic of nearby vegetation. Sixth, for invasion of foreign species, prevention of dominance by risky species and facilitation ecological stability with ecological management are to be considered. Influence according to the cause of damage has occurred in secondary(indirect) influence or simultaneous occurrence of several damage types. Considering all these aspects, when type of the damage is complex, restoration process for each of former mentioned 6 damage types with solitary influence should be considered in unison.