• Title/Summary/Keyword: 근접발파

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Influence of the Charged Explosives on the Steel Plate Cutting Performance in Bent-Shaped Charge Holder Blasting (드로잉 가공 성형폭약용기를 이용한 강재구조 발파공법에서 사용폭약의 종류가 절단성능에 미치는 영향)

  • Kim, Gyeong-Gyu;Park, Hoon;Min, Gyeong-Jo;Shin, Chan-Hwi;Cho, Sang-Ho
    • Explosives and Blasting
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    • v.39 no.1
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    • pp.1-9
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    • 2021
  • As the national economic growth and the rapid increase in industrial structures are aging, the demand for removing steel structures is increasing, and research on improving the penetration performance of the linear shape charge explosives. In the study, numerical analyses were performed on the effect of the type of explosive used in the self-made shape charging container and the initiation method on the cutting performance of the steel plate and the effect on the shaped explosive installed close to it. ANSYS LS-DYNA, which can analyze the large deformation problem of materials due to explosion, was used, and an ALE(Arbitrary-Lagrange-Eulerian) model was applied that enables interlocking analysis of gases, liquids, and solid.

Development of Vibration Prediction Program of Gas Pipeline by Construction Vibration (건설진동에 의한 가스배관의 진동예측 프로그램 개발)

  • Jeong S. Y.;Hong S. K.;Kim J. H.;Koh J. P.
    • Journal of the Korean Institute of Gas
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    • v.5 no.2 s.14
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    • pp.30-35
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    • 2001
  • Presently, working gas pipelines are being subjected to the influence of construction vibration. Especially on subway and road construction, gas pipelines are being influenced to construction vibration caused by use of construction equipment, passage of a large-sized vehicle and blasting. Buried gas pipelines are subjected to the influence of vibration caused by blast in the vicinity of pipeline, exposed gas pipelines are subjected to the influence of vehicle vibration. Therefore, in the study, it is developed to vibration prediction program of gas pipeline by analyzing measured construction vibration. This program is able to predict vibration of gas pipeline according to field conditions by using the results of structural finite element analysis and empirical equation by reliability analysis. And, this program contains the database of construction vibration. Additionally, this program is able to compute estimated blast vibration equation using measured blast vibration data in the field and to form graph of allowable charging gunpowder per delayed-action with the change of blast velocity. Therefore, field workers are able to predict construction vibration around gas pipeline and estimate safety of gas pipeline.

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The Vibration Velocity and Vibration Level of Near-field Blasting Vibration in an Urban Blasting Site (근접장 발파진동에서 진동속도와 진동레벨)

  • Lee, Yeon-Soo;Chang, Seo-Il
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.766-771
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    • 2005
  • To compare blasting vibration at blasting construction field in urban area, the vibration level (dB(V)) and vibration velocity (cm/sec) on the ground and the structure of buildings due to the differences of the measuring sites from the blasting source is investigated and the difference between the measured vertical vibration level and the calculated vibration level by using vibration velocity PVS and the correlation between vibration velocity and vibration level and is studied in the thesis.

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Applicability of Safe Blast Vibration Limits to the Blasting Work near Safety Related Structures (안전관련 구조물 근접시공시 발파진동 허용기준의 적용성에 관하여)

  • 류창하;서우춘;정소걸;이종림;주광호;이대수
    • Tunnel and Underground Space
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    • v.4 no.3
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    • pp.287-296
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    • 1994
  • Safety-related structures of power plants have to be protected against the effects of possible hazards and natural phenomena. Earthquakes are considered a major dynamic design loading as a requirement of plant design, but the effects of blast-induced vibratons are not. Due to the difficulties of obtaining construction site for new plants, following ones are inevitably being built in the site adjacent to existing power plants. Therefore considerable thought has been recently given to the dynamic loading generated by blasting works near the plants. In this paper, discussed is applicability of existing vibration standards and industrial codes to the blasting works near safety related structures. Also evaluated are the parameters for the safe vibration limits such as measure of vibration level, frequency consideration, structure response, propagation equation, etc.

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A Study on Precision Measurement of Rock Joint Using 3D-Laser Scanner (3D-Laser scanner를 이용한 암반 절리의 정밀측정에 관한 연구)

  • 이승호;황영철;김세현;심석래;정태영
    • Explosives and Blasting
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    • v.22 no.3
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    • pp.103-111
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    • 2004
  • The existing methods that can be adopted for measuring joints involve either to use borehole or photogrammetry. Due to restricted space, acquisition of data in limited area, and measurement errors, above methods have limitations acquiring the objective and correct results. To get over defects of existing joint measurement methods, joints have been measured using 3D-Laser scanner with accuracy and efficiency. This research aims to investigate an accuracy and applicabiliy of 3D-Laser scanner for measuring rock slope joints. Measurement of rock slope joints has been executed using 3D-Laser scanner & clinometer and then, results from both methods are compared. Results from both methods indicate that they show nearly equal features for joint distributions and numbers of joint information obtained by 3D-Laser scanner are much more than ones measured using clinomer. Therefore, 3D-Laser scanner turns out to be very effective by the fact that it contributes to reduce investigation costs & periods, objectify data from rock slope joints.

A Study on Vibration Analysis During the Slab Dismantling Using the Mechanical Dismantling Method (기계식 해체 공법을 적용한 슬래브 해체 시 발생하는 진동 해석 연구)

  • Noh, You-Song;Suk, Chul-Gi;Park, Hoon
    • Explosives and Blasting
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    • v.39 no.4
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    • pp.1-11
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    • 2021
  • In this study, the vibration data were obtained to analyze the vibration generated during dismantling of slab using the mechanical dismantling method. The obtained vibration data were classified according to the attachment device and then the waveform and dominant frequency analysis were performed. And the correlation was analyzed by the different methods of measuring the distance between the work section and the measurement point. As a result of the waveform analysis for each attachment device, there was little change in the phase of the vibration waveform and only the change in amplitude, which is the magnitude of the vibration velocity. And as a result of frequency analysis, the frequency band was lower when using a crusher method than a braker method and frequency band were close of the natural frequency of the structure to be dismantled. As a result of the correlation analysis, the separation distance was estimated a higher correlation when evaluated as the path through which the vibration propagates along the structure frame than the straight distance between the measurement point and the working section.

Dynamical Study on the Blasting with One-Free-Face to Utilize AN-FO Explosives (초유폭약류(硝油爆藥類)를 활용(活用)한 단일자유면발파(單一自由面發破)의 역학적(力學的) 연구(硏究))

  • Huh, Ginn
    • Economic and Environmental Geology
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    • v.5 no.4
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    • pp.187-209
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    • 1972
  • Drilling position is one of the most important factors affecting on the blasting effects. There has been many reports on several blasting factors of burn-cut by Messrs. Brown and Cook, but in this study the author tried to compare drilling positions of burn-cut to pyramid-cut, and also to correlate burn-cut effects of drilling patterns, not being dealt by Prof. Ito in his theory, which emphasized on dynamical stress analysis between explosion and free face. According to former theories, there break out additional tensile stress reflected at the free face supplemented to primary compressive stress on the blasting with one-free-face. But with these experimented new drilling patterns of burn-cut, more free faces and nearer distance of each drilling holes make blasting effects greater than any other methods. To promote the above explosive effect rationary, it has to be considered two important categories under-mentioned. First, unloaded hole in the key holes should be drilled in wider diameter possibly so that it breaks out greater stress relief. Second, key holes possibly should have closer distances each other to result clean blasting. These two important factors derived from experiments with, theories of that the larger the dia of the unloaded hole, it can be allowed wider secondary free faces and closes distances of each holes make more developed stress relief, between loaded and unloaded holes. It was suggested that most ideal distance between holes is about 4 clearance in U. S. A., but the author, according to the experiments, it results that the less distance allow, the more effective blasting with increased broken rock volume and longer drifted length can be accomplished. Developed large hole burn-cut method aimed to increase drifting length technically under the above considerations, and progressive success resulted to achieve maximum 7 blasting cycles per day with 3.1m drifting length per cycle. This achievement originated high-speed-drifting works, and it was also proven that application of Metallic AN-FO on large hole burn-cut method overcomes resistance of one-free-face. AN-FO which was favored with low price and safety handling is the mixture of the fertilizer or industrial Ammonium-Nitrate and fuel oil, and it is also experienced that it shows insensible property before the initiation, but once it is initiated by the booster, it has equal explosive power of Ammonium Nitrate Explosives (ANE). There was many reports about AN-FO. On AN-FO mixing ratio, according to these experiments, prowdered AN-FO, 93.5 : 6.5 and prilled AN-FO 94 : 6, are the best ratios. Detonation, shock, and friction sensities are all more insensitive than any other explosives. Residual gas is not toxic, too. On initation and propagation of the detonation test, prilled AN-FO is more effective than powered AN-FO. AN-FO has the best explosion power at 7 days elapsed after it has mixed. While AN-FO was used at open pit in past years prior to other conditions, the author developed new improved explosives, Metallic AN-FO and Underwater explosive, based on the experiments of these fundmental characteristics by study on its usage utilizing AN-FO. Metallic AN-FO is the mixture of AN-FO and Al, Fe-Si powder, and Underwater explosive is made from usual explosive and AN-FO. The explanations about them are described in the other paper. In this study, it is confirmed that the blasting effects of utilizing AN-FO explosives are very good.

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Case study of microseismic techniques for stability analysis of pillars in a limestone mine (석회석 광산 내 광주의 안정성 분석을 위한 미소진동 계측기술의 현장적용)

  • Kim, Chang Oh;Um, Woo-Yong;Chung, So-Keul;Cheon, Dae-Sung
    • Tunnel and Underground Space
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    • v.26 no.1
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    • pp.1-11
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    • 2016
  • This study deals with the case that was the field application of the microseismic monitoring techniques for the stability monitoring in a domestic mine. The usefulness and limitations of the microseismic techniques were examined through analyzing the microseismic monitored data. The target limestone mine adopted a hybrid room-and-pillar mining method to improve the extraction ratio. The accelerometers were installed in each vertical pillar within the test bed which has the horizontal cross-section $50m{\times}50m$. The measured signals were divided into 4 types; blasting induced signal, drilling induced signal, damage induced signal, and electric noise. The stability analysis was performed based on the measured damage induced signals. After the blasting in the mining section close to the test bed, the damage of the pillar was increased and rockfall near the test bed could be estimated from monitored microseismic data. It was possible to assess the pillar stability from the changes of daily monitored data and the proposed safety criteria from the accumulated monitored data. However, there was a difficulty to determine the 3D microseismic source positions due to the 2D local sensor arrays. Also, it was needed to use real-time monitoring methods in domestic mines. By complementing the problems encountered in the mine application and comparing microseismic monitored data with mining operations, the microseismic monitoring technique can be used as a better safety method.

Removal of Seabed Multiples in Seismic Reflection Data using Machine Learning (머신러닝을 이용한 탄성파 반사법 자료의 해저면 겹반사 제거)

  • Nam, Ho-Soo;Lim, Bo-Sung;Kweon, Il-Ryong;Kim, Ji-Soo
    • Geophysics and Geophysical Exploration
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    • v.23 no.3
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    • pp.168-177
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    • 2020
  • Seabed multiple reflections (seabed multiples) are the main cause of misinterpretations of primary reflections in both shot gathers and stack sections. Accordingly, seabed multiples need to be suppressed throughout data processing. Conventional model-driven methods, such as prediction-error deconvolution, Radon filtering, and data-driven methods, such as the surface-related multiple elimination technique, have been used to attenuate multiple reflections. However, the vast majority of processing workflows require time-consuming steps when testing and selecting the processing parameters in addition to computational power and skilled data-processing techniques. To attenuate seabed multiples in seismic reflection data, input gathers with seabed multiples and label gathers without seabed multiples were generated via numerical modeling using the Marmousi2 velocity structure. The training data consisted of normal-moveout-corrected common midpoint gathers fed into a U-Net neural network. The well-trained model was found to effectively attenuate the seabed multiples according to the image similarity between the prediction result and the target data, and demonstrated good applicability to field data.

Interactions between pre-existing large pipelines and a new tunnel (기존 대구경 파이프라인과 신설터널간의 상호작용)

  • Jeong, Sun-Ah;Choi, Jung-In;Hong, Eun-Soo;Chun, Youn-Chul;Lee, Seok-Won
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.11 no.2
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    • pp.175-188
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    • 2009
  • When a new tunnel is excavated by the drill and blast method near pre-existing underground structures or tunnels due to the region restricted condition such as urban area, the ground will be relaxed by the excavation. In this case, issues can be created in terms of stability of pre-existing underground structures. One of major factors determining the stability of pre-existing underground structures can be a separation distance between pre-existing underground structures and a newly excavated tunnel. The region of ground relaxation defined by the plastic zone due to new excavation can be varied by separation distance. In this study, in other to estimate an influence of new tunnel excavation in terms of separation distance on the stability of pre-existing large pipelines, two-dimensional scaled model tests using plaster were performed for six models which have a different separation distance, The results show that based on the analysis of induced displacement during tunnel construction, the displacement decreases as the separation distance between large pipeline and new tunnel is increased until the distance is 2.5 times of pipeline diameter. Beyond this point, however, the displacement has become stabilized.