• Geomechanics and Engineering
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• 제15권2호
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• pp.745-754
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• 2018

In the analysis of the effects of rock tunnel blasting vibration on adjacent existing buildings, the model of simplified equivalent load produces higher calculation result of vibration, due to the lack of consideration of the millisecond delay effect. This paper, based on the static force equivalence principle of blasting load, proposes a new determination method of equivalent load of blasting vibration. The proposed method, based on the elastic-static force equivalence principle of stress wave, equals the blasting loads of several single blastholes in the same section of millisecond blasting to the triangle blasting load curve of the exploded equivalent elastic boundary surface. According to the attenuation law of stress wave, the attenuated equivalent triangle blasting load curve of the equivalent elastic boundary is applied on the tunnel excavation contour surface, obtaining the final applied equivalent load. Taking the millisecond delay time of different sections into account, the time-history curve of equivalent load of the whole section applied on the tunnel excavation contour surface can be obtained. Based on Sailing Tunnel with small spacing on Sanmenxia-Xichuan Expressway, an analysis on the blasting vibration response of the later and early stages of the tunnel construction is carried out through numerical simulation using the proposed equivalent load model considering millisecond delay effect and the simplified equivalent triangle load curve model respectively. The analysis of the numerical results comparing with the field monitoring ones shows that the calculation results obtained from the proposed equivalent load model are closer to the measured ones and more feasible.

• 터널과지하공간
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• 제16권3호
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• pp.232-240
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• 2006

본 연구는 실제의 발파현상 및 지반진동을 더욱 정확히 반영할 수 있도록 시험발파에 의한 계측자료와 역해석기법을 사용하여 발파하중을 산정하였다. 실제 계측데이타와 비교를 통해 기존 추정식에 의한 하중에 비해 발파현상 및 지반진동특성을 보다 정확히 반영하는 것을 볼 수 있었으며, 이를 이용한 수치해석을 통해 구조물의 진동영향을 평가하여 타당한 결과를 얻을 수 있었다.

• 화약ㆍ발파
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• 제23권2호
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• pp.45-56
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• 2005

본 연구에서는 철근 콘크리트 기둥 발파시 수직하중과 철근의 영향에 따른 파쇄형태 및 파쇄체적에 대해 축소모형실험을 수행하였다. 수직하중이 증가할수록 수직하중에 의한 수직방향의 인장균열 및 철근에 의한 수직방향의 균열이 발생하였으며, 2.0톤에서는 수직방향의 인장균열이 철근에 의한 수직방향의 균열보다 우세하게 나타났다. 또한 수직하중이 증가할수록 수직방향의 인장균열이 우세하여 철근의 휨정도는 감소하였다. 발파공수가 증가하여도 수직하중에 따른 평균 파쇄체적은 크게 증가하지 않았으며, 이는 철근이 파쇄체적에 영향을 미치는 것으로 판단된다. 따라서 콘크리트 기둥 발파시 수직하중은 콘크리트의 파쇄형태와 철근의 휨정도에 중요한 영향을 미치며 철근은 파쇄체적에 영향을 미친다. 그러므로 철근 콘크리트 기둥 발파해체시 수직하중과 철근의 영향에 따라 천공패턴 및 발파패턴을 조절해야 한다.

• Geomechanics and Engineering
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• 제16권4호
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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.

• 화약ㆍ발파
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• 제25권2호
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• pp.1-10
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• 2007

본 연구에서는 1/5 축소모형 철근콘크리트 기둥을 이용하여 철근의 노출길이 및 수직하중과 발파공수와의 관계에 대해 연구하였다. 축소모형 철근콘크리트 기둥에 수직하중을 재하하여 철근의 노출 길이와 발파공수와의 관계를 비교하였다. 또한 발파된 축소모형 기둥의 무게와 철근이 노출된 축소모형 기둥의 무게를 발파공수와 비교하였다. 축소모형 철근콘크리트 기둥에 대한 시험결과로부터 철근의 노출길이 및 수직하중을 바탕으로 축소모형 철근콘크리트 기둥의 발파공수를 산정할 수 있으며, 이를 축소모형 구조물에 적용할 수 있음을 확인하였다.

• 한국정밀공학회지
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• 제26권8호
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• pp.142-147
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• 2009

Spinal fixation systems provide surgical versatility, but the complexity of their design reduces their strength and fatigue resistance. There is no published data on the mechanical properties of such screws. Screws were assembled according to a vertebrectomy model for destructive mechanical testing. A group of two assemblies was tested in static compression. One group was applied to surface a grit blasting method and another group was applied to surface a bead blasting method. Modes of failure, yield, and ultimate strength, yield stiffness, and cycles to failure were determined for six assembles. Static compression 2% offset yield load ranges was from 327 to 419N. Fatigue loads were determined two levels, 37.5% and 50% of the average load from static compression ultimate load. An assembly of bead blasting treatment only achieved 5 million cycles at 37.5% level in compression bending.

• 화약ㆍ발파
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• 제27권2호
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• pp.26-32
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• 2009

산업의 발달로 인해 도심지에서의 건물해체 및 발파공사가 증가하여 왔지만, 인접 구조물에 대한 영향 평가는 미미한 실정이었다. 본 연구에서는 탄성파속도 실험과 반발경도 실험으로 콘크리트 재료의 물성을 파악 하였고, 인접 구조물 부재의 내부 손상을 모사하기 위하여 콘크리트 재료에 충격 하중을 가하여 충격 전후의 탄성파속도를 도식화하였다. 결과적으로, 콘크리트 재료는 충격 하중에 따라 탄성파속도가 감소하는 경향을 보였고, 압축강도가 크고 탄성파속도가 빠른 재료일수록 충격 하중에 따른 손상이 작은 것으로 나타났다.

• 터널과지하공간
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• 제11권4호
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• pp.344-351
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• 2001

발파를 이용한 터널굴착에 있어서, 장약량 산정이나 터널 주변 암반 및 구조물웨 대한 영향 평가 등은 주로 간단한 경험식에 의해 이루어져 왔다. 또한 지금까지 발파의 충격에너지를 고려한 지하구조물의 동해석 연구는 매우 빈약한 실정이라 할 수 있다. 따라서 본 연구에서는 발파하중을 받는 불연속체 지하구조물의 비선형 거동을 평가하기 위하여 2차원 개별요소법의 수치모델기법을 개발하였고, 실제문제에의 적용성을 검토하기 위하여 제방하부에 위치한 터널발파의 수치해석을 통하여 시간별 지하 및 지상 구조물의 변위 및 입자속도의 전파과정을 살펴보았다. 해석결과 본 연구에서 제안한 발파하중의 모형이 실제 문제에 적용될 수 있었고, 이를 개별요소해석에 적용함으로써 발파지역 주변의 구조물의 안정성을 검토할 수 있었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1162-1170
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• 2011

Since there is 70% of the land in South Korea is forest, tunnel constructions by blasting are common for building railways and roads. The damage to the bedrock and the development of overbreak near the face of the tunnel during the blasting directly affect the safety of the tunnel and the maintenance after the construction. Therefore, there is a need to investigate the damage zone in the bedrock after the blasting. The damage zone changes the properties of the bedrock and decreases the safety. Especially, the coefficient of permeability of the damaged bedrock increases dramatically, which is considered very important in construction. There is a lack of research on the damage that bedrock is received with respect to the amount of explosives in blasting, which is required for the design of optimum support in blast excavation that maximizes the support of the bedrock. Therefore, in this research, numerical analysis was performed based on the field experiment data in order to understand the mechanical characteristics of the bedrock after to the blast load and to analyze the damage that the bedrock receives from the blast load. In addition, a method was proposed for selecting the optimum blast pressure for train tunnel design with respect to the damage zone.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.657-664
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• 2002

This study presents the influence of blasting-induced vibration on the adjacent structures in rocks of various RMR values. 3D finite element analysis was performed to simulate the behaviour of tunnel and adjacent structures during rock excavation. The blast loadings were evaluated from the blasting pressure which is depending on the type and amount of explosive charges. Influencing factors for the stability of adjacent structures and ground conditions were reviewed in terms of structural dimensions and RMR values. The stiffness and load of adjacent structures are modeled in the numerical analysis to Investigate blasting effects of the size of adjacent structures. The vibration velocity and maximum particle velocity was increase sharply when the RMR value changed from 30 to 50. The effect of particle velocity was minimized at the width of structure become 2 times of tunnel diameter.