• Title/Summary/Keyword: Ground Vibration Test

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A Study on Tunnel Excavation by Controlled Blast Vibration at Particular Environment Conditions (발파진동 제어에 의한 특수구간 터널굴착에 관한 연구)

  • Choi, Hyung-Bin;Lim, Han-Uk
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.257-267
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    • 2000
  • It was difficult to apply conventional excavation methods in some sections from Seoul to Pusan high speed rail road construction of 1 lot 2, due to highway concrete road, gas pipe, water pipe and nearby factories with automatic control system machine. To excavate safely and efficiently in these sections new blast patterns were employed within allowable blast vibration level, by test blast and controlled vibration by sequential blast. Behaviors of the rock mass including convergence and displacement around tunnel were measured with construction works and the crack width in concrete wall was also monitored for controlling allowable limits. The results can be summarized as follow : 1. The allowable blast vibration level in structure site is less 1.0cm/sec for highway concrete, 0.5 cm/sec for gas pipe, water pipe and building housing and 0.3 cm/sec for automatic control system machine. 2. The convergence displacement, single rod extensometer and multi rod extensometer around tunnel and cracks in concrete wall were measured, it was confirmed that the measured values were converged within allowable level. 3. The empirical formular of ground vibrations with 90% confidence lines for PD-3 was given as follow. $$V_{90%}=45.549({\frac{D}{\sqrt{W}}})^{-1.353}$$

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A Study on the Blasting Dynamic Analysis using the Measurement Vibration Waveform (실측진동파형을 이용한 발파 동해석 기법에 관한 연구)

  • 최성웅;박의섭;선우춘;정소걸
    • Tunnel and Underground Space
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    • v.14 no.2
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    • pp.108-120
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    • 2004
  • Dynamic analysis has been increased recently to analyze the effect of the blasting vibration on the rock mass as well as the surrounding structures. The major input parameter far the general dynamic analysis, however, is merely the blasting pressure which can be obtained from the blasting pressure-time history curves. But in case of the complicate geological condition it is not simple to apply the blasting pressure on the numerical analysis because e ground vibration characteristics should be obtained considering the complexity of ground condition. Therefore the authors tried to use the blasting vibration waveform as an input data This vinylation frequency could be obtained from the test blasting in the Pasir mine, Indonesia. Through the dynamic numerical analysis on the slopes in Pasir, the current situation of this slope could be simulated precisely.

Prediction of Ground Blasting Vibration using Superposition Modeling Data of Single Hole Blasting Waveform (단일공 발파파형 중첩모델링 자료를 이용한 지반 진동의 예측)

  • Kim, Jong-In;Kang, Choo-Won
    • Tunnel and Underground Space
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    • v.17 no.6
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    • pp.484-492
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    • 2007
  • The blasting vibration prediction in the country is mainly carried out by using the scaled distance method. But, this method needs a real-scale test blasting. The blasting vibration prediction has been performed using the data measured at borehole blasting for the purpose of a geological investigation before beginning a construction of a tunnel. In this prediction method, it is difficult to reflect the propagation characteristics of ground vibration generated from a real-scale blasting. propagation. This paper presents a new method for estimating blasting vibration by using superposed data of single hole blasting waveform with a delay time.

An Accuracy Improvement Method on Acoustic Source Localization Using Ground Reflection Effect (지면반사효과를 이용한 폭발 소음원의 위치 추정 정밀도 향상법)

  • Go, Yeong-Ju;Choi, Donghun;Lee, Jaehyung;Choi, Jong-Soo;Ha, Jae-Hyoun;Na, Taeheum
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.1
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    • pp.69-74
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    • 2016
  • A technique for improving estimation accuracy is introduced in order to locate the impact position of artillery shell during the weapon scoring test. Study on localization of impacts using acoustic measurement has been conducted and the usability of sensor array is verified with experiments. When the blast occurs above the ground in the firing range, the acoustic sensor above the ground can measure the directly propagated sound with the ground-reflected one. In this study, a method for reducing estimation error by using the reflection signal measurements based on the time difference of arrival method. Considering the reflection sound works as same as placing a virtual sensor symmetrically through the ground. This idea enables a virtual three-dimensional array configuration with a two-dimensional plane array above the ground as such. The time difference between the direct and the reflected propagations can be estimated using cepstrum analysis. Performance test has been made in the simulation experiment in the football size area.

Experience of the Application of a Rock Cracking Method Using Steam Pressure to Tunnel Excavation (증기압을 이용한 파암공법의 현장 적용성 연구)

  • Kim, Duk-young;Kim, Sun-Woong
    • Explosives and Blasting
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    • v.35 no.2
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    • pp.1-8
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    • 2017
  • In this study, the characteristics of a new rock cracking method using steam pressure are briefly presented. The rock cracking method was originally developed as a means to decrease the ground vibrations from underground rock excavations. The validation tests were also conducted by applying the method to an actual rock tunnel under construction. The ground vibrations were measured in the vicinity of the test site. The measured vibration results were compared with the values predicted by an attenuation equation, which had been proposed by a company in Japan. Also, a simple cost assessment for the method was conducted to demonstrate its cost effectiveness in underground tunnel excavations.

A Study on the Dynamic Behavior of Concrete Dam by Shaking Table Tests (진동대 시험을 이용한 콘크리트 댐의 동적거동 특성 연구)

  • Hwang, Seong-chun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.7 s.100
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    • pp.806-812
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    • 2005
  • This paper adresses the shaking table tests with 1/100 scaled model followed similitude law for OOdam main designing section to understand nonlinear behavior characteristics of concrete dam body by ground motion. As earthquake wave, Hachinohe and El Centre waves were used and acceleration and displacements are measured to analyze behaviors of dam body. For maximum ground acceleration range $(0.3\~0.9 g)$, the results showed linear behavior regardless of maximum 9round acceleration and secured safety of structure. To analyze the behavior of dam after tension cracking, 3 cm-notch was placed at the critical section of over-flowing section. As results of applying Hachinohe wave(0.8 g), Even though tension cracks were formed at over-flowing section by Hachinohe wave(0.8 g), it showed that the dam is stable for supporting upper stream Part of water tank of dam.

Visualization of pass-by noise by means of a line array of microphones affixed to the ground (지면에 고정된 선형 마이크로폰 어레이를 이용한 pass-by 소음의 가시화)

  • Park, Soon-Hong;Kim, Yang-Hann
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1479-1486
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    • 2000
  • This paper introduces the improved moving frame acoustic holography (MFAH) method and its application. MFAH allows us to visualize the noise generated by moving noise sources by employing a vertical line array of microphones affixed to the ground. The sound field generated by moving sources is different from that of stationary ones due to the movement of the sources. Therefore the measured sound pressure by the microphone on the ground has to be processed so that it cooperates the effect of the movement. This paper discusses the effect of moving noise sources on the obtained hologram by MFAH. This assures the applicability of MFAH to the visualization of moving sources. This paper also reviews the improved MFAH that can visualize a coherent narrow band noise and a pass-by noise. The practical applicability of the improved MFAH was demonstrated by visualizing tire noise during a pass-by test.

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A Study on the Dynamic Stability of Air-to-Ground Missile Using the Free Vibration Technique (자유진동기법을 이용한 공대지 미사일의 동안정성에 관한 연구)

  • 박재현;백승욱;조환기;허원욱
    • Journal of the Korea Institute of Military Science and Technology
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    • v.2 no.2
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    • pp.61-69
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    • 1999
  • A dynamic stability test was performed to determine dynamic stability derivatives for the pure pitching motion of air-to-ground missile model in the low speed wind tunnel. The free vibration technique was employed to acquire oscillation characteristics of the model for damping coefficients. Damping coefficients are obtained by the method of logarithmic decrement. Results show good damping effects and stability capability at Mach numbers 0.1 and 0.2, with the angle of attack ranging from -15 to +20 degrees.

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Influence of Delay Time and Priming Location on the Blast-Induced Ground Vibration (발파공 사이의 지연시차와 기폭위치가 지반진동에 미치는 영향)

  • Kang, Choo Won;Ryu, Bok Hyun;Choi, Tae Hong
    • Tunnel and Underground Space
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    • v.24 no.1
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    • pp.97-109
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    • 2014
  • In order to identify the characteristics of the propagation depending on delay time (20, 25 ms) and priming location (top priming, middle priming, bottom priming), test blasts were carried out a total of 4 times using different spacing, burden, drilling length, charge per delay and was derived the formula to predict blast vibration. This study investigated the characteristics of vibration by analysis of the nomogram and prediction of Peak Particle Velocity (PPV) from delay time and priming location by the formula to predict ground vibration. And it analyzed the trends of vibration increase by standards charge 0.5, 1.6, 5, 15 kg. Standards charge is "Blasting design and construction guidelines to road construction" by the Ministry of Land, Infrastructure and Transport. Depending on the charge in favor of vibration control method is proposed. Thus, when the design was to be used as a variable.

Modelling and simulation of a closed-loop electrodynamic shaker and test structure model for spacecraft vibration testing

  • Waimer, Steffen;Manzato, Simone;Peeters, Bart;Wagner, Mark;Guillaume, Patrick
    • Advances in aircraft and spacecraft science
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    • v.5 no.2
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    • pp.205-223
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    • 2018
  • During launch a spacecraft is subjected to a variety of dynamical loads transmitted through the launcher to spacecraft interface or air-born transmission excitations in the acoustic pressure field inside the fairing. As a result, spacecraft are tested on ground to ensure and demonstrate the global integrity of the structure against these loads, to screen the flight hardware for quality of workmanship and to validate mathematical models. This paper addresses the numerical modelling and simulation of the low frequency sine and random vibration tests performed on electrodynamic shaker facilities to comprise the mechanical-borne transmission loads through the launcher to spacecraft interface. Consequently, the paper reviews techniques and methodologies to derive a reliable and representative coupled virtual vibration testing simulation environment based on experimental data. These technologies are explored with the main objectives to ensure a stable, reliable and accurate control while testing. As a result, the use of the derived simulation models in combination with the added value of improved control and signal processing algorithms can lead to a safer and smoother vibration test control of the entire environmental test campaign.