scholarly journals Hollow Effect of Ground Vibration Induced by Electronic Detonator in Shallow Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Weijie Ding ◽  
Bei Jia ◽  
Dianshu Liu
Keyword(s):  
Field Experiments ◽  
Optimal Parameter ◽  
Ground Vibration ◽  
Dominant Frequency ◽  
Tunnel Construction ◽  
Shallow Tunnel ◽  
Horizontal Distance ◽  
Mode Decomposition ◽  
Blasting Excavation ◽  
Electronic Detonator

Blasting excavation is extensively used in tunnel construction, and the adverse effect of ground vibration induced by blasting on surrounding structures and inhabitants is a critical problem. This study aims to investigate the tunnel hollow effect on triaxial peak particle velocities (PPV) and dominant frequencies induced by electronic detonator. Field experiments were conducted in a shallow tunnel construction site and the ground vibration waveforms were recorded. Variational mode decomposition (VMD) was applied to denoise and correct the zero-drift phenomenon, and the proposed method of selecting the optimal parameter was verified. A series of statistical analyses and tests were performed to evaluate the differences of peak particle velocity and dominant frequency among various monitoring points. The results showed that the hollow effect on Z-axis PPV is significant, and triaxial PPV is also affected when the horizontal distance exceeds 30 m. The hollow effect on dominant frequency could not be identified since the hollow of tunnel is a free face, and the dominant frequency of reflected wave remains unchanged. An augmented factor of 1.229 is determined carefully as the hollow effect factor on PPV. Therefore, blasting vibration induced by electronic detonator of the excavated zone should be attached with greater importance, and hollow effect on PPV should be considered in the blasting design of tunnel excavation.

Study on the Blasting Excavation Method of Urban Shallow Tunnel

2014 ◽  
Vol 580-583 ◽  
pp. 1051-1055 ◽  
Author(s):  
Zi Qiang Li ◽  
Zheng Li
Keyword(s):  
Careful Consideration ◽  
Tunnel Construction ◽  
Shallow Tunnel ◽  
Railway Transport ◽  
Residential Areas ◽  
Construction Methods ◽  
Blasting Excavation ◽  
Core Soil ◽  
Shallow Buried Tunnel ◽  
The City

The construction method requires careful consideration in order to reduce impact of tunnel on the surface of the building in the city. It can have great significance in choosing appropriate blasting excavation method for the poor surrounding rock conditions and complicated ground constructions of shallow buried tunnel. This paper combines the Guanhui urban railway transport projects which the shallow buried tunnel through the dense residential areas, research on the influence of CD method and bench method with reserved core soil when use blasting excavation method on the surface buildings by finite element method. The suitability of two kinds of blasting excavation method in the urban shallow tunnels is analyzed and compared, eventually determine the CD method with blasting excavation is more suitable for the urban shallow tunnel construction, it provides reference and suggestion for future similar construction methods that tunnel construction under the city.

Utilization of Waste Tires to Reduce Railroad Vibration

2007 ◽  
Vol 544-545 ◽  
pp. 637-640 ◽  
Author(s):  
Sam Deok Cho ◽  
Jin Man Kim ◽  
Ju Hyong Kim ◽  
Kwang Wu Lee
Keyword(s):  
Field Experiments ◽  
Field Model ◽  
Ground Vibration ◽  
Dominant Frequency ◽  
Vibration Source ◽  
Railroad Transport ◽  
Waste Tires ◽  
Waste Tire ◽  
Tire Chips ◽  
Reduction Effect

This study proposes a means to recycle waste tires as a material to reduce ground vibration. A series of field experiments was carried out to assess the reduction effect of railroad transport vibration by utilizing waste tire chips. The ground vibration during the railroad transport operation was measured in two railroad lines to investigate the vibration characteristics prior to field model tests. Test results showed that the frequency of vibration induced by railroad transport ranged from 5Hz to 100Hz, while the dominant frequency was within the range of 20Hz to 40Hz. A series of field model test was carried out by using tire chips (5cm×5cm in size) as a reduction material for railroad vibration. The field experiment results showed that the reduction effect of waste tires for railroad vibration increased with increasing thickness of the waste tire layer and increasing frequency of the vibration source. From these experimental results, it can be concluded that waste tires can be recycled effectively for reduction of railroad.

Design and Evaluation of the Key Units in a Rapeseed Direct Seeder Integrated with Plowing-Rotating Combined Tillage

2021 ◽  
Vol 37 (6) ◽  
pp. 1005-1014
Author(s):  
Guoliang Wei ◽  
Qingsong Zhang ◽  
Biao Wang ◽  
QingXi Liao
Keyword(s):  
Field Experiments ◽  
Optimal Parameter ◽  
Structural Parameters ◽  
List Type ◽  
Oil Crops ◽  
Orthogonal Experiments ◽  
Heavy Soil ◽  
Tillage Depth ◽  
Working Parameters ◽  
Orthogonal Field

HighlightsThe seeder combined the plowing and rotating tillage to overcome the heavy soil and a large amount of straws.The plow could lift and turn the soil and straw before rotary tillage.The optimal working parameters of the seeder were obtained by orthogonal field experiments.Abstract. Rapeseed, one of the most important oil crops in China, is mainly planted in the mid-lower reaches of the Yangtze River. However, limited by the special long-term rice-rapeseed rotation, rotary tillage is applied in most of the planted areas apply instead of plow tillage, leading to a shallow arable layer. On the other hand, maintaining a high-quality seedbed for rapeseed becomes a challenge because a large amount of straw remains buried in the soil. As a solution, a rapeseed direct seeder that combines plow tillage and rotary tillage was designed. The structure of the plowing unit, whose key components were a lifting-turning plow and symmetrical plow, was analyzed based on the forming principle of the plow. Furthermore, a mechanical soil throwing model of the rotary tillage blade was built to determine the structural parameters. Then, the interaction between the rotary tillage unit and the lift-turning plow was analyzed. Finally, the performance and optimal parameters were evaluated by orthogonal field experiments. The seedbed after the operations indicated that the seeder could achieve the function of turning the soil and straw first and then rotating the soil with good passability, mixing the straw and the soil, flattening the surface of the seed bed, and stabilizing the tillage depth. Orthogonal experiments showed that the optimal working parameters of the seeder were as follows: the tillage depth was 180 mm, the equipment forward speed was 2.1 km/h, and the speed of the rotary tillage blade was 250 r/min. Under the optimal parameter combination, the power consumption of the seeder, the thickness of the tillage layer, the crop residue burial efficiency, the soil breakage efficiency, and the flatness of the seed bed surface were 30.48 kW, 231 mm, 90.88%, 93.26%, and 21.15 mm, respectively. The working performance of the seeder could meet the tillage requirements of rapeseed planting. Keywords: Direct seeder, Evaluation, Plow, Plowing-rotating combined tillage, Rapeseed.

scholarly journals Refactoring and Optimization of Bridge Dynamic Displacement Based on Ensemble Empirical Mode Decomposition

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3125
Author(s):  
Zou ◽  
Chen ◽  
Liu
Keyword(s):  
Empirical Mode Decomposition ◽  
Field Experiments ◽  
Low Frequency ◽  
Vibration Signal ◽  
Micro Electro Mechanical System ◽  
Ensemble Empirical Mode Decomposition ◽  
Reconstruction Method ◽  
Monitoring Methods ◽  
Dynamic Displacement ◽  
Mode Decomposition

Considering the lack of precision in transforming measured micro-electro-mechanical system (MEMS) accelerometer output signals into elevation signals, this paper proposes a bridge dynamic displacement reconstruction method based on the combination of ensemble empirical mode decomposition (EEMD) and time domain integration, according to the vibration signal traits of a bridge. Through simulating bridge analog signals and verifying a vibration test bench, four bridge dynamic displacement monitoring methods were analyzed and compared. The proposed method can effectively eliminate the influence of low-frequency integral drift and high-frequency ambient noise on the integration process. Furthermore, this algorithm has better adaptability and robustness. The effectiveness of the method was verified by field experiments on highway elevated bridges.

scholarly journals HHT based analysis on seismic response recordings for a base-isolated building

2019 ◽  
Vol 277 ◽  
pp. 02021
Author(s):  
Fei Wang ◽  
Xiandong Kang ◽  
Ting Yan ◽  
Ying Liu
Keyword(s):  
Seismic Response ◽  
Dominant Frequency ◽  
Data Series ◽  
Structural Systems ◽  
Original Signal ◽  
Intrinsic Mode Functions ◽  
Hilbert Huang Transform ◽  
Mode Decomposition ◽  
Frequency Components ◽  
Emd Method

Hilbert-Huang transform (HHT) is proposed to process the seismic response recordings in an 8-story frame-shear wall base-isolated building. Empirical Mode Decomposition (EMD) method is first applied to identify the time variant characteristics and the data series can be decomposed into several components. Hilbert transform is well-behaved in identifying the frequency components. The first 5 intrinsic mode functions (IMFs) are decomposed with their different frequencies. The analytical function is reconstructed and compared with the original signal. They are extremely consistent in amplitude and phase. Based on the IMFs obtained, frequencies of the original signal are inferred at 5 Hz and 1.6 Hz. The higher frequency is regarded as the vibration excited by surface waves. 1.6 Hz is suggested as the dominant frequency of the building. Analysis indicates that HHT is accurate in extracting the dynamic characteristics of structural systems.

scholarly journals Assessment of Lift Passenger Comfort by the Hilbert–Huang Transform

2019 ◽  
Vol 8 (2) ◽  
pp. 373-380 ◽  
Author(s):  
Kamil Szydło ◽  
Piotr Wolszczak ◽  
Rafał Longwic ◽  
Grzegorz Litak ◽  
Mieczysław Dziubiński ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Human Body ◽  
Dominant Frequency ◽  
Health Condition ◽  
Passenger Comfort ◽  
Hilbert Huang Transform ◽  
Mode Decomposition ◽  
Resonance Frequencies ◽  
As Stress ◽  
The Hilbert Transform

Abstract Purpose The comfort of lift passengers has a significant effect on their general health condition as well as stress levels during travel. This study reports the results of vibration measurements taken during travel in a passenger lift. Methods Vibration signals were analyzed by the empirical mode decomposition method and the Hilbert transform. Results Selected modes from the Hilbert spectral analysis were compared with the resonance frequencies of human body organs (range 20–90 Hz) as well as with the resonance frequencies of lift components. Conclusion The use of Hilbert spectral analysis enables the isolation of individual signal components and the determination of the dominant frequency in the signal. This, in turn, allows for the isolation of raw vibration frequencies from the signal that are particularly significant for passenger comfort assessment (resonance frequencies of human body organs) and analysis of their occurrence.

Geometrical considerations in the acquisition of borehole interferometric data for imaging near-vertical features: Design of field experiments

Geophysics ◽  
2013 ◽  
Vol 78 (3) ◽  
pp. K1-K10 ◽  
Author(s):  
Emma Brand ◽  
Charles Hurich ◽  
Sharon Deemer
Keyword(s):  
Stationary Phase ◽  
Field Experiments ◽  
Hard Rock ◽  
Critical Role ◽  
Seismic Profile ◽  
Dominant Frequency ◽  
Critical Parameters ◽  
Seismic Interferometry ◽  
Surface Source ◽  
Major Factors

Seismic interferometry applied to walkaway vertical seismic profile data has significant potential for imaging the steeply dipping structures often encountered in hard-rock minerals exploration. Using the interferometry process, surface shots can be redatumed to the borehole receivers resulting in virtual shot gathers. The virtual shot gathers can then be processed using a standard common midpoint (CMP) processing flow. Carrying out this procedure for a subvertical borehole results in a geometry that is optimal for imaging structures that are near vertical. Field acquisition parameters play a critical role in recovering reliable virtual source images. We evaluated the major factors that play a role in designing a field acquisition program with the objective of providing guidance to field practitioners. The major issue to be considered is insuring that correlation gathers created in the interferometry process have a stationary phase component that when summed produces events with correct timing and cancellation of nonstationary components. Consistent with previous work, the ray-tracing-based analysis identified the surface source spacing, surface source aperture, and dominant frequency as the most critical parameters. The analysis indicated that because of the high apparent velocities typically encountered in hard rock terrains, a surface source spacing of 20 m and an aperture of 1000 m will result in stationary phase components and avoid spatial alias in the correlation gathers for frequencies as high as 80 Hz. However, closer spacing of the surface sources provided more traces in the correlation gathers resulting in fewer artifacts during summation. These results were further verified by acoustic wave modeling that provided data from more complex targets that were processed through a complete interferometry and CMP flow. The analysis indicated that with care in designing field acquisition parameters, seismic interferometry is realizable within the terrain and access restrictions imposed by many mining camps.

Prediction of shear strain induced by blasting waves in surface structures based on coupled frequency, velocity, and displacement effects

2020 ◽  
pp. 107754632093525
Author(s):  
Reza Nateghi ◽  
Kamran Goshtasbi ◽  
Hamid Reza Nejati
Keyword(s):  
Response Spectrum ◽  
Simple Procedure ◽  
Structural Response ◽  
Ground Vibration ◽  
Horizontal Displacement ◽  
Dominant Frequency ◽  
Rock Formations ◽  
Frequency Peak ◽  
Geological Conditions ◽  
Relative Stress

Blasting ground vibration is an undesirable side effect of using explosives to fragment rocks. There is not any universally accepted standard to determine limitations of blast vibrations; however, velocity is the most commonly used method to measure ground vibrations. Because the structural response is highly frequency dependent, the frequency content is an essential characteristic of blast-induced shock waves along with the velocity. The magnitude of blast-induced displacement or velocity and their relative stress and strain are directly related to the quantity of charge, distance from blasting point, and geological conditions. These effects were not considered in the response spectrum theory of structures. This article tries to propose a new procedure to predict the shear displacement and relative strain for optimization of blasting patterns before the explosion. It can be accomplished by representing the effects of both velocity and frequency on the horizontal displacement of the structures based on measurements undertaken by the authors in two different rock formations. In this study, collected data were analyzed statistically to determine the coupled effects of dominant frequency, peak particle velocity, and peak particle displacement to propose a simple procedure for predicting the range of blast-induced displacement and related strain in structures.

Experimental Evaluation of Vibration Effects Induced by Planed Railway Line on Surrounding Historic Tower

2014 ◽  
Vol 501-504 ◽  
pp. 861-866
Author(s):  
Yuan Tian ◽  
Nan Zhang ◽  
Wei Guo Yang ◽  
Jia Ming Niu
Keyword(s):  
Field Experiments ◽  
Dominant Frequency ◽  
Vibration Velocity ◽  
Vibration Source ◽  
Vibration Level ◽  
Frequency Range ◽  
Structural Vibrations ◽  
Upward Trend ◽  
Railway Line ◽  
Different Types

Using field experiments, the vibration effects of historic tower induced by planed railway line are estimated. The vibrations include the construction vibration and the traffic-induced vibration. The results show that the blasting construction leads to the significant increase in vertical velocity and acceleration. There is no difference between the background vibration of field and foundation of tower. Different types of the sites soil around the tower cause little change. Each measurement time showed an upward trend of vibration level with the increase of frequency. The closer the tower is to the vibration source, the larger the structural vibrations would be. The dominant frequency range for highway-induced vibration is 10-20Hz. For train-induced vibration, the dominant frequency range is more than 40Hz. Surface waves will result in amplification phenomenon of vibration velocity of ancient structures within a certain range.

scholarly journals Time-Frequency Characteristics Analysis on Vibration Signals of a Three-Supported Rotor System with Misalignment

2011 ◽  
Vol 2-3 ◽  
pp. 717-721 ◽  
Author(s):  
Xiao Xuan Qi ◽  
Mei Ling Wang ◽  
Li Jing Lin ◽  
Jian Wei Ji ◽  
Qing Kai Han
Keyword(s):  
Wavelet Packet ◽  
Vibration Signal ◽  
Dominant Frequency ◽  
Intrinsic Mode Functions ◽  
Time Frequency ◽  
Mode Decomposition ◽  
Reconstructed Signal ◽  
Characteristics Analysis ◽  
Novel Method ◽  
Misalignment Fault

In light of the complex and non-stationary characteristics of misalignment vibration signal, this paper proposed a novel method to analyze in time-frequency domain under different working conditions. Firstly, decompose raw misalignment signal into different frequency bands by wavelet packet (WP) and reconstruct it in accordance with the band energy to remove noises. Secondly, employ empirical mode decomposition (EMD) to the reconstructed signal to obtain a certain number of stationary intrinsic mode functions (IMF). Finally, apply further spectrum analysis on the interested IMFs. In this way, weak signal is caught and dominant frequency is picked up for the diagnosis of misalignment fault. Experimental results show that the proposed method is able to detect misalignment fault characteristic frequency effectively.

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