scholarly journals The Vibration Characteristics of Ground of Rock Blasting in Silt-Rock Strata

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Tao Yin ◽  
Chuanbo Zhou ◽  
Changqing Zheng ◽  
Jugen Fu ◽  
Ziru Guo
Keyword(s):  
Dominant Frequency ◽  
Vibration Energy ◽  
Vibration Velocity ◽  
Distribution Characteristics ◽  
Rock Blasting ◽  
Rock Stratum ◽  
Frequency Bands ◽  
Tunnel Section ◽  
Geological Conditions ◽  
Rock Strata

As the shield section passes through the silt-rock strata, the rock stratum of the tunnel section has to be blasted into blocks in advance, and the diameter of the blocks should be less than 30 cm after breaking, and then, the blocks could smoothly enter the soil cabin through the opening of the tunnel boring machine (TBM) cutter head and finally be discharged through the screw machine. The geology of rock blasting in silt-rock strata is complex, and the vibrations caused by blasting threaten the safety of buildings around the blasting area. According to the measured data of blasting vibrations at the sites, the waveform duration of vibration acceleration and the distribution characteristics of dominant frequency of vibration velocity were analyzed, the energy characteristics of vibration velocity were researched by wavelet analysis, and the attenuation laws of vibration velocity were studied by dimensional analysis (DA). The dominant frequency bands of vibration energy of ground are in the range of 0–15.625 Hz, and the distribution characteristics of frequency bands of vibration energy in different directions of the ground are similar to each other, but the energy magnitude is different from each other. The research results could provide a reference for the safe blasting distance of buildings under similar geological conditions.

scholarly journals An Experimental Investigation of Moisture-Induced Softening Mechanism of Marble Based on Quantitative Analysis of Acoustic Emission Waveforms

2019 ◽  
Vol 9 (3) ◽  
pp. 446
Author(s):  
Huang Yiming ◽  
Deng Jianhui ◽  
Zhu Jun
Keyword(s):  
Acoustic Emission ◽  
Dominant Frequency ◽  
Uniaxial Compression Test ◽  
Test Results ◽  
Frequency Bands ◽  
Softening Mechanism ◽  
Final Failure ◽  
Shear Failures ◽  
Microcosmic Mechanism ◽  
Ae Signals

The decrease of strength after saturation of rocks is known as moisture-induced softening. To date, there are numerous studies on the mechanism of moisture-induced softening of different rocks. However, due to a lack of effective observational methods, the microcosmic mechanism of moisture-induced softening still needs to be understood. We collected and processed acoustic emission (AE) signals during the uniaxial compression test of marble specimens. The results of spectral and statistical analysis show that two dominant frequency bands of AE waveforms exist regardless of the specimen’s water content. Additionally, for the AE signals from the saturated specimens, the ranges of the low and high frequency bands are wider than dried rock samples. Besides, since the tensile and shear failures in the rock release low and high dominant frequency AE signals, respectively, the test results of this paper show that micro-shear and micro-tensile failures dominate the final failure of dried and saturated rocks, respectively.

Analysis on the Mechanical Behavior of Pipe Roof and Rock Bolt of Shallow and Unsymmetrical Tunnel in Soft Rock

2012 ◽  
Vol 443-444 ◽  
pp. 267-271
Author(s):  
Xu Dong Cheng ◽  
Peng Ju Qin
Keyword(s):  
Soft Rock ◽  
Surrounding Rock ◽  
Mechanical Behaviors ◽  
Maximum Displacement ◽  
Tunnel Excavation ◽  
Finite Element Software ◽  
Highway Tunnel ◽  
Geological Conditions ◽  
The Impact ◽  
Rock Strata

In this paper, the mechanical behaviors of pipe roof and bolt of shallow and unsymmetrical tunnel in soft rock are analyzed. Through the finite element software Phase2.0, combined with the geological conditions that construction site often appear, the mechanical behaviors of pipe roof and bolt and surrounding rock in the process of horseshoe highway tunnel construction in the condition that surface is soft rock and underground for the bedrock are analyzed. Research results show that: after tunnel excavation in soft rock, surrounding rock near the tunnel is easy to suffer soft-rock large deformation even failure, which needs to timely support；Due to the impact of the unsymmetrical tunnel, the mechanical behaviors of surrounding rock are unsymmetrical, such as the maximum displacement of tunnel around 0.4 m distant from apex of arch ring, the stress is asymmetrical on both sides of the tunnel arch ring etc; In addition, pipe roof can effectively prevent from the displacement of soft rock strata, improve tunnel strength factor, reduce the plastic zone of surrounding rock. This paper provides theoretical basis for the design of pipe roof and bolt.

scholarly journals Construction Technology of Composite Cofferdam for Main Pier Bearing Platform of Dongjiang Lichuan Bridge

2020 ◽  
Vol 165 ◽  
pp. 04047
Author(s):  
Jianping Wang
Keyword(s):  
Steel Sheet ◽  
Economic Benefits ◽  
Construction Technology ◽  
High Quality ◽  
Rock Stratum ◽  
Advantages And Disadvantages ◽  
Construction Methods ◽  
Bored Pile ◽  
Geological Conditions ◽  
Pile Cap

Dongjiang Lichuan Bridge in Dongguan City is a curved tower curved beam cable-stayed bridge with a main span of 138m and no back cable. The main pier cap is located on the bank slope of Dongguan Waterway on one side of Nandi Road. The cushion cap is dumbbell type, and the left and right cushion caps are connected by tie beams. In most areas, the top of rock stratum is above the bottom of bearing platform. The rock stratum within the buried depth of bearing platform is moderately to strongly weathered argillaceous siltstone. The geological conditions are complex and the construction is difficult. In line with the principles of speeding up the construction process and improving economic benefits, comprehensive analysis and weighing advantages and disadvantages, the main pier cap adopts a composite cofferdam of filling soil to build an island and combining bored pile rows and steel sheet piles. The construction task of bearing platform of main pier has been completed with high quality. Compared with other cushion cap construction methods, this construction method has the advantages of fast construction, high quality, simple safety, energy saving and environmental protection. This paper briefly introduces the design scheme of composite cofferdam, expounds in detail the operation steps of steel sheet pile construction and the problems needing attention in construction, and provides good reference experience for similar pile cap construction.

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 Vulnerability Of The Garut District Region In Tarogong Kalam, Tarogong Kidul, Garut Kota, And Karang Pawitan Sub-District Based On Microtremor Measurement

2020 ◽  
Vol 11 (1) ◽  
pp. 11
Author(s):  
Rahmat Setyo Yuliatmoko
Keyword(s):  
Seismic Vulnerability ◽  
Vulnerability Index ◽  
Dominant Frequency ◽  
Mitigation Measures ◽  
Ratio Method ◽  
Tectonic Earthquake ◽  
Wave Amplification ◽  
Geological Conditions ◽  
Microtremor Measurement ◽  
The Impact

The Tasikmalaya M 7.3 earthquake on September 2, 2009 had an impact on Garut, damaged infrastructure and claimed many lives. From the search results there were five areas that were severely damaged by tectonic earthquake shocks, which included Pemeungpeuk, Cisompet, Cikelet, Peundeuy and Banjarwangi Subdistricts, so that earthquake mitigation measures were needed. One of the mitigations that can research how the impact is if the potential for earthquake disasters occur below the southern surface of Java. The final objective of this research is to map disaster-prone zones in Tarogong Kaler, Tarogong Kidul, Garut City, and Karang Pawitan, Garut Subdistrict, based on dominant frequency values, Vs30, seismic vulnerability indexes, and GSS (Ground Shear Strains) so that they can know the land movement that is. Retrieval of data in this study by measuring geophysicaly methods in the field. Processing data using HVSR (Horizontal to Vertical Spectra Ratio) method, then mapped with ArcGis to interpret the zoning of the study area. Based on the research, we known that the dominant frequency distribution value is between 1-5.2 Hz. The seismic vulnerability index values calculated the study area are between 3 – 45, GSS values in the study area between 3 ×10-4 - 42×10-4. By looking at the spatial distribution of the values of f0, Kg and GSS the areas of Karangmulya, Jatiasih, Sidanggalih and Godog villages are types of young volcanic sediments classified as soft soils that are easily to wave amplification and earthquake vibrations, so that they are easily damaged during large earthquakes. in this region qualify as earthquake resistant buildings to minimize damage and losses, while Sukabakti, Kersamenak, Sukajaya, and Mekargalih villages in the west with the geological conditions of the surrounding area which is hard land so that it will be safer when an earthquake occurs.

scholarly journals Quantitative Eeg as a Biomarker in Mild Cognitive Impairment With Lewy Bodies

2020 ◽  
Author(s):  
Julia Schumacher ◽  
John-Paul Taylor ◽  
Calum A. Hamilton ◽  
Michael Firbank ◽  
Ruth A. Cromarty ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Lewy Bodies ◽  
Quantitative Eeg ◽  
Dominant Frequency ◽  
Alpha Power ◽  
Healthy Controls ◽  
Operating Characteristics ◽  
Frequency Bands ◽  
Beta Power

Abstract Objectives:To investigate using quantitative EEG (1) differencesbetween patients with mild cognitive impairment with Lewy bodies (MCI-LB) and MCI with Alzheimer’s disease (MCI-AD) and (2) its utilityas a potential biomarker for early differential diagnosis.Methods:We analyzed eyes-closed, resting state, high-density EEG data from highly phenotyped participants (39 MCI-LB, 36 MCI-AD, and 31 healthy controls). EEG measures included spectral power in different frequency bands (delta, theta, pre-alpha, alpha, and beta), theta/alpha ratio, dominant frequency, and dominant frequency variability.Receiver operating characteristics (ROC) analyses were performed to assess diagnostic accuracy.Results:There was a shift in power from beta and alpha frequency bands towards slower frequencies in the pre-alpha and theta range in MCI-LB compared to healthy controls. Additionally, dominant frequency was slower in MCI-LB compared to controls. We found significantly increased pre-alpha power, decreased beta power, and slower dominant frequency in MCI-LB compared to MCI-AD. EEG abnormalities were more apparent in MCI-LB cases with more diagnostic features.There were no significant differences between MCI-AD and controls. In the ROC analysis, beta power and dominant frequency showed the highest area under the curve values of 0.71 and 0.70, respectively. While specificity was high for some measures (up to 0.97 for alpha power and 0.94 for theta/alpha ratio), sensitivity was generally much lower. Conclusions:Early EEG slowing is a specific feature of MCI-LB compared to MCI-AD.However, there is overlap between the two MCI groups which makes it difficult to distinguish between them based on EEG alone.

scholarly journals Ensuring Seismic Safety of Underground Mines During Blasting Operations in Combined Surface-Underground Deposit Development

2020 ◽  
Vol 174 ◽  
pp. 01016
Author(s):  
Aleksey Novinkov ◽  
Sergey Protasov ◽  
Pavel Samusev
Keyword(s):  
Experimental Data ◽  
Coal Mines ◽  
The State ◽  
Industrial Safety ◽  
Underground Mines ◽  
Open Pit ◽  
Vibration Velocity ◽  
Seismic Safety ◽  
Experimental Data Processing ◽  
Geological Conditions

At present, there are no standard methods for assessing seismic safety of underground mines during blasting on the earth’s surface. The need for such assessments arises when underground mines are located near open-pit coal mines, when the mine fields development is continued into the open pit, and when open surface coal mines use highwall miners. The issues of assessing seismic safety can be complicated by the lack of experimental data on vibration parameters, for example, if the answer is already required at the stage of new mines designing. The paper also provides an analysis of experimental data, including the results of monitoring the state of underground mines during seismic impacts of varying degrees of intensity. It is shown that the spread of the observed PPV, at which local damage or deformation of the underground mines has taken place, attains high values. In the absence of such data for underground mines in specific mining and geological conditions, it is recommended that the maximum allowable PPV vпр be assigned taking into account the class of underground mines and the type of support. At the same time, it is noted that the recommended vпр values given in the literature relate to the openings that were driven in the solid without geological disturbances and anomalies; not deviating from regulatory requirements regarding the state of workings; in the absence of danger of groundwater breakthrough; in the absence of danger of gas-dynamic phenomena, and other negative factors. If this is not the case, according to the requirements of the Federal norms and rules of industrial safety, the seismic safety distance should be increased by 2 times. This requirement is equivalent to multiplying the maximum permissible vibration velocity by a decreasing coefficient k=2b, where the power of two is the regression parameter b obtained from the experimental data processing.

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