Peak Vibration Velocity Research Articles

Influence of the elevation effect of slope blasting on the vibration velocity of existing buried steel pipes.

Blasting vibration(BV) may cause the instability and damage to the surrounding structures and infrastructures, even leading to serious accident. As far as slope blasting is concerned, more and more attention has been paid to the elevation effect of BV of rock mass. However, scarce information is available on the influence of the elevation effect of slope blasting on the BV of surrounding structures, especially the existing buried pipes. As a consequence, the influence of the elevation effect of slope blasting on the BV of steel pipes was numerically investigated according to finite element model, which was verified against the experimental result. Moreover, the formula is presented to predict the peak vibration velocity (PVV) of steel pipes under slope blasting. It is found that PVV of the steel pipes has the elevation amplification effect in the terrain with positive or negative elevation difference. PVV of the pipes in the terrain with positive elevation difference is greater than that in the terrain with the same negative elevation difference. The elevation effect is more obvious under the condition of the positive elevation difference (2.1-5.1m). The modified Sadovsky's empirical formula is more suitable to predict PVV of the buried steel pipes during the slope blasting process.

Study on the Vibration Effects of Cyclic Blasting on Bridge Structures under Construction

This study investigates the impact of cyclic tunnel blasting on adjacent bridge structures under construction. Monitoring vibration velocities of the bridge deck, piers, and middle column adjacent to the Zhanma Tian Tunnel, a three-dimensional numerical model was developed using FLAC3D software, utilizing blasting vibration test data from the Zhanma Tian Tunnel project in Guizhou. Results show that, as the distance between the bridge and tunnel increases, vibration velocity at the bridge deck decreases more rapidly compared to the base of the pier. Peak vibration velocities recorded were 0.235 cm/s for the bridge deck, 0.081 cm/s for the pier base, and a predicted 0.209 cm/s for the middle column. The impact order from blasting vibrations on the bridge structure is: pier base, middle column, bridge deck. Peak vibration velocity induced by blasting ranged between 0.05 and 0.25 cm/s, within safe limits of bridge material strength. Eight daily blasting cycles do not compromise the safety of bridge structures located 43 m away.

Determination and application study of optimal delay time for tunnel millisecond blasting based on interference vibration reduction method

In tunnel excavation, blasting is widely adopted as an efficient excavation method. However, the influence of vibration on tunnel surrounding rock and support structures during the blasting process cannot be ignored. In this study, based on the background of tunnel blasting construction, we theoretically analyze the reasonable range for selecting the optimal delay time, considering the wave superposition cancellation effect and rock fragmentation effect. We use field measured single-hole waveform and calculate superimposed predicted waveforms for different delay time through linear superposition. This allows us to determine the optimal delay time; it is then validated through numerical simulation and field experiment. The results indicate that, based on the principles of interference vibration reduction and rock fragmentation, the optimal delay time in theory should be in the range of 6.14–8.06 ms. By performing superposition calculation on the measured single-hole waveforms, we determined that the optimal delay time for continuous detonation of cut-holes is 7 ms. The delay time of 7 ms falls within a reasonable millisecond range and it is consistent with the results of numerical simulation. When the optimal delay time was applied to field blasting, the measured vibration waveforms exhibited uniform distribution. Compared to blasting without delay, the peak vibration velocity of the cut-holes decreased from 2.08 cm/s to 0.20 cm/s, and the dominant frequency band shifted from 20 Hz–60 Hz to 30 Hz–120 Hz. This achieved the desired effects of reducing vibration and enhancing frequency. These findings can serve as a reference for future similar engineering projects.

Blasting Vibration Control and Signal Analysis of Adjacent Existing Deterioration Tunnels

Building a new tunnel adjacent to an existing tunnel has become a common means of transformation in engineering. Existing tunnels are prone to some deterioration, such as cavities and cracks under long-term traffic load. This kind of deterioration tunnel is prone to collapsing under the action of blasting. Therefore, the vibration caused by blasting should be strictly controlled. Based on the reconstruction project of the Bo Jiling Tunnel, this paper puts forward the method of mechanical cutting in a central position combined with an ordinary detonator to reduce blasting vibrations. ANSYS/LS-DYNA version 19.2, was used to simulate two conditions of full-section blasting and central mechanical cutting blasting. By comparing the stress and velocity of the existing tunnel, the damping effect of mechanical cutting blasting is analyzed. Via field experiments, the superiority of the mechanical cutting method in reducing blasting vibration is further discussed. At the same time, the relationship between the main vibration frequency and the peak velocity of the existing deterioration tunnel is obtained by wavelet packet analysis of the field experimental data. The frequency band energy distribution in each direction of vibration velocity is also obtained. The results show that the central mechanical cutting increases the blasting free surface, and the mechanical cutting method reduces the vibration velocity by 36.3%. The third frequency band (31.25~46.875 Hz) is the most concentrated, which is the dominant frequency band of the signal. The novelty of this paper is to propose mechanical cutting of the central hole instead of traditional blasting for existing deterioration tunnels. The feasibility of this method is verified by numerical simulation and field tests. The relationship between peak vibration velocity, band energy, and tunnel frequency is clarified, which can better control blasting vibration and ensure the safety of existing deterioration tunnels.

Discussion on the Discreteness of the Attenuation Parameters of the Peak Particle Velocity Induced by Blasting.

The research on the attenuation law of blasting vibration has become the foundation and precondition of the effective control of blasting vibration damage. Aiming at the characteristics of low frequency, low velocity, and strong amplitude of the R wave, an improved wave component separation method based on R wave suppression is proposed. Combined with the measured vibration signals of a field test, the attenuation parameters of different types of waves in the propagation process of blasting seismic waves are studied. The analysis results show that, in the process of blasting seismic wave propagation, the attenuation parameters of different types of waves are significantly different. With an increase in propagation distance, the proportion of the different types of waves will also change. The study of attenuation law with only coupled particle peak vibration velocity often showed high discreteness. The fitting correlation coefficient and prediction accuracy of peak vibration velocity without distinguishing wave modes are lower than those induced by the P wave or R wave alone, which should be attributed to the conversion of dominant wave modes in blasting vibration at different distances.

Study of BP and RBF Neural Networks Applied to the Prediction of Vibration Characteristics in Static Blasting of Dry Ice Powder

The novel dry ice powder static blasting rock breaking lacked working standards, especially for the vibration safety assessment of the construction site for the protection of the building structure, in comparison with the traditional drill and blast method which had a proven operational process and safety specifications. The Sadovsky vibration velocity prediction formula could only predict the vibration velocity and was project specific. Oscillation parameters that needed to be considered in the vibration safety assessment, such as the dominant frequency of vibration, could not be obtained through empirical formulas. Using the five parameters of hole depth, blast center distance, dry ice powder mass and rock classification as the main influencing factors, BP and RBF neural network models were constructed by Matlab software to predict the peak vibration velocity, main frequency and maximum displacement of dry ice powder blasting. Projection results revealed that it is structurally simpler than the BP neural network and that the RBF was more accurate in predicting the target than the BP network. The results of the study had significant implications for the safe application of the new technology, and more samples of field data need to be obtained in the future, along with the use of more advanced predictive modelling.

Study on the propagation and attenuation characteristics of tunnel blasting vibration waves at different blast center distances

Accurately determining the parameters of the dynamic constitutive model is significant to analyzing the dynamic response characteristics of the surrounding rock at the proximal and distal ends of a railroad tunnel blasting. Hence, this paper analyzes the propagation and attenuation of blasting vibration waves in the rock by utilizing the vibration velocity monitoring data of the Xinbin Tunnel at the Liaoning section of the Shenbai High-speed Railway. The data are provided by the drilling and blasting method. Additionally, the IA-BP inverse analysis method was established to invert the parameters of the JH-2 constitutive model of the rock by numerically analyzing the simulated blasting vibration waves using the inversion parameters. The results highlight that the inversion value obtained by the IA-BP algorithm is slightly different from the calculated test value but still highly accurate, demonstrating the rationality of the inverse analysis method. Meanwhile, the numerical simulation results supplement the proximal vibration velocity, which is difficult to monitor in the project. This is because the vibration velocity of the tunnel surrounding the rock has a noticeable directional effect. Specifically, the vibration velocity law varies as the blast center distance increases, where the peak vibration velocity direction at the far end of the blast changes from the Y direction (vertical direction) to the Z direction (blast direction). The linear attenuation formula of the vibration velocity in the three principles of the tunnel arch, arch shoulder, and arch foot is obtained by fitting, which is an adequate prediction of the safety of the subsequent construction.

Dynamic Responses of a Coupled Tunnel with Large Span and Small Clear Distance under Blasting Load of the Construction of Transverse Passage

In order to investigate the law of the dynamic responses of a coupled tunnel with a large span and a small clear distance induced by the blasting load applied on the excavation face of the new horizontal adit for vehicles, a dynamic 3D finite element model was established based on the blasting excavation project of Yonghe tunnel’s new transverse passage in Guangzhou, China. The laws of the induced vibration velocity and dynamic stress of the existing tunnel are systematically analyzed according to the numerical calculation results. The results show that the main affected area of the existing lining is the lower arch waist facing the blast, where both the maximum vibration velocity and the maximum tensile stress appear. The horizontally radial vibration velocity (along the axis of the transverse passage) is the main contributor in the resulting vibration velocity of the lining. The distributed law and varying trend of the dynamic stress of the lining are similar to the vibration velocity, and there appears to be a satisfied positive linear correlation between the two indexes. When the distance from the excavation face of the horizontal adit to the existing tunnel is 10 m, the blasting-load-induced maximal vibration velocity and dynamic tensile stress of the tunnel are only 2.96 cm/s and 0.20 MPa, respectively, which are far less than that stipulated by the related technical code. A negative power exponential relationship between the peak vibration velocity of the existing tunnel lining and the distance from the excavation face of the transverse passage to the tunnel was also found. According to this relationship, the induced vibration velocity will exceed the threshold stipulated by the standard, i.e., 8 cm/s, if the distance decreases to 5.9 m. To improve the safety redundancy of the construction, the threshold of the distance from the excavation face of the horizontal adit to the existing tunnel is suggested to be 10 m under the current construction scheme.

Vibration responses of the metro station induced by various train operations under unilateral deep excavation

Field noise tests found that the noise induced by train operation under unilateral excavation is more obvious than that without excavation. Therefore, it is necessary to explore the dynamic response characteristics of metro stations under unilateral deep excavation. Based on the Jincheng Plaza Station in China, this study simulates the impact of train vibration on the structure through a 3-D numerical model and verifies its reliability through field-measured results. Considering various train operations, the analysis is carried out from three perspectives, including time-domain analysis, frequency-domain analysis, and vibration acceleration level (VAL) analysis. The results show that unilateral excavation causes the instability of the station structure, which leads to an 80–140% amplification effect on the peak vibration velocity of the station caused by the train load. Secondly, at the location within the excavation area, the longer the train passes, the more significant the vibration amplification effect is. Thirdly, the station vibration induced by the double-sided train operation is the most significant, which makes the amplitude of frequency domain vibration enlarged by 100–140%. Notably, based on the VAL analysis, it shows that the vibration response of the metro station under excavation is the most significant when the center frequency is 40 Hz. In addition, the VAL under unilateral excavation is 4–7 dB larger than that without excavation, and the increase ratio is about 8–13%. Finally, the maximum VAL under excavation reaches 65.8 dB, which exceeds the specified threshold (52.5 dB). For metro stations with both unilateral excavation and train operation, vibration reduction measures and the lateral structural support in the excavation area should be taken to reduce the vibration response, to improve the comfort of passengers and staff.

A Study on the Surface Vibration Effect of CO2 Phase Transition Cracking Based on the Time-Domain Recursive Analysis Method

Supercritical CO2 phase change fracturing technology has been widely used in rock engineering. However, the surface vibration characteristics induced by phase change rock breaking have not been sufficiently studied. In this paper, a model for calculating the surface vibration velocity induced by supercritical CO2 phase change was established based on the time-domain recursive method, and the reliability of the model was verified using ls-dyna nonlinear finite element software; based on the model for calculating the blasting energy of a compressed gas and water vapor container, the surface vibration velocity and decay law induced by CO2 phase change fracturing and equivalent explosive blasting were compared and analyzed. The results show that the ground vibration velocity calculation model based on the time-domain recurrence method can better evaluate the ground vibration characteristics induced by supercritical CO2 phase change fracturing, and the vibration velocity decays exponentially with the fracture distance; the peak pressure of supercritical CO2 phase change is only 1/3.36 of that of explosive blasting, but the action time is 100 times longer than that of explosive blasting, and the peak vibration velocity is 1/74~1/78 of that of equivalent explosive blasting.

Determination of Blast Vibration Safety Criteria for Buried Polyethylene Pipelines Adjacent to Blast Areas, Using Vibration Velocity and Strain Data.

In order to ensure the safe operation of buried polyethylene pipelines adjacent to blasting excavations, controlling the effects of blasting vibration loads on the pipelines is a key concern. Model tests on buried polyethylene pipelines under blasting loads were designed and implemented, the vibration velocity and dynamic strain response of the pipelines were obtained using a TC-4850 blast vibrometer and a UT-3408 dynamic strain tester, and the distribution characteristics of blast vibration velocity and dynamic strain were analyzed based on the experimental data. The results show that the blast load has the greatest effect on the circumferential strain of the polyethylene pipe, and the dynamic strain response is greatest at the section of the pipe nearest to the blast source. Pipe peak vibration velocity (PPVV), ground peak particle velocity (GPPV), and the peak dynamic strain of the pipe were highly positively correlated, which verifies the feasibility of using GPPV to characterize pipeline vibration and strain level. According to the failure criteria and relevant codes, combined with the analysis of experimental results, the safety threshold of additional circumferential stress on the pipeline is 1.52 MPa, and the safety control vibration speed of the ground surface is 21.6 cm/s.

Field investigation on the impact of vehicle traffic on the vibration of ancient seawalls in Qiantang River

To investigate the vibrational impact of vehicular traffic on the ancient Qiantang River seawall, on-site measurements of the seawall’s pulsation and forced vibrations under different vehicle speeds and axle loads were conducted. The acquired data were analyzed in the time domain, frequency domain, and 1/3 octave bands, revealing the time-frequency vibrational characteristics of the ancient seawall structure. The results indicate that the characteristic frequencies of the ancient seawall are 3 Hz and 10 Hz, with the primary frequency band of the structural vibrations induced by vehicular traffic ranging from 0 to 30 Hz. Vehicle traffic primarily caused vertical vibrations in the seawall structure, with along-dike horizontal vibrations being significantly higher than cross-dike vibrations. Based on the measurement results, an empirical relationship between the peak vibration velocity of the ancient seawall and variations in vehicle speed and axle load was established. It was found that, compared to axle load, increased vehicle speed had a more pronounced amplification effect on the structural vibrations of the ancient seawall. To ensure the vibrational safety of the ancient seawall relics, maximum vehicle speeds for different loading conditions of tri-axle trucks were provided based on vibration limits: for an axle load of 10 t, speeds should be below 34 km/h; for 11.52 t, below 24 km/h; for 13.04 t, below 20 km/h; and for 14.56 t, below 15 km/h.

The influence of the number of free surfaces on the energy distribution and attenuation law of blasting vibration signals from peripheral holes: field experiment and simulation

Tunnels are commonly excavated using drilling and blasting methods, and the surrounding rock is greatly affected by the vibration of surrounding hole blasting. To study the influence of the number of free surfaces on the energy distribution and attenuation law of surrounding hole blasting vibration signals, on-site experiments and numerical simulation experiments were conducted. The research results indicate that the higher the number of free surfaces, the smaller the peak vibration velocity. The longitudinal Fourier main frequency decreases with the distance from the monitoring point. The more free surface, the greater the centroid frequency and zero crossing frequency. In addition, numerical simulation shows that the degree of rock fragmentation after blasting increases with the increase of the number of free surface of rock.

Operation characteristics of soil blasting vibration test device under vibration load

To improve the accuracy of vibration velocity monitoring during blasting in soil layers, this paper provides a method and device for data correction by combining finite element software and actual engineering test data. Based on the length of the test pedestal exposed to the surface of the geotechnical body, the finite element structural model corresponding to each length of the test pedestal is established. Moreover, a predetermined external excitation load is applied outside the finite element model and the correction function of the vibration data is obtained by analysis of the stress and vibration data. The device solves the problem of low accuracy of vibration velocity measurement in soil and establishes a correction method for measurement data. The results show the following: (1) With the propagation of blasting seismic waves, the maximum stress values of the test device appear in the footwall position, the middle of the extension rod, and the bottom position in that order. (2) At the end of the test, there is an obvious phenomenon of speed amplification at the top of the test device. (3) As the length of the test device exposed to the ground increases, the particle peak vibration velocity (PPV) of the test device varies exponentially with the PPV of the ground and the range of variation of the vibration velocity in the X-direction is the largest.

Influence of the spatial distribution of underground tunnel group on its blasting vibration response

The spatial distribution of underground tunnels is significant to the stress redistribution in the surrounding rock masses and blast wave propagation. The field blasting tests were first carried out to study the propagation of blast-induced seismic waves through underground tunnels of the Xiluodu Hydropower Station in China. The results show that the peak horizontal particle vibration velocity can be used as a safety criterion for underground tunnels. The effects of in situ stresses and spatial distributions of the tunnel group on the vibration velocities distribution is afterward investigated by numerical simulation. The results show that there is a significant amplification of the blasting vibrations in the adjacent tunnels, which depends on their vertical positions during the excavation of a tunnel. The peak vibration velocity decreases as the lateral separation between tunnels increases. When the separation between the tunnels exceeds the width of three tunnels, the impact of the blast waves on each part of the adjacent tunnel tends to be stable on the whole. In terms of the size of the tunnel, the blasting vibration velocity in the upper part of the straight wall on the front-blast side increases as the width increases (and then levels off), while the blasting vibration velocity in the lower part decreases as the width increases (and then levels off). Finally, a generalized formula of blasting vibration velocity considering the spatial distribution is established, which can well predict the vibration velocity of particles in underground tunnels.

Dynamic Response and Failure Mechanism of Deep-Buried Tunnel with Small Net Distance under Blasting Load

Under blasting load, a series of safety problems, such as lining cracking and surrounding rock instability, are prone to occur in deep-buried tunnels with a small net distance. It is significant to understand the dynamic response and failure mechanism of tunnels under blasting. The blasting attenuation formula is optimized through theoretical analysis and field experiments. The measuring point vibration is monitored in real time and the tunnel blasting model is established by ANSYS/LS-DYNA software. The model was set as having no reflective boundary and an uncoupled charge structure was used. The attenuation law of blasting seismic waves is studied from the adjacent tunnel lining and the direction of the tunnel cross-section and length. The inner and outer sides of the tunnel lining are investigated, respectively. The displacement and acceleration of lining measuring point are also analyzed. The dynamic response of the tunnel lining under blasting excavation is analyzed from multiple angles. The results show that the arch foot on the inner side of the lining (the side in contact with the tunnel headroom) is the first to generate vibration. On the outside of the lining (the side in contact with the rock),the peak vibration velocity is reached after blasting load unloading. There is little difference in the vibration velocity at different positions of the transverse section, but great difference in the vibration velocity of the longitudinal section. The influence of the horizontal displacement was greater than that of the vertical displacement. The vibration acceleration of the measuring point at the arch foot of the section is the largest and the detonation is also the largest.

Vibration safety evaluation and vibration isolation control measures for buried oil pipelines under dynamic compaction: A case study

As a common treatment method to improve the bearing capacity of soft soil sites, the strong impact vibration generated by dynamic compaction (DC) has adverse effects on the surrounding environment and adjacent structures. In this paper, a series of in-situ tests were conducted to evaluate the vibration safety of adjacent buried oil pipelines under DC shock. The vibration responses and attenuation rules of the site were analyzed. Meanwhile, a numerical method was employed to discuss and determine the minimum tamping distance and rational parameters for isolation trench. Furthermore, the vertical peak vibration velocity index was used to evaluate the vibration safety of the pipeline under DC load. The results show that the vibration response of the site is manifested as vertical vibration and horizontal vibration, while the vibration response of the buried pipeline is dominated by vertical vibration. The empty trench can block the propagation of vibration waves effectively, in which the depth and its distance to the ramming point are the main factors affecting the vibration isolation effect. The vibration isolation effect of the trench increases with the increase of trench depth and the decrease of the distance from the tamping point. The study proposed parameters for an empty trench with a depth of 5 m and a safety distance of 5 m from the compaction point for the final ground treatment scheme. Good results have been achieved in engineering practice. The analysis results provide new ideas and references for promoting the application of underground pipeline vibration protection technology in DC ground treatment.

Prediction of Tunnel Blasting Vibration Velocity Considering the Influence of Free Surface

The blast vibration attenuation will change as the tunnel cut hole is blasted to create a new free surface. To guarantee safe tunnel construction and optimize blast design parameters, it is crucial to understand the impact of the free surface on blast vibration attenuation. Previous studies have often only qualitatively evaluated the effect of the free surface on blast vibration, failing to quantify these impacts on vibration attenuation. In this paper, by analyzing the decay law of the blast vibration velocity under different free surfaces, we quantitatively assessed the effect of the number of free faces and burden distance on the peak vibration velocity. Then, we introduced free-face parameters to enhance the current formula for predicting blast vibration velocity. The results show that the peak vibration velocity decreases with the increasing free surface number and increases with increasing burden distance; the free surface factor cannot be ignored in the decay of vibration velocity and contributes about 21% more to the total decay factor than the scale distance factor. The average tolerance rises from 24.79% in the Sadovsky formula to 13.32% in the correction formula, and the correction formula more precisely predicts the peak vibration velocity. The accuracy of the correction formula provides a good scientific basis for the design of tunnel blasting parameters. The research results were successfully applied to the Jiujiawan proximity tunnel on the Duyun-Anshun highway in Guizhou, effectively guaranteeing blasting safety with a minimum clear distance of 17.2 m.

Study on Blasting Vibration Control of Brick-Concrete Structure under Subway Tunnel

In order to study the impact of the blasting vibration of subway tunnels on adjacent buildings, taking the tunnel mining method construction of the section between Zhifang Street Station and Metro Town Station of Wuhan Metro Line 27 as the engineering background, the blasting scheme is optimized by reducing the maximum single section charge, multi-section and densifying the surrounding holes. The HHT method and wavelet analysis are used to evaluate the advantages and disadvantages of the optimization scheme from the perspective of energy. The results show that the peak velocity of the blasting vibration is significantly reduced and the frequency is significantly increased after the blasting scheme is optimized. After the blasting scheme is optimized, when the working face is directly below the external wall of the building, the peak vibration velocity is the largest; from the back of the working face to the front of the working face, the peak velocity of the surface particle vibration first increases and then decreases. The frequency band of the optimized blasting vibration signal energy distribution is wider and the energy is more dispersed. This study can provide some practical experience for the design and construction of similar projects.

Study on dynamic response and safety control of reinforced concrete rigid frame structure under foundation pit blasting

Subway station is usually located in the dense area of urban buildings (structures). The blasting construction of subway station foundation pit is bound to have adverse effects on adjacent buildings (structures). Therefore, it is necessary to study the dynamic response of the building (structure) and propose the safety threshold of vibration velocity. Based on the foundation pit blasting project of Hejialong Station of Wuhan Rail Transit Line 12, the vibration monitoring of the field blasting test is carried out. Combined with LS-DYNA numerical simulation software, the dynamic response characteristics of a reinforced concrete rigid frame natatorium near the foundation pit are studied, and safety thresholds for structural vibration velocities are derived. It is worth noting that the structure is a large span reinforced concrete rigid frame structure, which is different from the general reinforced concrete frame structure. The safe allowable vibration velocity in the specification is not fully applicable to the structure. Therefore, it is necessary to focus on the dynamic response of the structure under the blasting effect and propose the safety threshold of structural vibration velocity, which can provide reference for the subsequent foundation blasting. The results are as follows: Blasting seismic waves in different propagation media, their energy attenuation is different. By analyzing the vibration velocity of reinforced concrete rigid frame structures, it is found that the high-level amplification effect occurred at specific height range. In addition, the vibration velocity changes abruptly at the parts where the shape and dimensions of the rigid frame cross-section change. The peak vibration velocity and the maximum principal stress of the concrete elements were statistically analyzed to obtain the linear relationship equation, and the vibration velocity safety control threshold of the structure was predicted to be V = 5.089 cm/s.