Papers by Keyword: Vibration Velocity

Abstract: Relying on the construction of a deep underground reservoir, vibration effects of ground were studied from two aspects: the peak value of vibration velocity and the basic frequency of blasting seismic waves, and were compared with the blasting vibration effect on the flat terrain surface. Research shows that blasting seismic wave’ impact on the surrounding building is relatively small because of its high frequency for the blasting excavation of underground reservoir. The frequency distribution in vertical and horizontal direction with scaled distance is roughly the same. And the peak value of vibration velocity in vertical direction is greater than that in horizontal direction, so blasting vibration effect in vertical direction is bigger than that in horizontal direction.

Abstract: By taking practical engineering cases as an example, this article judges the safety distance affected by ultrahigh energy dynamic compaction. Through the organization and analysis of the data of several ultrahigh energy dynamic compaction projects, the opinion that the judgment method of vibration acceleration exists flaws is proposed. Considering the possible influence of dynamic compaction vibration on person and other non-buildings, it suggests to use the method of vibration velocity to judge affected safety distance.

Abstract: Zhengyangmen gate tower is a national emphasis cultural relic unit along the north-south axis of Beijing, which is above the Beijing metro line 2. Based on dynamic analysis model of gate tower and the position of gate tower and subway, the dynamic response characteristics of gate tower induced by Beijing metro line 2 are calculated, and compared with the in-site vibration test data.

Abstract: In order to monitor and control the effect of blasting vibration on dam body, spillway overflow surface and mechanical and electrical equipment foundation at the excavation of resistance sliding key chamber, the fixed monitoring point scheme was used to monitor vibration speed of each point. According to the construction progress, a total of 44 times blasting vibration test were carried on, and data are integrity, which can accurately reflect the effect of resistance sliding key chamber excavation blasting on adjacent buildings. In blasting construction process, according to the analysis of monitoring data, the explosive dosage of single stage was adjusted, which effectively control the effect of blasting vibration. The results indicate that, in the process of resistance sliding key chamber blasting construction, particle vibration velocities of adjacent buildings such as dam body, spillway overflow surface, mechanical and electrical equipment foundation and etc. are in the velocity range of security vibration, which meets the requirements of design and specification, and real-time analysis of field monitoring guarantees the smooth completion of site construction.

Abstract: With the help of the grey system theory and without any prior information on probability distributions and trends, this paper focus on modeling for the tapered roller bearing vibration velocity as a data series. And the experimental investigation shows that the estimated residual is very small and can satisfy the engineering requirement, laying the foundation for controlling over the vibration of tapered roller bearings in the manufacturing process.

Abstract: Problems and flaws of existing safety criteria for vibration are reviewed. A simple consideration of particle vibration velocity cannot fully reflect the inherent law of effects of explosion earthquake on structures. Sometimes the occurrence of explosions exceeding the standard velocity for safety will not necessarily cause damage to structures and those below the standard velocity for safety may destroy structures. For this reason, the free vibration frequency of structures and the safety margin of the structure should be considered. Based on safe, practical and convenient conditions, that in respect of safety criteria for dike and slope exposed to vibration, two indicators, i.e., stability factor of dike and slope and vibration velocity of particle, can be used to determine the effect of vibration on them is proposed. That is to say, pseudo-static method is adopted to make vibration inertia force equivalent to a static force on slope bars and then strength reduction method or limit equilibrium method is used to calculate the safety factor, which can directly evaluate the stability of slope. In combination with the particle vibration velocity given in specifications, the safety of dike and slope can be determined. Lastly, specific engineering cases are used to validate the rationality of this criterion. This method can serve as a reference for similar projects

Abstract: Based on model tests, the wave function expansion method was used to study scattering on the interaction of explosive stress waves and the underground chamber, and analyze the influence of the incident angle, frequency and diameter on blasting vibration velocity of underground chamber. It is obtained that when the cavern was under the plane waves of the vault, the radial vibration velocity of the vault is the largest among the four measured data, and it is the most intense vibrating place. When the incidence direction offsets from the vault to the horizontal direction on the left, the radial velocity facing burst are all larger than the radial velocity back of the burst. When the incident direction is on the dome, the tangential vibration velocity will increase first and then decrease from the vault to the side wall. When the incident direction is at the haunch, the tangential vibration velocity in the corner should be noticed. With increasing of the frequency, the radial vibration velocity and tangential vibration velocity increase accordingly. At the forward part of the burst, the larger the chamber diameter is, the bigger the radial and tangential velocities are. At the back side of the burst, the bigger the chamber diameter is, the smaller the radial and tangential vibration velocities are.

Abstract: The high-power piezoelectric characteristics of lead-free piezoelectric ceramics, based on a bismuth layer-structured ferroelectric, MnCO₃-doped (Sr_0.7Ca_0.3)₂Bi₄Ti₅O₁₈ (abbreviated as SCBT0.3 + Mn x wt%), were studied. SCBT0.3 + Mn x wt% lead-free ceramics showed an extremely high mechanical quality factor (Q_m) of more than 3000 in the (33) vibration mode under small-amplitude vibration. The high-power piezoelectric characteristics of SCBT0.3 + Mn x wt% were measured using the high-power measurement method based on frequency sweep driving under a constant voltage condition. It was found that the vibration velocity v_0-p of SCBT0.3 + Mn 0.2 wt% linearly increased up to approximately 3.0 m/s. Therefore, the Mn-doped SCBT0.3-based ceramics are a promising candidate for lead-free high-power applications.

Abstract: High-power piezoelectric characteristics of (Bi_1/2Na_1/2)TiO₃ (BNT)- and KNbO₃ (KN)-based ceramics at continuous driving were investigated. The selected compositions of BNT- and KN-based ceramics were 0.88(Bi_1/2Na_1/2)TiO₃-0.04(Bi_1/2Li_1/2)TiO₃-0.08(Bi_1/2K_1/2)TiO₃ doped with 0.6 wt% MnCO₃ [BNLKT4-8Mn0.6] and KNbO₃-MnCO₃ 0.8 wt% [KN-Mn0.8] ceramics. It was found that the vibration velocity v_0-P of BNLKT4-8Mn0.6 and KN-Mn0.8 ceramics linearly increased up to approximately 0.8 and 0.6 m/s, respectively. The temperature increases of BNLKT4-8Mn0.6 and KN-Mn0.8 ceramics were approximately 5°C under continuous driving at the vibration velocity of 0.6 m/s.

Abstract: The blasting vibration in Qingdao Cross-harbor Tunnel Guide Line Project is monitored and analyzed. We discover that the surface particle vibration velocity in the range of 5metres around the working face reduces fast, and that does not conform to Sadaovsk formula. This inquiry adopts the hypothesis-fitting-testing method to modify Sadaovsk formula. The empirical formula of the ground vibration velocity caused by blasting in tunnel is obtained.