Influence Of Ground Vibrations Research Articles

Experimental study on ground vibration response in gun firing environment

In order to know the ground vibration response law of gun firing environment, a large caliber gun was taken as the research object, and the ground vibration response law of gun firing environment was tested. Several acceleration sensors are arranged on the ground around the gun, and the ground vibration acceleration response laws of the gun position in the firing environment are obtained. The firing of gun will cause the ground vibration of gun position. In the bore period, as long as the projectile is fired, there will be acceleration response on the ground of the gun position. The maximum acceleration response of ground vibration in the bore period of projectile is less than 0.03 g. The maximum acceleration response of ground vibration is less than 0.1 g after projectile exits the muzzle and before the muzzle shock wave reaches the ground. If the sensor bracket is placed on the ground around the gun, when the muzzle shock wave does not reach the sensor position, the influence of ground vibration on the sensor can be neglected. Once the muzzle shock wave reaches the sensor position, its influence should be paid attention to.

Influence of Vibration Isolator Failure on Vehicle Operation Performance and Floating Slab Track Structure Vibration Reduction Effectiveness

At present, steel‐spring floating slabs have been widely used in urban rail transit to reduce the influence of ground vibration caused by vehicle operation on the surrounding environment. As a core part of vibration reduction for floating slab track, the steel‐spring vibration isolator may fail in different forms during operation. In order to study the influence of vibration isolator failure on vehicle operation performance and floating slab track structure vibration reduction effectiveness, a rigid‐flexible coupling dynamic model of vehicle‐rail‐floating slab track is established by multibody dynamics and finite element simulation, and the rationality of the model and its parameters is verified by comparing the theoretical calculation results with the measured data. Based on the model, the failure conditions of steel spring are simulated, considering the failure position and number of steel springs. The results show that the failures of steel‐spring vibration isolators have a significant impact on operating safety and stability of vehicle, and the failure at end is more dangerous than that at midspan. In addition, it also changes the local restraint state of floating slab, resulting in the local vibration mode, which reduces the floating slab track structure vibration reduction effectiveness, mainly within 10 Hz. The different numbers of steel‐spring failures will change the natural modal frequency of floating slab to varying degrees, which may cause the resonance of a certain frequency of the vehicle‐track coupling system, leading to other track structure diseases.

Blast wave induced spatial variation of ground vibration considering field geological conditions

Drilling and blasting is one of the most widely-used methods for large-scale excavation in rocks and soils. However, rock blasting can induce many adverse effects, and the typical influence of rock blasting on the surrounding environment is illustrated in Fig. 1. Explosion induces ground and structures vibration1., 2. and annoying noise. When the explosive is detonated, an extremely high-pressure pulse is generated, which is transmitted into rock mass adjacent to the blast hole, producing a dilatational wave that propagates away from the charge. Stress waves due to blasts may cause damage to the surrounding rock and, furthermore, when the wave reaches a free face or open fissure (non-transmission), it will be reflected and converted into a tensile wave, which may produce tensile cracking and spalling if the tensile strength of the rock is exceeded by the tensile wave.3., 4. Also, due to the fact that some rock blasting projects are close to the inhabitant area, the surrounding buildings may be damaged due to blasting-induced ground vibration if large stress wave propagates in the soil foundation and shock wave propagating through the air.5 Disruption of some business activities, possible structural damage and emotional-traumatized residents are the problems that need to be addressed.2., 6. Therefore, the influence of ground vibrations on surrounding buildings, sensitive devices and people in urban environments is a significant consideration in obtaining project approvals.

Experimental research on influence of ground vibration on gun measurement instrument support

In order to know well the vibration law on influence of ground vibration on instrument support in gun firing process, a measuring method for the vibration response of the instrument support based on the principle of acceleration measurement is presented. The instrument support is arranged on the ground. When the gun fires, the acceleration response of the instrument support is measured. The vibration velocity and vibration displacement responses of the support can be obtained by the integral operation of the acceleration. The results show that when the gun fires with single shot and the period of the projectile in-bore motion, the vibration response of the instrument support caused by ground vibration is very small, and it can be ignored. When the projectile moves outside the bore, the ground vibration has a significant influence on the vibration of the instrument support. The vibration response of the instrument support in the range of muzzle shock wave is mainly caused by the muzzle shock wave.

A Developed Non-Contact Active Vibration Isolation Unit for Precision Machining Systems

Vibration isolation has been widely used for precision machining systems to reduce vibration errors caused by disturbance. In general, vibration isolation units have mechanical contact points between a base and a table, while ground vibration passes through these contact points. This paper presents a newly developed non-contact type active vibration isolation unit which consists of an air spring, a voice coil motor, and an aerostatic bearing. The developed unit also has an active vibration control function to reduce an influence of direct disturbance force. Vibration isolation experiments confirm that the resonances in ground vibration transmission and direct disturbance transmission can be reduced and the influence of ground vibration can be decreased.

INSTABILITY OF PRECISE GEODETIC INSTRUMENTS CAUSED BY GROUND VIBRATIONS

AbstractThe work reported here is a continuation of investigations carried out for determining the influence of vibrations on the accuracy of geodetic measurements. The purpose of this study is to determine the influence of ground vibrations on different groups of precise geodetic instruments.