Field test study for evaluation of vibration control capacity of cracked mass concrete layer

Passive control is typically implemented to regulate ground vibration in advanced ultra-precision and large-scale synchrotron radiation facilities. This paper presents the field test to evaluate the influence of cracks on the vibration control capacity of a mass concrete layer used as a passive control method of an advanced synchrotron radiation facility. Simplified finite element model (FEM) analysis is utilized to simulate the cracks and analyze the key factor that influences the vibration control capacity of the mass concrete layer. In the field test, cracks are artificially formed by creating cuts in two orthometric directions on the surface of a 3-m-thick concrete layer. Measurement points and a vibrator capable of generating simple harmonic excitation (1–100 Hz) are positioned along a straight line. Velocity signals vertical to the ground are obtained to study the vibration attenuation in the vertical direction. Test results indicate that the velocity signals on the concrete layer are sensitive to the cracks; the vibration control ability of the concrete layer is slightly affected by the depth, length and location of the cracks in the frequency band of 1–100 Hz. The proposed simplified FEMs can reflect the cracked concrete layer’s vibration control ability from 1 to 100 Hz. Numerical study results indicate that the thickness of the concrete layer rather than the density or elastic modulus is the key factor in vibration control ability.