Field experiment and numerical study on active vibration isolation by horizontal blocks in layered ground under vertical loading

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 69; pp. 251 - 261
• Main Authors: Gao, Guangyun, Li, Ning, Gu, Xiaoqiang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2015
• Subjects: Boundary element method; Excitation; Field experiment; Foundations; Ground vibration; Grounds; Horizontal; Layered soils; Mathematical analysis; Shear modulus; Thin layer method; Vibration; Vibration isolation; Wave impedance block; Wave impedance block; Ground vibration; Thin layer method; Vibration isolation; Layered soils; Field experiment; Boundary element method
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2014.11.006

In this paper, a series of field experiments were carried out to investigate the active vibration isolation for a surface foundation using horizontal wave impedance block (WIB) in a multilayered ground under vertical excitations. The velocity amplitude of ground vibration was measured and the root-mean-square (RMS) velocity is used to evaluate the vibration mitigation effect of the WIB. The influences of the size, the embedded depth and the shear modulus of the WIB on the vibration mitigation were also systematically examined under different loading conditions. The experimental results convincingly indicate that WIB is effective to reduce the ground vibration, especially at high excitation frequencies. The vibration mitigation effect of the WIB would be improved when its size and shear modulus increase or the embedded depth decreases. The results also showed that the WIB may amplify rather than reduce the ground vibration when its shear modulus is smaller or the embedded depth is larger than a threshold value. Meanwhile, an improved 3D semi-analytical boundary element method (BEM) combined with a thin layer method (TLM) was proposed to account for the rectangular shape of the used WIB and the laminated characteristics of the actual ground condition in analyzing the vibration mitigation of machine foundations. Comparisons between the field experiments and the numerical analyses were also made to validate the proposed BEM. •Field tests on vibration mitigation using WIB are performed.•The effectiveness of WIB increases as size and stiffness increase.•The effectiveness of WIB decreases as embedded depth increases.•An improved 3D boundary element modal with a thin layer method is proposed.•Both test and model indicate that improper design of WIB may amplify the vibration.