The Influence of Rigid Boundary on the Dynamic Response of the Foundation: An Experimental Investigation

 

Anirban Mandal

Research scholar, Department of Civil Engineering,
Indian Institute of Technology, Kharagpur, India.
e-mail: amandal@civil.iitkgp.ernet.in.

Dilip Kumar Baidya

Lecturer, Department of Civil Engineering,
The University of the West Indies,
St. Augustine, Trinidad.

 

ABSTRACT

In this paper the influence of the presence of a rigid boundary in the soil mass on natural frequency and resonance amplitude are studied experimentally by conducting model block vibration tests in vertical mode. The tests are carried out in two different pits in the field: one with rigid base and other with a large depth simulating the half space. A concrete block of size 400x 400 x 100 mm is used as the model block and a Lazan type mechanical oscillator is used for inducing vibration in vertical direction. The soil layers of different thickness are prepared in the pits and the test conducted over the surface of each layer. In total 80 tests have been conducted in different thickness of layer and different static and dynamic loading combinations and several important observations are reported. The results obtained from these two tests pits are also compared with the test result of laboratory test in a tank available in the literature. Damping factor and the stiffness are calculated from the test results. The damping ratio for different layer thickness and different pit conditions are presented.

Keywords: Damping ratio, dynamic response, natural frequency, stiffness, vibration.

 

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