EFFECT OF EMBEDMENT ON BLOCK FOUNDATION VIBRATION

Abstract

To study the "EFFECT OF EMBEDMENT ON BLOCK FOUNDATION VIBRATION" is of great importance. From the available literatures, it is seen that the earliest analysis neglects the embedment of the foundation. Thereafter analysis were done in which it is seen that embedment of the foundation to the soil significantly effects the dynamic response of the soil-mass-foundation system. In this dissertation, a rational analytical approach using mass-spring- dashpot mathematical model has been developed to predict the dynamic response of embedded block foundation. The vibrations in vertical, horizontal, rocking and coupled horizontal and rocking modes have been considered. In the analysis, the dynamic soil parameters are taken as frequency-dependent. The analysis brings out clearly the effect of embedment on i. Amplitude, ii. resonant frequency, iii. damping ratio, and iv. stiffness of the soil. From the analysis, it has been observed that a. For a constant value of embedment ratio(he/b), as the dynamic force to weight ratio(F/W) increases, the damping ratio and the stiffness of the soil-mass-foundation system decreases, which results in a higher magnitude of amplitude of vibration. b. For a constant value of force to weight ratio (F/W), as the embedment ratio (he/b) increases, both the damping coefficient and the stiffness of the soil-mass-foundation system increases as the side soil resistance is also coming into the picture. Therefore, in this case the amplitude of vibration is going to be decreased. c. For a constant value of embedment ratio (he/b), as the dynamic force to weight ratio (F/W) increases, the in-phase soil mass increases. For the same value of F/W, as the embedment ratio increase, the in-phase soil mass also increases. Thereafter, a verification of the analytical results were done with the experimental data [Vijayvergiya, 1981] and a reasonable tally has been observed..