Kinematic and inertial influence of a deep embedded foundation on an adjacent shallow foundation

New high-rise buildings are often constructed a few meters away from existing short buildings supported on shallow foundations. These tall buildings typically feature several underground basement floors. The paper aims to elucidate the effects of the oscillatory motion of a deep foundation on the surrounding soil and the motion experienced by a nearby shorter structure. This oscillatory motion of the deep basement arises from both the kinematic displacements imposed by incident and reflected waves, as well as the inertial forces on the superstructure. To fully understand and distinguish between these phenomena, the paper first examines the case of foundations alone without any superstructure to investigate kinematic effects. It then assesses the influence of the embedded foundation while it supports a heavy 1-degree-of-freedom (1-dof) oscillator on a lighter 1-dof structure on a shallow foundation. The focus is on the exploration the role of key parameters, such as the depth of caisson embedment (D) and the period of the input excitation. One outcome of the study is that when the shallow foundation is placed next to a deep caisson, it experiences different accelerations and displacements compared to its isolated counterpart. The extent of the variation in these values is primarily determined by the embedment depth (D) of the nearby caisson. For greater depths, a kind of kinematic “shadow” on the shallow foundation has been observed.