Study of Passive Isolation of Deep Foundations in Sandy ... - Ejge.com

Vol. 16 [2011], Bund. Q 1300
Figure 1: Wave propagation induced by deep foundation (Attewell and Farmer, 1973)
Wolf (1994)theoretically presents an equation between attenuation of ground vibration in the far field and
the distance from vibration source; � �� which r is the distance and n is the geometrical attenuation coefficient.
The latter is equal to 0.5 for surface waves propagating on a cylindrical wave front and equal to 1 for body
waves propagating on a spherical wave front in the interior of the half space and equal to 2 for body waves
propagating along the surface.
PROBLEM DEFINITION AND ASSUMPTIONS
In two-dimensional model the thickness of foundation is assumed 1.5m in order to be satisfied with the
foundation rigidity under compressive loads and evaluated under assumption of isotropic and homogenous with
linear soil behavior for low deformations.
A rigid concrete (table1) of a width of 4m (Bf),with 3 piles of diameter of 70cm and various length (D)
resting on a soil layer with dynamically and statically different characteristics (table2,3) of a limited thickness
underlain by a hard stratum at a depth of Hm and Length Lm is subjected to a harmonic (f = 50 Hz) compressive
concentrated load P0sin(ωt) (Figure 2) an open trench of depth H and width w is located at a distance of L from
the edge of the foundation Table 4)
Table 1: Model concrete properties
Young’s
Modulus
Poisson’s
Ratio
Density Material
Damping
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