Development of Design Charts for Installation of Granular Piles in Soft Clays

Abstract

The vertical loads on the soil reinforced with Granular Pile results in axial compression of both the soil and the Granular Pile material. The imposed stresses result in radial bulge of the pile material against the surrounding soil though it is restricted to the upper portion of pile length. Considering this nature of the Granular Pile, analytically solution for the strength of the composite ground reinforced with Granular Piles is discussed herein. The radial bulge extends up to the depth equal to the four times the diameter of the Granular Pile. Various factors such as undrained shear strength of the soil and the internal friction angle of the pile material are used to derive the capacity of the Granular Pile. The proposed solution is used to calculate the capacity of Granular Pile varying the properties of surrounding soil and Granular Pile material. Values of undrained shear strength (cu) were varied from 10 to 50 k Pa. Bulk density (γ) of the clay soil is assumed as 20 k N/m3. Angle of internal friction for Granular Pile material (ϕc) is varied from 380 to 420. The design charts between safe bearing pressure and the angle of internal friction for Granular Pile material are drawn. The diameter of Granular Pile is kept from 0.3 m to 1.05 m and the spacing between them is varied from 2D to 3.5D. The triangular pattern of Granular Pile arrangement is considered. For different spacing of the Granular Pile and undrained shear strength, the design charts explained and illustrated through an example.