Analysis of Stone Columns Reinforced Weak Soil under Harmonic Vibrations

The construction of stone columns is a relatively efficient technique and is a classic solution for soft and loose ground improvement. This method is usually a replacement of weak soil with granular course material to increase load carrying capacities of weak foundation soils, reduced excessive settlement, liquefaction remediation, and provide the shortest drainage path to the excess pore water. In some projects, dynamic loads may be exerted to the foundation soil due to, for example, operating industrial machines, earthquake, wind, waves, etc. In such cases, dynamic analysis of soil-foundation system with the presence of stone columns as reinforcing objects is necessary. In this paper, an approximate analytical solution is presented for the vertical dynamic response of stone columns. For this purpose, an element stone column is considered and reaction of the soil on loading the column is modeled using a one-dimensional simulation. The governing differential equation of the stone column-soil element is derived. For this purpose, the stone column is divided to series of lumped masses connected by springs and dashpots. The springs simulate the axial stiffness of the column material and the dashpots reflect the material damping properties of the stone column material. The reaction of the surrounding soil is taken into account by attaching some springs and dashpots. The former simulates the dynamic soil stiffness and the latter simulates the geometric damping due to wave propagation within the surrounding soil. The results show that with increasing the slenderness ration of stone column, the stiffness and damping parameters of soil-stone column system increase and vibration amplitude of stone column decreases. In addition, with increasing the dimensionless frequency a0, the stiffness of the system tends to decrease while damping of the system tends to increase. Further data extracted from analysis will also be presented

Keywords:

Stone Column , Harmonic Vibrations , Material Damping , springs and dashpots