Vibration Monitoring for Surface Compaction - A Case Study

The peak particle velocity and associated frequency of ground motion are considered important parameters for arriving at realistic safety criteria against vibration generated during the dynamic compaction of ground. The repeated dropping of a weight onto the ground's surface is one of the simplest and most basic methods of compacting soils. In this method the densification of the strata is primarily obtained by collapse of the soil structure and release of the gas phase of the soil from voids. The densification of soil results in increase in bearing capacity, reduction in total and differential settlement, decrease in liquefaction potential, increase in relative density and reduction in compressibility and void ratio. The dynamic compaction method has been used for improvement of ground at a site, at Greater Noida for improving the bearing capacity. The soil at Greater Noida consists of a surface layer of loose silty clay 1–2 meters deep, loose fine sand to depths of 10–12 meters underlain by silty clay. The treatment of soil consisted of four passes with 5 to 15 tons hammer falling 15 metres. The vibration studies have been conducted at site and the peak particle velocities of vibrations have been measured by varying distances, weight of hammer, height of fall and effect of trench. The vibration levels have been found to be within safe limit for the nearby structures. However, it causes disturbances in the daily lives of people living around.