MASW (Multichannel of Analysis of Surface Waves) Measurements on Very Dense Fill of Freeport Mining

Abstract

The MASW (Multi-Channel Analysis of Surface Waves) was conducted on fill soil at Tembagapura Freeport Mining. The fill was very dense and is the landfills where people dumped waste disposal like car tire rubber etc. Several attempts were made to make boreholes to collect soil samples and to run SPT (Standard Penetration Test), but they failed. The fill was so dense that the employed drill bits were worn out when penetrating the soil. The MASW team was invited to carry out the measurements and to produce shear wave velocities of the layers, which correspond to SPT Number. The number of measured MASW points was 8 points. They were successfully carried out on the surface of the fill without borings. The offset distance between the hammer blows, and the first geophone was 18 m, and the interval distance between 4.5 Hz geophones was 3 m. The MASW measurements resulted in an average shear velocity of 400 m/s which confirmed the soil was very dense soil. The information regarding the shear wave velocities of the layers was adopted as input of earthquake engineering software to predict the amplification when the earthquake happens.