Analysis Of Geoelectrical And Soil Test Data To Determine Subsurface Conditions In Makassar City, South Sulawesi

Abstract

Research has been carried out to determine subsurface conditions. The research objective was to determine the physical properties of the soil in order to evaluate and provide recommendations for solving foundation problems. The methods are the resistivity geoelectric and IP geoelectric method (induced polarization) with ERT (Electrical Resistivity Tomography), SPT (Standard Penetration Test) and laboratory test results. The results of the resistivity values obtained varied in the range from 17.0 - 172.0 ohm m with a depth of 0 m - 2.87 m, most of which were interpreted as alluvium soil, namely sandy loam. This is reinforced by the results of the IP method where the low chargebility value is around 0.130 - 4.70 msec. In addition, it was found that from the SPT test, it was obtained that the variation of blows from 14 to 21 N at a depth of 0 - 5.50 meters and >60 N from a depth of 5.50 - 20 m which stated that most of them consisted of clay and sandstones. Then based on laboratory tests, it was found that at a depth of 3 - 3.5 meters it consisted of 86.47% clay with a plastic limit of 37.07% and the water content was 39.41%, while at a depth of 9 -9.5 meters it consisted of sandstones which the characteristic is non- plastic with a water content of up to 72.04%. It is concluded that the surface soil is conductive, it is necessary to hold special treatment for this type of soil in order to avoid erosion when it is saturated with water and it is hoped that the stability of the soil will be better. One of two ways is by mixing high density soil and making a "chicken claw" foundation to strengthen the foundation with a depth of more than 5.0 meters. Keywords: Geoelectric, Standard Penetration Test, Resistivity, Chargebility, Foundation.