Subsurface Analysis of National Road Bts. Sidoarjo City – Gempol Using Geophisycs Method and Geotechnical Tests

Abstract

National road segment Bts. Sidoarjo City – Gempol from Km 30+000 to Km 33+000 is located at west side of the Sidoarjo Mud (LuSi) embankment which still have an active eruption for more than 15 years from 2006 to the present. Based on the observations which conducted by PPLS, it found that the LuSi embankment had lowered around 6 cm/year. This phenomenon can cause damage to the infrastructure nearby. National road segment Bts. Sidoarjo City – Gempol, one of important infrastructure is experiencing severe damage and disturbed due to land subsidence. Therefore, it is necessary to conduct research on these national roads to understand the problem throughly. This research was carried out using both geophysical methods and geotechnical investigations. In advance, resistivity geoelectrical using Wanner-Schlumberger configuration and GPR were used as non destrcutive test. Meanwhile, SPT boring were applied to determine subsurface conditions. According to field and laboratory works, below 6 m of sample depth is classified as soft to very soft soils with high plasticity. There were also suspected 2 fractures in the geoelectric path beside the LuSi embankment. The results are expected to help the preservation planning for handling soil improvement on National Road segment Bts. Sidoarjo City – Gempol to prevent land subsidence.