PEMANFAATAN SURVEI GEOLISTRIK DAN GEOTEKNIK UNTUK IDENTIFIKASI STRUKTUR BAWAH PERMUKAAN RENCANA JALAN LINGKAR POLITEKNIK PERTANIAN NEGERI SAMARINDA

Abstract

Soil conditions with weak zone points can cause damage to road structures such as
land subsidence. Geoelectric surveys can identify subsurface structures based on
variations in rock resistivity. Road infrastructure crash due to weak zones of soil
bearing capacity can be identified by geoelectric surveys and geotechnical tests as
supporting analysis. Based on the master plan of Politani Samarinda 2025-2029 in
the southern area, a ring road of ± 1.5 km will be built, so geoelectric and
geotechnical support data are first needed as a basis for road planning. The main
objective of this study is to mapping subsurface structure and identify the stability of
the strong and weak zones of the soil in the planned area of the ring road
construction. The geoelectric resistivity survey uses the Wenner Schlumberger
configuration with 2 longitudinal tracks of ± 100 m per track with a spacing (a) of 5
m which can identify the distribution of subsurface resistivity values laterallymapping.
The resistivity value obtained from 2D geoelectric inversion is the lowest
value of 2.62 ohm.m which is suspected as clay, medium 78.5 ohm.m which is
suspected as sand, and the highest 7716 ohm.m which is suspected as sandstone
and used as a reference in the strong zone of the road building foundation.
Furthermore, the USCS classification geotechnical test at 2 track points resulted in
sand (SM) and silt clay (MH) soil types based on mechanical laboratory tests. The
results of the identification of geoelectric surveys and geotechnical tests have a
significant correlation with road construction that has a potential strong zone
bearing capacity because the top soil is in the form of silt, clay, sand which is
underneath in the form of sandstone which is strong enough to withstand the load of
road construction.