INVESTIGATION OF THE CAUSES OF ROAD PAVEMENT FAILURE ALONG MARABA KAGORO - GIDAN WAYA ROAD, KADUNA STATE USING ELECTRICAL RESISTIVITY TOMOGRAPHY

Abstract

A  geophysical survey was undertaken using Electrical Resistivity Tomography to investigate the causes of road failure along Maraba Kagoro - Gidan Waya Road in Jema’a Local Government Area of Kaduna. The resistivity of the study area was measured using ABEM SAS (1000) Tetrameter. Two profiles, one on each side of the affected road, were laid, and the survey involved Vertical Electrical Sounding (VES) with Wenner configuration so as to get a better depth resolution and higher signal strength.  The measured VES data were taken by using four electrodes (two current and two potential electrodes) with current electrode spacing (AB/2) varying from 1 to 200 m. Both the two-horizontal profiling (1 and 2) were carried out using electrode separation, . During the survey, current was injected into the ground through the current electrodes.  and  and the corresponding voltages were obtained through the potential electrodes  and .  Resistivity values of the study area with their respective depths were delineated across the entire profiles. Profile  and Have resistivity values ( 400Ωm at depth 6.38m, 600 - 1700Ωm at depth 6.38m towards left and 2800 - 4700Ωm at depth  8m between 120 - 180m across the profile) and ( 300Ωm between 0-60m to the left of the profile at depth below 6.38m, 44167Ωm between 60-100m at depth 6.38m towards the centre from the left, 8000Ωm between 100 - 140m from the left of the profile. It showed that the left of the profile is clayed or high moisture weak sub-grade, the centre contains stronger sub-grade, and toward the right is more compacted soil. The sandy-clay contents account for the low resistivity values from the left towards the centre, causing uneven ground movement, suspected to be responsible for the perpetual road failure. It is therefore recommended that the portions containing the sandy-clay should be ripped to a depth of 6-7m and be filled with more competent materials of high resistivity, and further research using seismic refraction should also be carried out to strengthen these findings.