Monitoring the stability of highway cut slopes utilizing drone photogrammetry

Abstract

Roads have long been an integral asset for civilization. A lot of things have been said, drawn and shown regarding what and what not to do while drafting the routes. No matter how conscientious they are planned and laid out, mishaps occur while placing them on terrain. The demand to tie two points with the shortest possible route, create cut slopes and embankments. They both are bolstered with engineering reinforcements, however the cut slopes, which are always in sight while driving through, gave way in majority of time if those engineering principles are not sufficiently applied. Slope failure occurs when the downward movements of material due to gravity and shear stresses exceeds the shear strength. Therefore, factors exploiting these critical dynamics, increase the chances of slope failures. Six crumbling cut slopes en route to Karabuk from Kastamonu province were investigated in terms of the stability dynamics. Through stereo photogrammetric evaluation, digital surface models, which were sensitive to 0.08 to 0.22 m ground resolutions were constructed. Additionally, soil samples to understand the physical and chemical compositions of the cut slopes were taken from two depths; 0-15 cm and 15-30 cm. Analyses of the models showed that the considerable parts of all of the cut slope areas were graded over 87%, which was the collapse threshold for unprotected or untreated soil surfaces. Lab analyses showed that the binding agents e.g. organic matters, lime, etc. were rather weak because no vegetation to stabilize the already steep cut slopes was present on any of them.