VERTICALITY OF BOREHOLES

Abstract

The study contains the problem of the borehole shape of during drilling. Usage of a drilling bit and tubular or screw rods is traditional and most common drilling methods. The requirement of "verticality" for boreholes in the drilling process is necessary to comply with design solutions and design schemes. At the same time, the actual implementation of this important quality is often very difficult. An analysis of the regulatory documentation is carried out to ensure the requirement during conducting geotechnical investigations, and during installing pile foundations made in the ground: bored piles and continuous flight auger piles (CFA). Data about the researchers in the field of assessing of bending of the pile axis are presented for CFA piles. The article presents the results of field studies of the borehole verticality at two investigation sites. At the first site, a borehole was drilled with a depth of 9.0 m, at the second site, ten boreholes were drilled with a depth of 25.0 m. The spatial position of the boreholes was determined by an inclinometer. The results of the measured verticality deviations of the boreholes are presented on the spatial graph for clear visibility. A conclusion is made about the influence of the borehole shape on its vertical projection during conducting of geotechnical investigations. A series of comparative numerical calculations was performed using the Midas GTS NX program to assess the effect of the verticality deviations of the boreholes during installing bored piles on their bearing capacity. A single pile action in the ground was simulated for the pressing and pulling loads. It is concluded that the shape of the borehole influences on the single pile action in the ground.