Effect of prestressing force over excavation behavior in anchor supporting systems

Due to increasing growth of the population, dwelling increase and economic growth as well as dependently reduction of the free land, the demand for high buildings consisting of multi-storey basements increased considerably. In order to build such buildings' basements and groundwork, it is necessary to dig vertical and deep excavations. For the deep excavation, constructing of a support system is found to be compulsory to provide stability for the excavation hole and the limitation of the shape changes in the vicinity. This demand which was primarily provided with inner support timbering systems, was found necessary to be changed to much developed improved supporting systems due to limitation of the construction activities within the inner supporting systems in excavation holes, also design difficulties in wide excavations and so on. Development of the prestressing anchorages and the conducting supporting systems may meet this requirement and there is a complex mechanism of the supporting systems, supported by ground anchorages which prestressing applications takes places, and are the subjects to enlighten to determine the behavior of the supporting systems. Above all these subjects, shoring wall of the anchorage prestressing power and the effect of the possible place shifts taking place at behind the wall surface because of the excavation, numerical analysis of this subject was aimed to be considered. The numerical analysis was realized by Plaxis 2012 software which is used very commonly in geotechnical engineering. In these analyses, various prestressing powers and anchorage root paints were considered within an excavation system made by a two lined anchorage and diaphragm wall. In the analyses developed with these parameters, the anchorage prestressing power and horizontal shift in the Wall as well as the vertical shift behind the wall were all evaluated and their graphics were delineated. In these graphics, the ground shifts with the excavation depths, and the anchorage strength with the Rankine active soil pressure were normalized. In the prospected numerical model, with evaluating stability analysis, the effect of anchorage powers over the stability of the supported excavations was investigated. With the modelled system by Plaxis Finite Elements' method, the horizontal (ux) and vertical (uy) displacements behind the wall were determined and the relations of the excavation depth (H), length of anchorage root, peripheral friction point bearing (Tmax), security coefficient (Msf), active soil pressures (Pa) with each other were evaluated with graphics.