Investigation of the cantilever retaining walls constructed within highway projects

In this thesis, the limit values of internal parameters of natural soil layers and fill materials as well as external factors such as wall height and surcharge load were determined according to twenty-eight real retaining wall project data built in six regions of Turkey as Central Anatolia, Marmara and Black Sea regions mainly. A generalization was made with respect to theoretical calculations of mentioned limit values and finite element modelling was carried out in order to investing the effects of design parameters such as surcharge load, depth of frozen, groundwater level and surface slope on a retaining wall. Reinforced concrete cantilever retaining walls were designed and modelled according to boundary conditions, which they have a wall height starting from 4 m to 19 m with an increase of one meter. Besides, the approximate cost of the walls has been calculated using Sta4cad program. Dimensioning were performed within Rankine active pressure theory in design process. Analyzes were performed in Plaxis 2D software by taking the constant parameters of subbase soil, natural soil behind fill and granular backfill in line with design, while the surcharge load, depth of frozen, groundwater level, surface slope and wall height were selected as variables. The axial force, shear force and bending moment values acting on the retaining walls are compared and the effect of the parameters are interpreted due to variable parameters as a result of the analysis in addition to the horizontal, vertical and total deformation values that occur on the retaining walls. A total of 1280 design combinations were created within the limit values of real retaining structures, which are including wall height (H: 4-19 m), surcharge load (q: 0 - 20 kN/m2), depth of frozen or foundation depth (Df: 0 - 1.5 m), angle of surface slope (α: 0°- 18°) and ground water level (bottom level and top level of wall). It is thought that this thesis will provide an opportunity for preliminary planning to increase the correct design possibility of the retaining wall under the relevant boundary conditions as a result of the wide range of interpreted parameter combinations with data, tables and graphs. Moreover, it is also planned to make the construction of retaining walls faster and more economical.