Bemessung tiefer Baugruben mit rechteckigem Grundriss unter Berücksichtigung des räumlichen Erddrucks

Design of deep excavations with rectangular ground plan - Spatial earth pressure considerations

For the design of deep excavations with limited dimensions in ground plan usually vertical sections are designed as a plain strain situation, which applies finally for line-wise excavations. In engineering practice the shape of the ground plan is regularly considered only for shaft-shaped excavations, particularly excavations with circular ground plan. Although excavations with rectangular plan and large dimensions show a distinctive spatial bearing and deformation behavior, which is amongst others influenced by the relation of the flexibility of the excavation corners to the flexibility of the retaining walls along the sides of the excavation. Based on field measurements on the spatial deformation behavior of deep excavations with rectangular shape and a synopsis of the analytic approaches for the calculation of spatial active earth pressure, the results of a numerical parametric study are presented. These results illustrate for deep excavations with rectangular shape as a function of their geometric configuration the influence of the spatial bearing behavior on the deformations, the distribution of earth pressure and the internal stresses of the retaining walls and the excavation support system. Moreover they indicate that the consideration of the per se existent spatial bearing behavior of deep excavations with (almost) rectangular ground plan affords an optimized design of retaining systems in technical and economical view.