Mechanical and deformation characteristics of enclosure structure for annular extra-deep excavation

Based on the deep excavation of Shanghai 2010 Exposition 500 kV substation, the plane strain and axisymmetric elastic foundation FEM are used to simplify the space effect of the enclosure structure. The space effect of the annular enclosure structure, the inner liner and the different water and soil pressure distribution model are considered for the mechanical and deformation characteristics of enclosure structure. Through comparision between the calculated and measured results, several results are obtained: the space effect of the annular enclosure structure has a great influence on the mechanical and deformation characteristics of it; the ring stiffness of the enclosure structure must be considered during calculation; the inner liner is beneficial to the mechanical and deformation of the diaphragm wall, like a ring supporting; the measured horizontal displacement of the diaphragm wall is close to the result of axisymmetric finite element analysis when lateral pressure coefficient is 1.0; the measured hoop stress and bending moment of diaphragm wall are between the result of estimating water and earth pressure separately and lateral pressure coefficient is 1.0.