The FEM back-analysis of earth pressure coefficient at rest in Brno clay K0 with the homogenization of steel/shotcrete lining
Abstrakt
In the paper we estimate the earth pressure coefficient at rest by means of backanalysis of deformation measurements in underground circular unsupported cavity (constructed for the purposes of detailed geotechnical survey) in highly plastic overconsolidated clay. Because of an inability of the adopted FEM code to assume 2 different components of primary lining, the homogenization of steel/sprayed concrete ("shotcrete") lining was considered.
The main primary boundary conditions were conservation of static momentum and conservation of the axial and bending stiffness. In addition, the dependence of Young modulus of shotcrete on time was also taken into the account.
Our research focuses on Královo Pole tunnel in Brno city, which is one of the key parts of Brno city road ring. The backanalyses of circular cavity indicate K0 = 0,81.
This value was subsequently entered in a numerical 3D model of the whole tunnel and verified by confrontation of measured and calculated displacements.