Long-strip-shaped underground structure segment length determination method considering stratigraphic space variability

The invention discloses a long-strip-shaped underground structure segment length determination method considering stratigraphic space variability, which comprises the following steps: firstly, acquiring a drilling soil sample along the axis of a long-strip-shaped underground structure, carrying out creep tests under different stress states, and fitting to obtain a creep constitutive equation and parameters; secondly, statistical analysis is conducted on the bottom elevation and the thickness of the soil layer, and a statistical distribution fitting function is obtained; then, on the basis that the segment length is L, a random finite element model considering stratigraphic space variability is established; fourthly, random finite element calculation analysis is conducted, an accumulative probability curve of the maximum tensile stress or tensile strain in the underground structure is obtained, a corresponding reliability index value is determined, if the tensile stress corresponding to the calculated design r