Determination of Support Pressure for the Design of Square Box Culverts.

A box culvert is a tunnel under roadways or railways that transports open drains or streams. The geotechnical design of such a structure involves accurate evaluation of the earth pressure on the structure. This short technical note pertains to findings of stability factors in tables and charts as an aid to civil engineers in designing unlined square box culverts. A conventional equation that is similar to Terzaghi's bearing capacity factors (Nc, Ns, and Nγ) is adopted to examine the use of stability factors (Fc, Fs, and Fγ) to estimate the critical support pressures at collapse. Rigorous upper-bound and lower-bound solutions of the stability factors are computed using the adaptive finite-element limit analysis. To validate the present bound solutions, numerical results are compared with those published previously using other methods. Design tables, figures, and examples are presented for practical uses. [ABSTRACT FROM AUTHOR]