Scope of the design assumption for pressure tunnel steel linings under external pressure

The buckling design check of pressure tunnel steel linings under external pressure - caused by external infiltration water or cement injection pressure - is conventionally performed by using different sets of equations, which were either developed analytically or through the evaluation of test results. In this paper the range of validity of the commonly employed semiempirical design formula developed by Montel [1] is investigated by comparing it with an analytical design concept based on the assumptions of Amstutz [2], [3] and Jacobsen [4], which was formulated in terms of an elastic snap-through buckling mechanism with a first yield failure criterion, as well as with numerical calculations using the Finite Element Method. The initial objective of this study was to verify the applicability of the Montel formula to higher-strength steel grades. However the analytical approach was shown to be more accurate in describing known test results and better applicable to high-strength steels and cylindrical linings of high slenderness.