Experimental and analytical study of the structural response of segmental tunnel linings based on an in situ loading test: part 1: test configuration and execution

Abstract

During the last years the use of segmental linings in tunnels bored with tunnel boring machines (TBMs) have increased considerably. Despite this, uncertainties remain on the structural behavior of segmental tunnel linings. To overcome them, a new methodology for an in situ real scale test on this kind of tunnels was developed and applied on an experimental section placed at the new Line 9 (L9) of the metro of Barcelona. The main particularity of this test falls on its performance in the definitive placement of the rings and, therefore, in the real work conditions of the tunnel. The main advantage to previous real scale test experiences was the consideration of the real ground–structure interaction. The experimental section was composed by 15 rings built using steel fibers as a unique reinforcement. Significant loads were applied to the tunnel crown (max 3000 kN) by means of three hydraulic flat jacks embedded at the extrados of the loaded ring. A complete set of internal and external instrumentation was placed on the experimental section to obtain the necessary measurements to characterize the lining behavior. Such measurements were intensively treated and its main results are presented and analyzed in detail in this paper. This in situ test provides significant evidences of the structural response of SFRC segmental tunnel linings in hard ground conditions.