During TBM operations, thrust jacks apply high-concentrated forces to the last installed precast segment. These loads generate in the precast segment a disturbed region under the thrust jacks, in which significant tensile stresses (defined as splitting or bursting stresses) occur perpendicular to the load direction. In addition, due to the demand of compatibility, the combined effect of TBM high-concentrated loads determines tensile spalling stresses in the area far from the loads. Therefore, local rebars or fiber reinforcement are required in the aforementioned areas. In this context, the present paper focuses on the study of the effects generated by high-concentrated loads exerted by TBM hydraulic jacks, mainly in terms of both spalling and splitting phenomena. Experimental tests on small-scale specimens showed that polypropylene fibrous reinforcement significantly enhances both the bearing capacity and the ductility. Moreover, polypropylene fibers resulted very effective in the control of compatibility cracks as well.
Experimental study on the effects of high-concentrated loads exerted by TBM hydraulic jacks
CONFORTI, Antonio;TIBERTI, Giuseppe;PLIZZARI, Giovanni;
2016-01-01
Abstract
During TBM operations, thrust jacks apply high-concentrated forces to the last installed precast segment. These loads generate in the precast segment a disturbed region under the thrust jacks, in which significant tensile stresses (defined as splitting or bursting stresses) occur perpendicular to the load direction. In addition, due to the demand of compatibility, the combined effect of TBM high-concentrated loads determines tensile spalling stresses in the area far from the loads. Therefore, local rebars or fiber reinforcement are required in the aforementioned areas. In this context, the present paper focuses on the study of the effects generated by high-concentrated loads exerted by TBM hydraulic jacks, mainly in terms of both spalling and splitting phenomena. Experimental tests on small-scale specimens showed that polypropylene fibrous reinforcement significantly enhances both the bearing capacity and the ductility. Moreover, polypropylene fibers resulted very effective in the control of compatibility cracks as well.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
