Mechanical tests and engineering applicability of fibre plastic concrete used in tunnel design in active fault zones.

Abstract Articulated design is considered an effective anti-fault measure to prevent damage to tunnel lining caused by fault movement. A new type of plastic concrete was developed for the Xianglu mountain tunnel of the water diversion project in Yunnan Province. The effectiveness of this concrete was verified by laboratory tests and numerical simulations. The mechanical characteristics of this new type of fibre plastic concrete were identified through mechanical testing. The optimal fibre volume fraction (around 0.2%) was obtained and could increase the compressive strength, splitting tensile strength, ductility and toughness without causing a significant decrease in the elastic modulus. The internal forces and plastic strain of the lining under the action of strike-slip faulting were analysed by using the finite element method. The role of fibre plastic concrete as a flexible joint material to accommodate bending and shear deformation was studied. The results showed that the plastic strain was mostly concentrated in the flexible joints, where the fibre plastic concrete with favourable ductility and toughness properties absorbed the deformation, protecting the rigid segments from complete destruction. The fibre plastic concrete maintained its considerable integrity and strength and would not suddenly droop when subjected to bending-shear and tensile-compressive loads due to the cementation between the PVA fibre and the matrix. The characteristics mentioned above would facilitate maintenance of the tunnel after an earthquake and can provide a reference for the engineering of other anti-faulting designs. [ABSTRACT FROM AUTHOR]