Analytical Model of Piezoresistivity for an Inner-Adhesive-Type Carbon Fibre Reinforced Plastic Tunnel Reinforcement

Abstract

Cracks in a tunnel lining often emerge under the coupling action of earth and water pressures in a complex stratum environment, and accidents often occur in the process of repairing cracks. In this study, we used the force-sensitive properties of embedded carbon fibre to conduct early-warning research on lining reinforcement to prevent secondary damage during tunnel lining reinforcement. According to the earth load characteristics, a bond stress–slip model of the embedded carbon fibre under bidirectional earth pressure was established on the basis of the thick-walled cylinder theory and the semi-inverse method in elastic theory. The length change of a single fibre was obtained on the basis of the principle that the volume of a single carbon fibre is constant during the deformation process. The resistance and strain model of the single carbon fibre under the action of an external force was then established following the relationship between the resistance, the length change and the volume change of the single carbon fibre. The resistance of carbon fibre composite materials, according to their production technology and unidirectional force properties, was assumed to be a mixture of the series and parallel resistances of the single carbon fibre, and a piezoresistive model of carbon fibre composite materials was formed by using the multidimensional Taylor series expansion and the idea of the average equivalent. The comparison between the theoretical and monitoring values of the piezoresistive model in a tunnel project in Tibet, China revealed that the resistance of various types of carbon fibres increases with the radius of the lining reinforcement and earth pressure and decreases with an increase in the lining reinforcement thickness. Meanwhile, the angles at different positions of the lining reinforcement also have certain effects on the resistance value of the carbon fibre. The variation curve of the piezoresistive model was exponential in both deeply and shallowly buried tunnels, which verifies the rationality of the model.

An Experimental Study of the Mechanical Properties of Partially Rehabilitated Cable Tunnels

“…From the aspect of tunnel lining and reinforcement, Nie [ 18 ] analyzed the piezo resistivity for an inner-adhesive-type carbon fiber reinforced plastic tunnel reinforcement; Zhou [ 19 ] studied the dynamic response of the lining structure in a long tunnel subjected to a non-uniform seismic load; Sun [ 20 ] studied the spraying construction method of a non-water reacting polymer layer in the tunnel; Zheng [ 21 ] discussed the use of yielding elements in shotcrete linings in tunnel squeezing deformation control; Wang [ 22 ] studied the response characteristics of cross tunnel lining under a dynamic train load; and Zhang [ 23 ] studied the sustainability performance of reinforced concrete structures in tunnel lining induced by a long-term coastal environment.…”

“…As for polymer materials, most research has focused on the polymer materials modified with fibers and inorganic materials: Li [14] studied the anisotropic mechanical response and strain localization of a metallic glassy-fiber-reinforced polyethylene terephthalate fabric; Lionetto [15] studied carbon fiber reinforced polymers; Park [16] studied a microwave composite forming process based on a sic mold for manufacturing fiber metal laminate; and Lou [17] investigated the fatigue performance of an asphalt mixture reinforced by basalt fiber. From the aspect of tunnel lining and reinforcement, Nie [18] analyzed the piezo resistivity for an inner-adhesive-type carbon fiber reinforced plastic tunnel reinforcement; Zhou [19] studied the dynamic response of the lining structure in a long tunnel subjected to a non-uniform seismic load; Sun [20] studied the spraying construction method of a non-water reacting polymer layer in the tunnel; Zheng [21] discussed the use of yielding elements in shotcrete linings in tunnel squeezing deformation control; Wang [22] studied the response characteristics of cross tunnel lining under a dynamic train load; and Zhang [23] studied the sustainability performance of reinforced concrete structures in tunnel lining induced by a long-term coastal environment.…”