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In response to a series of engineering disasters encountered during the excavation and support construction of loess tunnels, considering the issues of water enrichment in surrounding rock induced by excavation disturbance and system bolt failure, drawing on the concepts of lime pile composite foundation and composite bearing arch, and based on the principle of the New Austrian Tunneling Method (NATM) that fully mobilizes and leverages the self-supporting capacity of surrounding rock, this study comprehensively considers the wetting and stress adjustment processes of the surrounding rock after excavation disturbance in loess tunnels. By adopting the technical principle of "water absorption and densification of shallow surrounding rock, suspension and anchoring of deep surrounding rock, and composite arch bearing", a new type of water-absorbing, densifying, and anchoring bolt was developed that can reduce the water content of surrounding rock while enhancing its resistance. To further investigate the water absorption, densification effect, and pull-out bearing characteristics of this new bolt, laboratory model tests were conducted, examining the temperature, pore water pressure, densification stress of the soil around the bolt, as well as the physical properties of the soil in the consolidation zone. The test results indicate that a cylindrical heat source forms around the water-absorbing, densifying, and anchoring bolt, significantly inducing the thermal consolidation of the surrounding soil. The variations in temperature, pore water pressure, and densification stress of the soil around the bolt truly reflect the qualitative patterns of hydro-thermal–mechanical changes during the water absorption, curing, and exothermic reaction processes. The water absorption and densification segment of the bolt effectively enhances the density of the soil in the water absorption, densification, and consolidation zone, improving soil strength parameters. Compared to traditional mortar-bonded bolts, the water-absorbing, densifying, and anchoring bolt exhibits a greater pull-out bearing capacity. The research findings provide important guidance for the theoretical design and engineering application of this new type of bolt. [ABSTRACT FROM AUTHOR]

This article, published in the International Journal of Applied Mechanics, discusses a new theory of fractional-order rate-dependent piezoelectric thermoelasticity and its application in analyzing the structural transient response of smart piezoelectric composite laminates. The authors develop unified forms of fractional-order strain and heat conduction by adopting different types of fractional derivatives. They establish a fractional-order rate-dependent piezoelectric thermoelasticity theory and derive constitutive and governing equations using an extended thermodynamics framework. The theory is then applied to investigate the dynamic thermo-electromechanical responses of smart piezoelectric composite laminates with imperfect interfacial conditions. The influences of different fractional derivatives, imperfect interfacial conditions, and materials constants ratios on wave propagations and structural thermo-electromechanical responses are evaluated and discussed. [Extracted from the article]

Based on the generalized thermoelastic diffusion theory with memory-dependent derivative in both the generalized heat conduction law and the generalized diffusion law, the transient response is investigated of a half-space subjected to a thermal shock and a chemical potential shock on its bounding surface. The coupled governing equations containing time-delay factors and kernel functions, which can be chosen freely according to specific problems, are solved by the Laplace transform together with its numerical inversion. The non-dimensional temperature, chemical potential, displacement, stress, as well as concentration at different values of time, time-delay factors, and kernel functions are obtained and illustrated graphically. The results show that: all the considered variables have obvious changes with the passage of time; the thermal time-delay and kernel functions hardly influence the distributions of the non-dimensional chemical potential, modestly influence the distributions of the non-dimensional concentration, while appreciably influence the distributions of the non-dimensional temperature, displacement, and stress; the diffusion time-delay and kernel functions barely affect the distributions of the non-dimensional temperature, slightly affect the distributions of the non-dimensional concentration, while remarkably affect the distributions of the non-dimensional chemical potential, displacement and stress. [ABSTRACT FROM AUTHOR]