Ice cementation and ice-substrate adfreeze force are the primary contributors to the high bearing capacity of pile foundations in cold regions and the stability of frozen walls in areas subjected to artificial freezing. Given the significant temperature sensitivity of ice's shear rheology, engineering structures in ice or ice-rich soils continue to deform even under constant external loads. A thorough understanding of shear creep and the long-term adfreeze force at the ice-substrate interface is essential for predicting the continuous deformation of these structures. However, research into the shear creep behavior at frozen interfaces has historically been constrained by the precision of temperature control in experimental settings and the complexity of load paths in shear testing devices. In this study, a temperature- and stress-control device for interface shear creep is assembled firstly, and multilevel loading-unloading creep tests on steel pipes embedded in layered frozen ice were conducted. Through the decoupling of deformation progression, the viscoelastic and viscoplastic shear behaviors at the steel-ice interface under various temperatures and shear stresses were characterized, the principle of sustainable interfacial shear creep along with its underlying physical mechanism were proposed. Subsequently, with the aid of a modified nonlinear Burger model, various interfacial shear creep parameters were derived. Results reveal that the interfacial generalized shear modulus continuously improves but with a gradually weakening degree until a point of accelerating creep is reached. Additionally, the long-term adfreeze force is found to be less than half of the short-term strength, which significantly decreases as the temperature approaches the water phase transition zone. Interestingly, the stress exponent associated with the interfacial steady creep rate is considerably smaller than that predicted by Glen's law. This research provides a theoretical basis instrumental in the engineering design in cold regions and those structures employing artificial freezing techniques.

Reservoir geologic fluid-bearing granular materials are characterized by multiscale nonuniformity and coupled multiphysical mechanisms, for which conventional poroelastic theory cannot accurately portray wave dispersion and attenuation characteristics. To design a suitable dielectric wave propagation model to characterize the dispersion and attenuation laws of dynamic waves in geologic reservoirs, first, the branching functions of frequency-dependent dynamic permeability and dynamic tortuosity are derived by considering the effects of the geometry and fractal structure of fluid-bearing granular materials on the high-frequency properties of permeability and tortuosity. Second, the stress-strain relationship of the fluid-particle system is redrawn by the viscoelastic-plastic constitutive relation, and the dynamic wave propagation model of fluid-containing granular materials at a unified frequency is constructed by an integrated dissipation mechanism including frictional dissipation, internal dissipation, and plastic energy dissipation-wave propagation model based on viscoelasticplastic constitutive relation and dynamic permeability (WVPDP model). Finally, the reliability of the WVPDP model is verified by carrying out wave velocity tests on saturated dolomite and sandstone, and the effects of different parameters on the wave velocity dispersion amplitude and attenuation peak are analysed. The results show that the WVPDP model can accurately characterize the dispersion and attenuation of dynamic waves in granular media under uniform high and low frequencies and can invoke different dissipation mechanisms at different excitation frequency intervals, which is shown by the fact that internal dissipation and the plastic mechanism play the main role in the low-frequency interval, and frictional dissipation gradually replaces internal dissipation and plastic dissipation to become the main dissipation mechanism with increasing excitation frequency. Parameters such as fluid viscosity, reference angular frequency and reference quality can have different effects on the dispersion amplitude and transition band range of the fast P-wave and S-wave, the two mechanical response mechanisms in the medium of fluid-containing granular materials.

With the widespread application of large- quasi-rectangular pipe-jacking tunnels in urban road traffic engineering in China, higher requirements have been put forward to control the influence of their construction on the surrounding environment. To scientifically evaluate the stability of large- quasi-rectangular pipe-jacking tunnels under-passing existing box culverts, we proposed a novel viscoelastic-plastic model coupling Biot consolidation with non-stationary parameter shear creep (NPSCBCVPM) to fully characterize the coupling effect of consolidation and rheology of saturated soft soil. NPSCCBVPM was developed in Fortran as an ABAQUS user material subroutine. In addition, the NPSCBCVPM was compared with the creep tests of undisturbed soft soil and the generalized Nishihara creep model (GNCM). Finally, the proposed model was applied to the large- quasi-rectangular pipe-jacking tunnel under-passing existing box culverts of Songhu Road in Shanghai. The results show that NPSCBCVPM are in good agreement with the creep tests of soft soil, and NPSCBCVPM can better reflect the nonlinear rheological characteristics of soft soil than GNCM. Furthermore, the proposed model can scientifically evaluate the viscoelastic-plastic stability analysis of large- quasi-rectangular pipe-jacking tunnel under-passing box culvert. Further research should focus on developing three-dimensional NPSCBCVPM to better evaluate the spatial response of the box culvert structure and surrounding soil to the entire construction process of large- quasi-rectangular pipe-jacking tunnels.