Journal of Engineering Mechanics

The rectangular pipe jacking method, as a new type of shallow tunnel excavation technology, is increasingly widely used in practical engineering due to its advantages of higher space utilization and fewer impacts on the surrounding environment. The construction process of pipe jacking will cause stress change and deformation of the surrounding soil. In this paper, on the basis of the complex variable elasticity, an analytical solution for a shallow rectangular pipe jacking tunnel under the action of rectangular cavity contraction and inner uniform pressure is proposed. Through the conformal mapping technique, the rectangular cavity in a semi-infinite plane is first transformed as a unit concentric ring. Then, the stress functions for the stress and displacement around the rectangular cavity under two types of boundary conditions are derived, which allows the stress change and deformation of the surrounding soil to be determined. The proposed analytical solutions are verified by comparison with the results of finite-element numerical simulations. Parametric studies are conducted to investigate the influence of the Poisson’s ratio effects of soil, tunnel aspect ratio, and tunnel burial depth on the stress and displacement of soil. The proposed analytical solution can be potentially applied to the problem of a rectangular tunnel using pipe jacking.

Thermal tempering can induce a permanent residual prestress in glass, which is beneficial because it compensates for the low tensile strength of the material. The characteristic design resistance of tempered glass is usually fixed as the simple sum of the 5% quantiles of the statistical distributions of pristine glass strength and heat-induced surface prestress, but this definition neglects the positive contribution of the statistical interference between the two stochastic variables. Here, a verification formula for structural design is discussed, in which this effect is considered through a statistical-interference factor. Its calibration is now obtained by comparing level III (full probabilistic) and level I (semiprobabilistic) methods of design in paradigmatic case studies, illustrative for a wide range of applications, which differ for what concerns the size effect, the level of prestress, the duration of applied actions, and the class of consequence. The results show that consideration of the interference factor can lead to significant savings in terms of material consumption.

The mechanical properties of viscoelastic (VE) dampers directly affect the aseismic performance of viscoelastically damped structures; therefore, it is of great significance to accurately describe the nonlinear mechanical characteristics of VE dampers in the aseismic design and analysis of structures. However, most of the existing mathematical models for VE dampers have been established from a macroscopic perspective, and there is a general lack of a comprehensive connection to the microstructure characteristics of VE materials and external influence factors such as loading frequency, ambient temperature, and strain amplitude. In this paper, inspired by the molecular chain network models and fractional derivative theory, a microstructure-based equivalent visco-hyperelastic model is proposed for VE dampers with consideration of temperature dependence and the filler reinforcement effect. To verify the characterization capacity of the proposed model, laboratory experiments on the dynamic property of VE dampers were carried out with varying frequencies, temperatures, and strain amplitudes, and the proposed model was then employed to predict the experimental results. Finally, model parameter analysis was conducted to clarify the relationship between material microstructure and its macroscopic performance. The experiments indicate that the VE damper possesses an excellent energy-dissipation capability, and characteristic parameters of VE dampers tend to be more sensitive in the low ranges of frequency and temperature than in the high ranges. Comparisons between the experimental and numerical results suggest that the proposed model can describe the mechanical properties of VE dampers at different frequencies, temperatures, and strain amplitudes with good accuracy. Parameter analysis demonstrates that the proposed model can reflect the influence of material microstructure on the macroscopic mechanical properties of VE dampers.

Coupled hydromechanical finite-element modeling of granular soils, taking into account internal erosion, is computationally prohibitive. Alternative data-driven approaches require large data sets for training and often provide poor generalization ability. To overcome these issues, this study proposed a physics-informed multifidelity residual neural network (PI-MR-NN) modeling strategy. The model was first trained using low-fidelity data to focus on capturing the main underpinning physical laws. Subsequent training on sparser high-fidelity data was then used to calibrate and refine the model. Physical constraints, e.g., boundary conditions, were incorporated through modifications to the loss functions. Feedforward and long short-term memory neural networks were considered as the baseline algorithms for training models. The PI-MR-NN was first used to reproduce synthetic results generated by the soil constitutive model SIMSAND and a published internal erosion model. The developed data-driven model was then applied to simulate the breach of a practical dike-on-foundation case and to predict its temporal responses. All results indicated that the hydromechanical response of porous media can be accurately captured using the proposed PI-MR-NN model. The novel training strategy mitigates the dependency of model performance on the training data set and architecture of the neural network, and the use of physical constraints improves training efficiency and enhances the model’s predictive robustness.