Journal of Engineering Mechanics

This paper presents a theoretical and numerical analysis of the length required for roll waves to become stationary in a free-surface laminar flow of a Newtonian fluid. Two types of stability analysis are brought to verify flow stability and obtain parameters for wave growth rate in a Saint-Venant like system. Then, numerical simulations are performed of the free-surface laminar transient flow of glycerin. The Navier-Stokes equations were solved using the finite volumes method, Euler schemes and PIMPLE, and the VoF technique to solve the interface. Boundary conditions were specified to obtain a steady and uniform regime given a Froude number. Then, a sinusoidal perturbation with controllable properties was applied to the inlet velocity. From the numerical results, the spatial development of the roll waves was evaluated, focusing on the establishment length as a function of the Froude number and the perturbation amplitude. The analyses performed allowed the verification of the influence of flow hydraulic regime over the establishment length, and it was possible to obtain a new equation as a function of the perturbation amplitude.

This paper mainly investigated the buckling behavior of corroded four-sided simply supported plates with longitudinal stress gradients. The effect of corrosion surface topography on the buckling behavior of the four-sided simply supported plate was investigated by reverse reconstruction. The eigenvalue buckling analysis was also carried out to reveal the influence of corrosion depth, area, and location on the buckling load of simply supported plates. Based on the analysis, the theoretical formula of the buckling load of corroded four-sided simply supported plates with longitudinal stress gradients was established by the energy method. The results showed that the first order buckling mode of corroded plates was asymmetric and the highest peak was located in the weak section. The stress state led the corrosion parameters to have different effects on the buckling load of four-sided simply supported plates. The corrosion location had little effect on the buckling load of four-sided simply supported plates under uniform pressure. However, for the plate under nonuniform pressure, the closer the distance between the corrosion location and the compression zone of plate, the smaller the buckling load was. The perforation changed the force mechanism of the plate, and the noncorroded part surrounding the opening hole formed a new three-sided simply supported plate, leading to an increase in the buckling load. Finally, on the basis of the response surface method, the key parameters governing the local buckling were identified, leading to an easy-to-use formula to determine the buckling load.

Most countries adopt the mechanical theory of a layered elastic system under vertical load as the design method for asphalt pavement. This calculation theory does not consider the influence of the horizontal force of the vehicle load, and it is also unable to calculate the creep, relaxation, and other behaviors of the pavement material under repeated loads. To overcome these limitations, this research derived the analytical solution of the layered viscoelastic system under horizontal and vertical loads and developed a numerical calculation program for viscoelastic half-space and multilayer system. The accuracy, efficiency, and stability of the calculation program were tested to meet the requirements. The viscoelastic mechanical responses of the checkpoints in structural design under different horizontal load factors were calculated through the program. The results showed that the horizontal load significantly affects the distribution of stress and displacement of the pavement structure and the extent of the horizontal load impact varies in different positions. The horizontal load should be considered in pavement mechanics analysis and structural design.

The rotation of the principal stress direction has a significant influence on the stress–strain relation and deformation characteristics of sand. This study proposes a hypoplastic model to simulate the noncoaxial response of anisotropic sand subjected to the rotation of the principal stress direction. The densification effect of sand is considered through a properly defined function, enabling the model to simulate a gradually stabilized strain accumulation upon rotational shearing. A fabric tensor is used to describe the anisotropic microstructure of sand, and worked in conjunction with the stress in the form of a joint invariant–based state variable to simulate the impact of fabric anisotropy on the behavior of sand. The fabric tensor is integrated with the hypoplastic flow direction, making the model capable of generating a noncoaxial response. The model response was compared with the experimental data for rotational shear tests under various conditions.

A novel semi-analytical solution is proposed to analyze the consolidation behavior of composite ground with a floating impervious column in unsaturated soil based on the equal-strain hypothesis. The basic governing equations in the reinforced zone and the underlying stratum are first obtained. Using the Laplace transformation and matrix analysis method, a final solution in the Laplace domain is derived. Afterwards, on the basis of Stehfest’s method, an inverse Laplace transform is conducted to derive the solution in the time domain. The effectiveness of the proposed solution is then evaluated against the results of finite difference analysis. Moreover, a sensitivity analysis is performed to assess the effects of area replacement ratio, depth improvement ratio, and column stiffness on the dissipation of excess pore-water/air pressure and the average degree of consolidation. Results show that only vertical seepage occurs during the consolidation process of unsaturated composite ground under a condition of equal-strain. The consolidation rate of unsaturated soft ground can be improved by introducing floating impervious columns. The use of larger area replacement ratio, depth improvement ratio, and column stiffness can increase the consolidation speed and reduce the settlement of composite ground with a floating impervious column in unsaturated soil.

Geotechnical site retrieval refers to the quantitative identification and extraction of sites similar to a given target site from predocumented generic sites in a database. This is known as the “site recognition challenge.” Recently, the second and third authors of this paper proposed a Bayesian similarity measure between a target site and generic records in the database. However, the proposed method can only retrieve “similar database records” but not “similar database sites”; that is, records are not grouped according to their test locations within a site boundary. The purpose of the current paper was to propose a novel Bayesian similarity measure between the target site and a database site to extract similar sites from a database. This “site retrieval” approach is more “explainable” to a geotechnical engineer because an engineer has an opportunity to accept or reject the identified “similar” sites based on his or her experiences and judgment. The human engineer can engage an explainable algorithm in a decision loop in a more meaningful way. Based on the hierarchical Bayesian model (HBM) previously developed by the second and third authors, this study further proposed a Bayesian method of measuring similarity between the target site and database sites for the purpose of geotechnical site retrieval. This hierarchical Bayesian measure elegantly reduces to the classical Kullback–Leibler divergence for complete multivariate data. The HBM was used to simultaneously model intrasite and intersite variability and construct the site-specific multivariate distribution for the database sites. Site retrieval was performed by measuring the similarity between the target and database sites in the form of a multivariate likelihood. It is shown that the proposed hierarchical Bayesian method can yield a meaningful interpretation of intersite similarity and can successfully be used for site retrieval. The proposed approach can also quantify the statistical uncertainty due to sparse (limited) and incomplete (missing) data.