An iterative cross-coupled surface and subsurface flows model is proposed to simulate the runoff generation and infiltration of a wide area hillside slope. Surface water on hillside slope was modeled as 2D shallow water equations and subsurface flow was modeled as 3D Richards’s equation. The infiltration capacity was controlled by Green-Ampt infiltration model. The water depth calculated by 2D shallow water equations was applied to 3D Richards’s equation as the water head boundary condition and the infiltration or exfiltration calculated by Richards’s equation was applied to the runoff simulation as source item. In this study, first, an approximation of shallow water equations that simplifies the equations of motion by considering only the main contributions was used. Then, the simplified runoff model was validated by the extensively used tilted impermeable V-catchment example with only simulating surface runoff flows. The iterative cross-coupled surface and subsurface flows model was verified by a simple 2D unsaturated-saturated model. The simulation results show that the iterative cross-coupled surface and subsurface flows model can reproduce rainfall generated runoff and infiltration. Finally, the runoff generation and infiltration of a natural mountain slope in Hokkaido were simulated, as the runoff caused several slope failures in this area during Typhoon 10 in 2016.

The high-speed railway has strict restrictions on the settlement of the roadbed, and the settlement value must not exceed 15mm. In the process of calculating the settlement of high-speed railway subgrade, the impact of soil creep should be considered. In the creep calculation, the calculation parameters should have practical physical meaning. Therefore, based on the UH model considering time effect, the secondary development of ABAQUS software is realized, and the finite element simplified model of the high-speed railway in a section near Qufu East Station is established. The creep settlement of the points on the surface of the natural roadbed under the high-speed railway is concave curve of distribution. With the change of time, the creep growth rate of each point becomes slower and slower, and the creep settling curve shows a tendency of gradual flattening.

To clarify the influence of large shear strain on the cyclic behavior on liquefiable granular materials, a series of undrained cyclic simple shear simulations were carried out by utilizing 3D discrete element method (DEM). The amplitudes of the cyclic shear strain loaded on specimens range from 0.3% to 100%. The results show that when the cyclic shear strain loaded exceeds a certain amplitude, both the loose and the dense specimens exhibited high energy absorption properties, positive dilatancy characteristics, and non-liquefaction behaviors. This phenomenon might be caused by the uneven spatial distribution of particles during cyclic shear loadings. In addition, the liquefiable cyclic shear strain amplitude range is affected by the density and particle size of specimens.

The region or the path of preferential seepage flow is inversely identified by a gradient-based Markov Chain Monte Carlo method called Hamiltonian Monte Carlo (HMC). Observing hydraulic head and discharge rate of seepage water, HMC method estimates the domain or the path of preferential seepage flow by changing the shapes of finite elements over which the seepage flow is numerically solved by the finite element method. One simple synthetic example is solved in this article, and the numerical result shows that HMC method with a moving mesh performs well for this geometric inverse problem.

The long-term settlement of high fill is large, which may affect the practical application of engineering. Therefore, it is crucial to study the calculation method and effective prediction range of long-term settlement. In this paper, a numerical back-analysis platform based on genetic algorithm and time-dependent UH model is established. It is verified that the numerical calculation based on time-dependent UH model is applicable to predict the long-term settlement by the settlement monitoring data of the high fill in Chengde Airport, Hebei province. The effective prediction interval method of long-term settlement is proposed and the corresponding calculation equation is derived. According to the existing measured data interval tm, the equation can be used to quantitatively calculate the effective prediction interval te under a specific settlement error limit. At last, the effective prediction interval is calculated through the monitoring data of the high fill in Chengde Airport.

We implement the particle finite element method (PFEM) in the general numerical simulation framework ABAQUS to investigate the quasi-static collapse of two-dimensional granular columns and landslides. As a recently proposed continuum approach, the PFEM inherits both the solid mathematical foundation of the particle of the traditional finite element method and the flexibility of particle methods in simulating ultra-large deformation problems. In our work, the governing equations of the PFEM are solved by the ABQUS iteratively to improve the accuracy and efficiency of simulation results. The typical collapse patterns of granular columns are reproduced in the PFEM simulation and the physical mechanism behind the collapse phenomenon is evaluated. We compare the simulated collapse processes with the experimental observations, where a satisfactory agreement is achieved.

A numerical simulation model, considering the distribution of minerals in intact rock, was proposed to predict the tensile strength as well as the processes for generating and propagating a fracture in radial compression tests. The objective rock sample was modeled by considering the mineral distribution obtained through an image analysis. The proposed model accurately estimated the tensile strength and the tensile stress-vertical strain relation. In addition, using the damage variable, the generation and propagation of the fracture were also estimated by the proposed model.

Like Smoothed Particle Hydrodynamics, the Finite Particle Method is conventionally formulated for dynamic problems and suitable for simulating dynamic motion of liquids and solids. In this work, the FPM is formulated as equilibrium problems large deformation of solids. Numerical aspects for implementation, including solution method, control of numerical instability, stress integration, are discussed. Application of the method to slope stability analysis is presented to demonstrates the effective, accuracy and the potential in solving large deformation and failure flow problems

In this paper, three types of stress integration algorithms are evaluated for the SANISAND-04 model based on Runge-Kutta method (RK4), cutting plane method (CPM) and closest point projection method (CPPM). Performance of the three integration schemes is first assessed in monotonic drained and undrained triaxial compression test simulations, and then in cyclic undrained triaxial test simulations. These simulations show that the errors of CPPM and CPM are similar and predictable, generally increasing with increasing strain step size. The error of the RK4 is highly dependent on the loading conditions and material parameters. Under undrained cyclic loading, the overall performance of CPM is the best in terms of both accuracy and convergence. As for the computational cost, CPM is the most efficient integration scheme, especially for small strain increments.