Search

Summary: Seepage‐stress coupling is a key problem in the field of geotechnical engineering, and the finite element method is one of the main methods to study seepage‐stress coupling in rock masses. However, the finite element method has issues of poor stability, low efficiency, and low accuracy in the simulation of the seepage‐stress coupling problem. In this paper, the homogeneous saturated rock mass is taken as the object to deduce the control equation based on the Biot's theory. Considering the singularity of the coupling matrix, the discrete equation is converted into a precise integral format, and the equation is solved by the precise integration method to avoid instability and low precision. The precise integration method in this paper has good numerical stability, fast convergence speed, and high simulation accuracy, which effectively facilitates the rapid and stable numerical simulation of the seepage‐stress coupling problem using the equivalent continuum medium model. The validity and accuracy of the precise integration method for seepage‐stress coupling problems are verified by numerical examples. [ABSTRACT FROM AUTHOR]

The prediction of the free-surface seepage flow behavior in fractured rock mass is of significance in geotechnical engineering. There are two major issues in solving the seepage flow in complicated fractured rock mass based on the fractured porous medium (FPM) flow model, in which groundwater is assumed to flow simultaneously in both rock matrix and embedded fractures: One is the mesh generation of rock mass in the presence of the fracture network, especially when there exist a large number of stochastic fractures; the other is that a robust iteration algorithm is required since the free surface is unknown at the beginning of solution. Aiming at these two issues, this paper proposes a novel numerical method by coupling radial point interpolation method (RPIM) and finite element method (FEM), in which RPIM is utilized to model the rock matrix and FEM is utilized to model the fractures. On the basis of the variational inequality (VI) theory for free-surface seepage analysis, the computation formulations of the numerical method are derived and the corresponding computation program is developed. Three examples are solved with the present method. It is found that the VI theory can be extended to solve the free-surface seepage problem based on the FPM flow model. A crucial advantage of the present method is that the mesh generation can be greatly simplified. The present method has been verified to be a robust, efficient and reliable method for modeling the groundwater flow in complicated fractured rock mass. [ABSTRACT FROM AUTHOR]

This study presents a theoretical framework for monitoring the stability of a slope in an efficient and cost-effective manner. The optimal arrangement of monitoring points is achieved using strength reduction finite element analysis and redundancy optimization analysis. Using a highway slope in South China as a case study, it demonstrates that the developed theoretical framework has the capability of designing the three-dimensional distribution of the monitoring points within the slope in an optimal way. In addition, it shows that, with the increase of the reduction coefficient, the plastic zone inside the slope gradually expands with the decrease in the shear strength of the soil. Furthermore, the simulation results suggest that the horizontal displacement of the slope reaches to its maximum value in the region around 12 m from toe of the slope. • The process and mechanism of arrangement of monitoring points are revealed. • The displacements of monitoring points increase is spatial dependent. • A new method of optimal arrangement of monitoring points is proposed. • The horizontal displacement of the slope reaches to its maximum value in the toe of the slope. [ABSTRACT FROM AUTHOR]

Soft rock slopes may undergo long-term cyclic slow-to-fast landslides due to the softening of clay minerals and frictional sliding under hydromechanical disturbance. We proposed a meso/macroscale cyclic slow-to-fast landslide model by coupling creep and frictional sliding model to address the abovementioned problem. The model can reveal the macroscopic catastrophic phenomena caused by the accumulation of mesoscale damage in soft rocks, thus providing a scientific basis for the simulation of cyclic slow-to-fast landslides. For modeling validation, we applied the model to the Spriana soft rock slope, which undergoes long-term instability under periodic groundwater level variation. By adopting the coupled finite element method and distinct element method (FEM-DEM), the model can mimic the stable creep and fast sliding in different phases of matured slow-moving landslides. The difficulties in simulating cyclic accelerated sliding are solved, where the simulation error of displacement is less than 5.7 % compared with field monitoring data. It may serve as a prediction tool for cyclic slow-to-fast landslides. [ABSTRACT FROM AUTHOR]

This paper aims at developing a pore-scale numerical model for non-Darcy fluid flow through rough-walled fractures. A simple general relationship between the local hydraulic conductivity and the flow velocity is proposed. A new governing equation for non-Darcy fluid flow through rough-walled fractures is then derived by introducing this relationship into the Reynolds equation. Based on the non-linear finite element method, a self-developed code is used to simulate the non-Darcy fluid flow through fractures. It is found that the macroscopic results obtained by the numerical simulation agree well with the experimental results. Furthermore, some interesting experimental observations can be reproduced. [ABSTRACT FROM AUTHOR]

This paper aims at developing a method for modeling rock mass with preexisting multiple discontinuities within the framework of the smoothed finite element method (SFEM). The discontinuity is simulated by an interface element with zero thickness, the stiffness matrix of which are derived explicitly based on the SFEM. An elastic damage constitutive relation with residual strength is introduced in order to describe the nonlinear mechanical behavior of the discontinuities. The computation codes of the present method were developed. The present method has been verified to be a sound approach for modeling discontinuous rock mass, inheriting the advantages of the SFEM. [ABSTRACT FROM AUTHOR]

[Display omitted] • The 3D concrete model with aggregates and interfacial transition zone is modeled. • The increase of aggregate volume ratios inhibited the chloride diffusion. • The aggregate volume ratio for back calculation has an important influence on model. • Different interfacial transition zone thickness is no influence on the model accuracy. • The reason for the better chloride resistance of nanocomposite concrete is studied. The chloride diffusion in concrete with different aggregate volume ratios (AVR) and interfacial transition zone (ITZ) were studied in this paper. According to the finite element method, the 3D concrete model with aggregates and ITZ is modeled, and the chloride diffusion characteristics were numerically simulated and compared with the experimental results. Furthermore, the reasons for the better chloride resistance of nanocomposite concrete are studied. The results show that the established model can well reflect the material properties of concrete and has a good application effect on chloride diffusion. The increase of AVR inhibited the chloride diffusion and there is significant influence on the simulation results when use different AVR to back calculation. However, it is little influence on the simulation results when change the ITZ condition of back calculation. The better chloride diffusion resistance of nanocomposite concrete is mainly due to the improved anti-diffusion properties of the ITZ. [ABSTRACT FROM AUTHOR]