It is believed that the relative density (Dr) can affect the internal stability of the gap-graded soils and hence the erosion of their fine particles (i.e. susceptibility to suffusion). This paper investigates the influence of Dr on the contribution of fine particles to soil fabric. A new procedure is proposed to produce samples with target Dr using the discrete element method (DEM). DEM simulations

Anisotropic clays are very common in practical engineering, where their constitutive relations were usually developed based on classical plasticity theory with associated flow rule. However, the softening responses of clays under compression following anisotropic consolidation can be non-associated and state-dependent. Fractional derivative is defined based on an integral form that can consider the

This paper presents machine learning aided stochastic reliability analysis of spatially variable slopes, which significantly reduces the computational efforts and gives a complete statistical description of the factor of safety with promising accuracy compared with traditional methods. Within this framework, a small number of traditional random finite-element simulations are conducted. The samples

An evaluation of slope stability using the finite element method is often performed as a complementary analysis to the plastic deformation analysis. The slope stability is typically evaluated by the reduction of the strength parameters c and φ of the Mohr-Coulomb model and it is represented by the so-called factor of safety. It is much less common to use the strength reduction method in combination

In spite of recent advanced geotechnical research regarding the influence of particle-scale morphology and fabric on the constitutive behavior of silica sands, there is still no published literature that investigated the influence of crystal structure of sand particles on their constitutive behavior. The main constituent of silica sand particles is quartz mineral, which has a trigonal crystal system

While performing the upper bound limit analysis, using an associated flow rule, the expressions for the power dissipation function corresponding to different forms of yield criteria for clays exhibiting shear strength anisotropy and transversely asymmetric properties (implying different strengths in compression and tension), have been derived in terms of velocities, strain rates and shear strength

The accuracy of rock property measurements in real-time heating loading tests has been considered as questionable due to the thermal effect on loading platens. In this study, the impact of steel platen performance at high temperatures (up to 1000 °C) on granite property measurements is analysed by numerical simulations. Simulation results show that a smaller stiffness of the loading platen can result

The evolution of the permeability of granite at high temperatures has a significant effect on geothermal exploitation. In this study, the fluid-solid coupling algorithm is improved based on the different intra-granular, inter-granular and crack seepage characteristics of granite, and the permeability characteristics of thermally treated granite specimens are simulated under different confining pressures

This paper proposes a method for nonlinear analysis of a rigid pile under lateral load at the crest of clay slope. It is assumed that the ultimate soil resistance in front of the pile and behind the pile vary nonlinearly with depth. The modulus of horizontal subgrade reaction in front of the pile and behind the pile vary nonlinearly with the pile displacement at ground surface. The horizontal shear

With recent advances in computational capabilities as well as broad improvements in ground motion characterization and inelastic modeling of structural and geotechnical systems, large-scale direct models for underground structures—e.g., tunnels, water reservoirs, etc.—can now be devised with relative ease and deployed in engineering practice. In this study, a fragility-based seismic performance characterization

A new macroscopic yield criterion is derived in the present work to describe the elastoplastic mechanical behavior of composite with a porous matrix-inclusion microstructure. The influences of porosity at the microscopic scale and the bigger inclusions at the mesoscopic scale are explicitly taken into account by this criterion. The solid phase at the microscopic scale obeys to a Drucker-Prager criterion

This paper investigates the effect of suffusion on the undrained behavior of an internally unstable soil using the coupled computational fluid dynamics and discrete element method (CFD-DEM). A series of eroded specimens are prepared by exerting an upward flow through the granular assembly under a range of hydraulic gradients and suffusion durations. Both the eroded and non-eroded specimens are then

The mechanical heterogeneity of unconventional gas reservoirs is a significant factor affecting the nucleation and propagation of hydraulic fractures. The ignorance of mechanical heterogeneity in the numerical calculation has been demonstrated to result in huge deviations from actual fracture propagation. In the present study, the eXtended Finite Element Method (XFEM) is used to simulate the propagation

This paper aims to model the thermo-mechanical behavior of saturated clays under undrained conditions. Classic thermo-hydro-mechanical formulations obtained using different approaches were compared and discussed, showing their compatibility and differences. A thermo-elasto-plastic model called TEAM, using a two-surface approach, was developed for saturated clays under undrained conditions in the framework

The geosynthetic-stabilized base course over a subgrade becomes a transversely isotropic layered system due to the degradation of the base modulus under cyclic loading. However, no elastic solution is available to quantify the stresses and strains of the geosynthetic-stabilized section considering base deterioration. In this study, the vertical shear modulus of the base course was modeled to decrease

This paper studies the influence of the grain size and the notch effect on the fracture of U-shaped notched rock beams through the variation of the apparent fracture toughness. The research is based on an exhaustive campaign that comprises numerical simulations of 300 four-point bending tests, 30 uniaxial compression tests and 60 tensile splitting (Brazilian) tests. Non-porous, isotropic ideal and

In this paper, a semi-analytical elastodynamic forward solver was proposed for the Multichannel Analysis of Surface Waves (MASW) using the spectral element technique for the first time. A root finding method based on Brent's algorithm was proposed to accurately extract the dispersion curves. The trust region reflective method, an effective bound-supported least square algorithm, was applied, for the

This study introduces the jackknife method to model the statistical uncertainty in the joint distribution of geotechnical parameters derived from a small sample and its effect on geotechnical reliability. A numerical example using simulated data is adopted to validate the accuracy of the jackknife method. The following three real examples are studied to illustrate and demonstrate the jackknife method:

In this paper, the governing equations and semi-analytical solutions are proposed to investigate the consolidation behavior of unsaturated composite ground with the permeable columns. Based on the stress and strain equilibrium conditions of composite ground and the strain–stress relations of unsaturated soils under the axisymmetric condition, a set of the basic equations are proposed for describing

In this study, by coupling the conditional and unconditional random field with finite element methods, the stability of a real slope is investigated. In the first method, which is used for the case of an Unconditional Random Field (URF), the analysis is carried out similar to the approach of the Random Finite Element Method (RFEM) using the mean and standard deviation (std.) of soil parameters derived

Retrogressive spreading failure occur frequently in sensitive clay deposits due to triggering such as gradual natural erosion and degradation or artificial cut. The large scale of failure observed in retrogressive landslides have been attributed to quasi-horizontal shear band propagation along a weak layer. This study explores the critical conditions for such failure and develops the criteria for catastrophic

This study developed a combined dynamic analysis model for analyzing the response of piles when subjected to inertial and kinematic effects under seismic loading. A structure-pile-soil model connected to a shear beam model was established to simultaneously account for both these effects. Centrifuge shaking table testing was conducted on two piles that were partially embedded in dry sand to verify the

A better understanding of the gravity flow mechanism of caved material is required to increase ore recovery in caving mining. This study presents a novel computational framework PRF3D (3D particle random flow) capable of simulating the flow behavior of caved ore and rock in sublevel caving mining. The PRF3D framework combines the advantages of the discrete element method and stochastic medium theory

Due to the complexity and inherent spatial variability of the strata and the limited availability of borehole information, the subsurface stratigraphic configuration at a site is hard to characterize accurately, which gives rise to stratigraphic uncertainty. This paper presents a random field-based approach for modelling the stratigraphic uncertainty, in which, the spatial correlation of the stratum

This paper presents the seismic analysis of stone column (SC) improved liquefiable ground using a three-dimensional (3D) plasticity model with unified description of coarse-grained soil (CGS). The model is a modification of an existing plasticity model for large post-liquefaction deformation of sand, with improvements on the formulation for strength characteristics exhibited by CGS. According to requirements

This paper presents a model that describes the gradual yielding of unsaturated cemented soils subjected to isotropic loading. The model relies on the definition of a “cementation bonding function” which accounts for the progressive breakage of inter-granular cementation caused by loading. The combination of this cementing bonding function with the unsaturated model of Gallipoli and Bruno (2017) leads

In this study, hydromechanical hybrid finite-discrete element method (FDEM) models were employed to investigate hydraulic fracturing from oriented perforations at the microscale. Numerical calibrations were first used to obtain the microproperties that can represent the realistic behavior of sandstone. The fracture morphology and breakdown pressure obtained from the numerical hydraulic fracturing show

The analyses of active earth pressure subjected to earthquake shaking are routinely explored concerning dry or saturated soils. However, the fact often neglected in previous literature is that soils are mostly unsaturated in nature. This work puts forward a kinematical approach for the assessment of active resistance of a rigid retaining structure against unsaturated backfills with pseudo-dynamic approach

Fabrics of granular media play an important role in understanding sophisticated soil behaviors and developing constitutive models. In this study, the evolution of fabric anisotropy in terms of both contact normals and local void distributions under drained and undrained loading conditions is explored using DEM simulations. It is observed that the anisotropy degree of both contact-based and void-based

This paper presented a dynamic fluid-solid coupled finite element (FE) method incorporating the soil cap yield hardening model to analyze the improvement on saturated foundation under dynamic compaction (DC). Biot’s dynamic u–U–p formulation was employed to describe the coupling of pore fluid and solid phases, which was discretized into finite elements by application of the Galerkin method and viscous

This study investigates the characteristics of vertical soil deformation induced by fully overlapping tunnels constructed using a tunnel boring machine (TBM). The Peck formula is improved to consider the variation in the tunnel axis depth and stratum loss ratio. Comparing the settlements both monitored and simulated on the fully overlapping tunnels of the Tianjin Metro, it is shown that our improved

Debris flows have been widely researched during the last decades since they are catastrophic events with significant infrastructure and environmental impacts. Typically, they are composed of various materials which interactions are worth for studying, to improve the prediction of some variables, such as velocities, forces and affected areas. Constitutive models and numerical methods are fundamental

The tunnel-type anchorage (TTA) is recently being used in large-span suspension bridge, however, the reliability is not yet investigated and the pullout load carrying behavior is also not fully understood. Hence, in this paper, the pullout behavior of TTA during loading was investigated using a finite element program. Subsequently, extensive parametric studies were carried out to assess the factor

This study presents a novel Bayesian framework for statistical calibration of spatially distributed physical-based landslide prediction models. The calibration process is formulated in a statistical setting with the model parameters simulated as spatially variable with random fields and the model calibration defined within the Bayesian framework. The implementation of such calibration process is challenging

Rock mass behaviour model selection, in particular, to represent the post-failure behaviour and time-dependent behaviour of rock masses, are critical issues in the correct application of tunnelling design techniques such as the convergence-confinement method or numerical modelling. This study provides a general numerical approach for predicting longitudinal deformation profiles using a coupled Vis

This paper first proposes an original procedure to implement three-dimensional (3D) surfaces of rough existing unbonded contact specimens, i.e. fully open with no chemical bond, into non-linear finite element models to numerically simulate shear tests conducted under Constant Normal Load (CNL) conditions. The developed procedure is applied to 18 contact specimens drilled from concrete, concrete-rock

An analytical model for lightweight cemented backfill is presented. The model integrates elasto-brittle and elasto-plastic bodies, replicating responses of low-density materials and cementation that are present in backfills. The model uses a semi-implicit algorithm to iterate stress-strain solutions, and the universal shear contraction. The model was validated on a lightweight cemented backfill containing

The carbonate reservoir contains numerous randomized natural fractures and cavities. Due to the stress concentration surrounding the cavity, the conventional hydraulic fracturing technique is very hard to connect the artificial fracture with the cavity. Under such situation, the pulsed fracturing (PF) technique should be an alternative stimulation approach. To investigate the PF process in the complex

Buoyancy is one of the most serious manifestations of underground structure’s instability during strong ground motions. Soil liquefaction along with significant reduction of its shear modulus beneath these structures are the main driving factors of this phenomenon. In this article, the seismic behavior of underground access structures embedded in sandy deposits was analyzed using the finite differences

A new deterministic constitutive model is developed that has a form that is efficient for use in a stochastic constitutive model in which the material properties and the stress and stiffness fields are considered uncertain and modeled as random variables. Simplifications are made to the deterministic model to allow for efficient propagation of uncertainty of model inputs using the Polynomial Chaos

Holes, including their shape and distribution, significantly affect the performance in rocks. In this paper, a numerical investigation, based on a FEM-CZM method, was developed to explore the shear behavior of rock-like materials containing fissure-holes. The laboratory uniaxial compression test was initially performed, and a corresponding numerical model was established by inserting zero-thickness

The injection of large volumes of pressurized water and grout into the subsoil during jet grouting generates a sudden increase in excess pore water pressure. This study proposes a theoretical approach to evaluate the variation in excess pore water pressure caused by the installation of a jet grouting column in clay, accounting for the chronological sequence of construction. The jet grouting column

To date, only a very few number of models are available to study the shear characteristics of the backfill-rock interface, and none of them have incorporated the effect of the interactions between sulphate ions and cement hydration on the interface shear behaviour. Therefore, a coupled chemo-elastic cohesive zone model (CZM) has been developed to simulate the shear characteristics of the cemented paste

Pile foundations are constructed using a variety of installation methods, which can significantly influence their behavior under axial loading. In this study, numerical simulations of a bored pile, a full-displacement pile and a full-displacement pile with attached expander body have been carried out using standard finite-element analysis where constitutive model parameters are estimated based on various

The discrete element method is used to simulate shear wave propagation resulting from bender element tests in confined granular materials. The effects of particle size, wave travel distance, confining pressure, void ratio, input frequency, and adopted damping methods on the output frequency and calculated shear wave velocity are systematically analyzed. The research findings indicate that the output

In this paper, we develop a novel 3D computational method that describes the behaviour of rock bolts and rough rock-shotcrete interfaces as support systems. Specifically, a Finite Element model has been formulated and implemented using the user-defined element (UEL) subroutine with ABAQUS. The input parameters of the bolted cohesive model are determined experimentally. Once the location of the bolts

We present a formulation for the extension of the stochastic finite element method with non-linear material models. Stress and stiffness fields, as well as displacements at each degree of freedom, are modeled as random processes and are expanded along the Polynomial Chaos (PC). PC terms of displacements are solved incrementally under load control by performing stochastic Galerkin projections on the

The microscopic characteristics greatly influence the nonlinear mechanical behavior and failure process of rock materials. In the present work, the experimental investigations are firstly performed including microstructural observations and macroscopic laboratory tests. Based on various experimental evidences, a micromechanical damage model is proposed according to the microscopic characteristics for

We perform a set of tomographic studies on polymer bonded frictional granular material to systematically characterize the structure through quantification of the relative orientation of its constituents. A three-dimensional network is constructed by considering the centroid of granules as vertex and polymer bridge as a link. We present the spatial distribution of coordination numbers in the network

Quantitative risk assessment of spalling damage needs to address three key tasks: risk probability estimation, loss estimation and risk level determination. Here, based on uncertainty analysis of the damage initiation and spalling limit method, a general risk assessment method for spalling damage in hard-rock tunnels is proposed. First, with a reliability-based design method, a probability reliability

The Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS), which consists of closely-spaced layers of geosynthetic reinforcement and compacted granular fill material, is a fast, sustainable and cost-effective method for bridge support. The in-service performance of this innovative bridge support system is largely evaluated through the vertical and horizontal deformations of the GRS abutments

This study presents the effects of the particle shape on soil arching by simulating the trapdoor problem using the discrete element method (DEM). A new method for preparing the samples with irregular particle in the DEM is proposed to obtain a similar and reasonable initial stress state. Simple monitoring of the strain field is demonstrated. The results indicate that as the trapdoor moves downward

This study investigates the nonstationary vibration problem of a three-dimensional tunnel-soil system under moving stochastic loads. A semi-analytical model combing an integral-transform method (ITM) with the pseudo-excitation method (PEM) is proposed to calculate the stochastic responses of the tunnel-soil system. Due to the load movement and randomness, the dynamic responses of the tunnel and soil

Triaxial compression experiments on dry Ottawa sand are numerically simulated using Finite Discrete Element Method (FDEM) in conjunction with X-ray CT imaging. A novel framework is introduced and validated where particle shape is captured in FEM simulations using shell elements for simulating triaxial boundary value problem. The proposed approach is well suited for load cases with low/intermediate

Ultrasound wave propagation through a porous medium results in a temperature increase due to mechanical dissipation. This temperature increase has different applications in medical science, food industry, and engineering. A fully coupled dynamic thermo-hydro-mechanical (THM) model is presented for numerical modelling of this phenomenon in deforming porous media. The temperature increase due to wave

Classification and stratification (or zonation) of subsurface soils are important tasks in geotechnical site investigation. Due to the limit of time, budget, or access to subsurface soils, subsurface soil information obtained from investigation points (e.g., boreholes, cone penetration tests (CPTs)) in a specific site is often limited (e.g., a few boreholes or CPT soundings), resulting in great challenge

Face bolting and umbrella arch techniques are widely adopted to increase the stability of tunnels in conventional tunnelling. Nevertheless, owing to incomplete theoretical analysis models, their design mainly depends on the judgment and experience of engineers. Therefore, a safety factor analysis model and a concise design flow for a reinforced tunnel face are established based on the limit equilibrium

This study establishes a random model for evaluating the secant failure induced by the variation of pile diameter and drilling inclination. Based on the borehole shrinkage theory, the shape of piles in a spatial heterogeneous stratum can be generated by establishing a non-stationary random field. The drilling direction is described by two-dimensional random variables. The influences of different factors

It is in general difficult to construct piled foundations in karst area due to the lack of a stable holding layer. A new large step-tapered hollow pile (LSTHP) is used to address this issue. In this work, the load transfer model and the theoretical solution for the settlement of the new pile are presented. FLAC3D was used to study the load transfer mechanism of LSTHP and the load transfer model was

While simulation of the drained true triaxial response of particulate assemblies using discrete element method (DEM) has caught the attention of researchers in the recent years, simulation of the undrained condition under generalized stress condition has not yet been well addressed in the literature. This treatment suggests an applicable coupled fluid-discrete element scheme to simulate the undrained