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Quantifying the process of particle breakage is essential whenever a macroscopic investigation into the phenomenon is addressed. Some authors relate an indicator of the evolution of particle breakage, usually the surface created, to a measure of the mechanical loading. Others refer to the evolution of the particle size distribution (PSD) to better understand the problem. In this study, a shape factor of the PSD curve is used as a breakage parameter. The slope of the linear trendline of the PSD in a log-log plot was found to be reasonably representative of the shape of the PSD, for engineering granular materials. It was shown that the new breakage parameter is adapted to both well graded and uniformly graded materials, but cannot be used to describe gap-graded soils. This parameter is first studied from a micromechanical point of view, before being compared to three widely used breakage parameters: Hardin, Marsal and Einav's breakage parameters. The transition between these three parameters and the proposed parameter is provided. The main objective of this study is to allow the operation and utilisation of experimental results, which are reported in the literature through one of the available breakage parameters, or through PSD plots. [ABSTRACT FROM AUTHOR]

In this study, the thaw consolidation properties of fine-grained permafrost soils are investigated in terms of the characteristics of the relationships between the effective stress (σv′), the void ratio (e), and the hydraulic conductivity (kv). A total of 182 individual soil samples are included in the analysis covering a wide range of hydromechanical properties. The data are obtained from geotechnical studies undertaken for the Canadian Arctic Gas Pipeline project in the 1970s in the Mackenzie River Valley, Canada. The investigated characteristics are defined in agreement with the definition formulated by previous thaw consolidation models for fine-grained soils. Based on the general interpretation of the behavior of thawing soils, relationships are developed for the compression index of the thawed soil, the residual stress, the hydraulic conductivity change index of the thawed soil, and the initial hydraulic conductivity of the thawed soil. All properties are influenced by the ice content, which is characterized by the initial thawed void ratio for ice-rich soils and by the thawed void ratio for ice-poor soils. The liquid limit, the clay content, and the median grain size of the fine fraction are used as predictive parameters in combination with the initial ice content. The median grain size of the fine fraction yields the lowest error for the prediction of the characteristics of the σv′−e−kv relationships. [ABSTRACT FROM AUTHOR]

The finite element method (FEM) is a powerful tool for the nonlinear modeling of dynamic problems. In the present work, the equivalent linear method (EQL) has been implemented into the FEM. For stratifying the radiation damping condition and rigorously modeling canyon as an elastic unbounded domain, the scaled boundary finite element method (SBFEM) was utilized. The FEM‐SBFEM technique, wherein FEM is coupled with SBFEM, has been extended to take into consideration the effect of earth dam material nonlinear behavior. It was observed that the nonlinear behavior greatly affects the natural frequency, the amplification function (AF), and peak crest acceleration of the earth dam located in canyons. The effects of canyon geometry and flexibility on the nonlinear behavior were examined, and it was seen that by increasing the flexibility of the canyon, the effect of nonlinearity was decreased. The El Infiernillo dam was modeled by 3D proposed technique, and a comparison of the crest AF obtained by the proposed method with the recorded data shows the accuracy of the methodology. [ABSTRACT FROM AUTHOR]

The recently developed framework for modeling grain breakage in granular materials is shown to be valid for saturated/unsaturated conditions. The model describes the initiation, development, and stabilization of breakage using three parameters, all depending on the strength of a representative particle size. When water is introduced, the strength of the soil's particles is expected to weaken, which leads to increased breakage intensities. The model is able to predict the early onset of crushing and the increase in particle breakage rate, both considered characteristic behaviors of a crushable granular medium in wet conditions. Initially dry and saturated model lines limit the evolution of the model parameters in the intermediate saturation states. A mid-loading change in the saturation of the granular medium results in an increased rate of particle breakage. The experimental data available in the literature is analyzed in light of the proposed model, which allows a better understanding of the development of particle breakage under the influence of water. [ABSTRACT FROM AUTHOR]

This article presents a study on 15 concrete face rockfill dams (CFRDs) carried out to characterize in situ rockfill compressibility. The stress-strain-time behavior of rockfill for each CFRD was evaluated at the embankment centerline, during and after construction and before the onset of reservoir impoundment. By comparing the behavior in different case studies, the rockfill in situ compressibility parameters were defined and related to key material properties. It was shown that short-term and long-term response of rockfill to changes in stress level is a function of two parameters: the strength of individual rock particles and the void ratio of the rockfill assemblage. Moreover, the timedependent and short-term rockfill compressibility parameters are connected. This study provides a good framework to characterize and estimate the behavior of rockfill during and after construction of embankments. Moreover, the concepts presented in this paper can be used for predicting postconstruction deformations of structures constructed by using compacted rockfill on the basis of their behavior during construction. [ABSTRACT FROM AUTHOR]

The design of convective embankments generally hinges on the use of numerical models that describe buoyancy-driven flow and heat transfer in porous media. A review of the literature reveals that most of the models used in the study of convective embankments assume that heat transfer occurs by conduction and convection, and that airflow can be described with Darcy’s law. This is inconsistent with recent experimental evidence that suggests that radiative heat transfer is significant, and that Darcy’s law does not adequately describe the relation between superficial flux and gradient in rockfill materials. In response to these shortcomings, a new model is herein derived to account for both radiative heat transfer and non-Darcy effects. After demonstrating its ability to solve fairly complex steady-state problems, the model is used to gain insight into the relative importance of radiative heat transfer and non-Darcy flow on the thermal response of a typical railway embankment. The radiative heat transfer is shown to be greater during the summer months. This increases the temperature at the base of the embankment, which in turn, increases the wintertime convective heat transfer. This additional heat extraction does not counteract the effect of the radiative heat transfer, and the wintertime temperatures below the embankment are shown to be warmer than that computed without radiative and non-Darcy effects. [ABSTRACT FROM AUTHOR]

A dynamic analysis based on the spectral element method is described for the interpretation of falling weight deflectometer (FWD) tests on flexible pavements. This dynamic approach was implemented in the computer code Dynamic Analysis of Pavement - Université Laval (DYNAPAV-UL) that includes both frequency-independent hysteretic damping and frequency-dependent viscous damping material models. A parametric study was conducted on a four-layer flexible pavement to evaluate the influence of different layer moduli on deflection basins and deflection histories. The viscous behaviour of the asphalt concrete layer was also investigated. While the deflection basin currently used in static methods gives some details of the pavement response under transient loading, the simulations of FWD tests using the dynamic model suggest that the time histories should be included as well for the interpretation of FWD deflection measurements. In fact, important dynamic phenomena due to inertial effects and viscous effects are only revealed by deflection histories. [ABSTRACT FROM AUTHOR]

A robust backcalculation methodology that uses the Levenberg-Marquardt iterative minimization technique is presented to identify the value of unknown layer parameters from falling weight deflectometer (FWD) tests using a dynamic approach based on the spectral element method. Backcalculation is performed in the time-domain with 20 observations on each deflection history. The efficiency of the proposed methodology is demonstrated by interpreting FWD tests on three flexible pavements that cover a variety of structures, soil, and bedrock conditions. Results indicate that the dynamic approach is capable of simulating quite well the measured deflection histories using effective backcalculated moduli. In addition, comparison of critical strains between static and dynamic interpretation of FWD tests indicates that both approaches predict similar traction strains at the bottom of the asphalt concrete layer. However, the prediction of the compression strain in the subgrade with the static approach is erratic compared with the dynamic method. [ABSTRACT FROM AUTHOR]

Abstract: A numerical model for convective heat and mass transport of compressible or incompressible gas flows with soil-water phase change is presented. In general, the gaseous phase is considered as compressible and the model accounts for adiabatic processes of compression heating and expansion cooling. The inherently compressible gaseous phase may nevertheless be considered as incompressible by adopting the Oberbeck–Boussinesq approximations. The numerical method used to solve the equations that describe natural convection is based on a Galerkin finite element formulation with adaptive mesh refinement and dynamic time step control. As most existing numerical studies have focused on the behavior of incompressible fluids, model substantiation examines the influence of fluid compressibility on two-widely used benchmarks of steady-state convective heat and mass transport. The relative importance of the effect of pressure-compressibility cooling is shown to increase as the thermal gradient approaches the magnitude of the adiabatic gradient. From these results, it may be concluded that pore-air compressibility cannot be neglected in medium to large-sized enclosures at small temperature differentials. After demonstrating its ability to solve fairly complex transient problems, the model is used to further our understanding of the thermal behavior of the toe drain at the LA2-BSU dam in the province of Quebec, Canada. [Copyright &y& Elsevier]

Abstract: The effect of structure on the thermal conductivity of geomaterials is studied for solid–fluid combinations representing a wide variety of two-phase porous geomaterials. Nearly 200 thermal conductivity data sets from the literature were analyzed for geomaterials made of natural soil particles, crushed rock particles and sedimentary rock. Two analog models are studied to quantify the effect of structure. It appears that the effect of structure increases with decreasing fluid/solid thermal conductivity ratio and structure effects are negligible from a ratio of approximately 1/15 and higher. A new simplified model is proposed to compute the effective thermal conductivity as a function of the fluid/solid thermal conductivity ratio and the structure of geomaterials. The model applies well to independent data of homogeneous and heterogeneous materials including industrial cement concrete. [Copyright &y& Elsevier]

Abstract: This paper presents the results of a numerical study on the differential icing risk at the surface of pavements with insulated sections in the Province of Quebec, Canada. Differential icing situations occur when slippery conditions form on the surface of insulated pavement sections while adjacent conventional pavement sections maintain dry surface conditions. A heat transfer model that considers the climate conditions and the pavement properties is used to compute the surface temperature of conventional and insulated pavements. Variations of climate conditions on daily cycles are obtained from a new ideal climate model developed on the basis of 30-year period monthly data of solar radiation, air temperature, wind speed and cloud cover. It was established that the period with the highest icing risk on all pavements (insulated or not) occurs during the late Fall season. However, as soon as the frost front reaches the insulating layer, the icing risks on insulated pavement sections increase drastically. In the Province of Quebec, the current insulated pavement design method prevents most of the differential icing situations only for the warmest regions of the Province. Future design method will have to relate the thickness of the granular layer placed atop of the insulating layer to mean climate conditions and pavement properties. [Copyright &y& Elsevier]

Presents information on a study which investigated the effect of freezing temperature on the hydraulic conductivity of a silty clay from Lachute, Quebec. Freezing conditions for clay barriers in covers; Experimental setup and procedure; Test conditions and results.

The geometry and flexibility of a canyon are the parameters that greatly affect the value of natural periods in earth dams. The canyon surrounding dams can be assumed as an unbounded domain. To take into account these two effects, the canyon was modeled by SBFEM and the earth dam, which has limited geometry, by FEM. The hybrid technique of SBFEM-FEM for dynamic three dimensional analysis of soil-earth dam interaction was validated with available results in the literature. Because the dynamic-stiffness matrix of the unbounded domain is complex and frequency dependent, the classical mode-superposition method is not straightforward for the soil-structure interaction system. Thus, to obtain the fundamental natural frequency, the dam was excited in the upstream-downstream direction. The natural period of the earth dam for canyons with different geometry shapes and impedance ratios were obtained. They were found to have significant effects on the natural period. The results were compared with actual recorded data. It was found that the proposed graphs in this study may be used by practical engineers for the estimation of natural periods of earth dams in canyons with different shapes and material properties. [ABSTRACT FROM AUTHOR]

In this study, the influence of seismic load characteristics including amplitude, period/frequency contents, and duration on the response of concrete face rockfill dams (CFRDs) was examined. The significant role of the tuning ratio, which is the ratio of a dam's natural vibration period to the predominant period of an earthquake, on the seismic crest settlement was investigated. The case histories of existing CFRDs were analyzed and a new index, as an appropriate intensity measure, was defined to quantify the severity of ground motions as a function of the tuning ratio. A semi-empirical relationship for predicting the earthquake-induced crest settlement was also proposed using a database of CFRD cases. The proposed approach links the ground motion parameters, dynamic characteristics of a dam, and the observed seismic crest settlement. The proposed semi-empirical relationship addressed the limitation of existing approaches by considering the resonance effect on the crest settlement. The validation of the proposed relationship was carried out using the observed data in CFRD case histories and the data obtained from numerical simulations of a typical case CFRD. • The influence of motion's characteristics on the response of a concrete face rockfill dam (CFRD) was numerically analyzed in terms of crest acceleration and crest settlement. • The significant role of the resonance phenomena on the response of the concrete face rockfill dams (CFRDs) was highlighted. • From analyzing the real case histories of the existing CFRDs, an intensity index of earthquake was developed considering both dam's and ground motion's characteristics. • A novel empirical relationship was developed for estimation of the crest settlement of CFRDs subjected to earthquake ground motions. [ABSTRACT FROM AUTHOR]

The seismic behavior of the concrete slab in concrete-faced rockfill dams (CFRD) is investigated, considering concrete slab-cushion layer interface effect. The interface is simulated by an advanced constitutive model capable of simulating the complex behavior of soil–structure interfaces such as particle breakage, stress-dilatancy, stress-hardening, cyclic accumulative contraction, and stress degradation. Stage construction and reservoir impoundment of the dam are simulated and the dam is subjected to two earthquake records. The concrete slab responses under static and dynamic conditions are examined, and the effects of reservoir water level, interface roughness, and the interface modeling approach on the concrete slab response are investigated. [ABSTRACT FROM AUTHOR]

Abstract In this paper, an implementation of an advanced two-surface plasticity interface constitutive model in a general-purpose finite element code ABAQUS for application in soil-structure interaction problems under static and dynamic loading conditions is presented. A recently developed constitutive model by the authors for gravelly soil-structure interface was improved to simulate the behavior of both gravelly and sandy soil-structure interfaces. A new failure surface was introduced into the model in order to simulate the softening behavior of interfaces under monotonic and cyclic loading. The constitutive model was then implemented in ABAQUS as a thin-layer interface element to demonstrate its capabilities in representing the complex behavior under different stress paths and normal stresses, including debonding and rebonding mechanisms at interface zones. The accuracy and robustness of the numerical implementation algorithm was examined by considering the effect of time step size, and by simulating different boundary value problems. The numerical predictions under different loading and boundary conditions were compared with experimental observations. Highlights • Implementation of an advanced interface constitutive model in a general purpose finite element code is presented. • Advanced interface constitutive model simulates both monotonic and cyclic behavior of granular soil-structure interfaces. • Performance of proposed model validated using single element, slide block test, shaft pullout test and CFRD numerical examples. • The numerical predictions under different loading and boundary conditions were compared with experimental observations. [ABSTRACT FROM AUTHOR]

Abstract The behavior of interfaces between granular soils and structural construction materials has an important impact on the monotonic and cyclic response of many soil–structure interaction (SSI) systems. Understanding the mechanics and modeling of these interfaces is an important step towards a safe and effective design and analysis of SSI problems. An extensive literature search for a 'one-stop shop' providing a comprehensive exposition on the mechanical characteristics and numerical modeling approaches of granular soil–structure interfaces yielded less than encouraging results. This paper seeks to bridge this knowledge gap in as concise manner as possible. To this end, the effects of the essential elements of the SSI problem, including soil and structural features as well as loading conditions, on the deformation and stress transformation mechanism of the interface are critically examined. Simple and advanced interface constitutive modeling methods are discussed, and implementation techniques of interface elements in finite element codes are explained. Additionally, a method to incorporate the effect of particle breakage to improve the capabilities of an elasto-plastic constitutive simulation of the cyclic accumulative contraction in granular interface modeling is introduced. [ABSTRACT FROM AUTHOR]

A plasticity constitutive model is proposed to simulate the monotonic and cyclic behavior of granular soil–structure interfaces. The model is built on two-surface plasticity models previously developed for interfaces between gravelly soils and structural materials (Saberi et al., 2016, 2017), which simulate strain hardening, stress degradation and phase transformation behavior. The proposed model in this study incorporates the softening behavior likely to occur in dense sandy soil–structure interfaces under monotonic and cyclic loading, and it provides a unified formulation for simulating the behavior of both sandy and gravelly soil–structure interfaces. The model accounts for the stress path dependency behavior of interfaces, and it requires a single set of nine calibration parameters, which can readily be obtained from standard interface shear tests. The interface model’s performance is evaluated for Constant Normal Load, Constant Normal Stiffness, and Constant Normal Height stress path conditions by comparing its predictions with experimental data. [ABSTRACT FROM AUTHOR]

An elasto-plastic model is proposed for modeling the constitutive behavior of the interface between gravelly soils and structural materials. This model is based on the two-surface plasticity formulation and it is compatible with the concept of critical state soil mechanics. The model requires the same set of eight calibration parameters for predicting the monotonic and cyclic responses of both loose and dense interfaces. The model simulates cyclic densification, shear degradation and the effects of normal pressure, soil density, and stress path. The performance of the proposed constitutive model is validated by tests data under different normal stresses and boundary conditions. [ABSTRACT FROM AUTHOR]

The thermal conductivity of bitumen concrete is a key parameter in the thermal analysis of pavements submitted to widely varying climate conditions. This paper presents the experimental results of thermal conductivity of bitumen concrete typically used in the Province of Quebec. The results show that the thermal conductivity of bitumen concrete is dependent on the aggregate's mineral origin and on the amount of air voids. It is also shown that the presence of bitumen increases thermal conductivity compared to unbound aggregates. The paper demonstrates that the effect of bitumen creates thermal bridges between aggregate particles similarly to other types of binders such as Portland cement and natural binders found in sedimentary rocks. Based on these observations and on the analyses of over 80 data sets from the literature, an existing model is used to develop a simplified thermal conductivity equation to estimate this parameter for bitumen concrete. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of the effect of porosity and particle size on the hydraulic conductivity and thermal conductivity of sand-sized crushed granite particles with diameters ranging from 0.08-10 mm. The results show that the hydraulic conductivity varies with particle size and porosity, but thermal conductivity varies primarily with porosity. Estimating methods found in the literature are used in an attempt to predict the measured hydraulic and thermal conductivities of the crushed granite materials. The results show that the hydraulic conductivity model of Chapuis generally yields accurate estimated values for d102n3/(1-n)2 larger than 0.01 mm2. Below this critical point, the estimating method progressively yields larger values of hydraulic conductivity. A new set of empirical parameters are proposed to extend the use of this method to crushed granite materials at low d102n3/(1-n)2 values. It is also shown that predicted thermal conductivity values obtained with the Côté and Konrad model agree well with the experimental data. Issues regarding the extension of the models to coarser materials are discussed. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present macro- and micro-study on the yielding of microstructured geomaterials by numerical experiments. This target is achieved by carrying out 63 one-dimensional and biaxial compressions tests on an idealized bonded geomaterial with an extension of distinct element method, into which bond contact models proposed were implemented. Numerical results indicate that: (a) preconsolidated pressure appears to attribute to bond and looseness in the geomaterials, and an increase in void ratio leads to a decrease in yielding stress in one-dimensional tests; (b) an increase in bonding strength at interparticle contacts results in an increase in yielding stress and cohesion, and an internal friction angle that is smaller than the critical state value; (c) the observed first-yielding (initiation of bond breakage) is stress path dependent, and gross-yield (defined with respect to volumetric strain) of microstructured geomaterials is evidently related to bond breakage. [ABSTRACT FROM AUTHOR]

The forward modeling of the dispersion curve of a layered medium calculated from the spectral characteristics of Rayleigh waves requires an efficient algorithm for predicting the surface displacements of the medium under a dynamic load. The usual methods for solving the wave equation are based on matrix methods prone to numerical problem or yielding to the determination of complex modes that are difficult to interpret. A modified linearized stiffness matrix method is proposed in this technical note to solve the discrete stiffness matrix. The developed algorithm is based on a finite element equation associating each surface wave mode to the resonant frequency of a structure with a stiffness depending on the wavelength. The filtering of complex wave modes to keep only suitable surface waves is avoided. Furthermore, the mesh design is based on the actual wavelength of each mode providing a better representation of higher modes. The new algorithm is validated with two irregular stiffness profiles. [ABSTRACT FROM AUTHOR]

Many soil-structure interaction systems experience a three-dimensional loading condition (i.e. shear coupling) at their interfaces. In this study, an elasto-plastic constitutive formulation for interfaces in soil-structure interaction problems is proposed considering the effects of 3D shear coupling loading conditions. The proposed model is capable of simulating granular soil-structure interfaces for both monotonic and cyclic loading over a wide range of normal stress and normal stiffness using a single set of eleven calibration parameters. The model is capable of simulating a number of complex interface behaviour, including hardening and softening, compaction, dilation and phase transformation, stress path dependency, accumulative contraction and stabilization, stress degradation and particle breakage under monotonic and cyclic loading. The constitutive model performance is examined using available experimental data for gravelly and sandy soil-structure interfaces subjected to monotonic and cyclic loads involving shear coupling. • An advanced 3-D elasto-plastic constitutive model for soil-structure interfaces under cyclic loading is proposed. • Capability of simulating cyclic behavior of granular soil-structure interfaces with a single set of 11 calibration parameters without recalibration. • Capability of simulating complex interface behavior, including shear and tangential coupling and stress path dependency. [ABSTRACT FROM AUTHOR]

Suffusion, as one of the main internal erosion processes in earth structures and their foundations, may increase their failure risks. The paper aims at presenting a general method to assess the suffusion susceptibility of core soil samples belonging to zoned hydraulic embankment dams. On one hand, the suffusion susceptibility of the soil samples is evaluated by an erosion resistance index. Thanks to existing statistical analyses, the erosion resistance index is estimated from several soil parameters that can be easily measured in situ or in laboratory during the construction of a dam. On the other hand, the saturated hydraulic conductivity of the soil samples is evaluated based on the amount of fines content and on available construction data. Moreover, the power dissipated by the flow is inferred based on the saturated hydraulic conductivity and simplified fluid boundary conditions. The combined consideration of the erosion-resistant index and of the power dissipated by the flow permits to identify zones characterised with a relatively larger suffusion potential (lower erosion resistance index and larger power than their respective average). Throughout, the method is applied to a particular zoned dam with a till core, from Northern Quebec, as a proof of concept. [ABSTRACT FROM AUTHOR]

The surfaces of real sands are often rough and a discrete element modeling of rough granulates is very important to understand the behavior of real sands. This paper presents a two-dimensional discrete element method (DEM) to capture the roughness of particles. The model consists of two parts: equations governing the motion of rough particles and mechanical contact models controlling rough-contact behavior. The key point of the theory is that the assumption in the original DEM proposed by Cundell and Strack in 1979 that a pair of particles are in single-point contact, is here replaced by that the particles are in rough contact over a width. By making the idealization that the contact width is homogeneously distributed with a finite-number of the normal/tangential basic elements (BEs) (each BE is composed of spring, dashpot, slider, or divider), we relate the governing equations to local equilibrium and also establish a rolling contact model together with normal/tangential contact models. The three main features of the theory are that: two physical parameters need to be introduced in the theory to represent particle roughness in comparison to the original DEM; rolling stiffness, rolling viscous-damping parameter, and rolling strength due to roughness are all linked with their respective counterparts in the normal direction in a simple and complete formula through these two parameters; the equations governing motion of rough particles satisfy the local equilibrium condition. The present theory was incorporated into a DEM code to investigate the mechanical response of the material of different roughness, particularly the angle of internal friction [lowercase_phi_synonym]. Twenty-four DEM simulations showed that [lowercase_phi_synonym] predicted by the theory was significantly increased in comparison to the standard DEM prediction. [ABSTRACT FROM AUTHOR]