References of "Charlier, Robert"
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See detailShear banding simulation in clay rock around an underground opening, and its contact mechanism with the gallery’s lining
Charlier, Robert ULg; Salehnia, Fatemeh

in Proc. 5th International conference on geotechnical engineering and soil mechanics (2016, November 15)

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See detailIn situ and laboratory mechanical characterization of a loess sequence from Middle Belgium
Delvoie, Simon ULg; Charlier, Robert ULg; Collin, Frédéric ULg

Conference (2016, May 25)

A 10 m thick loess (aeolian silt) layer located beside the Romont quarry (Eben-Emael, Middle Belgium) has been investigated in order to characterize the mechanical behaviour of the silty material. Cone ... [more ▼]

A 10 m thick loess (aeolian silt) layer located beside the Romont quarry (Eben-Emael, Middle Belgium) has been investigated in order to characterize the mechanical behaviour of the silty material. Cone penetration tests (CPT) have been performed with different cones (M1-type, M2-type and electric) in order to evaluate the influence of the cone on the mechanical behaviour interpretation. Concurrently, laboratory tests have been performed on undisturbed samples from core drillings. Laboratory tests consist of a physical characterization (grain size distribution, Atterberg limits) and a mechanical characterization (oedometer tests). This comprehensive investigation study focuses on the comparison of the loess characterization between in situ and laboratory approaches. CPT-based soil behaviour type charts are analyzed and compared with the Unified Soil Classification System. Many relations also exist in the literature between parameters obtained from CPT results and from laboratory tests. The study explores the existing relations between the cone resistance and the oedometer constrained modulus in order to verify the related coefficients proposed in the literature for silty material. [less ▲]

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See detailInteraction entre la zone endommagée autour d’un tunnel et son soutènement – Simulation numérique
Charlier, Robert ULg; Sillen, Xavier; Li, Xiangling et al

Conference (2016, May)

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See detailDrying induced shrinkage of Boom Clay: an experimental investigation
Prime, Noémie; Levasseur, Séverine; Miny, Laurent et al

in Canadian Geotechnical Journal (2016), 53(3), 396-409

Drying induced shrinkage of geomaterials may have a strong effect on geostructure stability and deformation. Settlement of foundations, fracture opening on slopes, roads, tunnel walls may be due to drying ... [more ▼]

Drying induced shrinkage of geomaterials may have a strong effect on geostructure stability and deformation. Settlement of foundations, fracture opening on slopes, roads, tunnel walls may be due to drying shrinkage. However, there is still a lack of knowledge concerning shrinkage evolution in time and shrinkage propagation within the material. In this study, the shrinkage of a specific clayey rock, Boom Clay, under drying conditions is experimentally investigated. This rock is a deep geological formation which is under study for high-level and long-life radioactive waste storage in Belgium. Two experimental campaigns are here presented. The first one, based on vapour equilibrium drying technique and completed by sample size manual measurement, aims to characterize the material shrinkage in balanced states. The second one, based on convective drying technique completed by shape monitoring using X-ray tomography, aims to analyse how shrinkage develops before reaching a steady state. Both approaches put in evidence the shrinkage anisotropy of this structurally bedded rock, with a ratio around 2 between the direction of maximum strains and the direction of minimum strains. However, the two drying techniques also provide complementary results, as the relation between the amount of shrinkage and the retention curve (for the uniform drying imposed with saline solutions) and the kinetics of shrinkage propagation inside the material (for the non-uniform drying imposed with air convection). [less ▲]

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See detailEtude de la séquence stratigraphique des loess de la carrière de Romont (Eben-Emael, Belgique) par une campagne géotechnique
Delvoie, Simon ULg; Pirson, Stéphane ULg; Charlier, Robert ULg et al

in Notae Praehistoricae (2016), 36

The Romont quarry is recently considered as a new type section for the Middle Belgium loess deposits. The site displays a nearly 10 m thick loess sequence mainly dating from the Upper Pleistocene. The ... [more ▼]

The Romont quarry is recently considered as a new type section for the Middle Belgium loess deposits. The site displays a nearly 10 m thick loess sequence mainly dating from the Upper Pleistocene. The Rocourt Pedocomplex, the Humiferous Complex of Remicourt, the Malplaquet Soil and the Nagelbeek Tongued Horizon are especially well developed. Classical approaches to study the loess sequence need observable sections. Unfortunately these sections are rare in Middle Belgium, often temporary and not deep enough. To identify reference horizons, archaeologists and geologists use to resort to hand auger sampling techniques. Investigation of loess by cone penetration tests could offer an alternative to the lack of outcrops and could be used complementary to hand drilling techniques. This study focuses on a methodology to approach as a first step the loess sequence to identify the presence or not of some layers and their extension. The investigation campaign performed on the site of Romont aims to define reference horizons based on mechanical properties by comparison with an observable outcrop. Then 16 cone penetration tests have been realized behind the working face. The campaign results reveal the existence of some horizons into the loess sequence. The transition between the Humiferous Complex of Remicourt and the Rocourt Pedocomplex is the most noticeable horizon. These two pedostratigraphic units are important due to the presence of archaeological materials in Middle Belgium and borderlands. Closer to the surface the Nagelbeek Tongued Horizon and the decarbonation limit are also highlighted from results of the geotechnical campaign. [less ▲]

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See detailFormulation of a 1D finite element of heat exchanger for accurate modelling of the grouting behaviour: Application to cyclic thermal loading
Cerfontaine, Benjamin ULg; Radioti, Georgia ULg; Collin, Frédéric ULg et al

in Renewable Energy : An International Journal (2016), 96

This paper presents a comprehensive formulation of a finite element for the modelling of borehole heat exchangers. This work focuses on the accurate modelling of the grouting and the field of temperature ... [more ▼]

This paper presents a comprehensive formulation of a finite element for the modelling of borehole heat exchangers. This work focuses on the accurate modelling of the grouting and the field of temperature near a single borehole. Therefore the grouting of the BHE is explicitly modelled. The purpose of this work is to provide tools necessary to the further modelling of thermo-mechanical couplings. The finite element discretises the classical governing equation of advection-diffusion of heat within a 1D pipe connected to ground nodes. Petrov-Galerkin weighting functions are used to avoid numerical disturbances. The formulation is able to capture highly transient and steady-state phenomena. The proposed finite element is validated with respect to analytical solutions. An example consisting of a 100 m depth U-pipe is finally simulated. A first continuous heating simulation highlights the nonsymmetric distribution of temperature inside and near the borehole. An estimation of the error on the results as a function of the resolution parameters is also carried out. Finally simulations of cyclic thermal loading exhibit the need to take into account all daily variations if the grouting behaviour must be modelled. This is true especially in case of freeze-thaw damaging risk. [less ▲]

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See detailHeterogeneous bedrock investigation for a closed-loop geothermal system: A case study
Radioti, Georgia ULg; Delvoie, Simon ULg; Charlier, Robert ULg et al

in Geothermics (2016)

This paper investigates bedrock heterogeneity by applying three different geophysical approaches, in order to study the long-term behaviour and the interaction between closed-loop geothermal systems. The ... [more ▼]

This paper investigates bedrock heterogeneity by applying three different geophysical approaches, in order to study the long-term behaviour and the interaction between closed-loop geothermal systems. The investigated site consists of four boreholes equipped with geothermal pipes on the campus of University of Liege, Belgium. The first approach includes acoustic borehole imaging, gamma-ray logging and cuttings observation and results to a detailed fracture characterisation, rock identification and layer dip angle determination. The second approach consists of measuring the thermal conductivity of cuttings at the laboratory. Study of cuttings thermal conductivity measurements can contribute to bedrock heterogeneity knowledge concerning the transition of one formation to another and the layer dipping. The third approach is based on high-resolution temperature profiles, measured during the hardening of the grouting material and the recovery phase of a Distributed Thermal Response Test. Through this approach a correlation of the temperature profiles to the geological characteristics of the surrounding bedrock is identified. The analysis of this correlation can provide information on fractured zones, alternation of different rock types and layering dipping. This latter approach can be easily applied on closed-loop geothermal systems to characterise the bedrock and investigate its heterogeneity as well as contribute to the their long-term behaviour prediction and to the optimisation of their efficiency. [less ▲]

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See detailCompeting effects of volume change and water uptake on the water retention behaviour of a compacted MX-80 bentonite/sand mixture
Gatabin, Claude; Talandier, Jean; Collin, Frédéric ULg et al

in Applied Clay Science (2016), 121-122

Bentonite-based materials have been studied as potential barriers for the geological disposal of radioactive waste. In this context, the hydro-mechanical behaviour of the engineered barrier is first ... [more ▼]

Bentonite-based materials have been studied as potential barriers for the geological disposal of radioactive waste. In this context, the hydro-mechanical behaviour of the engineered barrier is first characterized by free swelling conditions (as a consequence of the progressive filling of technological gaps) followed by constant volume conditions. This paper presents an experimental study conducted in order to characterize the water retention behaviour of a compacted MX-80 bentonite/sand mixture. The water retention properties upon wetting were investigated under both free swelling and constant volume conditions. In the high suction range, the water content was not influenced by the imposed volume constraints. On the contrary, swelling significantly affected the water retention behaviour at low suctions, and the quantity of water stored was higher under free swelling conditions than it was under prevented swelling. In this case, competing effects between bentonite swelling and water uptake did not lead to an increase of the degree of saturation upon wetting, as it was observed for samples wetted under constant volume conditions. The influence of the very strong hydro-mechanical coupling is further discussed. [less ▲]

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See detailNumerical modelling of transient cyclic vertical loading of suction caissons in sand
Cerfontaine, Benjamin ULg; Collin, Frédéric ULg; Charlier, Robert ULg

in Geotechnique (2015), 65(12),

This paper presents numerical investigations of the monotonic and cyclic behaviours of suction caissons upon vertical transient loading. Both drained and partially drained conditions are investigated ... [more ▼]

This paper presents numerical investigations of the monotonic and cyclic behaviours of suction caissons upon vertical transient loading. Both drained and partially drained conditions are investigated. Monotonic compression and traction simulations are carried out to qualitatively compare results with the literature and validate the model. They highlight the different modes of reaction of the caisson to both compression and traction loading. A sensitivity analysis points out the strong influence of some parameters on the resistance of the caisson but also on the failure mechanism. The transient behaviour of the caisson upon different kinds of cyclic load signals is analysed. Results reproduce the settlement and pore water pressure accumulations observed during experiments. The influence of the key design parameters on the settlement accumulation is also assessed. Finally a cyclic diagram is proposed to describe the evolution of the final settlement upon different magnitudes of loading. [less ▲]

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See detailTu gme 10: Efficiency of shaft sealing for co2 sequestration in coal mines
Bertrand, François ULg; Charlier, Robert ULg; Collin, Frédéric ULg et al

in International Workshop on Geomechanics and Energy: The Ground as Energy Source and Storage (2015, October 13)

This work examined the efficiency of a shaft sealing system for the CO2 sequestration in abandoned coal mines. The particular case of the coal mine of Anderlues was considered. The performed simulation ... [more ▼]

This work examined the efficiency of a shaft sealing system for the CO2 sequestration in abandoned coal mines. The particular case of the coal mine of Anderlues was considered. The performed simulation took into account the anisotropic behaviour of shale and the presence of coalbeds. [less ▲]

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See detailWe gme P08: Fiber-optic temperature profiles analysis for closed-loop geothermal systems-a case study
Radioti, Georgia ULg; Delvoie, Simon ULg; Sartor, Kevin ULg et al

in Second EAGE Workshop on Geomechanics and Energy: The ground as energy source and storage (2015, October)

In order to study the behaviour of shallow closed-loop geothermal systems four borehole heat exchangers equipped with fiber optics were installed on the campus of the University of Liege (Liege, Belgium ... [more ▼]

In order to study the behaviour of shallow closed-loop geothermal systems four borehole heat exchangers equipped with fiber optics were installed on the campus of the University of Liege (Liege, Belgium) over a surface area of 32m². This paper presents the analysis of continuous, high-resolution temperature profiles measured along the boreholes length. The undisturbed ground temperature measurements indicate heat loss from ground structures located close to the boreholes. A 3D numerical model is presented to reproduce the measured temperature profiles. Temperature profiles during hardening of the grouting material indicate extended fractured zones in the rock mass. Temperature measurements during the recovery phase of a Distributed Thermal Response Test indicate the succession of rock layers with different mineral content. The results are in good agreement with those of the borehole televiewer logging method. The presented analysis could provide information on bedrock heterogeneity, on the anisotropic thermal behaviour of the rock mass and on the ground temperature variations due to heat loss from ground structures. These information could significantly contribute to the long-term behaviour prediction of the geothermal system and the geothermal reservoir potential. [less ▲]

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See detailAnalysis of the retaining wall design problem in the framework of the Tyler Rationale
Charlier, Robert ULg; Bertrand, François ULg; Cerfontaine, Benjamin ULg et al

Poster (2015, September 28)

The coherence of any education system lies on the respect of the Tyler Rationale which puts the relationship between the objectives, the teaching method and the evaluation forward. The practical part of ... [more ▼]

The coherence of any education system lies on the respect of the Tyler Rationale which puts the relationship between the objectives, the teaching method and the evaluation forward. The practical part of the examination of the course of Geotechnics generally includes a retaining wall design problem. We listed and classified the mistakes identified in the student answers for the retaining wall design problem. In this classification, the mistakes specific to geotechnics are distinguished from the ones which are not specific to geotechnics. This list allows the teacher to be aware of the most common mistakes so he can insist on things not to do during the learning experiences. The classification is also fundamental. Indeed, if a student failed essentially because of a lack of pre-requisites, there is no reason he succeed by repeating the course in the same conditions. He should be therefore redirected to a self-regulating. [less ▲]

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See detailRetour en grâce du grisou
Bertrand, François ULg; Charlier, Robert ULg; Collin, Frédéric ULg

Diverse speeche and writing (2015)

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See detailCoupled modeling of Excavation Damaged Zone in Boom clay: Strain localization in rock and distribution of contact pressure on the gallery’s lining
Salehnia, Fatemeh ULg; Collin, Frédéric ULg; Li, Xiang Ling et al

in Computers and Geotechnics (2015), 69

Around galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for ... [more ▼]

Around galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for high-level radioactive waste, the resulting change in the host rock properties in this damaged zone may potentially be important with respect to the long-term evolution and the performance of that system. In this context, predicting the extent of the so-called Excavation Damaged Zone (EDZ) and, possibly, the fractures' network topology remains a challenge. This study is aimed to simulate numerically the extension of this zone at the large scale's excavation, around the Connecting gallery (HADES URL, Mol, Belgium), in Boom clay host rock through analyzing the evolution of strain localization in shear bands mode. To realistically model the involved phenomena, the concrete lining is considered on the gallery wall highlighting its impacts on the evolution of convergence and EDZ around the gallery. The focus of the current paper is made on analyzing the coupled hydro-mechanical behavior of Boom clay host rock during and after the gallery excavation with respect to the evolution of localized shear bands around the gallery. This study is accompanied by the analysis of the contact mechanism on the interface between the clay massive and the lining. The obtained results reveal some interesting features regarding the contact phenomenon relatively to the evolution pattern of shear bands within the clay around the gallery. To assess the reliability of the proposed approach, a discussion on some in-situ observations during the gallery's construction is also performed based on which a good agreement is found between the in-situ evidence and simulated results. [less ▲]

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See detailMechanical approach for the characterization of loess deposits from the CBR’s Romont quarry (Eben-Emael, Belgium) and correlations with loess stratigraphy
Delvoie, Simon ULg; Boulvain, Frédéric ULg; Cerfontaine, Benjamin ULg et al

Conference (2015, June 01)

Aeolian silts (loess) are near surface deposits covering about 10% of the continent surfaces . Therefore a good knowledge of their mechanical behavior is an issue for designing subsurface engineering ... [more ▼]

Aeolian silts (loess) are near surface deposits covering about 10% of the continent surfaces . Therefore a good knowledge of their mechanical behavior is an issue for designing subsurface engineering structures. Usually this material is considered as homogeneous for an engineering point of view. Aeolian silt deposits are continuously well developed in Hesbaye Region (Belgium) reaching locally 20m thick (see document in attachment). They are mainly related to the last interglacial (Eemian) and glacial (Weichselian) periods . Nevertheless the pedostratigraphical, chronostratigraphical and paleoclimatic approaches have shown these silt deposits are usually composed of a series of paleosoils (i.e. Rocourt soil, Humiferous Complex of Remicourt, Harmignies Soil, Nagelbeek Tongued Horizon) interbedded with stratified or homogeneous aeolian silt layers. This study aims to characterize the variability of the in situ mechanical characteristics of the loess deposits from Hesbaye Region at the site scale and at the laboratory scale. Cone penetration tests (CPT), electrical resistivity tomographies (ERT) and drillings have been performed through a 10m thick loess layer in an investigation site located close to the CBR’s Romont quarry (Eben-Emael, Belgium) . Continuous undisturbed silt samples from drillings have been physically (granulometry, Atterberg limits, water content, organic matter content, carbonate content) and mechanically (oedometer test, triaxial test) characterized at the laboratory. Mechanical behavior and physical characteristics have underlined a series of layers with variable mechanical properties through depth. Some of these layers correlated with a detailed stratigraphy cross-section close to the investigation site could correspond to well-known paleosoils. [less ▲]

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See detailFractured bedrock investigation by using high-resolution borehole images and the Distributed Temperature Sensing technique
Radioti, Georgia ULg; Delvoie, Simon ULg; Radu, Jean-Pol ULg et al

in ISRM Congress 2015 Proceedings - Int’l Symposium on Rock Mechanics (2015, May)

In order to investigate the fracturing of the bedrock and its possible heterogeneous distribution in situ, four boreholes equipped with double-U geothermal pipes of 100 m long were installed on the campus ... [more ▼]

In order to investigate the fracturing of the bedrock and its possible heterogeneous distribution in situ, four boreholes equipped with double-U geothermal pipes of 100 m long were installed on the campus of the University of Liege (Liege, Belgium) over a surface area of 32 m². The bedrock, which starts at a depth approximately of 8 m, is quite fractured and consists mainly of siltstone and shale interbedded with sandstone. Different geophysical methods are applied at two different phases, after drilling the boreholes and after injecting the grouting material. The first approach consists in lowering an ultrasonic borehole imager (borehole televiewer; Zemanek, Glenn, Norton, & Caldwell, 1970), an instrument that acts as an ultrasonic transducer and receiver, into the boreholes to obtain high-resolution, continuous images with 360° coverage of the local geology and fracturing. Moreover gamma-ray logs of the four boreholes are obtained and inclinometry is conducted. After drilling the boreholes fiber optic cables are attached along the pipe loops and the double-U pipes are installed inside the boreholes. Then the grouting material is injected. The second approach consists in measuring the temperature along the fibers by applying the Distributed Temperature Sensing technique (Soto, Sahu, Faralli, Bolognini, Di Pasquale, Nebendahl, & Rueck, 2007). A laser pulse is injected into the optical fiber and the temperature along the fiber is determined by the intensity of Raman stokes and anti-stokes reemitted signals. Temperature evolution is measured during hardening of the grouting material. Local maxima of the temperature curve are probably due to a local lower thermal conductivity and/or a local larger quantity of grouting material due to gathering of fractures. A detailed fracture characterisation (position, opening, orientation, dip angle) is obtained based on the acoustic signal travel time and amplitude. The fractures are characterised by the same dipping and orientation but significantly vary in number and location in the four boreholes, despite the close distance between them. Gamma-ray data and observation of the cuttings during drilling result in rock identification through depth as well as in determination of the layer dipping. The inclination of the four boreholes tends to be perpendicular to the dipping. The combination of the two geophysical methods as presented provides information useful for the hydro-thermo-mechanical behaviour of the bedrock. The contribution of the thermal behaviour of borehole heat exchangers to bedrock investigation will be further studied by conducting Distributed Thermal Response tests (Fujii, Okubo, & Itoi, 2006). During the tests we will measure the temperature variation thanks to the installed fiber optics. These data will allow us to correlate any anisotropic thermal behaviour to the geological characteristics. The available information could be used for a detailed numerical model. [less ▲]

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See detailStrain localization modelling around an underground gallery in Mol with an analysis of the contact pressure on the lining
Salehnia, Fatemeh ULg; Dizier, Arnaud; Li, Xiang Ling et al

Poster (2015, March)

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