Developing a numerical model of tunnel excavation using a tunnel boring machine (TBM) is a difficult task due to the complexity of the phenomena involved in the advancement of the machine through the ground. The ease of use of calculation software often masks (at least in part) the representation in the numerical simulation of the actual phenomenon. Many simulations use nodal forces to account for stress relaxation at the boundary of the excavated ground and for the interaction between the TBM, the grout, and the surrounding soil. However, calibrating these models may prove difficult. This paper proposes a simple approach called the swelling method, which aims to take into account the TBM control parameters, especially the grout injection parameters. This approach allows directly defining the final stress applied to the tunnel contour, taking into account the grout pressure. The conventional and the new approaches are implemented in the finite-element code CESAR (version 2024.0.5) and tested to simulate surface settlements and lateral soil displacements induced by tunneling using a full-scale research project called TULIP (Tunneling and Limitation of Impacts on Piles) as a background. The results show a strong agreement between the two methods, but the swelling method is easier to handle and has the potential to capture the complex interactions between the TBM and the surrounding soil. The influence of the model parameters on the width of the surface settlement trough is discussed.

The use of tunnels for harnessing shallow geothermal energy in heating and cooling has gained increasing attention in recent years. Consequently, it is crucial to further investigate the influence of different ground conditions on the thermal performance of energy tunnels. In practice, tunnels may locate above groundwater level, within a partially saturated zone. Since ground thermal properties are moisture dependent, the heat transfer is affected by soil type, groundwater level, and soil air entry suction. Therefore, this study investigates the impact of groundwater level and soil air entry suction across different soil types. The results indicate that in sand, heat exchange rates are significantly influenced by groundwater presence. Additionally, the influence of groundwater flow is more significant when groundwater level is above tunnel invert. Within the studied range, groundwater level exhibits a moderate effect on heat exchange rates in silt, whereas in clay, this effect is negligible. The rate of change of heat exchange with varying air entry suction is significant in silty soils, marginal in clayey soils, and negligible in sandy soils.

Energy tunnels represent an innovative solution for meeting heating and cooling needs through heat exchange with the ground. Among the key factors influencing their thermal performance, there is the groundwater flow which drives continuous thermal recharge of the surrounding ground. The extent to which this recharge occurs depends significantly on the flow velocity, which is mainly governed by hydraulic gradient and permeability. While previous studies typically assumed homogeneous hydraulic properties, the effect of spatial variability on the thermal exchange remains unexplored. Therefore, this study investigates how spatial variability of intrinsic permeability impacts the thermal performance of an energy tunnel under seepage. A numerical model was developed and validated against field tests data available in the literature. Then, lognormally distributed, autocorrelated random fields of intrinsic permeability were generated and incorporated into the model as a series of Monte Carlo simulations (MCS). The results indicate that assuming homogeneity is acceptable when the coefficient of variation of permeability (COV kappa) is below 1.0, in both heating (winter) and cooling (summer) modes. However, for higher variability (COV kappa > 1.0), this effect becomes significant and assuming homogeneous conditions may lead to a substantial underestimation or overestimation of the heat exchange. Only in cases with a large difference between internal air temperature and fluid temperature, the homogeneous assumption may remain reasonably valid even at high COV kappa up to 4.0. The effect of spatial variability increases with increasing groundwater flow velocity up to 0.5 m/d, beyond which the variability effect remains similar. This study highlights the critical importance of field measurements of hydraulic properties in order to accurately estimate the heat exchange rates of energy tunnels.

Shield tunnelling in urban areas may induce ground movements that affect the serviceability and load-transfer mechanisms of existing pile foundations. This paper investigates the response of loaded piles to EPB shield tunnelling using a simplified three-dimensional finite element approach, referred to as the swelling method. The contribution of the present paper lies in extending and assessing this method for a full threedimensional tunnel-soil-pile interaction problem, with explicit modelling of the tunnel, annular mortar layer, soil stratigraphy, loaded instrumented piles and staged TBM advance. The method represents excavation-induced stress release and annular grout confinement through a single equivalent loading applied in the tail-void zone, using operational grout-related parameters while avoiding complex step-by-step pressure definitions. It is implemented in CESAR and validated against the TULIP full-scale experiment, where surface and subsurface ground movements and the response of three loaded instrumented piles were monitored during TBM passage. The simulations reproduce the main settlement response, with final surface settlement magnitudes of about 8 mm and transverse trough-width parameters of 9.4 m and 9.2 m, compared with measured values of 9.5 m and 9.0 m. The method also captures the pile-head settlement trend P1 > P2 > P3, with computed final settlement magnitudes of approximately 10.5 mm, 7.5 mm and 4.2 mm, respectively. Axial-force redistribution is predicted with physically consistent trends, but its magnitude is more difficult to reproduce: good agreement is obtained for P1, whereas the response is overestimated for the offset piles, with a maximum axial-force variation of about 1.6 MN computed for P3 compared with approximately 0.8 MN measured. Overall, the proposed 3D modelling framework provides a practical and interpretable tool for design-oriented analyses of TBM-induced pile response, with strong performance for pile-head settlements and current limitations mainly related to axial-force redistribution.

In recent years, energy tunnels have gained significant attention as sustainable solution for heating and cooling demands in urban environments. Meanwhile, with the increasing demand for underground space, twin tunnel configurations are often adopted to optimize space utilization and accommodate dense city infrastructures. Therefore, this paper investigates the thermal performance of twin energy tunnels operating simultaneously. A numerical model, based on an approach validated against field test results of Turin Metro line 1, was developed to study the influence of groundwater flow velocity, groundwater level, and clear distance on heat exchange rates and thermal interactions of twin energy tunnels embedded in sand. The results show that when tunnels are fully submerged under the ground water table, the thermal plumes induced by the upstream tunnel decrease the heat exchange efficiency of the downstream tunnel. This decreasing efficiency continues to increase with increasing groundwater flow velocity up to 0.5 m/d. Beyond this velocity, the growing influence of thermal recharge becomes more significant, reducing the thermal plumes effect of one tunnel to the other. At the same time, a smaller clear distance results in higher thermal interactions and consequently lower efficiency of the downstream tunnel. Additionally, the optimal clear distance was observed to significantly depend on groundwater flow velocity. The influence of thermal plumes of the upstream tunnel become less significant when the groundwater level at or below the tunnel invert. The performance of both tunnels was found to remain consistent over three years of thermal operations, and this is attributed to groundwater flow and sufficient recovery periods.

This study investigates the long-term thermo-mechanical behaviour of an energy pile installed in clay using field experiments and numerical simulations, aiming both to understand its response under sustained mechanical loads and cyclic thermal loading, and to develop a novel numerical model that can provide practical guidance for the design of energy piles. Firstly, full-scale experiments were performed on energy piles (0.42 m in diameter and 12 m in length) subjected to constant axial loads combined with three or five cyclic thermal loads. One pile was loaded to 30 % of its bearing capacity, and another to 50 %. Under these constant axial loads, the piles were subjected to several thermal loading cycles. Mechanical loading was finally applied to these piles after thermal cycles. A third pile was only mechanically loaded until the pile's bearing capacity was reached. Results for the pile temperature and axial strain, pile head displacement, and axial load are shown. Secondly, a numerical model was developed based on a one-dimensional nonlinear finite element approach to investigate the long-term thermomechanical behaviour. This model was validated against the experimental results. It was then used to simulate 30 thermal cycles, revealing that the irreversible settlement of the pile head increases with higher axial loads, and that the first thermal cycle induces the largest irreversible settlement.

Energy geostructures are more and more considered as a possible solution to cover heating and cooling needs. They function according to the principle of shallow geothermal energy, exchanging heat with the ground. This results in a zone underground where the temperature of the ground is affected by the presence of the geothermal system, which is called thermal influence zone. As the number of energy geostructures increases, determining their thermal influence zone becomes crucial, especially in environments where adjacent energy geostructures or other geothermal systems coexist. Indeed, avoid or minimize the overlap between the thermal influence zones of different geothermal installations is important to ensure their efficiency. This study investigates the effects of groundwater level, thermal operation period, and ground permeability, in both heating and cooling modes, on the thermal influence zone generated around an energy tunnel. The results indicate that the thermal induced change in groundwater density and viscosity due to geothermal operations generates groundwater circular flows. These flows play a major role in shaping the thermal influence zone. In the heating mode (winter), when the groundwater is within the vicinity of the tunnel, i.e., above, at or just below the tunnel, the thermal influence zone takes an oval shape elongated below the tunnel invert. In the cooling mode (summer), the thermal influence zone does not follow a specific shape, and it is remarkably changed by the groundwater level. For instance, when the groundwater level is shallow, the thermal influence zone extends significantly upward, potentially overlapping with the surface layer affected by atmospheric air temperature. However, when the groundwater level at the tunnel centreline, the thermal influence zone takes a horizontal oval shape, which might interfere with adjacent similar installations. The expansion of the thermal influence zone is highly dependent on the operation duration. In winter, the downward elongation after 6 months operation reaches around 1.5 times that after 3 months.

The use of tunnels for exploiting shallow geothermal energy has gained significant attention in recent years. Consequently, understanding the influence of various ground conditions is essential for accurately estimating heat exchange rates. In practice, tunnels may locate above groundwater level, within a partially saturated zone. Since thermal properties of ground are moisture dependent, heat exchange rates vary according to soil type, groundwater level, and air entry suction. A numerical model was developed and validated to investigate influences of groundwater level and air entry suction in sand, silt, and clay soils. The results show that the heat exchange in sand improves in the groundwater presence, and this positive effect disappears when the groundwater level falls more than half a tunnel diameter below the invert. The known influence of groundwater flow becomes significant when groundwater level is above the invert. In silt, the presence of groundwater level between ground surface and five tunnel diameters below the tunnel centreline has a moderate effect, while in clay, this effect is negligible. Finally, parametric analyses were employed to create design charts that enable preliminary estimation of heat exchange rates in sand based on groundwater level.

The utilization of ground-embedded structures for harnessing geothermal energy in space heating and cooling has gained significant attention over the past two decades. In this context, this paper reviews the use of tunnels, commonly known as energy tunnels, for exploiting shallow geothermal energy, providing an overview of the current status and future prospects. The different tunnel construction methods and their respective thermal actixvation processes are described. The factors influencing thermal performance and mechanical responses are analysed, alongside the economic and environmental benefits. This review confirms the viability of energy tunnels as a sustainable and renewable solution, as several studies have demonstrated their potential in providing a substantial amount of thermal energy and reducing natural gas consumption and significantly cutting CO2 emissions. Energy tunnels can also potentially provide a reliable solution for road de-icing or enable efficient thermal energy storage when groundwater flow is negligible. Finally, current, and future innovations aimed at maximizing shallow geothermal exploitation are discussed, with a call for further research to explore additional thermal retrofitting techniques for the existing tunnels, innovative additions for lining concrete, fluid and pipe materials and integrating energy tunnels with other renewable energy sources in district heating networks.

A calculation model including an original cyclic t-z method is proposed for the analysis and the design of piles subjected to cyclic axial loads both in terms of displacements and resistance. This model allows the assessment of pile displacement and axial force distribution with depth for each load increment. The cyclic effects and especially the decrease of the shaft friction are accounted for by considering the current state of stress at the pile-soil interface. The approach is based on the 'ABC' method developed by the Imperial College. A procedure is developed to combine this method with t-z cyclic curves. Comparisons are made between the numerical results obtained from this cyclic t-z model and the experimental data of tests which were carried out during the project GOPAL (Grouted Offshore Piles For Alternating Loadings) and the French National Project SOLCYP (SOLlicitations CYlcliques sur Pieux): four cyclic loading sequences are considered for both driven and bored piles. The reliability of the proposed model is evaluated according to the loading level and the number of cycles. The use of this model also leads to the construction of cyclic stability diagrams.

The transport sector is the second leading emitter of greenhouse gas emissions (GHGEs) from fuel combustion activities on a global scale. Reducing emissions related to this sector requires detailed data about the emissions by vehicle type and traveled distance. Generally, these data are missing in developing countries, which makes difficult the establishment of effective policies for the reduction of these emissions. This paper presents a hybrid method to estimate these emissions using the IPCC 2006 guidelines. The method combines bottom-up and top-down approaches to estimate vehicular emissions using data about the vehicle type, vehicle kilometers traveled, and fuel consumption. This method is applied for the first time for the Palestinian territory. Data have been collected from the administration, official reports, and papers. The results show a significant increase in the total vehicles in Palestine, particularly diesel vehicles. Emissions from the on-road transport system were approximately 2,207,834 tons of CO2eq in 2019. Diesel vehicles were responsible for about 75% of these emissions. Private cars were the most significant contributor to these emissions, with a share exceeding 50% of the total emissions, followed by commercial vehicles and light trucks (20%), public taxis (9%), and buses (7%). These results show clearly that the GHGEs reduction policies in Palestine should focus on diesel and private vehicles by developing the public transport systems and replacing diesel and gasoline vehicles with more environmentally friendly vehicles, such as hybrid and electric cars.

This paper aims to investigate greenhouse gas emissions (GHGEs) in conflict areas, emphasising Palestine. This estimation faces several difficulties, particularly in data collection. The paper first presents the geopolitical context of Palestine and its consequences for the analysis of GHGEs. Then, it presents the estimation of the GHGEs related to energy, which constitutes the major contributor to GHGEs in Palestine. The emissions were estimated according to Tier 1 in the 2006 IPCC guidelines. For the first time in Palestine, (i) the International Energy Agency methodology for calculating emission factors from electricity consumption is used to estimate the emission factors of GHG at the final point of consumption, and (ii) the scope 2 emissions from imported electricity are accounted for in the total emissions. The GHGEs from the Palestinian electricity generation (excluding imported electricity) were 446,471 tons of CO(2)eq in 2019, representing 11% of the total emissions from the energy sector. The total GHGEs from electricity final consumption (including imported electricity) in all sectors were 3,929,829 tons of CO(2)eq. More than 60% (2,316,465 tons of CO(2)eq) of these emissions were attributed to the consumption of electricity by the households. Emissions from fuel consumption in 2019 were about 3,912,566 tons of CO(2)eq. Transport was found to be the main emitter of GHGs, with more than half of the total emissions (2,207,834 tons of CO(2)eq). Considering imported electricity in estimating the total GHGEs from the energy sector doubled the emissions. It increased the share of household emissions in the total GHGEs from the energy sector to become the most significant contributor to the total emissions.

A City Information Model (CIM) is a 3D model composed of the city structure and various interconnected city layers such as mobility, environment, and social inclusion. CIM has attracted attention in recent years, but improvements are still needed for data collection, integration, and visualization in CIM. Also, limited research is available on citizen participation and integration into CIM, which is crucial for realizing a human-centered digital replica of the city. This paper explains the thorough integration of both tangible and intangible data around mobility, road security, and social participation in CIM. The study embarks on the creation of a CIM prototype based on (1) integrating data from different sources, and (2) collaborating with residents to highlight specific feelings around the neighborhood. The general methodology comprises (1) data collection, (2) data analysis, and (3) platform build-up. This methodology is projected onto a selected neighborhood in Lille, France where collected quantitative and qualitative data is analyzed, and then visualized. This study can provide stakeholders and city planners with a means of decision-making to improve the quality of life in cities.

The growing use of fossil fuels and other non-renewable energy sources has made climate change a critical global issue. In order to counter this threat, several countries are engaged in an ecological transition, and are looking for technologies using renewable energy sources. In this context, energy geostructures, such as thermo-active (or energy) piles, have been developed, consisting in fixing heat exchanger pipes to the reinforcement cages of foundation piles to extract/inject the heat from/into the ground with the purpose of meeting the building heating and cooling demands. Their specificity is their dual function: structural support and energy exchanger. In the case of energy piles, two aspects can be critical and should be considered in their design. The first is the nature of the cyclic thermal loading, which can affect the mechanical response of the energy pile. In fact, during temperature variation along the pile, stresses change and pile head movements are induced (Figure 1), due to the thermal dilatancy/contraction of the pile and the behaviour of the soil-pile interface [1, 2, 3, 4, 5, 6]. Consequently, cyclic thermal loading can induce a deterioration of the shear stresses at the soil-pile interface and hence a deterioration of the pile's bearing capacity [7]. The second aspect concerns the adaptation of design under combined lateral and axial loads. Indeed, the co-existence of a lateral loading can affect the axial response of the pile and vice-versa [8]. These configurations are the most favourable for installing heat exchanger pipes since, mechanically, they require reinforcement cages all along the pile height. Studies on energy piles have mainly investigated their behaviour under axial loading. Energy piles under lateral loading have hardly been considered [9]. The aim of this paper is to present a practical calculation tool for modelling energy piles that takes into account the combined loading on the pile response. An original 1D finite element approach is developed for engineering practice, taking into account the rheology of the problem. The pile is discretised in beam finite elements with three degrees of freedom at each node (vertical displacement, horizontal displacement and rotation). The soil is modelled by surface shear and normal springs. This tool is based on the solution of the equilibrium equation of the global system by an iterative plastic correction procedure. This correction is based on the yield criterion defined in the code. The main strength of this approach lies in its capability to consider a 3D failure envelope for an energy pile, capturing its behaviour under combined axial, lateral and cyclic thermal loading. It can clearly represent the critical effects of these loads by adopting an appropriate behaviour law for the soil-pile interface. In addition to being practical and easy to use, this tool has the advantage of reducing calculation time compared to more complex 3D numerical methods, especially in the case of cyclic thermal loading.

Abstract The assessment of the head load-displacement response of a pile under axial loading is the key aspect for analysing the pile behaviour under such type of loading. Therefore, an adequate modelling of the soil-pile interface makes it possible for numerical investigations to give a relevant prediction of the pile response. The commonly used approaches for displacement analysis either consider that the soil resistance can be simulated by a series of discrete springs, or that the soil is a continuum. However, the use of either approaches presents some drawbacks related to the disregard of the rheological aspect of the problem, or to the need of time-consuming numerical techniques. This paper presents a practical 1D approach, based on the finite element method, for soil-pile interface modelling. This approach is coupled with a simplified flow rule, used to simulate the interface response, based on the analogy between the behaviour of the soil-pile interface and the interface of a direct shear test. The response of a theoretical pile using the developed approach is compared to results of a load-transfer analysis and results of a 3D analysis using the commercial finite difference software (FLAC3D). The results allow to estimate the change in pile shaft resistance induced by normal stress variations along the pile.

The present work aims to evaluate the kinematic interaction effects of a rigid inclusion reinforced soil mass under seismic waves.In order to understand the seismic behaviour of the system, a three-dimensional finite element code (FEM) is used (code Aster).Two numerical studies are presented.The first is a simple case study of a single Rigid Inclusion (RI), carried out to evaluate the influence of the RI modelling taking into account a beam element or a pile void element (called hybrid method).This technique consists of modelling the vertical reinforcements as void elements with the introduction of a beam element in their central axis.The use of this method makes it easier to determine the internal forces in the vertical reinforcements, taking into account the element rigid section.The second numerical work is a parametric study to highlight the effect of parameters such as the soil stiffness, mattress stiffness and RI diameter on the seismic response of a 5x5 rigid inclusion group considering a linear elastic behaviour.

Design of piles in chalk is considered as an important issue for a number of geotechnical applications in Northern Europe. Few methods exist for predicting the ultimate axial pile capacity in chalk, but little guidance can be found regarding the design of driven piles in this complex material as experience is rather limited. This paper aims to study the short and long-term predictive performance of different pile design methods used in France and the UK where chalk is found widespread in the north-west coast and the south-east coast, respectively. Conventional methods used in France and the UK are compared by considering seven full-scale static load tests performed in Paris Basin and extracted from the LCPC pile database. The ratio of the measured vs calculated pile shaft resistance and base resistance value is analysed and the scatter of each method is studied. The comparison shows large differences between results. Extension of the database is of great importance to improve the predictive reliability. The last part discusses the evolution of the long-term capacity of driven piles in chalk due to ageing effects. Results show an increasing trend after driving, following a hyperbolic evolution curve.

Reinforced concrete bridges constitute the major part of existing bridges. The purpose of this paper is to present a serviceability evaluation methodology for RC bridges under probabilistic conditions. It will be based on analytical calculations with no need to complex modeling or advanced software. For this purpose, a realistic traffic model is simulated based on existing weigh-in-motion WIM data from some European sites. The probabilistic distributions of the time-dependent load effects, moment and deflection, are then deduced after hundreds of simulations. The degradation effects are introduced in the analysis by considering the concrete creep and shrinkage. A simplified model to introduce creep effect under variable traffic load is also proposed. The time dependent reliability indices are then calculated for a set of 21 simply supported RC T-beam bridges with varying parameters such as span lengths, number of girders, girder spacing and number of design lanes. The first order reliability method FORM, is used in the reliability calculation in order to evaluate the structural performance under the considered failure scenario.

This paper proposes a three-dimensional fully-coupled numerical model intended for the simulation of the dynamic behavior of ballasted railway tracks under real excitation. It is employed to reproduce the response of a French site located at the high-speed line connecting the two regions Bretagne and Pays de la Loire. The equation of motion is solved in the time domain by means of the finite difference method in which the rails and sleepers are represented by rectilinear beam elements which are rigidly attached to a spatial grid composed of rectangular cuboids. An adaptive meshing scheme based on the creation of load-attached moving nodes is adopted to model the moving train loads which are supposed to be time-independent. To validate the numerical simulations, a measuring campaign is performed in which tow aligned deflectometers are used to measure the displacement of the railway foundation just below the ballast layer under the track centerline. The velocity range of the high-speed passenger trains is covered in which four cases are taken into consideration ranging from 162 to 342 km/h. An excellent agreement between measurements and predictions is found. Therefore, the presented model can be considered reliable for the design of new high-speed lines.

Improving the energy efficiency of the building sector has become an increasing concern in the world, given the alarming reports of greenhouse gas emissions. The management of building energy systems is considered an essential means for achieving this goal. Predicting indoor temperature constitutes a critical task for the management strategies of these systems. Several approaches have been developed for predicting indoor temperature. Determining the most effective has thus become a necessity. This paper contributes to this objective by comparing the ability of seven machine learning algorithms (ML) and the thermal gray box model to predict the indoor temperature of a closed room. The comparison was conducted on a set of data recorded in a room of the Laboratory of Civil Engineering and geo-Environment (LGCgE) at Lille University. The results showed that the best prediction was obtained with the artificial neural network (ANN) and extra trees regressor (ET) methods, which outperformed the thermal gray box model.