Indoor Model Research Articles

Experimental study on negative skin friction characteristics of double-sleeve pile

Pile foundation structures are widely used in the construction of high-piled wharves in coastal soft soil areas due to their excellent adaptability to such environments. However, the extensive, deep backfilling involved in constructing these wharves can easily induce negative skin friction (NSF) on the piles, resulting in safety issues such as excessive settlement during the service life of the structures. This paper presents an indoor model experiment to examine the distribution of the THE NSF under varying pile-top loads and surcharge effects on single pile and double-sleeve pile foundations. The potential of double-sleeve pile foundations to mitigate the NSF was also explored. The results show that the axial force within the double-sleeve pile’s protected section remains essentially stable, though it is affected by the surface surcharge in the unprotected section. Time effect is exhibited both for the axial force and the NSF, gradually increasing over time. Compared to single piles, double-casing pile foundations can effectively isolate the down drag load caused by surrounding soil settlement, thereby reducing or eliminating the NSF on the pile sides.

Voxel Size Performance in 3D Indoor Model Creation for 3D Evacuation Simulations

Abstract. 3D voxel models facilitate simulating 3D pedestrian motions within indoor environments with diverse furniture, equipment, and complex room layouts featuring stairs and ramps. Reasonable voxel sizes enable the effective identifications of indoor spaces, navigable surfaces, and vertical links from voxel models for the simulations. However, the performance of different voxel sizes on these identifications has yet to be thoroughly investigated. The choice of appropriate voxel sizes for various 3D evacuation scenarios has to be clarified to avoid unreliable simulation outcomes. Therefore, this paper aims to assess the performance of different voxel sizes on the identifications of the spaces, surfaces, and links. Firstly, we introduce three key metrics for the assessment: accuracy, robustness, and efficiency. Then, three IFC models are selected based on predefined criteria for the tests. Experimental procedures are elaborated to include data preparation, collection, and analysis. The primary findings of this investigation are: 1) with increasing voxel sizes, accuracy decreases, robustness changes, and efficiency increases; 2) larger indoor spaces exhibit smaller changes in accuracy across different voxel sizes, while smaller indoor spaces show more significant changes in accuracy. 3) when the voxel size is tiny, it becomes challenging to complete identifications. Conversely, with relatively larger voxel sizes, some indoor spaces and vertical links cannot be identified. 4) Indoor spaces with complex and non-orthogonal geometries require more identification time. This work is expected to advance the creation of 3D indoor model to facilitate 3D evacuation simulations.

Progressive failure mechanism of existing-supplementary double-layer piles retaining excavation beneath existing underground space

The increasing degree of urbanization has resulted in traffic and space congestion. When there is no longer any aboveground space for development, the existing space underground is excavated, and the construction of underground buildings is expected to solve the above problems. In the excavation of an underground layer, it is necessary to drive supplementary and existing piles into the soil to form a double-layer pile-supported structure. Aiming at an existing–supplementary double-layer pile-supported structure and considering the pile spacing of the supplementary piles, use of crown beams, and other factors, this study performed a series of indoor model tests and an simulation analysis in combination with finite element analysis software to reveal the bearing characteristics of this structure. The results showed that the installation of supplementary piles could effectively inhibit soil slippage after pile driving, redistribute the soil pressure load of the existing piles, and reduce the number of soil cracks between the piles. With the increase in the supplementary pile spacing, the deformation of the existing–supplementary double-stacked piles gradually intensified, and the bending moment of the pile body and the horizontal displacement at the top of the piles increased. The installation of crown beams in the existing piles could strengthen the connection between the existing and supplementary piles, reduce the number of soil cracks between these piles, and change the force mode of the pile body. Considering the geological conditions and the influence of existing buildings, the deformation laws of the supporting structure and the soil around the foundation piles during the excavation of an underground layer of an L-shaped foundation pit were revealed. The research results are expected to provide a scientific and theoretical basis for the design and construction of downward additional support structures for existing buildings, along with socio-economic significance.

Analysis of dynamic response and impact resistance of corrugated plate-reinforced concrete under simulated rockfall

In this study, corrugated plate material is used as the internal mold for the reinforced concrete structure, proposing a combined shelter structure designed to protect against rockfall hazards in mountainous areas. The research focuses on the impact of low-velocity rockfall (below 150 km/h) directly hitting both the reinforced concrete structure and the corrugated plate and reinforced concrete combined shelter structure. The accuracy of the numerical simulation results is validated through comparative analysis with indoor model experiments. Further investigation reveals the impact resistance and failure characteristics of RC (Reinforced Concrete) structures, CPRC(D) (Corrugated plate double-layer reinforced concrete composite structure) structures and CPRC(S)（Corrugated plate single-layer reinforced concrete composite structure）, with the residual resistance index (RRI) introduced for the quantitative analysis of the residual load-bearing capacity of the protective structures post-impact. The results indicate that the shape of impact craters and the maximum impact force obtained through numerical simulations closely match the experimental findings, demonstrating the validity of the simulation parameters. Under the same impact energy, the maximum peak stress at various points in the CPRC structure is reduced by more than 50 % compared to the RC structure. Damage to the RC structure under rockfall impact is primarily characterized by central penetration failure and extensive development of diagonal cracks. In contrast, the CPRC structure effectively suppresses penetration, dent deformation, and crack propagation, significantly reducing the volume of concrete damage and the proportion of rebar damage, with the residual resistance index consistently remaining above 0.27.The corrugated plate and reinforced concrete combined structure outperforms the reinforced concrete structure in several impact resistance factors, including maximum impact force, effective stress extremes, structural damage, and penetration depth. Additionally, after reinforcement with corrugated plates, the CPRC structure maintains a high level of impact resistance in most scenarios, even when the lower layer of rebar is eliminated, providing a theoretical basis and preliminary feasibility proof for the lightweight modification of the structure.

A voxel-based 3D indoor model to support 3D pedestrian evacuation simulations

Three-dimensional (3D) indoor models enable realistic simulation of pedestrian evacuations in 3D space. However, existing indoor models do not fully identify navigable spaces located above/below physical components (e.g., chairs, stairs, desks), and the connections between these spaces and their navigable surfaces remain underexplored. These limitations hinder the accurate modelling of 3D pedestrian motions during evacuations. To address the shortcomings, we present novel automatic approaches to create a voxel-based 3D indoor model. First, based on different types of 3D motions, indoor spaces are automatically identified as freely navigable spaces, navigable spaces under conditions and non-navigable spaces. Then, navigable surfaces are identified to simulate moving above/below in 3D space. Vertical links are identified to connect the spaces and surfaces at different heights. A 3D pathfinding approach is subsequently developed to validate the model’s effectiveness. Finally, we evaluate the created model’s accuracy, robustness and efficiency across different voxel sizes. The primary findings are: 1) as voxel size increases, accuracy decreases, robustness changes and efficiency improves; 2) with very small voxel sizes, identification becomes challenging, while larger voxel sizes prevent some spaces and vertical links from being identified; and 3) indoor spaces with complex geometries require more time for identification. Our key contributions are: 1) an approach for automatically identifying indoor spaces for 3D motions; 2) two approaches for automatically identifying navigable surfaces and vertical links; and 3) a 3D pathfinding approach considering distinct 3D motion costs. This work advances 3D modelling to facilitate more realistic evacuation simulations.

Influence of silicon carbide incorporation on the macroscale and microscale heat transfer characteristics of energy piles

This paper explores the impact of silicon carbide (SiC) incorporation on the heat transfer capabilities of energy piles by deploying a suite of methodologies that includes standard specimen tests, scanning electron microscopy (SEM) analysis, and indoor modeling tests. The findings indicate that SiC doping enhances the thermal conductivity, compressive strength, and flexural strength of the pile material at the macroscopic level. Whereas, the doping of SiC forms a new cluster structure in the concrete compared to that without SiC at the microscopic scale. In contrast to conventional energy piles, the SiC-enhanced energy piles exhibit superior heat transfer efficiency and accelerated temperature growth rates. In addition, SiC helps to mitigate the heat accumulation around the heat exchange tube. The temperature-induced upward displacements at the top of the SiC-enhanced energy pile increase at elevated temperatures, while the additional displacement reduces when the pile top is loaded. On the contrary, the temperature induces downward displacements as well as the top decreases during the cooling process, with heavier loads resulting in large settlements. Finally, this research assists in establishing an experimental foundation for the design and implementation of SiC-enhanced energy piles.

A New Framework for Generating Indoor 3D Digital Models from Point Clouds

Three-dimensional indoor models have wide applications in fields such as indoor navigation, civil engineering, virtual reality, and so on. With the development of LiDAR technology, automatic reconstruction of indoor models from point clouds has gained significant attention. We propose a new framework for generating indoor 3D digital models from point clouds. The proposed method first generates a room instance map of an indoor scene. Walls are detected and projected onto a horizontal plane to form line segments. These segments are extended, intersected, and, by solving an integer programming problem, line segments are selected to create room polygons. The polygons are converted into a raster image, and image connectivity detection is used to generate a room instance map. Then the roofs of the point cloud are extracted and used to perform an overlap analysis with the generated room instance map to segment the entire roof point cloud, obtaining the roof for each room. Room boundaries are defined by extracting and regularizing the roof point cloud boundaries. Finally, by detecting doors and windows in the scene in two steps, we generate the floor plans and 3D models separately. Experiments with the Giblayout dataset show that our method is robust to clutter and furniture point clouds, achieving high-accuracy models that match real scenes. The mean precision and recall for the floorplans are both 0.93, and the Point–Surface Distance (PSD) and standard deviation of the PSD for the 3D models are 0.044 m and 0.066 m, respectively.

Internal Stress Evolution in Thrust-Type Soil Landslides: Insights from Indoor Model Testing and Numerical Simulation

Internal Stress Evolution in Thrust-Type Soil Landslides: Insights from Indoor Model Testing and Numerical Simulation

Mosquito dynamics and their drivers in peri-urban Antananarivo, Madagascar: insights from a longitudinal multi-host single-site survey

BackgroundAntananarivo, the capital city of Madagascar, is experiencing a steady increase in population growth. Due to the abundance of mosquito vectors in this locality, the population exposed to mosquito-borne diseases is therefore also increasing, as is the risk of epidemic episodes. The aim of the present study was to assess, in a resource-limited setting, the information on mosquito population dynamics and disease transmission risk that can be provided through a longitudinal entomological study carried out in a multi-host single site.MethodsMosquitoes were collected every 15 days over 16 months (from January 2017 to April 2018) using six CDC-light traps in a peri-urban area of Antananarivo. Multivariable generalised linear models were developed using indoor and outdoor densities of the predominant mosquito species as response variables and moon illumination, environmental data and climatic data as the explanatory variables.ResultsOverall, 46,737 mosquitoes belonging to at least 20 species were collected, of which Culex antennatus (68.9%), Culex quinquefasciatus (19.8%), Culex poicilipes (3.7%) and Anopheles gambiae sensu lato (2.3%) were the most abundant species. Mosquito densities were observed to be driven by moon illumination and climatic factors interacting at different lag periods. The outdoor models demonstrated biweekly and seasonal patterns of mosquito densities, while the indoor models demonstrated only a seasonal pattern.ConclusionsAn important diversity of mosquitoes exists in the peri-urban area of Antananarivo. Some well-known vector species, such as Cx. antennatus, a major vector of West Nile virus (WNV) and Rift-Valley fever virus (RVFV), Cx. quinquefasciatus, a major vector of WNV, Cx. poicilipes, a candidate vector of RVFV and An. gambiae sensu lato, a major vector of Plasmodium spp., are abundant. Importantly, these four mosquito species are present all year round, even though their abundance declines during the cold dry season, with the exception of Cx. quinquefasciatus. The main drivers of their abundance were found to be temperature, relative humidity and precipitation, as well as—for outdoor abundance only—moon illumination. Identifying these drivers is a first step towards the development of pathogen transmission models (R0 models), which are key to inform public health stakeholders on the periods of most risk for vector-borne diseases.Graphical

The association between cumulative exposure to PM2.5 and DNA methylation measured using methyl-capture sequencing among COPD patients

BackgroundParticulate matter with a diameter of < 2.5 μm (PM2.5) influences gene regulation via DNA methylation; however, its precise mechanism of action remains unclear. Thus, this study aimed to examine the connection between personal PM2.5 exposure and DNA methylation in CpG islands as well as explore the associated gene pathways.MethodsA total of 95 male patients with chronic obstructive pulmonary disease (COPD) were enrolled in this study. PM2.5 concentrations were measured for 12 months, with individual exposure recorded for 24 h every 3 months. Mean indoor and estimated individual PM2.5 exposure levels were calculated for short-term (7 days), mid-term (35 days), and long-term (90 days). DNA methylation analysis was performed on the blood samples, which, after PCR amplification and hybridization, were finally sequenced using an Illumina NovaSeq 6000 system. Correlation between PM2.5 exposure and CpG methylation sites was confirmed via a mixed-effects model. Functional enrichment analysis was performed on unique CpG methylation sites associated with PM2.5 exposure to identify the relevant biological functions or pathways.ResultsThe number of CpG sites showing differential methylation was 36, 381, and 182 for the short-, mid-, and long-term indoor models, respectively, and 3, 98, and 28 for the short-, mid-, and long-term estimated exposure models, respectively. The representative genes were TMTC2 (p = 1.63 × 10-3, R2 = 0.656), GLRX3 (p = 1.46 × 10-3, R2 = 0.623), DCAF15 (p = 2.43 × 10-4, R2 = 0.623), CNOT6L (p = 1.46 × 10-4, R2 = 0.609), BSN (p = 2.21 × 10-5, R2 = 0.606), and SENP6 (p = 1.59 × 10-4, R2 = 0.604). Functional enrichment analysis demonstrated that the related genes were mostly associated with pathways related to synaptic transmission in neurodegenerative diseases and cancer.ConclusionA significant association was observed between PM2.5 exposure and DNA methylation upon short-term exposure, and the extent of DNA methylation was the highest upon mid-term exposure. Additionally, various pathways related to neurodegenerative diseases and cancer were associated with patients with COPD.ClinicalTrials.gov identifierNCT04878367.

Spatial Analysis with Detailed Indoor Building Models for Emergency Services

This paper presents a systematic approach to perform spatial analysis with detailed indoor building models for emergency service decision supports. To achieve a more realistic spatial application, this research integrates three-dimensional (3D) indoor building models and their attributes to simulate an emergency evacuation scenario. Indoor building models of a complicated train station with different levels of detail are generated from two-dimensional (2D) floor plans and Building Information Model (BIM) datasets. In addition to the 3D building models, spatial and non-spatial attributes are also associated with the created building models and the objects within them. The ant colony optimization (ACO) algorithm is modified to analyze the indoor building models for emergency service decision support applications. The detailed indoor models and the proposed spatial analysis algorithms are tested in simulated emergency evacuation scenarios to select the best routes during emergency services. The experimental results demonstrate that the proposed system is helpful for selecting the optimal route with the least cost at varying time stamps. Together with the developed spatial analysis framework, they have a great potential for effective decision support during emergency situations.

Modeling Indoor Inorganic Aerosol Concentrations During the ATHLETIC Campaign with IMAGES.

In 2018, the ATHLETIC campaign was conducted at the University of Colorado Dal Ward Athletic Center and characterized dynamic indoor air composition in a gym environment. Among other parameters, inorganic particle and gas-phase species were alternatingly measured in the gym's supply duct and weight room. The Indoor Model of Aerosols, Gases, Emissions, and Surfaces (IMAGES) uses the inorganic aerosol thermodynamic equilibrium model, ISORROPIA, to estimate the partitioning of inorganic aerosols and corresponding gases. In this study herein, measurements from the ATHLETIC campaign were used to evaluate IMAGES' performance. Ammonia emission rates, nitric acid deposition, and particle deposition velocities were related to observed occupancy, which informed these rates in IMAGES runs. Initially, modeled indoor inorganic aerosol concentrations were not in good agreement with measurements. A parametric investigation revealed that lowering the temperature or raising the relative humidity used in the ISORROPIA model drove the semivolatile species more toward the particle phase, substantially improving modeled-measured agreement. One speculated reason for these solutions is that aerosol water was enhanced by increasing the RH or decreasing the temperature. Another is that thermodynamic equilibrium was not established in this indoor setting or that the thermodynamic parametrizations in ISORROPIA are less accurate for typical indoor settings. This result suggests that applying ISORROPIA indoors requires further careful experimental validation.

Approximate analytical algorithm for pull-out resistance-displacement relationship of combined anchor system

Building upon an evaluation of the distinct advantages and limitations of anchor rods and anchorage plates, this paper introduces an integrated anchor-tensioning system that combines these elements in series. This innovative approach significantly enhances the pullout bearing capacity of the overall anchorage system. Based on the hyperbolic model of the distribution of lateral friction resistance of the anchor solid and the Winkler′s foundation model of load transfer of the anchorage plate, the theoretical analysis method for the analysis of the pullout bearing capacity and deformation of the combined anchorage system was established, and an approximate analytical equation for the relationship between pullout force and displacement was obtained. The results from indoor model tests, numerical simulations, and theoretical analyses were compared, verifying the reliability of the theoretical methods employed. The findings of this study significantly advance the discourse on the innovation of structural support configurations, thereby enhancing the operational efficiency of anchor-pull support systems.

Experimental study on the influence of extremely broken surrounding rock grade on the mechanical characteristics of tunnels

To study the significant deformation and distortion issues in certain sections of the Qinyu tunnel extremely fragmented surrounding rock under identical conditions, six tunnel sections with the same depth of burial and lithology were selected for on-site monitoring of stress. The experimental data were then used to explore the impact of gradation on the mechanical characteristics of the extremely fragmented surrounding rock tunnels. The results indicate that the tunnel experiences larger stresses at the crown and smaller stresses at the side walls and invert, showing the influence of gradation on the stress behavior of extremely fractured surrounding rock. A dual-fractal structure model was employed to quantitatively describe the gradation of the surrounding rock, yielding fitting coefficients above 0.9. The model demonstrated good applicability for extremely fractured rock with significant particle size differences. Additionally, the relationship between fractal model parameters and the maximum rock pressure at various tunnel sections was discussed, revealing an exponential correlation between the absolute difference in fractal dimensions of coarse and fine particles and the maximum rock pressure. To further understand the factors and the influence of gradation on tunnel rock pressure, indoor model tests were conducted using six different gradations. The experimental results once again confirmed the importance of gradation on the stress behavior of highly fragmented rock tunnels and validated the functional relationship between the absolute difference in fractal dimensions and rock pressure. The results can provide guidance for the design of tunnels with extremely fractured surrounding rocks in the future.

Experimental study on granule trajectory tracking for the EPB shield tunneling in sandy cobble stratum

An investigation into the movement characteristics of granules during Earth Pressure Balance (EPB) shield tunneling contributes significantly to understanding the interaction between the shield machine and the soil. This understanding also enables researchers to gain deeper insights into the cutting and guiding effects of the shield cutterhead on the soil, thus providing a scientific basis for optimizing shield tunneling parameters and cutterhead designs. To achieve this, indoor model shield tunneling experiments were conducted using independently developed shield tunneling equipment and spatial positioning devices developed by our research group. The research investigated the spatial movement trajectories, radial diffusion, and axial movement characteristics of granules at the face subjected to the action of a spoke-type cutterhead. Furthermore, the study proposes the use of average diffusion degree and movement rates of granules as metrics for evaluating the cutting and steering performance of the cutterhead. The influence of cutterhead rotational speed and advance rate on the movement characteristics of granules was further explored based on these two indicators. The study’s findings reveal the following: (1) Granules at the face predominantly exhibit a spiral movement trajectory when the EPB shield tunneling machine operates in a dynamic equilibrium state. (2) The cutting and steering performance of the cutterhead’s various areas is enhanced progressively from the center to the outer edge, as evidenced by a gradual decrease in the average diffusion degree of granules and an increase in the average axial movement rate (AMR). (3) The AMR and average diffusion degree of granules are influenced by both the rotational speed of the cutterhead and the advance rate of the shield machine. Optimal matching of the rotational speed and advance rate maximizes the average AMR of granules, minimizes the average diffusion degree, reduces the torque on the cutterhead to its lowest point, and consequently, optimizes the efficiency of shield tunneling. This research presents a novel perspective and methodology for understanding the movement characteristics of granules during shield tunneling operations. The outcomes of this study provide valuable insights for the structural design of shield machine cutterheads and the optimization of tunneling parameters.

Mechanical Response in Existing Structure under Varied Subsurface Excavation Techniques

With the slowdown of urban incremental construction in China, reinforcement and renovation of existing buildings have become a hot topic in the fields of engineering and theoretical research. Underpinning pile foundations and underground excavation are commonly used methods for foundation renovation and reinforcement in existing buildings reinforcement and renovation projects. Nevertheless, there remains a dearth of relevant research concerning the effects of different excavation methods on the stability of existing structures during foundation reinforcement and underground space excavation. In the context of existing building pile foundation underpinning and underground excavation, this paper adopts a numerical simulation research method based on the modification of experimental model parameters, and it compares the overall stress changes and settlement of the underpinning pile foundation and the building under two modes of lateral and vertical excavation. The results indicate that there is a good agreement between the stress and settlement changes of the components in the indoor model experiment and the finite element simulation. Both excavation methods show that lateral and vertical excavation will generate maximum stress on the bottom components of the upper structure and the upper part of the pile. In terms of differences, vertical excavation will cause greater overall settlement of the building, but the settlement in different areas is basically the same. On the other hand, lateral excavation will have smaller overall settlement but may cause the structure to tilt. At the same time, lateral excavation will cause greater stress changes in the columns in the structure. Based on these findings, relevant engineering suggestions are provided to choose different excavation methods and strengthen existing buildings.

Study on causes and laws of crystallization blockage for dolomite tunnel drainage pipeline

AbstractIn order to study the crystallization blockage law and crystallization mechanism of dolomite tunnel drainage system, based on the indoor model test, the simulated crystal blockage and growth process were simulated. The phase composition and microstructure of the crystal were analyzed by energy‐dispersive X‐ray spectroscopy (EDS), scanning electron microscopy (SEM), and X‐ray diffraction (XRD). Combined with the pipeline crystal weighing, the crystal growth law and the internal cause of pipeline blockage were analyzed. The results show that the pipeline crystallization mechanism is divided into the first mechanism, the second mechanism, and the third mechanism. The crystallization blockage of the longitudinal and horizontal pipes are more serious, while the crystallization blockage of the ring pipes are less harmful. The crystallization is positively correlated with ion concentration, crystalline ions having a great influence on the blockage of pipeline crystallization, while noncrystalline ions having little influence. The crystal growth law is fast first and then slow, the crystallization affected by the coupling concentration of Cl−‐K+‐Na + ions, and positively correlated with the coupling concentration of CO32−‐SO42−‐Ca2+‐Mg2+‐Al3+ ions. Compared with the longitudinal pipes and the ring pipes, the horizontal pipes have more crystallization and higher degree of crystallization blockage per meter, while the crystallization degree of the longitudinal pipes are between the horizontal pipes and the ring pipes.

Failure analysis and comparative study on tunnels under strike-slip fault and oblique-slip fault movements

To deeply study and compare the failure characteristics of tunnels under strike-slip and oblique-slip active faults, with the engineering background of a railway tunnel in western China crossing both strike-slip and oblique-slip active faults, two sets of large-scale indoor model tests with a geometric similarity ratio of 1:35 were conducted. The fissure development patterns and strain trends of the tunnel under the movement of both types of faults were monitored and analyzed. Meanwhile, a three-dimensional model of tunnel-rock-fault interaction was established using ABAQUS finite element analysis software to determine the variation patterns of bending moments and shear forces of the tunnel under the movement of both types of faults. The results showed that under the movement of strike-slip and oblique-slip active faults, circumferential bending fissures appear at the right waist of the hanging wall and the left waist of the footwall of the tunnel, and shear oblique fissures appear at the vault of the fault fracture zone. Among them, the number of cracks, the range of tunnel cracking and the degree of crack damage under the condition of the oblique-slip fault are obviously more serious than those under the condition of the strike-slip fault. Under the dislocation of the oblique-slip fault, a large area of broken zone appears in the vault of the fault fracture zone, the lining falls off, the steel bar is exposed, and there is an obvious uplift phenomenon. The right waist of the tunnel’s hanging wall mainly experiences tension while the left waist experiences compression, whereas on the hanging wall, the right waist experiences compression while the left waist experiences tension. Under the fault movement, the maximum bending moment value mainly occurs at a distance of 10 m from the fault fracture zone on both the hanging wall and the footwall, with the bending moment values at the fault fracture zone nearly approaching zero. The maximum shear force value occurs at the fault fracture zone. Under the movement of both types of faults, the failure mode of the tunnel is mainly characterized by bending failure of the hanging wall and the footwall and shear failure at the fault fracture zone. Compared to strike-slip active faults, the development of fissures in tunnels under oblique-slip active faults is more severe, with larger bending moment and shear force values, and a wider range of tunnel failure. These results can provide theoretical and technical experience for future similar projects.

Recent advances and effectiveness of machine learning models for fluid dynamics in the built environment

ABSTRACT Indoor environmental quality is crucial for human health and comfort, necessitating precise and efficient computational methods to optimise indoor climate parameters. Recent advancements in machine learning (ML) and computational fluid dynamics (CFD) are promising. However, applying ML to complex building airflow presents challenges. This research aims to investigate the integration of ML with CFD in the context of built environment applications using a systematic review approach. It highlights a critical knowledge gap: the need to synthesise innovative approaches that address the limitations of indoor modelling using data-driven ML methods. The review examines contemporary literature, identifying current developments and suggesting potential future directions. It delves into the innovations in combining ML with CFD to predict thermal comfort and indoor air quality, uncovering key limitations such as the lack of high-quality experimental data for training and validation, the computational complexity of detailed CFD simulations, and the interpretability issues of ‘black-box’ ML models. The emergence of data-driven techniques in fluid mechanics offers promising prospects for modelling in the built environment. Future research should focus on incorporating physics-based rules in ML models, adapting turbulence closure models for indoor flows, and enhancing model validation using real-world datasets. The research emphasises the synergistic relationship between ML and CFD; it proposes pathways to overcome current limitations, aiming to enhance the precision and efficiency of indoor environment modelling through their integration.

Evaluation of Heating Time on Vacuum Preloading Treatment

A comparative study of the effect of a vacuum preloading combined intermittent heating method and conventional vacuum preloading treatment was designed and carried out through indoor model tests to investigate the optimal intermittent heating time. It is concluded that the mechanism of vacuum preloading combined with the intermittent heating method is to improve the permeability of soil to alleviate the clogging effect, and therefore has a treatment effect far beyond the conventional vacuum preloading method. The results also show that setting a heating time of 120 min and a stopping time of 60 min can obtain the best consolidation effect.