查看更多>>摘要：The study is based on the combined advantages of PVA fibers and EPP materials, a new PVA fiber EPP concrete was prepared as a filler material for tunnel buffer layers. 10 groups of specimens with different working conditions were designed and prepared. The failure pattern, physical and mechanical parameters and energy absorption index of the material were analyzed by static mechanical test and Hopkinson pressure bar (SHPB) dynamic compression test. The results indicate that E0 specimen showed brittle failure in static tests and SHPB tests. When PVA fiber and EPP beads were added to the specimen, the failure mode of the specimen changed from brittle failure to ductile failure, and the specimen shows typical core-remaining failure under impact load. The static test results reveal that EPP volume content significantly influences the axial compressive strength, elastic modulus, and confined compressive strength of PVA fiber EPP concrete, while fiber content has the most pronounced impact on splitting tensile strength, Poisson ratio, and dynamic compressive strength. the confined uniaxial compression ontological relationship of PVA fiber EPP concrete under confined compression was established by confined uniaxial compression test, and the formula fitting was carried out. The fitting results were in good agreement with the test data. Based on the stress-strain curve of confined compression, the static energy absorption performance of PVA fiber EPP concrete was discussed. The results show that the energy absorption effect of E60-P18-1.2 concrete is the best; The results of SHPB test showed that comparing the energy absorption value and dissipation rate of each group of specimens under 0.06 MPa air pressure, it was found that the concrete of E50-P12-0.7 had the best energy absorption effect under dynamic compression. These studies provide a valuable theoretical basis for optimizing the design of tunnel buffer layers.
查看更多>>摘要：Safe evacuation of crowds from deep underground spaces is challenging owing to large building sizes, enclosed indoor spaces, and long upward-evacuation distances. A virtual-reality (VR) scenario was created to study human behavior during fire emergencies in deep underground space, and a series of immersive VR experiments for evacuation was conducted. The experiment investigated evacuee pre-movement time (also called pre-evacuation time or response delay) and its distribution characteristics in deep underground space, in addition to their exit-selection ratio under five factors: left-right habituation, crowd effect, visibility, spatial familiarity, and luminance. A post-experiment questionnaire also examined participant impressions of aspects such as the realism and emotion of the VR experience. The results show that pre-movement time was shorter in deep underground space than in aboveground buildings and shallow underground space. Individual pre-movement time was significantly influenced both by their real experience with fire emergencies and whether the student participants majored in architecture. Spatial familiarity, crowd effect, and visibility had a more significant impact on human decision-making overall. Left-right habituation and luminance are less influential; crowd effect reinforces under-risk behavior and a sense of grouping, when crowd effect and visibility reduction work together. The study conclusions are likely to influence future VR-evacuation experiments and fire-safety design. The empirical data can also be input into computer simulations that model building evacuations. Quantifying experimental data on pedestrian behavior is essential for developing performance-based evacuation safety designs in deep underground spaces.
查看更多>>摘要：This paper investigates the in-situ protection technique for buried pipelines straddling deep braced excavation and the relevant structural performance. A deep braced excavation case history for constructing the West Yuanhetang tunnel in Suzhou, China is reported. The excavation is straddled by two shallowly-buried largediameter pressurized pipelines, with a straddling distance of about 31 m. Considering the significance of the pipelines for the normal life of local citizens, in-situ protective measures is thus necessary for ensuring the pipeline serviceability and stability during excavation. In an attempt to overcome the shortcomings of traditional pipeline protection technique, a new pipeline protection technique based on the suspension method is proposed. This technique takes advantage of the excavation support system. It eliminates the need for installing an exclusive structure for suspending pipelines, which is frequently practiced in conventional methods. Moreover, the original use of several kinds of materials for restraining pipeline displacement and transferring pipeline weight also contributes to a better protection of the pipelines. Furthermore, the performance of the proposed pipeline suspension system during excavation is investigated by using three-dimensional finite element method. The method is validated via reproducing the observed typical behavior of the deep excavation. Results has shown that the maximum axial forces, shear forces, and bending moments in the suspension supporting beams, as well as the maximum axial forces in the finish-rolling screw-thread (FRST) steel bars and the maximum bending moments and shear forces in the composite steel beams, all exhibit a stepwise growth pattern as the construction stage progresses. This research provides practical reference for in-situ protection of buried pipelines within deep braced excavation.
查看更多>>摘要：Urban Underground Space (UUS) is recognized as a critical contributor to urban safety, resilience, and sustainable development. As urban development transitions into the phase of stock renewal, issues such as the functional misalignment between aboveground and underground spaces, mismatched supply and demand, low utilization efficiency, and poor spatial quality have become increasingly prominent, particularly in urban block renewal projects. This study develops an Urban Underground Space Reuse Value Evaluation model (UUS-RVE) based on the coupling coordination degree of UUS at the street level and the regeneration potential of UUS at the community level. The objective is to identify value tiers for UUS regeneration and reuse, thereby providing scientific decision-making support for the precise and efficient utilization of underground spaces. Using Fangzhuang Subdistrict-the large residential area in Beijing-as a case study, the findings reveal a significant correlation between the reuse value level of UUS and its "distance to metro stations." Additionally, factors such as "proximity to metro station entrances, spatial ownership, functional diversity of the underground space, 15minute living circle accessibility, and average housing prices" exhibit strong associations with the reuse value of UUS. The reutilization potential of UUS is jointly influenced by the coupling and coordination degree of aboveground and underground functions (D) and the regeneration potential of underground space (P). Simultaneously, by integrating the "value assessment levels" and "community residents' needs," this study proposes strategies for the regeneration and reutilization of UUS from four perspectives: functional layout, functional diversity, management units, and multi-stakeholder implementation frameworks. These strategies aim to provide planning and decision-making support for advancing neighborhood renewal and urban diagnostic evaluations.
查看更多>>摘要：Floor heave is a typical form of roadway damage in underground mining, often causing transportation and ventilation issues, as well as restricted access. While shear-induced slip is universally acknowledged as the predominant failure mode in roadway surrounding rock, existing research has not recognized the mechanism from the perspective of full-range surrounding rock movement source identification and main slip zone control, resulting in a lack of scientific basis for selecting support types and parameters. Therefore, failures in controlling floor heave are frequently reported, with severe cases exhibiting complete roadway closure due to fully uplifted strata. To achieve precise control of roadway floor heave, a high-resolution Flac3D numerical model incorporating stress-release simulation technology, borehole imaging, and multi-layer compressive arch theory was employed. The initiation and evolution of floor heave were successfully reconstructed, with the morphology and location of the main slip zone as well as the surrounding rock structure being accurately characterized. In contrast to conventional control theories, this study presents the following key findings: The slip displacement in the main slip zone is identified innovatively as the critical control target. By suppressing the slip of the main slip zone, the formation of the multi-layer compressive arch is promoted, and thereby the stability of the comprehensive surrounding rock can be achieved. This study provides an accurate calculation method for the location of the main slip, which can more effectively guide the selection of the support systems and parameters. The proposed method was successfully validated in the 11,500 belt conveyor roadway of Shanghaimiao Coal Mine, Inner Mongolia, China. This control strategy represents a leap from empirical to precision-based floor heave management, establishing a new paradigm in roadway stability control.
查看更多>>摘要：Assessment of tunnel lining resilience is critical to ensure long-term structural stability under soft rock excavation. In this paper, a novel analytical approach is proposed to assess its performance, considering the time-dependent properties of tunnel deformation. Based on the complex stress behavior of lining, the ratio of compressive and tensile stress to its strength is selected as a performance indicator (Q) of resilience. A new resilience metric (Re) is defined to explore the non-uniform stress behavior of the lining. This metric is calculated as the ratio of the integral of disturbed Q to that of undisturbed Q by incorporating the spatial parameters of the lining. Subsequently, the rationality and applicability of the proposed method are validated through a case study involving a diversion tunnel exhibiting time-dependent deformation behavior. The parameters of compressible layer support are optimized based on Re. The results indicate that the lining Re decreases substantially (Re < 0.6) within three years and stabilizes at 0.34 after 50 years. The analysis of lining Q behavior reveals that the arch foot and invert experience more substantial reductions in Q during operation. The incorporation of compressible layers as support enhances the sustained resilience of the lining once a critical threshold is reached, maintaining Re at an approximately constant level over time. This improvement depends on the energy absorption capacity and utilization efficiency of compressible layers.
查看更多>>摘要：Subway stations face an increasingly serious risk of flooding as climate change leads to frequent extreme rainfall events. The suddenness of external flood disasters and the uncertainty of hazard factors have posed severe challenges to the safety and reliability of traditional evacuation plans in complex closed space structures and dense passenger flow environments. To address the above technical demands and problems, we propose a robust path optimization model and safety assessment method for passenger evacuation paths in flood scenarios, aiming to improve escape efficiency and safety while avoiding the sensitivity of the optimization scheme to parameter disturbances. The robust optimization model of the evacuation path constructs the evacuation time and road risk uncertainties through the box-type intersection budget uncertainty sets, so that the optimization strategy can find a balance between efficiency and risk and has strong adaptability; a new QIPSO algorithm is proposed to solve the model; the adopted relative entropy weighting model (REWM) introduces the relative entropy theory into the entropy weighting model, which can reasonably deal with the differences and consistency of different weight vectors among safety evaluation indicators. The performance analysis of the passenger evacuation simulation effect under the environment of flood intrusion in a subway station is carried out. The results show that: (i) the robust path optimization model can seek feasible and reliable evacuation decision-making solutions under the uncertain environment caused by floods; (ii) the designed innovative QIPSO algorithm shows strong potential in reducing evacuation time, alleviating passenger congestion and reducing instability risks when solving the robust model; (iii) the evaluation results based on the REWM further verify that the evacuation path optimization strategy can effectively improve the safety level of the station in dealing with flood risks.
查看更多>>摘要：Compared to open roads, highway tunnels' continuous semi-enclosed wall structures exacerbate sight distance challenges for vehicles equipped with automation systems (AV) in curved segments. However, AV's adaptability to existing road geometry in tunnels, which was primarily tailored for traditional human-driven vehicles, remains inconclusive. Therefore, this study aims to investigate the influence of horizontal curved-tunnel geometry on AV's available sight distance (ASD) and analyze AV's sight distance safety (SDS). To this end, we established a virtual co-simulation platform for emulating AV's ASD in diverse tunnel scenarios, which include light detection and ranging (LiDAR)-based sensing configurations and tunnel geometry combinations. On this basis, the important features related to ASD were extracted using the recursive feature elimination algorithm and several widely-used machine-learning models were developed to predict ASD estimation. The Shapley additive explanation analysis was conducted on the most performant model to interpret the feature effects. Moreover, reliability analyses under varying driving automation levels, speeds, and pavement conditions were conducted to quantify the probability of noncompliance with SDS in scenarios focusing on circular curves, followed by proposing an SDS evaluation framework. The results show that: i) random forest model outperforms other machine-learning models in predicting ASD estimation; ii) higher-type tunnel geometry, higher-end sensing configurations, driving on the outside curve lane, and higher mounting height of LiDAR achieve longer ASD; iii) lower-end sensing configurations cause ASD to be less sensitive to the tunnel geometry; iv) SDS deteriorates in the orders of moist, dry, and wet pavement conditions and automation levels 4, 3, 1, and 2; v) AV adapt to low-type highway tunnels' horizontal curves from the sight distance perspective, but may fail in high-type designs. These findings shed light on the impact mechanism of tunnel curves on AV's ASD and serve to improve AV's road-oriented operational design domain and identify the tunnel segment that is significantly non-compliant with SDS.
查看更多>>摘要：In tunnel seismic forward-prospecting, the accuracy of migration imaging impacts the geological interpretation of the area ahead of the tunnel face. However, the traditional reverse time migration (RTM) method, which is the adjoint of the Born forward modeling, often yields approximate estimations of reflectivity. This approximation error becomes even more pronounced in the context of small offset tunnel conditions. To address this issue, we propose a novel method for enhancing tunnel RTM imaging by leveraging Gabor Convolutional Neural Networks (CNN). In our approach, we employ a Gabor CNN that incorporates learnable parameters within the Gabor filters to extract pertinent features from tunnel RTM imaging results. By training the network with RTM images as input and the true reflectivity as labels, we enable the network to learn underlying patterns and improve the quality of the imaging. Notably, we tackle the challenge of limited labeled field data by introducing MLReal, a domain adaptation method. MLReal enhances the generalizability of the proposed network to field data by employing an inter-processing and transformation approach that aligns the target data with the synthetic dataset. This alignment allows the network to adapt to real-world field conditions, bridging the gap between synthetic training data and field applications. Extensive numerical experiments validated the superiority of the Gabor CNN, showcasing its ability to generate results closely resembling true reflectivity while outperforming LSRTM. Furthermore, a field case study is conducted in a water transmission tunnel as a practical application to verify the potential of the MLReal-assisted Gabor CNN.
查看更多>>摘要：Engineering, Procurement, and Construction (EPC) is a widely adopted project delivery method that centralizes responsibility but frequently faces challenges related to fragmented documentation in pumped storage hydropower projects. Although Building Information Modeling (BIM) integrates multidisciplinary data to create digital representations, interoperability issues continue to hinder seamless collaboration between design and construction teams. To overcome these challenges, we propose a cross-platform EPC collaboration framework that integrates Industry Foundation Classes (IFC) with Semantic Web technologies. We validated the feasibility of the prototype system through a case study, providing technical guidance for applying recursive reasoning to query sequential data within the IFC-graph model. This proposed method improves the benefits of BIM by improving accessibility and management of engineering information. The findings of this study advance the development of automated workflows in construction management through the adoption of open standards.
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