Search Results (27)

Investigating the seismic damage mechanism of large underground complexes is essential for the safe development of urban underground space. This paper examines a five-story and three-span underground complex situated in a soft soil site. Shaking table tests were designed and conducted on both the free field and the soil–underground complex interaction system. The time–frequency evolution of the free field under various seismic motions was investigated. A combined experimental and numerical simulation approach was employed to examine the seismic response of the soil–underground complex interaction system. The structural deformation evolution, stress distribution, and development process of plastic damage under different seismic motions were analyzed. The results reveal that soft soil exhibits a significant energy amplification effect under far-field long-period ground motions. Structural deformation is mainly governed by horizontal shear. Under strong seismic excitation, plastic damage first initiates at the end of the bottom-story columns and extends to column-to-slab and wall-to-slab connections, where abrupt stiffness changes occur. Under the far-field long-period ground motion, the structural deformation, stress distribution, and plastic damage are significantly greater than those under the Shanghai artificial wave. These findings provide valuable insights for the seismic design of large underground complexes in soft soil sites. Full article

Understanding the complex phenomena of interactions between the elements of a combined piled raft foundation (CPRF) is essential for the proper design of such foundations. To evaluate the effects of mutual influence among the CPRF’s elements, a series of long-term measurements of selected physical quantities related to the performance of the foundation were conducted on a building with a frame structure, stiffening walls, and monolithic technology, consisting of seven aboveground stories and one underground story. The analysis distinguishes the real deformations resulting from temperature changes and from stress strains resulting from load changes. The two types of deformations were subjected to further interpretation of only changes in the stress and strain over time. Changes in stress values in the subsoil, as well as strain measurements in the vertical direction of concrete columns, were recorded to assess the load distribution between the CPRF’s components. The numerical analysis results obtained for a fragment of the monitored foundation were compared with actual measurement results to verify the numerical model of interaction between the structure and the soil. Field monitoring and FEA methods were used to compare the long-term deformation analysis, and they helped to minimize the monitoring time. This comparison also served to supplement and simultaneously expand the dataset of test results on a real-world scale. Full article

To reduce earthquake damage and its effect on the structures, tuned mass dampers (TMDs) are generally positioned on the top of the structures for effectiveness, but existing TMDs on the story levels have problems due to space and additional vertical load issues. Underground-tuned mass dampers (UTMDs) can be used for base-isolated structures to limit deformations of base isolation systems. This study aims to determine the optimum design parameters of an underground tuned mass damper (UTMD) combined with based isolated systems. The best-performing algorithm among the metaheuristic algorithms selected for the optimal design of the UTMD system was investigated. Classical and hybrid forms of several metaheuristic algorithms were used in the methodology. The hybrid of the Jaya algorithm and Teaching Learning-Based Optimization was found to be the most effective one for the reduction of maximum accelerations. The cases limiting the damping of the base-isolation system and various mass ratios of UTMD were also conducted. In conclusion, the control system can reduce the maximum acceleration of the optimum base-isolated structure by 4% to 23% according to the mass ratio of UTMD and provide a low-damping isolation design as the optimum one. Full article

The seismic damage of underground structures has been extensively investigated, and it has been demonstrated that underground structures located at weak interlayer sites are more prone to damage. In this study, a two-story two-span rectangular frame subway station structure is analyzed. A two-dimensional soil-underground structure model is developed using the large-scale finite element analysis software ABAQUS. The equivalent linear soil-underground structure dynamic time-history analysis method is employed to examine the seismic response of underground structures at weak interlayer sites. Variations in the thickness and shear wave velocity of the weak interlayer soil are analyzed. The seismic mitigation effects of split columns and prototype columns in underground structures at weak interlayer sites are systematically compared. The findings indicate that the relative displacement and internal force of key structural components significantly increase when the weak interlayer intersects the underground structure. Furthermore, as the thickness of the interlayer increases, the displacement and internal force also escalate. When the thickness of the weak interlayer remains constant and the shear wave velocity decreases, the relative displacement and internal force of the key structural components gradually intensify. Replacing ordinary columns with split columns substantially reduces the internal force of the middle column, providing an effective seismic mitigation measure for underground structures. Full article

Flooding in underground spaces, such as subway stations, underground malls, and garages, has increased due to intensified rainfall, urbanization, and population growth. Traditional 2D simulations often overlook crucial vertical flow variations, especially in steep transitions like stairs and ramps. The current study aims to investigate the flood dynamics in large underground geometries by taking a parking lot in Beijing, China, as a study case. The model overcomes the limitations of previous simulations by adapting a full 3D mesh-based simulation with reasonable computational cost. Unlike earlier studies, this model employs a high temporal resolution transient inflow at the inlet to the underground space. Simulation scenarios consider different return periods (5, 20, and 100 years) and inlet water depths, providing an analysis of their impact on flood status in the underground structure. The model generates high spatial–temporal results, enabling precise detection of flood-prone locations, evacuation times, and suggested mitigation techniques. The results recommend evacuating from hazard areas before the 10th minute during extreme flood events. Additionally, the study estimates a 40% increase in flood hazards for scenarios with direct connections between levels. Overall, the study highlights the importance of 3D simulations for accurate risk assessment. Full article

Research on the characterization of ground motion intensity and damage of underground structures is limited, while reasonable selection of ground motion intensity measures and structural damage measures is a crucial prerequisite for structural seismic performance evaluation. In this study, a two-dimensional finite element model of soil and structures was established based on the Daikai subway station in Japan. Through incremental dynamic analysis, 32 ground motion intensity measures and seven structural damage measures were comprehensively evaluated from seven properties, including efficiency, practicality, proficiency, scaling robustness, relativity, hazard computability, and sufficiency. According to the analysis results, the purpose and significance of each property during measure optimization were hierarchically sorted out. The results show that peak ground acceleration, acceleration spectrum intensity, and sustained maximum acceleration are recommended as ground motion intensity measures, while maximum inter-story drift ratio, column end displacement angle, and two-parameter measures are recommended as the structural damage measures for seismic performance evaluation of the shallow-buried subway station. Furthermore, measure optimization approaches are proposed as follows: the basic selection of IMs should satisfy scaling robustness, hazard computability, and sufficiency to site condition; the optimal selection of IMs is suggested to be evaluated mainly through efficiency, practicality and proficiency, and verified through relativity and relative sufficiency between IMs. The optimal selection of DM is suggested to be evaluated through four properties, including efficiency, practicality, proficiency, and relativity. Full article

The behavior of center columns in shallow-buried underground subway station structures resembles that of high-rise buildings. In both cases, these columns experience significant vertical loads during earthquake events and are susceptible to brittle failure due to inadequate deformation capacity. In this study, the design concept of split columns, commonly employed in high-rise structures, is adapted for application in a two-story, two-span subway station. Initially, a comparative analysis was conducted using quasi-static pushover analysis to assess the horizontal deformation characteristics of traditional and split columns under high axial loads. Subsequently, a comprehensive quasi-static pushover analysis model encompassing the soil–structure interaction was formulated. This model was employed to investigate differences in seismic performance between traditional and innovative underground structures, considering internal forces, deformation capacity, and plastic damage of crucial elements. The analysis results demonstrate that the incorporation of split columns in a two-story, two-span subway station enhances the overall seismic performance of the structure. This enhancement arises from the fact that split columns mitigate excessive shear forces while effectively utilizing their vertical support and horizontal deformation capacities. Full article

Smart parking is an artificial intelligence-based solution to solve the challenges of inefficient utilization of parking slots, wasting time, congestion producing high CO₂ emission levels, inflexible payment methods, and protecting parked vehicles from theft and vandalism. Nothing is worse than parking congestion caused by drivers looking for open spaces. This is common in large parking lots, underground garages, and multi-story car parks, where visibility is limited and signage can be confusing or difficult to read, so drivers have no idea where available parking spaces are. In this paper, a smart real-time parking management system has been introduced. The developed system can deal with the aforementioned challenges by providing dynamic allocation for parking slots while taking into consideration the overall parking situation, providing a mechanism for booking a specific parking slot by using our Artificial Intelligence (AI)-based application, and providing a mechanism to ensure that the car is parked in its correct place. For the sake of providing cost flexibility, we have provided two technical solutions with cost varying. The first solution is developed based on a motion sensor and the second solution is based on a range-finder sensor. A plate detection and recognition system has been used to detect the vehicle’s license plate by capturing the image using an IoT device. The system will recognize the extracted English alphabet and Hindu-Arabic Numerals. The proposed solution was built and field-tested to prove the applicability of the proposed smart parking solution. We have measured and analyzed keen data such as vehicle plate detection accuracy, vehicle plate recognition accuracy, transmission delay time, and processing delay time. Full article

The main building of Zone II of Zhanjiang Bay Laboratory R&D Building adopts a steel frame–core tube shear wall structure system, with a 53.4 m large-span and heavy-load-transfer truss on the fourth floor. In order to propose the optimal construction and installation scheme for the large-span and heavy-load-transfer truss, the simplified model, single model, and 3D model are utilized to compare Scheme 1 with rigid connection and Scheme 2 with elastic connection and rigid connection. After completing the construction of the underground layer and towers on both sides, in Scheme 1, the fourth-floor transfer truss is directly connected to the towers on both sides in a rigid manner. Subsequently, the support at the bottom of the transfer truss is removed, allowing for layer-by-layer construction. The transfer truss remains rigidly connected to both side towers throughout. On the other hand, in Scheme 2, initially, the transfer truss is connected to both side towers through upper chords and diagonal bars before being constructed upwards until reaching the sixth floor. Once formed as a whole with two floors above using large diagonal tie rods, lower chords of the large-span and heavy-load-transfer truss are then connected with another diagonal bar to establish a rigid connection between the transfer truss and towers; thereafter, upward construction continues. Following completion of constructing a seven-story large diagonal tie rod, whereupon removal of support at the bottom of the conversion truss occurs, subsequent layer-by-layer construction takes place accordingly. It has been observed that employing Scheme 2 can enhance stress distribution within core barrel shear walls as well as transfer trusses while ensuring deflection and stress levels meet requirements for the large-span and heavy-load-transfer truss, thereby rendering structural stress more rationalized, leading to significantly improved overall safety. Full article

Black creators who tell Harriet Tubman’s story engage in an ongoing rhetorical battle over historical memory with regard to slavery and the Civil War. This essay examines the challenges Tubman’s story poses to a Lost Cause narrative that took root in the nineteenth-century and manifests in the work of celebrated children’s author Robert Lawson. Reading Ann Petry’s YA biography Harriet Tubman: Conductor on the Underground Railroad (1955), Jacob Lawrence’s picture book Harriet and the Promised Land (1968), and Kasi Lemmons’ film Harriet (2019) together, and within the context of Lawson’s award-winning They Were Strong and Good (1940) and his historical primer Watchwords of Liberty: A Pageantry of American Quotations (1943) offers an opportunity to assess the rhetorical firepower of creative work about a historical figure who continues to fascinate people of all ages. Such reading also underscores the extent to which the apartheid in and of children’s literature limits the imaginations of critics, thereby hindering efforts to promote social justice. Full article

Well (2020) is an installation by Israeli artists Noga Or Yam and Faina Feigin. It investigates the story of an underground passage in Tel Aviv designed by a British Mandate-era Jewish architect. Starting from this building, the artists’ archival research leads them to the story of a water source which does not figure in the architect’s plan. While the story of the well is unearthed, so is one about the tense relations between the Jewish architect and the Palestinian orange merchant who inhabited the site before 1948. By restaging a hypothetical archive, Well reminds us of the problems inherent in narrative formation and erasure in the context of the Palestinian–Israeli conflict. Noga Or Yam also examined space and water in an earlier work, Black Soldier, White Soldier (2018): with the background sound of water drilling in southern Israel, urban photographic landscapes of Palestinian rooftops covered with water tanks are projected onto the walls. Water, either concealed or lacking, emerges in both works as a vehicle for unearthing a historical narrative that counters the official one. This research article reflects on contemporary art’s engagement with the formation of history, and how such engagement shapes the identity of present-day art in postcolonial realities. Full article

The control parameter of the complex underground space structure with the Track Panel Tunnel and wall columns was studied. An analysis method of the control parameter was established based on the complementary energy principle with mixed variables. The general analytical solution of the structure under the trapezoidal load was obtained. Then, the correctness of the solution was verified by two-dimensional finite element simulation. The three-dimensional global model is built to analyze models with different story heights, the distance of two adjacent wall columns, and the thickness of the earth covering; the consequences prove the assumptions’ rationality and the engineering applicability of the analytical solution. The sensitive region of the control parameter is found through the analytical solution, which is meaningful in determining the reasonable stiffness ratio of column and beam for structural design optimization with cost savings. It can be the reference for complex underground space engineering designs. Full article

Today, dismissed mines are considered significant local tangible and intangible cultural heritage elements and they are more and more often at the core of dedicated enhancement processes, being sometimes inscribed in the UNESCO list; included in geoparks; transformed worldwide into industrial museums; or reused. Italy has a peculiar approach to the topic even if it has been underestimated, and research in the field might be improved. Which models should be looked at? Is it possible to identify some basic criteria to look at to obtain positive results? If yes, where should one start? Our proposal is that the application to the newly born class underground built heritage (UBH) can provide instruments for their historical functional classification and introducing several criteria for their interpretation and reuse could eventually support future enhancement projects in this specific sector. This methodology has been already applied worldwide to this category of good, giving positive results and motivating the authors to continue the research following this hypothesis, with the aim of creating a framework of good practices to be used as a reference for new projects. This paper summarizes the authors’ research in this direction. After the introduction of the academic scenario and the UBH theoretical approach, this study proposes the results from applying this new methodology to several worldwide case studies from Greece, Germany, Italy, Japan, and Poland in order to evaluate best practices and/or unsuccessful stories. This study, based on data collected during onsite inspections by the authors within several international financed projects, consists of two steps. In the first, a general overview of all the aspects connected to the historical and contemporary reuses of dismissed mines under analysis was carried out, proposing a reclassification on the basis of the UBH methodology. The second section is dedicated to a new case study: Valle Imperina dismissed mines complex. This section includes an analysis of tangible and intangible values connected to the site and that of the state of the art of the corresponding enhancement. At the end, an evaluation of its potentialities and some critical issues was conducted. Full article

This paper presents the process of advanced numerical analysis of interaction between a building and the subsoil. The analysis covered a wide range of work for both computing and research. As part of the research work, field and laboratory subsoil tests were carried out, as well as geodetic measurements of building settlement and measurements of natural vibrations of an object. The computational work included the analysis of a total of 47 FEM models. The subsoil was described using the Modified Cam-Clay model, with parameters determined using field CPT and SDMT tests, as well as triaxial and edometric laboratory tests. Parts with geodetic benchmarks were separated from the building model, and then multi-variant calculations were made on smaller, partial models with parameters obtained from various methods. Calibration of the main models was performed using 8 partial models for which calculations were carried out in 4–5 variants of parameters. This gave a total of 38 partial models. Then, calculations were carried out on the full model of the building with subsoil. At each stage, the results of vertical displacements were compared to the geodetic values. The measured settlement of the real building in the time from the construction of the underground story to its use for the period of 1 year, was from 2.3 mm to 7.8 mm. The settlement from FEM calculations of small calibration models for the same benchmarks was from 2.0 mm to 9.8 mm with parameters derived from CPT tests and from 1.8 to 7.3 mm for parameters derived from SDMT. For the full building model, settlement from FEM calculations ranged from 2.2 to 8.8 for the variant with a simplified subsoil model, and from 3.7 to 10.5 for the model taking into account the inhomogeneity of the subsoil. As a result, it was found that the displacements from the numerical analysis were convergent with the geodetic values. Detailed numerical analyses also allowed to detect the deviations of the segments from the vertical and to indicate potential damage to the structure. It was also indicated how the work of the subsoil influences the stress distribution in selected structural elements. Behaviour of the subsoil has an impact on the behaviour of the building and its deformations, as well as on the distribution of stresses in the structural elements, and, as a result, on the change in the distribution of internal forces in the structure. Full article

In 2021, the unexpurgated second novel of American author Richard Wright was at last unearthed from the depths of the archive. In a vivid demonstration of the affective capacity of written sound, The Man Who Lived Underground tells the story of a man who finds an unlikely refuge from imminent death in the sewer beneath the city streets. This article listens closely to Wright’s portrayal of architectural acoustics and sonic distortion within the text, attending to sensory and metaphorical dimensions of urban and social stratification. Drawing on Stefano Harney and Fred Moten’s co-conceived “fantasy in the hold”, I push back against the overwhelmingly dystopian readings of Wrights subterranean as a scene of racialized subjection. Their “undercommons” allows me to reframe the undercity as a site of refusal and a source of collective empowerment. Returning to Wright himself, I connect the subterranean metaphor to deeper biographical themes of intellectual exile and his eventual expatriation to Europe. In a gesture redolent of the undercommons, he followed his character in locating a quality of freedom underground. I read this autonomous inversion of the Middle Passage—the lateral motion of the middle crossing—as comparable to the vertical mobility that frames the events and stakes of the story. Full article