Utilization Of Underground Space Research Articles

Model Test and Numerical Simulation of Two Typical Close-Fitting Pile–Wall Integrated Structures in Deep Excavation

Compared to conventional support methods, the close-fitting pile–wall integration technique features a minimized construction spacing between the retaining pile and the basement retaining wall. This approach leverages the pile stiffness to minimize the wall thickness and enhance underground space utilization. However, it currently lacks significant discussions and measured data about the interaction laws between the pile and the wall. The model test and finite element method (FEM) are employed to study the deformation and internal force interaction laws of two typical close-fitting pile–wall integrated structures, and a comparison with conventional design is conducted. Furthermore, this study separately investigates the impact of sensitivity factors, specifically the pile–wall stiffness ratio and floor plate stiffness, on both structures during the basement construction and serviceability stages. The test results can closely match the numerical simulation. The study results reveal that the wall impacts the bending moment of the pile to some extent. The internal force in the wall is significantly influenced by the lateral deformation of the pile and the floor plate. Compared to conventional designs, this structure significantly reduces the bending moment of the wall, particularly in the composite structure. Additionally, the analysis of sensitivity factors reveals their considerable influence on the pile–wall interaction.

Enhancing Urban Landscapes through Underground Space Utilization: Public Perceptions

Landscape occupation and green space reduction have decreased livability and hindered the sustainable development of cities. The urban landscape affects the quality of life and physical and mental state of the public, and urban underground space utilization is important for improving the urban landscape. Therefore, underground space utilization must be explored from a public perspective. Referring to typical underground municipal, transportation, and public space projects, an online questionnaire survey of 377 Nanjing residents was performed to construct a structural equation model investigating their perceptions and preferences regarding underground space usage to improve the landscape, focusing on the links between their preferences and opinions. Underground works that provide diverse open spaces were considered to have the most positive impact on the landscape (82.8%). The aesthetic value of the surface landscape (83.5%) and the vitality of historical sites (82.1%) were the most significantly affected, whereas stock underground space had no significant effect on landscape protection. In terms of age, profession, and place of work, the respondents demonstrated heterogeneous preferences. These findings indicate that targeted publicity and public participation are important to strengthen the cooperative utilization of space and realize the potential of the underground space, helping address actual requirements and develop sustainable cities.

Centrifuge model test of the influence of tunnel excavation with different spacings on existing tunnels

The continuous development and utilization of underground space has led to an increasing number of short-distance constructions between new and existing tunnels. New tunnel construction affects the surrounding strata and destroys the structure and operation of the adjacent existing tunnel. Therefore, investigating the influence of new tunnels on the deformation of existing tunnels is crucial. Four centrifugal model tests simulating tunnel excavation processes were conducted to study the influence of tunnel excavation with different spacings on existing tunnels. Liquid was drained one section at a time to simulate the formation loss ratio produced by tunnel excavation and unloading during centrifuge operation, which eliminated the error caused by centrifuge shutdown–restart. Test results indicated that new tunnel excavation led to uneven settlement of the existing tunnel, and the settlement of the existing tunnel was greater than that of the two sides. Under the same burying condition of the new tunnel, the smaller the net distance between the new and existing tunnels, the greater the influence on the vertical and horizontal displacement of the existing tunnel, and the smaller the settlement of the ground surface. New tunnel excavation caused tensile stress near the excavation surface of the existing tunnel. A smaller clear distance resulted in a higher tensile stress. The centrifugal model tests provide technical support for tunnel construction and underground space development.

Research on the Driving Factors and Prediction Model of Urban Underground Space Demand in China

The development and utilization of urban underground space (UUS) have emerged as critical strategies to address the challenges posed by urban population growth and land resource depletion. Accurate prediction of UUS demand serves as the cornerstone for scientifically planning underground space and promoting sustainable urban development. In this study, statistical analysis methods were used to investigate the relationship between potential driving factors and UUS demand based on collected data from 16 cities in China. The identification of primary driving factors involves correlation, path, and determination coefficient analyses. Subsequently, univariate regression, multiple linear regression, and LASSO regression methods are employed to construct prediction models for UUS demand. Additionally, the link between historical data and UUS demand in each city was studied separately. The findings reveal that GDP per km2 and GDP per capita comprehensively capture the influence of urban population, economy, and transportation on UUS demand. Notably, GDP per km2 makes the most significant contribution to the proposed regression models, followed by GDP per capita. The application of LASSO regression proves effective in selecting potential factors while maximizing data utilization, presenting itself as a valuable auxiliary tool for UUS planning.

Investigation of Displacements in Tunnel-Constructed Liquefiable Soils with Numerical Analysis

The rise in industrialization and population has led to an increase in the economic significance of existing urban areas, and thus the utilization of underground space has become quite remarkable It is an undeniable fact that in seismically active regions, the underground areas are also exposed to the risk of earthquakes. The devastating 1995 Kobe-Japan, 1999 Chi-Chi-Taiwan and 1999 Kocaeli-Turkey earthquakes are known to have caused major damage to existing underground structures. In this study, numerical models based on finite differences in FLAC 2D were established to evaluate the displacements of the ground around the tunnels located in liquefiable soils. In order to represent the liquefaction condition in the models, soils in the Adapazarı region, which have alluvial characteristics, were used. Soil deformations were examined in models with varying tunnel depths and diameters, for both liquefiable and non-liquefiable soils within the same layers. As a result of this study, it is stated that more stability losses are observed in analyzes where liquefaction can be defined - that is, changes in pore water pressures can be modeled - compared to analyzes without liquefaction. The layout of the ground layers is important for the positioning of the tunnel. The placement of the tunnel towards the solid layers caused the deformations to decrease.

Bibliometric analysis of research challenges and trends in urban underground space

AbstractThe utilization and development of urban underground space play a crucial role in optimizing the layout of civic architecture and enhancing the urban ecological environment, which contributes toward increasing the overall carrying capacity and promoting sustainable development in megacities. To delve into the research progress of urban underground space, knowledge maps were created using the information visualization software VOSviewer. The literature was systematically extracted from three prominent databases, namely, Web of Science, Scopus, and China National Knowledge Infrastructure. According to the bibliometric analysis of the co‐citation and core words co‐occurrence, the trends and challenges of research on urban underground space were identified. As highlighted by the results obtained, it still remains highly challenging to achieve interdisciplinary collaboration in urban underground space research; the research trends of urban underground space consist of collaborative planning and whole life cycle sustainable development, multisource geological data informatization and resource evaluation, infrastructure design optimization, and intelligent construction. The knowledge map, drawn using bibliometric methods, offers a quantitative analysis of literature retrieval across various levels. It is recognized as an essential tool for exploring and identifying challenges and trends in urban underground space.

Regulation of Underground Space in Realising Community Welfare and Legal Certainty for Investment

The purpose of this research is to analyze and discover the regulation of underground space in realizing public welfare and legal certainty for investment and offer future concepts of underground space regulation in realizing public welfare and legal certainty for investment. This research is normative juridical research with statutory, historical, comparative, and conceptual approaches. The findings of this research show: (a) it has not been regulated regarding property rights, utilization of underground space for private and public, the authority of the central and local governments as well as the authority of notaries and/or PPAT, institutions, and the implementation of underground space. (b) has been regulated but the norms are unclear and not yet comprehensive regarding rights to underground space in the form of Right of Use, HPL and HGB. (c) there are still norms that regulate optional in the regulation of underground space; (d) there are conflicts of legal norms between sector laws. This research concludes that the current underground space regulation is inadequate to support welfare and legal certainty for investment, because there is no support from the Underground Space Law as an instrument of renewal. In addition, the main concept of the Draft Basement Law for the future is directed at public welfare and legal certainty for investment. The draft builds on the philosophical foundation of the welfare state the sociological foundation of the need for underground space utilization, the recognition of rights to underground space, and the juridical foundation of legal certainty.

An Integrated Model for Risk Assessment of Urban Road Collapse Based on China Accident Data

With the deepening development and utilization of urban underground space, the risk of urban road collapse is becoming increasingly prominent, which is a serious threat to the safety of life and property. Therefore, the risk assessment of urban road collapse has vital significance for the safety management of cities. The main idea is to predict ongoing accidents by analyzing historical accident cases in depth. This paper explores the combination of Interpretative Structural Modeling (ISM) and Bayesian Networks (BNs) to construct a risk assessment model of road collapse. First, the main risk factors of road collapse and their coupling relationships are identified, which is used to increase the low reliability of complex systems. Then, the risk factors of road collapse are logically divided by ISM to obtain the BN hierarchy. Finally, the BN node probabilities are evaluated by the Expectation–Maximization (EM) algorithm using the collected 92 real road collapse accident cases. The model can be used to quantify the coupling strength and influence degree of each risk factor on the occurrence of road collapse accidents, which in turn can predict the probability of road collapse accidents in a given scenario. This study can provide a theoretical basis for urban safety management and reduce the risk of road collapse and potential loss of life and property, which is important for the sustainable development of societies.

Estimation of the ecological carbon sink potential of using urban underground Space: A case study in Chengdu City, China

Urban carbon sinks from plant photosynthesis in urban blue-green spaces (BGSs) effectively sequester CO2 and achieve carbon neutrality. Building urban facilities underground saves land for the development of urban BGSs. Development and utilization of urban underground space (UUS) is increasing rapidly in most advanced cities globally, many of which are located in China. This study combined the planting design strategy of urban BGS and the vegetation carbon sequestration efficiency estimation method to quantitatively assess the ecological carbon sink potential of the use of UUS. Three types of BGSs: partly open green space (GPO), closed green space (GC), and partly open blue space (BPO), were first constructed based on their practicability in the city, and a planting strategy was designed for urban BGSs accordingly. Secondly, a model for the conversion of UUS development intensity into surface space to achieve ecological carbon sinks under three scenarios of UUS development intensity (low, medium, and high intensity) was constructed. Thirdly, methods for the calculation of carbon sequestration by GPO, GC, and BPO, were established based on the land-use carbon emission model. The developed method was finally validated through a case study in the Tianfu New District Directly Administered Area of Chengdu in Sichuan Province, China. The results of the study in Chengdu show that the higher the intensity of the use of UUS, the greater the proportion of carbon sink contribution to the CO2 emissions of the building industry for the planned population, and a maximum of 7% of carbon emissions absorbed from the building industry for the planned population was achieved. These findings serve as a reference for assessing the use of UUS to achieve urban carbon neutrality in other cities.

Study of a high-precision complex 3D geological modelling method based on a fine KNN and kriging coupling algorithm: a case study for Jiangsu, China

A high-precision, complex, three-dimensional (3D) geological model can directly express the attributes of stratum thickness, geological structure, lithology and spatial form, which can provide a reliable basis for the development and utilization of underground space and planning decisions. However, it is difficult to perform accurate modelling due to the lack of basic data. As such, this paper proposes coupling a machine learning algorithm (K-nearest neighbour (KNN)) with the kriging algorithm to construct the topological relationship between the Delaunay triangle and the Thiessen polygon in order to perform the simulation and prediction of virtual drilling. Based on KNN, support vector machine (SVM) and neural network algorithms as well as the virtual borehole encryption data, data standardization processing and analysis are carried out. Through model verification, algorithm optimization is realized, and the optimal modelling method is explored. The results show that the fine KNN algorithm improved by Bayesian optimization can effectively improve the modelling accuracy through 0.1-m encryption, standardization processing and 5-fold cross-validation. Stratum modelling combined with the fine KNN and kriging algorithms can obtain a more accurate modelling without adding virtual boreholes. The improved levels of upper and lower hybrid modelling with an appropriate number of profile boreholes can also effectively optimize model accuracy. Both modelling accuracy and efficiency can be significantly improved by using Delaunay triangles and Thiessen polygons with virtual boreholes. Stratum modelling can effectively express the geological pinch-out in areas with adequate degrees of stratification, and hybrid modelling performs well in irregular geological bodies such as karsts and lenses.

Study on flexible/rigid protection mechanism of hydrogen/methane premixed gas explosion in urban underground space

Explosion accidents are one of the factors that impede urban underground space development and utilization, and it is imperative to study safety precautions in case of an explosion in an urban underground space. Given this problem, a polyurethane sponge and carbon fiber board with Blocking Rates (BR) of 0.2, 0.4 and 0.6 were used to explore the combustion and explosion characteristics of hydrogen/methane premixed gas in a confined space in the presence of a flexible and rigid obstacle. The results indicated that both the flame and pressure exhibit Helmholtz oscillation characteristics in case of a rigid obstacle. When the BR of both flexible and rigid obstacle were 0.4, the explosion intensity index was the highest. It first increased and then declined with the increase of flexible obstacle BR. In the presence of a flexible obstacle, the Helmholtz oscillation phenomenon was completely suppressed, and explosion intensity indices were minimized, as the flexible obstacle BR increased, it first increased and then declined. Under the rigid obstacle preset conditions, the explosion hazard significantly increased compared to the flexible constructions. The research results provide a theoretical basis for protective facilities to suppress combustion and explosion phenomena in underground spaces.

Application of Borehole Geophysical Prospecting Method in Pile Foundation Detection of Existing Buildings

It is particularly important to find out the pile foundation of existing buildings for building safety protection and engineering construction safety during the development and utilization of urban underground space. As a non-destructive, efficient and economic method, the borehole geophysical techniques such as magnetic gradient method, ground penetrating radar method and parallel seismic test method are used to detect the pile foundation of existing buildings, which have obvious advantages. According to the combined abnormal characteristics such as "strong magnetic anomaly, electromagnetic wave in-phase axis change and diffraction wave anomaly at the pile end, P-wave velocity variation", the pile foundation length can be judged.

Electrical Resistivity Tomography for Urban Underground Space by COMSOL Multiphysics

The development and utilization of urban underground space are of great significance to urban sustainable development. Geophysical methods have the characteristics of non-destructive detection, and electrical resistivity tomography has an obvious response to underground resistivity structure and can be used in urban underground space exploration. In this paper, COMSOL Multiphysics is used to realize the finite-element simulation of geoelectric models, and electrical resistivity tomography is used to explore resistivity anomalies of karst and fault models in urban underground environments. The results show that electrical resistivity tomography can identify karst and fault distribution effectively, and COMSOL Multiphysics promises to be a powerful tool for exploring urban underground space.

Human-based Urban Underground Spaces Future Improvement

Supercities around the world concentrated on urban underground space (UUS) development and utilization as a solution to urban expansion issues. However, engineering and construction studies are far more prevalent than in other UUS fields. The underground has become an integral part of contemporary urban life, and an increasing number of people will be forced to coexist with it in the foreseeable future. Therefore, human-centered UUS strategies must be strengthened. The paper explores the development of UUS utilization in recent years by comparing Tokyo, Singapore, Boston, and China. It then examines the psychologically influential factors of human-based UUS development and utilization, including physiological needs, security needs, and affection needs, and suggests future UUS development based on the human-based underground space enhancement theory.

Comprehensive evaluation of the underground space resources in Xianyang city

With the rapid development of urbanization and the sharp increase in population, urban land is becoming increasingly scarce. The efficient and reasonable development of the underground space is a crucial way to solve the problem of urban diseases, and comprehensive evaluation of urban underground space resources is an important basic task to achieve reasonable planning of the underground space. Adopting Xianyang city as an example, in this paper, we comprehensively evaluated the underground space resources in the main urban area and established evaluation models for the amount of resources available for development, development difficulty, potential value, and comprehensive quality of the underground space. Evaluation indicators, including urban environmental constraints, geological conditions, socioeconomic conditions and many other factors, were determined. With the use of the method of item-by-item elimination of restrictive elements and the analytic hierarchy process for determining the weight of each evaluation index, GIS technology was used to calculate and evaluate the underground space resources (0–30 m) in the main urban area of Xianyang city that could be reasonably developed, as well as the corresponding development difficulty and potential value, and we obtained the underground space that could be reasonably developed under different types of land use in the main urban area of Xianyang city on the basis of the resource quantity and comprehensive quality evaluation results. The results showed that in terms of quantity, the amount of underground space available for development in the main urban area of Xianyang city accounts for approximately 25.11% of the total development amount, and the underground space that could be developed and utilized is approximately 82.3 km2. The underground space resources that could be developed within a 30 m depth interval in the main urban area reached 2.465 billion m3, accounting for approximately 79.5% of the total shallow underground space resources, and the potential for development and utilization is enormous. In terms of the comprehensive quality, the highest comprehensive quality level of shallow underground resources is located in the core areas along Renmin Road, Weiyang Road, and Century Avenue, with an area of 21.52 km2, and the highest comprehensive quality level of subshallow underground resources is located along Renmin Road and Weiyang Road, with an area of 4.37 km2. The evaluation results could provide high reference value for urban development planning and underground space development and utilization in Xianyang.

Seismic wavefield characteristics in translational and rotational components for isolated velocity-anomaly bodies in two-dimensional shallow media

With the increasing utilization of underground space, detecting shallow isolated velocity-anomaly bodies such as karst and boulder has become a critical challenge in engineering seismic exploration. This study employs the finite-difference algorithm to investigate two-dimensional seismic wavefields in translational (X and Z) and rotational (Y) components for homogeneous half-space and layered medium models that incorporate low-velocity and high-velocity spheres. The dispersion characteristics analyses of Rayleigh wave for these models are conducted to compare the wavefield differences caused by shallow velocity-anomaly bodies using the methods including Multichannel Analysis of Surface Wave, Horizontal-to-Vertical Spectral Ratio (HVSR), and Rotational to Vertical-and-Horizontal Spectral Ratio (RVHSR). Results demonstrate that the velocity-anomaly bodies cause noticeable influences on kinematics and dynamics dispersion characteristics of Rayleigh waves, which can be visually depicted on the rotational Y component. It can be more effective to accurately delineate the property and spatial distribution of underground velocity-anomaly bodies by combining the seismic response of translational and rotational components.

Suitability Assessment of Multilayer Urban Underground Space Based on Entropy and CRITIC Combined Weighting Method: A Case Study in Xiong’an New Area, China

Suitability assessment is an essential initial step in the scientific utilization of underground space. It plays a significant role in providing valuable insights for optimizing planning and utilization strategies. Utilizing urban underground space has the potential to enhance the capacity of urban infrastructure and public service facilities, as well as mitigate issues such as traffic congestion and land scarcity. To effectively plan and utilize urban underground space, it is crucial to conduct a suitability assessment. This assessment helps identify the factors that influence the utilization of underground space and their impacts, offering guidance on avoiding unfavorable conditions and ensuring the safety of planned underground facilities. To achieve objective and reasonable evaluation results, this paper proposed an assessment method that combines entropy and CRITIC (CRiteria Importance Through Intercriteria Correlation) weighting. Taking Xiong’an New Area as a study area, a suitability assessment indicator system for underground space was established. The system included criteria indicators and sub-criteria indicators. By analyzing the weights, the study identified the difference of suitability and critical affecting factors for shallow, sub-shallow, sub-deep, and deep underground space. The results showed that deep layers had better suitability than shallow layers in the study area. The regions with inferior and worse suitability were mostly located around Baiyangdian Lake, with proportions of acreage at 54.69% for shallow layer, 42.06% for sub-shallow layer, 41.69% for sub-deep layer, and 42.03% for deep layer. Additionally, the dominant affecting factors of suitability varied in different layers of underground space. These findings provide valuable evidence for the scientific planning and disaster prevention of underground space in Xiong’an New Area, and also serve as references for studying suitability in other areas.

Prediction of back-layering length in subway tunnel with on-fire train running

The exploitation and utilization of urban underground space effectively contribute to the sustainable development of society. Tunnel fire safety is necessary to ensure normal operation. Motion train fire is more serious and complex than stationary fire in tunnels due to the influence of unsteady piston wind. This study investigates the smoke back-layering characteristics of a burning subway train during emergency braking. A three-dimensional unsteady numerical model adopting the dynamic mesh technique is built to investigate the smoke diffusion characteristics of motion train fire. Experimental tests are conducted based on a 60 m-long scaled-down experimental setup to verify the accuracy of the numerical model. On this basis, the dynamic characteristics of smoke back-layering length as the longitudinal wind pressure is less than the critical value are studied, considering the influence of heat release rate (HRR), train speed, and train deceleration. The results indicate that the maximum back-layering length follows the logarithmic law with the variation of longitudinal wind pressure. An empirical model is proposed to predict the maximum back-layering length at various longitudinal wind pressure, and it is helpful to the optimization design of ventilation systems for tunnel motion fire.

Vibration Reduction and Explosion Control Investigation for an Ultra-Shallow Buried Tunnel under Crossing Buildings Based on HHT Analysis.

With the rapid development of underground space utilization, the excavation of new tunnels with ultra-shallow under crossing buildings using the drilling and blasting method is gradually increasing. The blasting vibration will undoubtedly affect the surrounding buildings. Reducing the impact of blasting vibration on ground buildings has become an important technical challenge faced by tunnel blasting technicians. The inlet end of the Xi'an-Chengdu High-Speed Railway Xiannvyan Tunnel passes below a village through an ultra-shallow buried section; as a result, blasting vibration control is a major concern. A design scheme for a 0.6 m footage in tunnel was proposed and verified through field tests. A 0.8 m footage scheme and 1.8 m footage millisecond interference vibration reduction scheme were proposed, respectively. Based on the HHT analysis, by comparing the surface vibration velocities and instantaneous energy obtained from the millisecond delay detonation of cutting holes and the detonation of different charging schemes, we found that the free surface, mass of single dynamite charges, and tunnel burial depth had significant influences on the surface vibration.

Review on the Research and Application Progress of TRD Construction Method in Foundation Pit

with the development of the times, the expansion of urban scale and the development and utilization of underground space, the building foundation pit is developing in the direction of "large and deep". The traditional deep foundation pit support construction technology can no longer meet people's needs for the construction of deep and large foundation pits, thus deriving a new construction technology TRD construction method, which has a wide range of application, guaranteed wall quality and depth, and high construction efficiency. This construction method has been born for more than 30 years and has been popularized and applied in China for more than 10 years. This paper will briefly introduce the trd method from the aspects of its development, characteristics and academic research process of related applications. It is not difficult to see from the relevant research that the trd method has broad application prospects in China.