Bibliometric analysis of research challenges and trends in urban underground space

The 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.

An experimental study on fire characteristics of urban complex underground space based on BIM

Compared with the space on the ground,if there is a fire in the urban complex underground space,the loss will be greatly harmful.In addition,the complex underground space is usually connected with other large space areas and densely populated.Once a fire occurs in the complex underground space,it will cause huge property losses and casualties.In order to reduce the risk of fire,it is necessary to deeply understand the development rules and characteristics of fire in the complex underground space of the city.This article has mainly carried on the following work:(I)A particularly complex model of the multi‐storey subway station was built.On this basis,three groups of comparative experiments were conducted to study the effects of fire power,fire location and smoke control system on fire development,and the conclusion that fire location is the most important factor for fire development was obtained;(II)In order to explore the entire space fire and the local space fire,CFD(Computational Fluid Dynamics)is used to build a large‐size fire model and a small‐size fire model respectively;(III)Multiple detector data as temperature slices were built,and it is expected to make full use of the simulation data to deduce the important index of fire location in the early stage of fire.All of the works in this paper will provide reference experimental data for the prevention and firefighting of a sudden fire in the complex underground space.

Design Strategy of Underground Space of Urban Rail Transit Complex Based on Integration Concept

With the accelerated development and utilization of urban underground space,the underground space design of complex based on rail transit has attracted much attention.By sorting out the integration concept and constructing the logical framework of integrated design,the integrated design strategy is proposed from the aspects of function,transportation,space and environment on the urban scale,and the evaluation points of integrated design effect are put forward from the aspects of accessibility,coordination,openness and symbolism.

Development of urban underground space in coastal cities in China:A review

The development of urban underground space is a critical way to alleviate the lack of urban resources,and improve environmental conditions as well as residents'quality of life,which has important practical significance.As the most densely populated and economically developed areas,coastal cities face many challenges in underground space development owing to their unique environmental geological conditions.This study examined the current situation of underground space development,academic research,technology application,evaluation methods,planning,and legislation in coastal cities in China.On this basis,it analyzed the future development trends,and presented reasonable suggestions for the critical scientific and technical problems faced by the development of underground space in coastal cities.The key suggestions are as follows:it is necessary to define and clarify the critical geological issues,distributions,and hazards that affect underground space development and major engineering construction in coastal cities;the land-sea integrated detection technology for sea crossing bridges and submarine tunnels needs to be studied;in evaluating the suitability of underground space in coastal cities,the land and sea area evaluation factors should be integrated;and the evaluation system of landsea integration needs to be established.

Evaluation of urban underground space resources using a negative list method: Taking Xi'an City as an example in China

Utilization of urban underground space has become a vital approach to alleviate the strain on urban land resources,and to optimize the structure and pattem of the city.It is also very important to improve the city environment,build livable city and increase the capacity of the city.Based on the analysis of existing evaluation methods and their problems,a method for evaluating underground space resources based on a negative list of adverse factors affecting underground space development is proposed,to be primarily used in urban planning stages.A list of the adverse factors is established,including limiting factors,constraining factors and influencing factors.Taking Xi'an as an example,using a geographical information system platform,a negative list of adverse factors for the underground space resources in Xi'an City are evaluated,and preventive measures are proposed.Natural resources,exploitable resources,and the potential growth of exploitable underground space resources are evaluated.Underground space assessment in the different development stages of the city,collaborative utilization and safety evaluation for multiple subsurface resources,environmental impact and assessment,as well as evaluation methods based on big data and intelligent optimization algorithms are all discussed with the aim of serving city planning and construction.

Assessing the Sustainability of Underground Space Usage——A Toolkit for Testing Possible Urban Futures

A description of the future as it might be without forecasts, predictions and trend analysis can be referred to as a 'future scenario'. An abundance of scenarios literature exists in which numerous pictures have been painted of changed future worlds. However, upon closer inspection it becomes apparent that virtually all of this literature refers to changes occurring above ground, ignoring the inevitable consequences (or opportunities) for sustainable use of underground space, not least in densely populated urban areas, some of which may be underlain by complex geological conditions. This paper reports on the development (to date) of an 'Urban Futures' (UF) toolkit for sub-surface environments (including infrastructure and utilities) which, through use of 'key' questions 'sustainable' indicators and a 'contextual' narrative, allows for better definition and measured performance of underground space in the UK, both today and in the future. The toolkit explores possible uses for underground space within 4 plausible and well-cited future scenarios (i.e. New Sustainability Paradigm, Fortress World, Market Forces and Policy Reform). This forms part of a much larger generic toolkit which the UF research team are developing for exploring possible future scenarios over a range of UK urban regeneration case study areas.

Characters of Urban Development and Its Spatial Morphology Underground Space Influences on Urban

Underground building with such major functions as underground traffic, commerce, culture and recreation, especially the multifunctional underground large-scale public complex, has become a significant part of the overaU functional structure or even the core of a city. Therefore, the expression of the architectural appearance, and characters of underground building, as well as the integration between the building and its external environment constitute an important part in improving overall functional structure and optimizing cityscape. From the perspective of space and environment shaping, the author explores the architectural appearance, and characters of underground building and its external environment, provides several basic design patterns with further discussion.

Analysis of Geotechnical Engineering Safety Technology in Urban Underground Space Construction

With the accelerating pace of urbanization,the development and application of urban underground space has attracted much attention.In the construction of urban underground space,geotechnical engineering safety is the key point for construction.Based on this,this paper analyzes the application of geotechnical engineering safety technology in urban underground space construction,in hope that this analysis can provide a scientific reference for the rational application of geotechnical engineering safety technology as well as the construction and development of urban underground space.

Construction Technology and Strategy of Natural Light Environment in Urban Underground Space

In underground space,daylighting plays an important role in increasing the spacious sense,improving the ventilation effect,and more importantly,reducing the negative visual and psychological effects brought by the underground space,such as enclosed monotony,unknown direction and isolation.In this paper,the technical means of utilizing natural light in underground space were elaborated from the two aspects of passive daylighting method and active daylighting method,aiming to bring natural light into the underground as much as possible so as to fully satisfy people's longing for nature for those who work and live in the underground space.

Quantitative evaluation of the contribution of underground space to urban resilience:A case study in China

Urban underground space(UUS)development has been acknowledged as a positive contribution to urban resilience(UR).Such contribution has been qualitatively addressed in recent years,but only quantitatively discussed in few studies.Quantitative evaluation methods for UR are widely used in China and around the world,but the role of underground space is barely included.This paper provides a way to bridge this gap on the city scale.A UR evaluation framework was carefully constructed that covers the basic aspects and elements of UR.The contributions of UUS to UR were identified and integrated into the UR evaluation framework,and the measurement methods for each indicator related to UUS were determined.A case study of 19 sample cities in China were conducted using the integrated evaluation model.Correlation analysis and clustering analysis were further adopted to interpret the evaluation results,mainly with three indicators reflecting the level of UUS development,namely UUS area(m^(2)),UUS density(104 m^(2)/km^(2))and UUS area per capita(m^(2)/person).The results showed a strong correlation between UUS area and UR.The average proportion of UR provided by UUS in the 19 sample cities was 16.46%,while the maximum figure reached 29.20%.The sample cities were clustered into four categories based on the relationship between the proportion of UR provided by UUS,UUS area,and GDP per capita,where both high and low UUS area tend to provide less proportion of resilience than the medium UUS area.Corresponding suggestions for UUS utilization were proposed to assist cities in achieving urban resilience.

3D suitability evaluation of urban underground space using a variable weight method and considering ground restrictions

The evaluation of urban underground space(UUS)suitability involves multiple indicators.Assigning weight to these indicators is crucial for accurate assessment.This paper presents a method for spatially variable weight assignment of indicators using the order relation analysis method(G1-method),the entropy weight method,an improved grey relational analysis(GRA)and a set of spatial weight adjustment coefficients.First,the subjective and objective weights of indicators for engineering geological and hydrogeological conditions were determined by the G1-method and entropy weight method,respectively,and their combined weights were then obtained using the principle of minimum discriminatory information.This study highlighted the impact of surface restrictions,such as buildings,on UUS,and the degree of the influence of these buildings gradually decreased with the increase in depth of the rock and soil mass in UUS,which resulted in changes in weights of indicators with depth.To address this issue,a coefficient was defined as the standardized value of the ratio of additional stress applied by restrictions to the self-weight stress of soil at the same depth to modify the combined weights so that all weights of indicators could vary in space.Finally,an improved GRA was used to determine the suitability level of each evaluation cell using the maximum correlation criterion.This method was applied to the 3D suitability evaluation of UUS in Sanlong Bay,Foshan City,Guangdong Province,China,including 16 evaluation indexes.This study comprehensively considered the influence of multiple factors,thereby providing reference for evaluating the suitability of UUS in big cities.

Review of constraints and critical success factors of developing urban underground space

The development of urban underground space(UUS)is of great significance for sustainable urban development because it has potential to solve many urban problems.However,the development of UUS is limited because there are still a lot of constraints and challenges.To better understand the constraining factors of developing UUS and improve the development and utilization of UUS,this study conducts a comprehensive survey of existing literature retrieved from the Web of Science Core Collection database.Five main constraining factors,including the limited geological conditions,high cost,lack of natural light and ventilation,high incidence,and difficulty in collecting data and information on UUS,have been discussed to better understand how they affect the development of UUS.Based on the survey,the critical success factors of developing UUS,such as the effective governance structure,planning system for integrating UUS into urban development,coordination of the design of ground and underground,delineation of land property rights of UUS,and application of information techniques in the use of UUS,have been identified and discussed.In addition,knowledge gaps in the studies on development of UUS have been identified.Finally,the research trends and future directions have been proposed for better understanding and practice of UUS development.

Systems approaches to urban underground space planning and management-A review

The necessity to recognize the subsurface or underground and all its current and potential uses as part of our urban environment,to integrate this into urban planning and governance,and to foster conscious allocation of subsurface space has been increasingly recognized over the last century.At the same time,systems thinking as a‘buzz-word’has gained relevance for approaching complex problem areas in all kinds of disciplines including those preoccupied with the subsurface.This paper reviews the literature about urban underground planning through a systems-lens.To set this in context,it is outlined how organizational principles for the urban subsurface have evolved,and the main aspects of systems thinking are introduced followed by a discussion of how this thinking could be applied to the urban underground.Strategies and tools presented in the recent literature in the field are then reviewed based on this perspective,asking how systemic the proposed strategies and tools are when the local geology,as well as legal and institutional settings are accepted as a baseline for analysis or intervention.Systemic approaches built on this premise have the potential to capture existing and evolving complexities,foster a better understanding of the value of subsurface space for a city and ultimately enable an efficient and fair allocation of underground space.However,propositions for holistic solutions remain dispersed,interventions often remain based in an engineering mindset,and a shift in mind-set remains a challenge.More research in collaboration with local and regional administrations or authorities based on systems thinking frameworks could help to facilitate this shift.

A collaborative approach for urban underground space development toward sustainable development goals:Critical dimensions and future directions

The utilization of urban underground space(UUS)offers an effective solution to urban problems but may also negatively affect urban development.Therefore,UUS development needs better concerted guidelines to coordinate various urban systems and the multiple components of the underground world.Sustainable Development Goals(SDGs),which should be viewed as important yardsticks for UUS development,do not explicitly mention urban underground space,although many of them are affected by both the positive and negative consequences of its development.To fill this gap,this review lays the foundations of relevant UUS concepts and uses exemplary cases to reveal that 11 out of 17 SDGs can be linked with UUS uses.These linkages also manifest that land administration,integrated planning,architectural design,and construction technology are critical dimensions for increasing the contributions of UUS to the realization of SDGs.To achieve multi-disciplinary synergies among these four critical dimensions,a collaborative approach framework based on spatial data infrastructure is required.Thus,this work provides academics and practitioners with a holistic view of sustainable UUS development.

Evaluation of urban underground space resources using digitalization technologies

Exploitation and utilization of urban underground space resources is gaining increasing attention in cities’sustainable development.Due to the attributes of fragility and irreversibility,urban underground space resources can be extremely vulnerable to damage and it is often difficult in restoring their original state once damaged.Therefore,scientific and reasonable evaluation of urban underground space resources is of vital importance in urban planning and development.This paper first describes the content and methods for the evaluation of urban underground space resources,and introduces the digitalization technologies to handle the problems of strong subjectivity,low efficiency and rough precision encountered when using traditional evaluation tools.Then,the related concepts and main technologies for digitalization were demonstrated and an intelligent GIS-based engineering geology system was built.Based on the drilling information in Changzhou City,stratum standardization and 3D modeling of strata,underground structures and pipelines were conducted in the built intelligent system.Finally,with the help of spatial overlay analysis in the GIS-based platform and a combination of other digitalization technologies,the urban underground space resources of Changzhou City were evaluated.Maps of geological suitability were produced,which provide scientific guidance and reference for the exploitation and planning of urban underground space resources in Changzhou City.In addition,site selection for key projects was conducted based on the evaluation results using this platform.

Legal considerations for urban underground space development in Malaysia

In 2008,the Malaysia land code,named the National Land Code 1965(NLC 1965),was amended to add Part Five(A)to deal with the disposal of underground space.In addition,the Circular of the Director General of Lands and Mines No.1/2008 was issued to assist the application of Part Five(A)of the NLC 1965.However,the legislation is still questiona ble and has instigated many arguments among numerous actors.Therefore,this research was undertaken to examine legal considerations for the development of underground space.The focus is on four legal considerations,namely underground space ownership,the bundle of rights,depth,and underground space utilization.Rooted in qualitative methods,interviews were conducted with respondents involved in the development of under-ground space in Malaysia.The obtained data were then analyzed descriptively.The findings diferentiated the rights of landowners for surface land and underground space,and their liability for damages and the depth.It was indicated that the current legislation in Malaysia,namely Part Five(A)of the NLC 1965 and the Circular of the Director General of Lands and Mines No.1/2008,is adequate to facilitate the development of underground space in terms of legal considerations.However,to further facilitate the development of underground land in the future,based on the research,four enhancements are recommended for legal considera tions pertaining to the development of underground space in M alaysia.

Future cities,resilient cities-The role of underground space in achieving urban resilience

The need for future cities to be resilient stems from the fact that now more than ever in history,both natural and human-made hazards are threatening cities in the forms of shocks and stresses.The ability of cities to resist or restore themselves following these events is dependent on their resilience.As we now firmly enter the Anthropocene,the geological epoch in which human activity,for the first time in history is directly influencing the Earth’s systems,we need to develop resilient cities that can cope with the increase in hazards.Although climate change is one factor influencing urban resilience,it is not the only one.A lack of understanding of the subsurface can also influence a city’s resilience,as can the unplanned use of its underground spaces.In planning and developing our cities of the future,a deep understanding of the geology that supports the city is required not only to be able to determine the possibilities of future use but also to determine whether there are natural processes that could threaten human existence over time.The destruction of ecosystem services through unchecked human activities could be one of these activities.In this paper,the authors will investigate how the subsurface and use of underground spaces can influence urban resilience.The role that underground spaces can play in achieving urban resilience for our future cities will be described.

Underground space use of urban built-up areas in the central city of Nanjing:Insight based on a dynamic population distribution

With the expansion of cities and the emergence of various urban problems,urban underground space has been developed as a solution.In China’s urban transition context,there is a need for the development of underground space in urban built-up areas.In this casestudy of the central city of Nanjing,we used spatial analysis and statistical methods to characterize the underground space use of urban built-up areas from a dynamic spatiotemporal perspective.We first analyzed the relationship between the population distribution and the underground space use of the central city of Nanjing based on a Baidu heat map,which can reflect the real-time population distribution,and then,we explored the spatiotemporal characteristics and spatial structure of the underground space use in urban built-up areas.The analysis results provide a reference for planning to improve and optimize the layout of underground space in the central city of Nanjing and,more generally,for the stock-type planning of underground space in urban built-up areas.

Japanese Ways of Developing Urban Underground Recreation Space

This paper defines the concept of urban recreation space at first, and then?focuses on the six aspects of experience in?functional orientation, joint development, business planning, environment designing,?recreational route designing, operation and management based on reviewing the development process of the underground street in urban recreation space in Japan.?The results show that the overall planning and detailed design of urban recreational space in Japan is worth learning and drawing lessons for all countries in the world.

The Influence of Residents’ Opinions on the Redesign of Urban Underground Streets: A Case Study from <i>Diyi</i>Underground Street

The rapid development of urbanization and rapid growth of urban population have brought about various urban problems, and the development of cities to the ground and underground has become an inevitable choice. Underground street is a kind of underground space types, and it is also an important urban recreational resources and tourism resources. The evaluation of underground street users, especially the residents and tourists, has important reference value for the recreational resources’ redevelopment of underground street. Firstly, this paper reviews the relevant research literature on underground street and Post-Occupancy Evaluation theory, then chooses Diyi Underground Street, Chengdu, China, as the research object, and conducts a questionnaire survey and in-depth interviews on residents’ shopping intention from five dimensions of underground street environment, decoration, commercial form, public facilities and other aspects. Finally, the survey data are analyzed quantitatively. The results show that some influence factors such as air quality, daylighting, decoration style etc. greatly affect the willingness of residents to enter the street. Therefore, residents’ recreational experience should be emphasized during the underground street re-planning according to the above factors.