Development Of Underground Space Research Articles

Rapid safety monitoring and analysis of foundation pit construction using unmanned aerial vehicle images

With the large-scale development and construction of urban underground spaces, the safety monitoring of foundation pit construction has gained much attention. Current safety monitoring of foundation pits is often achieved through manual onsite measurements with complex equipment and relies on complicated methods, which are labour intensive, time consuming, and tend to ignore the risk of accidental collapses caused by serious local deformation. To address this issue, this study develops a rapid safety monitoring and analysis method for foundation pit construction using Unmanned Aerial Vehicle (UAV) images. The safe inclination angle of the foundation pit slope was proposed as the safety-monitoring index. Taking the images of the foundation pit captured by the UAV as input, point cloud reconstruction and surface fitting were carried out. The local deformation distribution was introduced to evaluate the local safety state of the foundation pit. The experimental results validate the potential advantages of the method.

Research on the Utilization Mode of Underground Space in the Protection of Shanghai’s Industrial Architecture Heritage

With the arrival of the era of stock optimization, urban existing industrial areas and industrial buildings through renovation and upgrading to improve the building performance and expand the building function, more and more become an important content of urban renewal. With rich industrial building heritages in Shanghai as an example, the study was based on the ground of the industrial heritage protection status and function of underground space utilization, exploring the development and utilization of underground space to realize city both with industrial zone industrial building heritages protection development, expansion of land space and function optimization, summarized based on the industrial building heritages protection of underground space utilization patterns and their characteristics. It can provide a reference for the existing urban environmental stock renewal and expansion.

Research on the Optimal Clearance Distance of Super-Large-Diameter Shield Tunnel Underpassing the Existing Metro Tunnel

With the accelerating urbanization in China and the constant development of underground space, shield tunnels have been extensively applied to underground roads in central urban areas. However, the central areas are featured with complex surroundings, such as numerous subways, bridge pile foundations, basements, pipelines, and other structures and buildings. Therefore, it will be an unavoidable engineering difficulty for the construction of shield tunnel in the central urban area to cross at a close range buildings (structures) such as existing tunnels, underground pipelines, underground passages and basements. At present, there are remarkable research results for the crossing of subway shield tunnel with an outside diameter of 6.0 m, and rich research results for the crossing of shield tunnel with an outside diameter of 10-14 m. However, there are relatively few studies on the shield tunnel with an outer diameter of 15 m and above crossing existing buildings (structures). Based on Shanghai Beiheng super-large-diameter shield tunnel (outside diameter 15.0 m), the Midas_GTS finite element analysis software was used herein to study the relation between the underpassing clearance distance h and the peak settlement of existing metro tunnel S. The optimal clearance distance of the super-large-diameter shield tunnel underpassing the existing metro tunnel in the soft soil area h was drawn to be 7.0∼8.0 m. Through analysis, it was found that the ground loss rate ρ and the tunnel peak settlement S of the existing tunnel was linear, with the slope = 2.795 > 1. It proved that the tunnel peak settlement S of the existing tunnel was significantly influenced by the ground loss rate ρ. Therefore, it’ s quite reasonable to take the ground loss rate ρ as the evaluation indicator and control requirement for crossing construction.

An intelligent planning model for the development and utilization of urban underground space with an application to the Luohu District in Shenzhen

Development and utilization of Urban underground space (UUS) is one of the key ways for developing sustainable cities. However, the development and utilization of UUS is currently occurring in a passive manner, lacking proactive and quantitative planning. In this paper, an intelligent planning model was established to guide the future development and utilization of UUS. The proposed model, in which more than twenty factors were considered, is capable of analysing the suitability of UUS development in different regions and at different depths. In addition, an improved artificial intervention genetic algorithm (AIGA) with an additional correlation operator was integrated into the proposed model to achieve the optimal two-dimensional (2D) planning scheme by quantitively analysing the matching of the ground surface and underground space, and the compactness and suitability of underground space. A three-dimensional (3D) planning scheme was obtained by analysing the stratification of the underground space and hierarchical development. The proposed intelligent planning model was, subsequently, applied to the development and utilization of UUS in Luohu District in Shenzhen. An analysis of the geological conditions and the current construction status of the ground surface showed that 69.4% of the underground space is suitable for shallow layer developments, and this proportion further increases to 76% for the sub-shallow, sub-deep and deep layers, indicating that the Luohu District is highly suitable for developing underground space. Furthermore, the derived optimal 2D planning scheme indicated that the suitability component plays a greater important role in the objective values than the matching and compactness components, and more attentions should be paid to the development of municipal facilities in the shallow layer in Luohu District. The derived 3D planning scheme of Luohu District showed the characteristics of an “inverted cone”, where the utilization rate significantly decreases with increasing depth. The findings in this paper provide new insights for the future development and utilization of UUS.

Research on the Construction Technology for the Reconstruction of Existing Retaining Piles under the Condition of the New and Old Foundation Pits in Close Proximity

In view of the development of the city and the development and utilization of underground space, the new building foundation pit is close to the existing foundation pit. In view of this problem, a common reconstruction technology of existing retaining piles under the condition that the new and old foundation pits are adjacent to each other is proposed. The main construction process includes: primary selection of common pile section, design change, bored pile inspection, construction of steel pipe pile with pilot hole, depth judgment of new and old foundation pit, construction of locking anchor rod, foundation pit construction, monitoring and acceptance, etc. The reconstruction and reuse technology of the existing foundation pit supporting pile has been applied in a foundation pit in Zhuhai, which proves that it is safe and reliable, saves the construction period, reduces the construction difficulty, and improves the construction efficiency, which can provide reference for similar projects.

Experimental Investigation of the Fracture Performance of Hard Rock with a Single Borehole by Using a Hydraulic Splitter

The continuous expansion of urban areas is severely restricted by limited land resources. A promising and universal solution to this problem is the development of underground spaces. However, during the excavation of underground rock tunnels, mechanical tools undergo severe wearing due to the strengthened mechanical properties of the rock. Engineering applications have demonstrated that hydraulic splitters can effectively fracture hard rocks. Therefore, in this study, the effect of the rock compressive strength, confining pressure, and borehole margin on the rock fracture performance was experimentally investigated. The hydraulic splitter can be effectively applied to fracture hard rock. The peak fracture pressure increases with the increase in the rock compressive strength, confining pressure, and borehole margin. Moreover, the peak fracture pressure under a bidirectional unequal stress confining pressure is lower than that under bidirectional equal stress, and the difference between these pressure values gradually decreases as the confining pressure increases. The peak fracture pressure with the free surface is lower than that without the free surface, which demonstrates that the presence of the free surface can alleviate the difficulty in realizing rock fracturing.

Analysis of earth pressure distribution on deep circular shafts in composite geological strata using centrifuge modelling

With the rapid development of urban underground space, the depth of working shaft has been gradually becoming deeper to accommodate the underground construction needs. The existing studies for earth pressure distribution of shafts are mainly focused on sandy soils within 30 m. There is a strong need to investigate the earth pressure distribution on deep shafts (more than 30 m) in complicated soil conditions using centrifuge modelling to fill the knowledge gap and provide experimental basis for design. In this paper, geotechnical centrifuge modelling was used to investigate the earth pressure distribution along deep circular shaft structures (with a depth of 100 m) in composite geological strata. Three centrifuge tests on model shafts in layered ground with different thickness of clay and sand were carried out, respectively. Drainage method was used in the experiment to simulate the unloading effect caused by excavation of soils inside the shaft model. The earth pressure distributions along the shaft lining before and after the excavation were investigated. The results were analysed and compared with other existing earth pressure theories. This research provides valuable insights for earth pressure distribution for design of circular deep shafts (e.g. 100 m) in composite geological strata.

Suitability of Underground Space Development in Plateau Cities Based on Geological Environment Analysis: Case Study in Kunming, China

Geology forms the basis for underground space development. In mountainous plateau areas, developing underground spaces requires detailed analyses and appraisal. This study used the index scale analytic hierarchy process (AHP) to analyze the geological conditions and to propose an evaluation system suitable for Kunming, China. An evaluation model was established using mathematical principles, and a geological suitability evaluation of Kunming was conducted using GIS. According to the evaluation, underground space in Kunming considered suitable, medium suitable, unsuitable, and forbidden for development accounts for 37.81%, 20.38%, 17.61%, and 24.2% of its total area, respectively. Soft soil and karst topographies are the primary disqualifying factors, followed by groundwater and geological fault zones. Our results reveal that most of the underground spaces in the plateau area are suitable for development. However, there are areas where construction should be strictly regulated, such as those adjacent to geological fault zones. With this study, the superiority of the index scale method was demonstrated, and the consideration criteria of the evaluation system and indexes in plateau cities were proposed.

Research on the development and utilization of underground space in Beijing Old City

As a concentrated embodiment of urban historical sites, cultural relics and cultural heritage, the old city of Beijing has the most intensive historical and cultural resources and the most stringent requirements for historical protection. At the same time, it also faces a series of development problems to be solved, such as insufficient development space, lagging public service facilities, and urgent improvement of living environment. How to effectively utilize the underground space resources and coordinate the relationship between historical protection and urban renewal is an important issue for the sustainable development of the old city of Beijing. In this paper, the development and utilization strategies of the underground space in the old city of Beijing are systematically studied, as well as the reasonable utilization methods of the underground space in the historical protection areas. Through the development and utilization of underground space, we can make up for the shortage of public service and better improve the ground space environment. In addition, this paper also discusses the integrated development of underground space and metro stations, so as to enhance the urban renewal and development of the station areas. The relevant data and conclusions are from the latest planning and practical experience of Beijing old city, in order to provide useful reference for the sustainable development of historical urban areas and the scientific utilization of underground space resources.

Adoption of size effect combined with Winkler elastic foundation beam theory in section shield tunnel under underground space development

It aims to discuss the adoption value of combining the size effect and Winkler elastic foundation beam theory in the large-section shield tunnel under the background of underground space development. Two kinds of soil layers of silty clay and sand pebble are simulated. The difference of settlement, longitudinal deformation, and earth pressure of large-section shield tunnel in the simulated soil layers is analyzed. The longitudinal design model of shield tunnel based on large-section and compound stratum is constructed according to Winkler’s elastic foundation beam theory and the longitudinal equivalent continuous model of shield tunnel. The results show that the tunnel diameter has an exponential relationship with the effective rate of longitudinal stiffness and equivalent longitudinal stiffness. The overall longitudinal settlement curve of the tunnel in the compound stratum presents the “S” shape. The maximum differential settlement of the tunnel is −55 mm. The soil pressure around the tunnel from high to low is arch bottom, left arch waist, right arch waist, and arch top. The maximum settlement of the tunnel in the silty clay and sand pebble is −6.08 mm and −15.85 mm, respectively; the maximum uplift of the arch bottom is 11.65 mm and 17.74 mm, respectively; the earth pressure around the arch top is 2.184 MPa and 4.22 MPa, respectively; and the earth pressure around the arch bottom is 2.236 MPa and 3.88 MPa, respectively. At the boundary of the two strata, the maximum earth pressure around the top of the arch is 4.56 MPa, and the maximum earth pressure around the bottom of the arch is 4.17 MPa. It suggests that the longitudinal design model of shield tunnel with large-section and compound stratum is successfully constructed according to the size effect combined with Winkler elastic foundation beam theory, which provides a reference method for the design of the tunnel structure with large cross-section.

A literature review of medical support in cave rescue and confined space medicine – implications in urban underground space development.

Objective: To conduct a literature review and knowledge synthesis of medical support in cave rescue and confined space medicine (CSM), thereby, extrapolating the knowledge gained from cave rescue and CSM to consequence management in Urban Underground Space (UUS) development. Methodology: A review of current medical literature was conducted. Data sources: Search engines utilized include PubMed, Medline, Cochrane Library, Science Direct and Google Scholar. Results and Recommendations: The synthesized knowledge based on available literature was extrapolated to application during consequence management in UUS development. Conclusion: As underground urbanization progresses to create sustainable habitats for the world’s increasing population, city planners need to consider the need for consequence management in UUS. The knowledge and experience gleaned a posteriori from cave rescue and CSM should be utilised to optimize the planning of emergency response in an urban underground environment.

Spatial accessibility and functional layout impacts on urban underground space development: a case study of Shanghai

Over the past decade, China’s megacities such as Shanghai and Beijing have witnessed great progress in their metro networks. With the rapid development of metro system, urban underground space (UUS) in China has been widely utilized in a systematic manner, following the principles of transit-oriented development. A comprehensive understanding of the impacts of the built environment on UUS is doubtlessly conducive to the high-quality and sustainable urban development. However, there are fewer researches conducted to study the impacts on UUS compared with those studies focusing on ground level space. Moreover, quantitative researches using multi-source big data on underground space are limited, which makes it hard to reveal the development regulation with high-precision at a large scale. This paper aims to study the impacts of spatial accessibility and functional layout on UUS. Shanghai, as one of the most prosperous megacities in China with well-developed underground space, was selected as the case study. In this paper, open data from Open Street Map and Point of Interest (POI) in AMAP was adopted. Indices such as integration (index of space syntax) of metro line, road length, road density, POI density, and entropy of POI were chosen to reflect the spatial accessibility and functional layout. Underground POI (UPOI) density was set as a proxy of UUS development intensity. A quantitative analysis using multiple linear regression model was conducted. The results showed that both two kinds of indices strongly correlated to the underground space development, whereas the influences of selected indices on UUS were different. At last, the characteristics of UUS in Shanghai and further development strategies were discussed, which provided a perspective of smart growth for planners, designers and authorities.

Underground space in metro area: constituent, influencing factors and improving strategies of the spatial vitality

Nowadays, the shortage of available urban land and the booming construction of urban subway are driving the rapid development of Underground Space in the Metro Area (USIMA) which is an important constituent in the compact development of cities. Spatial vitality, as one of the most important evaluation indicators for the layout of such metro-related underground space, is closely related to spatial efficiency. Therefore, taking Shanghai People’s Square Metro Station (SPSMS) as a case study, this paper investigated the variable factors of the spatial vitality in USIMA by using methods of space syntax, field investigation, and pedestrian counting. Results revealed that the spatial vitality of USIMA is comprehensively affected by related variables, including accessibility and visibility of spatial configuration, degree of functional mixture, layout of station hall as well as entrances/exits, and the organization of business forms. Finally, improvement suggestions and discussions are put forward from the aspects of entrance/exit layout, spatial organization, and functional distribution, to provide reference for future planning, design and optimization of USIMA with effective vitality.

An Exploration of the Planning Approach for New Development Area with Underground Space in Hong Kong

Hong Kong is a densely populated city. Development of New Town or more recently called New Development Area (“NDA”) has been adopted to create more space for housing, working places and community facilities in the last few decades. But till now the planning of NDA remains focusing on above ground intervention without consideration in making use of underground strata and the opportunities for underground space development as a major land asset have not been fully explored. Whenever the potential use of underground spaces would arise, they are usually found to conflict with the established surface land development and difficult to be pursued.With the public aspiration for better living and working environment, the demand for enhanced utilization of underground strata as one of the spatial solutions is ever increasing in Hong Kong. As a response, underground space is now considered by a government appointed task force as one of the medium-to-long term options in increasing land supply. This paper will endeavour to propose an integrated approach of land use planning incorporating underground space for the future NDA planning, drawing on the experiences from recent plans and projects in other cities.

Quantitative analysis of spatial vitality and spatial characteristics of urban underground space (UUS) in metro area

The implementation of transit-oriented development (TOD) policies and the vigorous development of urban rail transit construction have promoted the rapid development of the urban underground spaces (UUSs) in metro construction areas. Spatial vitality, as one of the important evaluation indicators for the layout of the UUS, is closely related to spatial efficiency. Taking the UUS of the Shanghai People’s Square (SPSUUS) as a case study, the distribution regularities of the spatial vitality in the UUS were investigated by analyzing its spatial characteristics and vitality distribution quantitatively. Space syntax, point of interest (POI) data, traditional field investigations, and pedestrian counting were adopted to measure the spatial features and population density of the SPSUUS, and then comparisons were made. The correlations between each spatial characteristic variable and the spatial vitality were further explored using the SPSS software. The results showed that the spatial vitality of the SPSUUS was comprehensively affected by related variables, including the visibility and accessibility of the spatial structures, the degree of the functional mixture, the layout of the station hall and entrances, and the organization of business forms. Depending on the feedback results, corresponding improvement suggestions and discussions are proposed from the aspects of entrance layout, spatial organization, and functional distribution to provide a reference for future planning, design, and optimization of UUSs with effective vitality.

Stability Evaluation of TBM Pilot Tunnels to Rear Blasting Using the Protection Shield

Recent studies have increasingly investigated construction methods for tunnel excavation because of growing underground space development. Although the New Austrian tunneling method (NATM)—a representative tunnel excavation method—can be applied to various ground conditions, as well as having good constructability and economic feasibility, it suffers from problems such as vibration and noise. By contrast, excavation using a tunnel boring machine (TBM)—a representative mechanized construction method—affords advantages such as stable excavation, minimized ground and environmental damage, noise, and vibration. However, it cannot be applied easily to various ground conditions, and it suffers from problems such as high construction costs and delays owing to equipment defects. Therefore, the simultaneous pilot tunnel excavation using the TBM—which affords advantages such as constructability, economic feasibility, and minimized noise and vibration—and rear enlargement blasting using NATM was investigated in this study. A protection shield was installed to minimize accidents occurring from equipment defects (a disadvantage of TBM) and analyze the decrease in the effect of NATM blasting, which depends on the use of the protection shield and the separation distance through 3D numerical analysis.

Influence of Foundation Pit Excavation and Precipitation on Settlement of Surrounding Buildings

With the large-scale development of urban underground space, foundation pit engineering has become one of the important geotechnical engineering topics in urban construction. In this paper, the effects of foundation pit excavation and precipitation on adjacent buildings are studied in detail. The main research work includes the following aspects: summarizing and analyzing the soil consolidation theory, foundation pit excavation, and precipitation process; the influencing factors of the adjacent soil layer displacement; the influence mechanism and influence types of foundation pit excavation and precipitation on adjacent buildings. The finite element model considering the whole process of foundation pit excavation is established, and the variation law of the upper layer displacement around the foundation pit is analyzed. The deformation law of the retaining structure, the calculation results of precipitation and nonprecipitation, and different excavation methods will be analyzed and compared. The calculation results show that the displacement of the soil layer around the foundation pit is also different between different excavation methods. As the distance between the foundation pits increases, the lateral displacement of the underground continuous wall near the frame structure gradually decreases. The distance from the foundation pit wall is 30 m. The maximum value of the lateral shift is reduced by 4.7% compared with 5 m. The foundation pit is studied, as well as the law of internal force variation of adjacent buildings caused by digging and precipitation, and checking the safety and adaptability of structural members. The calculation results show that a large additional internal force will be generated on the bottom floor of the adjacent building, and some structural members will be damaged by the bearing capacity.

Analysis of Influencing Factors of Modification Potential of Abandoned Coal Mine Into Pumped Storage Power Station

Abstract By modifying underground spaces of abandoned coal mines into underground pumped storage power stations, it can realize the efficient and reasonable utilization of underground space and, at the same time, meet the increasing demand for energy storage facilities of the grid, bringing social, economic, and environmental benefits. Previous research in this area has been limited to the stage of conceptual discussion, and there is no scientific evaluation method for the modification and utilization potential of abandoned coal mine spaces. Establishing a scientific evaluation indicator system forms the basis for evaluating the underground space development and utilization capacity of abandoned mines. Based on the principle of pumped energy storage and the characteristics of coal mine roadway conditions, this paper utilized an analytical hierarchy process (AHP) to evaluate the main influencing factors, including elevation difference between the upper and lower reservoirs, reservoir capacity, roadway surrounding rock stability, and roadway permeability. It analyzed the modification potential of underground spaces and then verified the development potential of the underground spaces of abandoned mines by a statistic model. The study found that the elevation difference between the upper and lower reservoirs is the most influential indicator; second, the capacity of the upper and lower reservoirs is also an important evaluation indicator. The research methods and conclusions will provide useful tools and decision-making basis for analyzing the feasibility and techno-economic benefit of modifying the underground spaces of abandoned coal mines into pumped storage power stations.

New View on the Genesis of the Bashuihe Pluton, Laoshan Granites, China: Indications from Fluid Inclusions and H–O Isotopes

Oval caves have recently been discovered in the Bashuihe granite pluton of Laoshan Mountain, China. Oval caves typically occur in alkaline granites. This study conducted microthermometry and stable isotope analysis of quartz inclusions from oval caves and host rocks from the Bashuihe pluton to reconstruct the diagenetic evolutionary history of the Laoshan area. The temperature measurement results indicated a homogenisation temperature range from 162.5 to 261.6°C (mean 203.9°C), a salinity range of 2.1–8.3 wt% (mean 5.07 wt%), and a density range of 0.8–0.98 g/cm3 (mean 0.90 g/cm3), indicating a low-temperature, low-salinity, and low-density fluid. The emplacement depth ranged from 2.73 km to 4.43 km, indicating medium-shallow granite. A hydrogen and oxygen isotope analysis ( δ D = − 83.58 – − 67.17 , δ 18 O H 2 O = 0.83 – 0.39 ) revealed that the diagenetic fluids of the Bashuihe pluton represented a mixed hydrothermal solution composed of meteoric water and magmatic water. The results of a whole rock, H–O isotopes, rare earth element, and high field strength element analysis on the Laoshan alkali granites suggest significant hydrothermal activity in the late stage of magmatism. Primary oval caves in the Bashuihe pluton most likely evolved in the following sequence: fluid was enriched in the late diagenetic stage, diagenetic minerals crystallised under low temperature and pressure conditions, the crystallisation rate accelerated, and the magma condensed rapidly. Moreover, the increase in magma fluid enabled the movement and convergence of fluid. The accumulated fluid and volatiles occupied more space, and rapid magma condensation trapped the accumulated fluid and volatiles in the pluton, forming the oval granite cave. This research provides a crucial theoretical reference for the development and utilisation of underground space and engineering buildings in granite regions.

Research on towed TEM on off-centre self-compensation technology for urban underground space detection

Transient electromagnetic (TEM) is a geophysical method that can obtain the electrical information of underground media. It will provide strong technical support for the safe development and operation of urban underground space. However, the coupling effect of the transmitting current on the receiving loop leads to the shallow blind area of TEM. Especially, the coupling effect is more serious when the multi-turn and small-size coil structure is required because of the limitation of urban buildings and ground facilities. To solve these problems, this paper proposes a towed TEM technology based on off-centre self-compensation with the small size structure. The new technology adopts the idea of non-coplanar eccentricity structure to design a self-compensation system, which can eliminate the coupling effect. In this paper, the distribution of primary field in receiving coil is studied, and the key structural parameters of transmitting coil and receiving coil is obtained by theoretical model. The experimental results show that the towed TEM system based on the new technology can directly obtain pure secondary field signal. Compared with other TEM structures, it has higher tolerance for physical size error and higher practicability. The towed TEM technology proposed in this paper will provide a theoretical basis for the realization of blind area free, high-speed and accurate scanning measurement of urban underground space.