Construction Of Underground Space Research Articles

Performance of Diaphragm Walls during Ultra-Deep Excavations in Karst Areas: Field Monitoring Analysis

Deep foundation pit excavations have become more extensive for the construction of underground spaces with rapid urbanization. Diaphragm walls are commonly used to support deep excavations. However, due to the complex geological conditions in karst areas, construction accidents frequently occur during the excavation of foundation pits. This study aims to investigate the performance of diaphragm walls in karst areas through field monitoring analysis. A kick-in deformation mode of the diaphragm wall is revealed during the foundation pit excavation. Furthermore, the results show that the diaphragm walls present multiple deformation modes rather than a single mode. Additionally, this study proposes a method to calculate the lateral displacement of the diaphragm walls at different depths. It is found that the karst caves have a considerable impact on the stability of diaphragm walls, as demonstrated by their lateral displacement. The hidden karst caves reduce the bearing capacity of the bedrock, rendering it insufficient to resist the active earth pressure. As a result, the bottom of the diaphragm wall is kicked into the foundation pit, causing significant lateral displacement and posing risks during excavation. The findings of this study contribute to the design and construction of similar excavations in karst areas.

Analysis of the Load‐Bearing Capacity of the Steel‐Shell Concrete Support Structure Formed by the Construction of the Pipe Curtain Freezing Method

The Sanya estuary passage project is the latest and highly technical underground project after the large shield underground construction, which is of great significance to the construction of the Hainan free trade port and underground space construction innovation. In this paper, we use finite element software to analyze the deformation, stress, and surface settlement of the pipe curtain structure during construction under two conditions (original riverbed line and maximum scour riverbed line) in order to provide guidance for the actual project. Numerical simulations show that due to excavation and unloading, the bottom and top of the pipe curtain structure are subject to tensile stress; the bottom rises, the top settles, and converges in the horizontal direction; under the original riverbed line condition, the displacement values of each index are larger; changing the riverbed line does not change the maximum and minimum main stress of the pipe curtain structure significantly, and the stiffness of the pipe curtain structure can meet the maximum water level and the maximum scour in two unfavorable conditions; the pipe curtain structure can meet the structural. The pipe screen structure can meet the structural load‐bearing requirements. Suggestions for the design and construction of the project: strengthen the thickness of the pipe curtain at the side wall position, that is, use larger diameter steel pipes; do a good job of antiseepage and anticracking of the concrete at the corner of the pipe curtain structure and the side wall position during the construction process.

A Methodology of Comprehensive Quality Evaluation for the Underground Space

AbstractUnderground space resources are very important for the purposes of urban sustainable develop Underground space resources are very important for the purposes of urban sustainable development and are an important way in which to realize three‐dimensional urban development. A reasonable and scientific evaluation of underground space resources is the basis for the rational use of land resources and urban planning. On the basis of the geological conditions concerned by predecessors, this study adds the analysis of the two influencing factors of social and economic value, existing facilities and protection needs. The evaluation index is quantified, and the comprehensive quality evaluation system of underground space resources is constructed. Finally, taking Nanshan District of Shenzhen as an example, the evaluation of underground space resources is carried out. The results show that for shallow underground space, the comprehensive quality of underground space resources development in Nanshan District is generally high. Nantou, Nanshan, and Yuehai streets are recommended to actively develop underground space, and Qianhai and Houhai areas are recommended to be cautious in the development and construction of underground space. In addition, this study also provide reference for the purposes of underground space planning in Nanshan District of Shenzhen.

Stability Analysis and Safety Factors of the Excavation Face of a Pipe Screen Tunnel in a Soft Soil Area

With the rapid development of urban rail transit and underground space construction, the advantages of the concealed excavation method are gradually highlighted in the urban center area affected by a complex engineering environment. At present, the pipe curtain method with a flexible section and wide application of the soil layer is being widely used in engineering, but the research on the stability of the excavation face during the construction of the pipe curtain method in soft soil areas still has not formed a complete system. Therefore, this paper analyzes the stability of the excavation face under different reinforcement conditions and the influence of different spacing, numbers, and strength of MJS (metro jet system) zones on the stability of the excavation face of the pipe curtain method based on the actual project of the Guiqiao Road Station of the Shanghai Metro, China, and gives a reference for the reinforcement of the palm face in the excavation process of the pipe curtain method in soft soil areas. The study shows that the safety coefficient of the excavation face decreases with the increase in the slope angle of the excavation face, with the increase in spacing of the MJS zone, and with the increase in height of the MJS zone arrangement, while the safety coefficient of the excavation face increases with the increase in strength of the MJS zones themselves and the increase in the strength of the soil between the MJS zones. Further, the machine learning model is applied to predict the stability of the excavation face under different cases, and the relevant fitting accuracy is above 0.9, which can predict the stability of the excavation better.

Low carbon urban rail transit station city integration based on building information modeling and sensor fusion

In order to better play the role of information technology in the construction management of rail transit projects, we analyze the application of geographic information system (GIS) + building information modeling (BIM) technology in the construction management of rail transit projects by combining the characteristics of GIS+BIM technology and aiming at the overall improvement of project management efficiency and technical management methods. This study is mainly conducted with the support of BIM technology and sensing technology. In the design stage, carbon emissions are classified according to the source activities of building carbon emissions, and the carbon emissions in the building life cycle are quickly calculated by using BIM technology, and the design is optimized according to the analysis of the budget results. The experimental results prove that the low-carbon building evaluation standard cloud model of all-electronic computer interlocking system for urban rail transit established in this study, combined with the comprehensive weighting results, calculates the low-carbon index cloud model and comprehensive cloud model, and derives the operational safety risk level of the all-electronic computer interlocking system, and the model optimization effect is good. Practice shows that GIS+BIM technology can realize the refinement and informatization of construction management, and has a broad development space in the field of urban rail transit and urban underground space construction.

DGM-MDS: Dynamic grouting monitoring with a novel multi-channel distributed system

With the development of engineering construction, the construction of underground space with complex geological structures is increasing, resulting in more potential engineering problems (e.g., water inrush). Grouting, as a technology for prevention and control, has been widely used in engineering applications such as tunnel construction and pile foundation engineering. To the best of our knowledge, a trenchless visualization method, which can effectively control and evaluate grouting fluid filling of underground space for energy saving, environmental protection and reliable construction quality, is underexplored today. To this end, a novel distributed wireless sensor network-based solution is proposed in this paper. Specifically, metal electrodes are first inserted into the ground in the grouting area to collect data from underground space during the grouting process. Then, by leveraging resistivity inversion imaging software, an effective dynamic monitoring can be achieved so that the grouting effect can be evaluated accurately by observing the grouting diffusion, filling range and evolution process in the underground. Finally, the proposed distributed system can collect multiple profile data in quasi real-time by flexible wireless networking mode, leading to comprehensive and effective monitoring of underground filling for grouting engineering. Experiments on lossy clay area show the effectiveness of our proposed distributed system for engineering monitoring in the field of grouting.

Deformation Mechanism and Control of In-Situ Assembling Caisson Technology in Soft Soil Area under Field Measurement and Numerical Simulation.

With urban space becoming much more crowded, the construction of underground spaces continues to expand to deeper, and the requirements for the large depth and minor deformation in urban engineering construction are getting more urgent. A new kind of in-situ assembling caisson technology (called VSM) is a vertical shaft method (VSM), which excavates the stratum under water with a mechanical arm and assembles the prefabricated caisson segments at the same time. This paper takes the Shanghai Zhuyuan Bailonggang Sewage Connecting Pipe Project as an example, which is the first construction project in the soft soil area, such as Shanghai, and makes a technical analysis of the VSM by comparing the field measurement and numerical simulation. Ground settlements and layered deep displacements were monitored in the field measurement during the VSM construction. It shows that the maximum ground settlement caused by the VSM is 15.2 mm and the maximum horizontal displacement is 3.74 mm. The influence range of the shaft excavation on the ground settlement is about 30 m away from the shaft center. The results demonstrate that the VSM construction has great applicability in the soft soil area. A finite element simulation model of the VSM shaft is established and verified by field measurement. There is a certain error between the traditional theoretical calculation by analogy to the common retaining walls of the deep foundation pit and the measured results, while the simulation results are relatively consistent with field measurements. The reasons for the difference are well-analyzed. Finally, the effects of the VSM construction method on the engineering environment are analyzed, and the suggestions for deformation control in the future are put forward.

Constructive and technological solutions for underground space safety amidst dense historical buildings and weak foundation soils

The article considers the issues of geotechnical substantiation and application of constructive and technological measures for the construction of underground space up to 4.4 m deep in the closed courtyard of the Palace built in the 18th century in conditions of weak water-saturated soils in the historical center of St. Petersburg. The underground space of 18.4 x 29.4 m was arranged in close proximity to the enclosing structures of civil buildings built in the 18th - 19th centuries. The article presents design solutions based on the finite element calculation method for strengthening the foundations of existing buildings, enclosing the pit and the foundations of the new structures, which comprehensively ensure compliance with the required safe additional deformations of the surrounding buildings. The results of geotechnical monitoring are presented in comparison with the results of a numerical calculation of the main load-bearing structures of new and existing buildings of the surrounding development during the construction process.

Analysis of moisture migration, temperature, and pore structure characteristics of the muddy clay column subject to artificial ground freezing based on LF NMR

Nowadays, artificial ground freezing (AGF) is widely used in the construction of underground spaces in soft soil areas. Most of the existing studies are focused on micro and macro analyses of small volume samples under AGF, while the research on large soil column is insufficient. Therefore, it’s crucial to explore the characteristics of the large soil column by AGF. In this paper, the low field nuclear magnetic resonance (LF NMR), and the unidirectional freezing test of large muddy clay columns were carried out. The results indicate that the most difference is that along the soil column, each soil layer has a connection with each other, owing to the pore structure connectivity and moisture migration within it. Moreover, slow-growing platforms or even temperature crosses appeared during thawing, due to the downward movement of water under consolidation and gravity which may interfere with heat transfer (upward movement). Along the large muddy clay column, moisture migration in the soil column is coupled with temperature as well as pore structure. Specifically, temperature difference and pore structure provide the power source and transport channel for moisture migration, respectively, while the moisture migration changes the temperature of each layer of the soil column and the composition of the pore structure. The pore structure indirectly influences the temperature of soil column by affecting the amount of moisture migration, while temperature significantly changes the number and size of pores inside the soil column. Furthermore, by LF NMR experiments, it was found that the pore size distribution was relatively dispersed and the characteristics of moisture migration at different heights of the soil column could be divided into three stages. This study can be used as theoretical guidance for understanding the change laws among moisture migration, temperature, and pore structure of the muddy clay as well as for helping the construction of AGF in the underground space.

Using multi objective optimization in term of position and area of the air outlet shaft in Showadan

Using the geothermal energy is one of the best solutions that led to construction of underground spaces in different parts of the world. “Shovadan” is one of the underground buildings which can be seen in the southwestern regions of Iran, especially in the cities of Dezful and Shushtar. Shovadan consists of a main space called “Sahn” that is usually built at a depth of 8 to 12 m under the ground and is accessed by a stairs. Fresh air enter the Sahn through these stairs and exit through a vertical channel called the air outlet shaft (AOSh). The configuration of various components of the Shovadan have a great impact on the thermal performance and ventilation efficiency inside it separately. In this paper a multi-objective optimization method is used to find the best position and the most optimal cross-section area of the AOSh. First, one of the most common forms of the Shovadan in Dezful city was selected as the base sample; then based on the different positions and cross sectional areas of the AOSh, 45 case studies were extracted for analysis. In the next step, the case studies were simulated in CFD and the average temperature and velocity inside their Sahns were calculated. Finally, using EDT analysis and Genetic algorithm (GA), the most optimal position and cross-section area of the AOSh were determined. The results showed that the most optimal case for thermal comfort in summer is formed when the distance between the stairs and the AOSh is increased and the cross-sectional area of the AOSh is decreased.

Evaluation of underground space perception: A user-perspective investigation

The underground environment has different characteristics from the above-ground space. An in-depth understanding of the user perception towards the underground space is essential for constructing a human-friendly underground space. However, research on the requirements of underground space from the user’s perspective is lacking. To fill this knowledge gap, the evaluation indexes of the user perception of underground space (UPUS) were constructed in this study on the basis of principal component analysis and the information entropy method, and the fuzzy comprehensive evaluation method was used to assess the UPUS of the Xinjiekou underground complex in China. Then, the advantages and disadvantages of the Xinjiekou underground complex were analysed using importance-performance analysis. Results indicate that the UPUS is multidimensional and can be evaluated from eight aspects: space connectivity and positioning, physical environment, convenience, safety, facility, landscape, application of smart technology and environmental diversity. The findings shed light on the theoretical investigation and practical construction of underground spaces in urban areas.

Development and application of a full-scale mechanical rock-cutting platform for measuring the cutting performance of TBM cutter

With the massive development of mechanical equipment for underground space construction, understanding the cutting mechanism and measuring the cutting performance of various cutters used in tunnelling boring machine prior to the construction is vital for increasing tunnelling efficiency and reducing cost. Mechanical rock-cutting tests have been an indispensable method for investigating the cutting characteristics, which can be effectively used for guiding the mechanical excavation of underground engineering. In this paper, a novel full-scale cutting platform developed by Shanghai Shield Design and Experimental Research Center Co., Ltd is introduced. The rock types, rock structure types, cutter types, cutting radius, rotation speed, penetration depth, cutting modes, cutter spacing and cutter installation angle are considered and integrated into the design of cutting platform. Specifically, different cutters, including disc cutters, scraper cutters, shell cutters and pick cutters, can be considered in this platform. Moreover, the circular cutting mode can be conducted with cutting diameter ranging from 0 to 6.2 m, and the arc cutting method is originally proposed to perform a rotary cutting test with cutting diameter above 6. 2 m. Notably, a laser measurement method is newly performed to measure the rock surface profile and calculate the rock cutting volume in the rotary cutting mode. The rock-cutting platform consists of mechanical system, hydraulic system, cutterhead system, control system, data sensing and acquisition system. The measuring reliability and accuracy of the newly designed rock-cutting platform and laser measurement is experimentally verified by the rotary cutting tests on granite and mortar using disc cutter and scraper cutter. A critical cutting radius of 1000 mm for side force is acquired, and the effects of cutting radius and cutting depth are initially investigated. The development of the full-scale rock-cutting platform is an effective measurement method for cutting performance, which can provide data support for optimization of cutterhead layout and determination of working parameters.

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.

Deformation characteristics and failure evolution process of the existing metro station under unilateral deep excavation

With the rapid development of underground space construction, there are more and more large-scale deep foundation pit projects on one side of the metro station. Unilateral deep excavation will result in an imbalance of the earth pressure on both sides of the existing metro station, which is a major engineering risk. Therefore, considering the station width and the excavation depth, this study focuses on the deformation characteristics and failure evolution process of the existing metro station structure caused by unilateral excavation based on the physical model test and discrete element method (DEM) analysis. This research shows that the lateral deformation of the top of the station caused by unilateral excavation is the most significant. Secondly, as the excavation depth increases and the station width decreases, the increase rate of the station overall inclination and lateral displacement becomes more significant. Thirdly, the structure fails when the excavation depth is 5/6H (H is the station height). Then the station instability leads to three disturbed regions in the adjacent stratum. The contact force between soil particles in the disturbed region is small and the stability is poor. Finally, the failure evolution process of the existing station under unilateral excavation is divided into three stages: (a) when the excavation depth is 0–1/2H, the soil and structure are stable; (b) when the excavation depth is 1/2–3/4H, the lateral deformation and inclination of the station reach the security warning range; (c) when the excavation depth is 3/4–1.0H, the structure is unstable and slips laterally, resulting in the ground collapse and local soil extrusion failure. This study reveals the risks of the existing station at different excavation stages, which can make risk prediction for the construction of the project.

Study on Development and Utilization of Underground Space in Linyi’s Smart City

The construction of underground space of intelligent city can improve the efficiency of service-oriented government, improve the urban ecological environment and demand of “intelligent and efficient, environmental intensive and low-carbon ecological”.The paper firstly introduces the development of underground space in Linyi Smart City. Secondly, the problems in the development of the underground space in Linyi Smart City are analyzed. Finally, the author puts forward some Suggestions on the development and utilization of underground space in Linyi Smart city, so as to promote the sustainable development of Linyi to the eco-type and economical Smart city.

Unloading Response Characteristics of Cross Fault Caverns: Effect of Fault Angles

The research of unloading response characteristics of caverns with weak structure has important engineering value for the development and construction of underground space. In this paper, firstly, the cross fault cavity model is established based on particle flow code (PFC) software, considering different fault dip angles. The parallel bond model (PBM) is used in the cavern model and the smooth joint model (SJM) is used in the fault model. Then, the mechanical, acoustic emission (AE), energy response characteristics and failure modes of the cavern model with different fault angles are explored. The research result show that the fault angle has a great influence on the stress distribution and failure modes of surrounding rock. The existence of faults does not change the overall law of AE evolution curve, that is, the number of AE hits increases first and then decreases. However, the existence of faults changes the maximum number of AE hits and the duration of AE. When the cavern is unloaded, the strain energy of the model first decreases and then increases.

Analysis on Technical Difficulties and Quality Control Factors of Large Underground Space Construction

Analysis on Technical Difficulties and Quality Control Factors of Large Underground Space Construction

Mechanical properties of a new string capsule drainage anchor and its supporting effect in deep foundation pit

With the increase of the scale and depth of urban underground space construction in coastal soft soil area, the traditional anchoring technology has been difficult to meet the requirements of deep foundation pit excavation and support. This paper puts forward a new type of string capsule drainage anchor supporting structure, introduces its structure composition, analyzes its working mechanism and mechanical characteristics, the calculation formula of ultimate bearing capacity of small cylindrical shear failure between anchor and surrounding soil is given, finally, the supporting effect of the new structure in deep foundation pit engineering is simulated and analyzed by finite element software. It is concluded that the stress of the new type of anchor can be divided into three stages: static earth pressure, plastic zone development and plastic zone breaks through; the new anchor can quickly dissipate the pore water pressure in the surrounding soil, which is more conducive to the stability of foundation pit; the axial force distribution presents a “sawtooth” shape, and the axial force increases sharply in the expanding section; the supporting effect of the new anchor is more obvious than that of the traditional anchor, which can more effectively inhibit the horizontal displacement of the slope.

Underground space optimization of smart city based on information processing technology

This study explores the underground space optimization method of smart city based on information processing technology to save space optimization operation time. Taking coordinate of intersection point, radius of intersection point, mileage of vertical slope change point and elevation of slope change point as design variables, taking total cost of underground space construction of smart city as objective function and taking plane, vertical section, horizontal and vertical combination and environmental impact as constraint conditions, a multi-objective optimization mathematical model of underground space of smart city was constructed. Parete genetic algorithm in information processing technology was used to solve the multi-objective optimization mathematical model of the underground space of smart city, realize the automatic search for the optimal scheme of the underground space of smart city, and complete the intelligent optimization process of the underground space construction scheme of smart city. The results show that the method obtained from this study can effectively optimize the underground space of smart city and obtain the optimal subway laying line, save space and optimize operation time and improve the convergence of the method.

The main characteristics of urban underground space regulatory plan from the perspective of China’s spatial planning: A practice in Beijing Sub-Center

In order to better solve the new problems encountered in the national development, China is gradually establishing a new national territory spatial planning system. It can implement the requirements of whole-area and multi-element control of land and space. Underground space planning is a special planning in the new spatial planning system. We will explore how to scientifically and reasonably prepare underground space planning. Combined with the planning practice of Beijing and Sub-Center, we propose that the underground space planning system should be further improved, especially at the regulatory planning level. It can not only refine the master planning requirements of underground space, but also effectively guide the detailed planning and project construction of underground space. This paper attempts to put forward the main characteristics of underground space regulatory planning, hoping to provide reference for other cities’ underground space planning. The first is ecological priority and limited utilization. Detailed geological survey is the basis of underground space planning. In the Sub-Center, we evaluated the requirements of geological ecological protection and the impact of geological disasters, and delineated the three-dimensional utilization boundary of underground space and the influence scope of geological disasters. The second is the improvement of space management and space vitality. We explore the allocation method of underground space covered area, and divide the covered area into each construction site, giving priority to the key areas such as Universal Studios and metro station areas. The third is multi-dimensional utilization and planning integration. The underground facilities are planned in depth and intensively. The plan puts forward detailed in-depth layout guidance, focusing on the construction of Facility Service Ring, and coordinating the intensive construction of underground tunnels, metro and underground municipal facilities. The fourth is to encourage the application of new technologies. The planning will reserve sufficient space for future development, such as the construction of underground logistics, multistage rainwater collection and underground heat utilization in the Sub-Center.