Underground Utilities Research Articles

Challenges in Underground Utility Tunnel Construction and Strategies for Intelligent Management

With the rapid advancement of urbanization, the importance of municipal infrastructure construction is increasingly highlighted. The municipal underground pipeline project, as a key link, aims to optimize the living environment and improve the quality of life services for the people. Given the continuous growth of urban population and the increasingly scarce land resources, the municipal comprehensive underground pipeline project effectively alleviates the pressure on urban land resources by efficiently utilizing underground space. However, the construction of such projects involves complex construction technologies, and scientific and reasonable intelligent management methods are needed to ensure project quality and construction efficiency. In view of this, the author discusses the challenges faced in municipal underground pipeline construction and the intelligent management strategies through participation in the design and construction of several pipeline projects.

Pushing boundaries in slurry microtunneling: Innovations in microtunnel boring machine design for hard rock conditions

AbstractFor microtunneling in hard rock, as it is encountered very often in alpine tunneling, the continuous further development of technologies plays a key role to overcome the limitations in drive length and to improve performance. During the last decades, the application range of slurry microtunneling has been considerably extended and more demanding projects have been designed for underground utilities installations worldwide, including many sewage tunnels and hydropower plants. The prevailing ground conditions still play a key role and determine the limits for alignment design and the possible use of trenchless construction methods. In hard rock conditions with high rock strength and/or abrasivity, the applicability of slurry microtunneling has been especially limited in the non‐accessible diameter range in the past. With the new AVN 800 HR for hard rock microtunneling, Herrenknecht has developed a machine concept, enabling drives of up to 200 m, with precise steering of the MTBM. Longer drives, even through hard rock, make microtunneling a more economic, flexible, and more environmentally friendly construction method. New opportunities for clients and consultants in the planning of tunnel routes in alpine environments for different infrastructure installations can be considered, making trenchless installations even more cost‐effective, while improving public acceptance.

Seismic behavior of soil-tunnel-building system considering earthquake frequency contents

Rapid urbanization has led to limited land availability, prompting the construction of residential and underground utility facilities in close proximity, forming an interconnected system with the surrounding soil. However, studies on the seismic behavior of such integrated systems are scarce due to their complex soil-structure interaction (SSI) mechanism. Furthermore, the dynamic behavior of these coupled structures depends heavily on earthquake characteristics like frequency content, an aspect that remains largely unexplored. This study aims to investigate the effects of earthquake frequency on the dynamic behavior of soil-underground structure-aboveground structure coupled systems. Using a novel experimental-numerical approach, two centrifuge tests were used to validate the numerical modeling framework. Three cases (soil-building, soil-tunnel, and soil-tunnel-building coupled systems) are then analyzed under earthquakes with varying frequency content. Results demonstrate how seismic response and SSI indicators of the structures evolve with changing seismic frequencies, offering valuable insights for enhancing safety measures in urban megacities.

Assessment of Energy Recovery Potential in Urban Underground Utility Tunnels: A Case Study

Underground spaces contain abundant geothermal energy, which can be recovered for building ventilation, reducing energy consumption. However, current research lacks a comprehensive quantitative assessment of its energy recovery. This research evaluates the energy recovery potential of the Xingfu Forest Belt Urban Underground Utility Tunnels. Field experiments revealed a 7 °C temperature difference in winter and a 2.5 °C reduction during the summer-to-autumn transition. A computational fluid dynamics (CFD) model was developed to assess the impact of design and operational factors such as air exchange rates on outlet temperatures and heat exchange efficiency. The results indicate that at an air change rate of 0.5 h−1, the tunnel outlet temperature dropped by 10.5 °C. A 200 m tunnel transferred 8.7 × 1010 J of heat over 30 days, and a 6 m × 6 m cross-sectional area achieved 1.1 × 1011 J of total heat transfer. Increasing the air exchange rate and cross-sectional area reduces the inlet–outlet temperature difference while enhancing heat transfer capacity. However, the optimal buried depth should not exceed 8 m due to cost and safety considerations. This study demonstrates the potential of shallow geothermal energy as an eco-friendly and efficient solution for enhancing building ventilation systems.

Transverse seismic analysis method of underground interchange prefabricated utility tunnel

The rapid development of underground utility tunnels has led to the formation of a large number of interchange utility tunnels. Due to significant differences in the lateral resisting stiffness in orthogonal directions, coupled with the close relationship between soil deformation and the depth of the utility tunnel, the seismic response mechanism of the interchange utility tunnel is complex. This paper proposes a method for transverse seismic analysis of the underground interchange utility tunnel based on the response displacement method. A load-structure analysis model of a certain underground cross-type interchange utility tunnel is first established. Then, the different conditions corresponding to maximum relative deformation between layers of the interchange node are discussed, and the proposed method is validated via the time-history analysis method. Based on the proposed analysis method in this paper, seismic response analysis is performed on the interchange utility tunnel considering the condition of vertical incidence of three different input seismic waves. Discussions are conducted in terms of internal forces, inter-story displacement angles, and damage responses under seismic excitations in different principal axis directions. The results show that under major earthquakes, the maximum inter-story displacement angle of the interchange node exceeds the standard limit by up to approximately 184 %, while the tensile damage can reach up to 0.985, significantly surpassing the tensile damage limit. Accordingly, the interchange node is the weakest part of the interchange utility tunnel. There exists deformation inconsistency between the interchange node and standard segments due to significant stiffness differences, with the influence range of the interchange node on internal forces, inter-story displacement angles, joint deformations and damage of the utility tunnel is approximately 7, 6, 8, and 6 prefabricated standard segments, respectively. Since the maximum relative deformation between layers of the interchange node does not occur simultaneously, for double-layered and multi-layered interchange utility tunnels, it is necessary to comprehensively consider the maximum inter-story displacement angle between each layer to determine their most unfavorable condition. The analytical method and related research conclusions presented in this paper can provide references for the transverse seismic design of interchange utility tunnels.

Detection of shallow underground targets using electrical resistivity tomography and the implications in civil/environmental engineering

Applying the electrical resistivity tomography (ERT) technique in detecting very near-surface targets is quite challenging in geophysical investigation, especially in civil and environmental engineering for adequate planning and designing of structural foundations, contributing to the overall safety and efficiency of construction projects. However, locating the exact position and depth of underground targets such as faults, underground utilities, and contaminants is more challenging. Therefore, this study is aimed at examining the geophysical response of various buried targets and evaluating the ability of ERT to detect buried targets in terms of locations and depths of occurrence in the context of engineering investigation and environmental studies. A laboratory test was conducted on the targets to determine their electrical conductivity and resistivity before burial. The two-dimensional (2D) ERT survey was performed on thirteen targets buried at the site using both Wenner and dipole–dipole (DD) arrays. Both arrays captured the metallic targets with a low electrical resistivity contrast (< 0.1 Ωm) corresponding to the laboratory results. In comparison, the positions of the non-metallic buried targets were found to have a high resistivity contrast greater than 3000 Ωm, matching the laboratory results. The modelled pipes and the car engine block captured by both DD and Wenner arrays on 1.0 m electrode spacing were relatively smeared and poorly resolved in shapes, sizes and geometries, while some were not captured. The electrode spacing of 0.25 m and 0.50 m was explored on undetected targets, which provide a better resolution with sizes and depths compared to 1.0 m spacing but did not produce satisfactory results in some cases. The success and failure of ERT to detect a few targets were discussed alongside the environmental and engineering implications. The effectiveness of both arrays was assessed by their sensitivity in mapping the change in subsurface resistivity values. The DD array shows sensitivity to horizontal variations in resistivity values with low signal. In contrast, the Wenner array shows a good signal strength with a good change in the horizontal and vertical resistivity values. In addition, both arrays show capacity in mapping the geophysical signature of the buried targets and subsurface structures, which has significant application in engineering and environmental investigations.

Strategic Considerations for Enhancing Civil Defense Systems in Subways and Underground Utility Tunnels Amid Evolving National Defense Mobilization Needs

Strategic Considerations for Enhancing Civil Defense Systems in Subways and Underground Utility Tunnels Amid Evolving National Defense Mobilization Needs

Oedometer Study Regarding the Consolidation Behavior of Nanjing Soft Clay

Ground settlement resulting from consolidation may lead to tilted buildings, cracks in the pavement, damage to underground utilities, etc. Therefore, it is crucial to understand the consolidation behaviors (including primary consolidation and secondary compression) of the soil of the subgrade. There is a large amount of soft clay deposited in Nanjing, located in the Yangtze River Basin. The consolidation behavior of Nanjing soft clay can significantly affect foundation design and the cost of construction. In this study, experimental measurements of the consolidation behavior of Nanjing soft clay were conducted, and parameters (such as pre-consolidation pressure, secondary consolidation index and secondary consolidation ratio) related to consolidation were assessed. The concept of simulated over-consolidation ratio (OCRs) was proposed, and the close relationship between primary consolidation and secondary compression settlement and the OCRs of Nanjing clay was investigated.

Interactive Mixed Reality Methods for Visualization of Underground Utilities

AbstractThis research aims to overcome the difficulties associated with visualizing underground utilities by proposing six interactive visualization methods that utilize Mixed Reality (MR) technology. By leveraging MR technology, which enables the seamless integration of virtual and real-world content, a more immersive and authentic experience is possible. The study evaluates the proposed visualization methods based on scene complexity, parallax effect, real-world occlusion, depth perception, and overall effectiveness, aiming to identify the most effective methods for addressing visual perceptual challenges in the context of underground utilities. The findings suggest that certain MR visualization methods are more effective than others in mitigating the challenges of visualizing underground utilities. The research highlights the potential of these methods, and feedback from industry professionals suggests that each method can be valuable in specific contexts.

Comparison of Seismic Responses of Underground Utility Tunnels Using Simplified Analysis Methods

Comparison of Seismic Responses of Underground Utility Tunnels Using Simplified Analysis Methods

Review of One Call Operator Membership and Exemptions for State Departments of Transportation

One Call centers are part of a nationwide system in the U.S. that aims to reduce the probability of excavators causing damage to underground utilities during construction projects. Laws dictating which utility operators must participate in One Call systems differ across states. In some states, certain utility operators have membership exemptions in One Call systems. However, these exemptions have come under scrutiny as they limit grant opportunities available for One Call centers. State Departments of Transportation (DOTs) are one group of institutions frequently exempted from One Call requirements, though they operate underground utilities as part of their transportation networks. To discern the impacts of exemptions or required membership in state One Call systems, this study involves a comprehensive literature review on One Call legislation, a national survey of state DOT subject-matter experts, and 12 in-depth case studies with DOT personnel. These efforts show that a definitive solution is not apparent. When a state DOT evaluates its One Call operator membership, the DOT must carefully consider many variables and potentially complex interactions. Moreover, quantifying the costs and benefits of operator membership proves challenging, as they vary as a result of the diverse criteria. This study reveals that deciding on One Call memberships or exemptions at a national level is not judicious. In fact, the findings emphasize that the state DOT is the most suitable entity to determine whether the One Call operator membership is warranted. Thus, their voices should be decisive when deliberating over their One Call operator memberships.

Automatic classification of underground utilities in Urban Areas: A novel method combining ground penetrating radar and image processing

Precise determination of the location of underground utility networks is crucial in the field of civil engineering for: the planning and management of space with densely urbanized areas, infrastructure modernization, during construction and building renovations. In this way, damage to underground utilities can be avoided, damage risks to neighbouring buildings can be minimized, and human and material losses can be prevented. It is important to determine not only the location but also the type of underground utility network. Information about location and network types improves the process of land use design and supports the sustainable development of urban areas, especially in the context of construction works in build-up areas and areas planned for development. The authors were inspired to conduct research on this subject by the development of a methodology for classifying network types based on images obtained in a non-invasive way using a Leica DS2000 ground penetrating radar. The authors have proposed a new classification algorithm based on the geometrical properties of hyperboles that represent underground utility networks. Another aim of the research was to automate the classification process, which may support the user in selecting the type of network in images that are sometimes highly noise-laden. The developed algorithm shortens the time required for image interpretation and the selection of underground objects, which is particularly important for inexperienced operators. The classification results revealed that the average effectiveness of the classification of network types ranged from 42% to 70%, depending on the type of infrastructure.

The 3D localization of subsurface pipes from Ground Penetrating Radar images using edge detection and point cloud segmentation

This research introduces an innovative algorithm using Ground Penetrating Radar (GPR) for inspecting underground infrastructure non-destructively, surpassing R-CNN methods by combining signal processing with computer vision techniques including hyperbola correlation, point cloud segmentation and noise reduction based on linearity, density and echo patterns. Utilizing on-vehicle multi-channel GPR and without training, it maps pipes in 3D with high precision on both experimental fields and real roads. The method demonstrated remarkable accuracy, with an average error of 0.1175 m in locating pipes, outperforming deep learning methods requiring numerous training data. The ablation study and sensitivity analysis on hyperparameters further prove the improvement from the proposed method and its robustness. These outcomes offer notable improvements in infrastructure monitoring, highlighting the potential for automated underground utility detection.

Numerical modeling of optimum spacing of TBM disk cutters, using a finite element method simulation

AbstractDue to the growing demand for underground communication methods, water transfer, and utility tunnels, employing mechanized tunneling methods is unavoidable. Diverse disk cutters are built and operated. A proper cutterhead design will have a direct impact on the net advance rate and therefore significantly contribute to the project success. The research effort presented in this contribution is dealing with the spacing effect on the forces on disk cutters, and their specific energy (SE) has been investigated. It uses finite element numerical modeling with ABAQUS software to simulate the rock‐cutting process to find an optimal spacing in barre granite. The results show that theratio of the disk spacing to the penetration rate, the normal and rotational forces on the disk cutters, and the SE values increase to the optimal level and then decrease. The optimal spacing for the examined rock type is discussed in further detail, and a recommendation for the optimum cutterhead layout is presented.

Energy-based coupling risk assessment (CRA) model for urban underground utility tunnels

As a kind of highly integrated urban critical infrastructure, the urban underground utility tunnel hosts various pipelines to facilitate the city life. But the integration of hazardous pipelines like natural gas pipelines and electric cables inside a confined infrastructure also brings emerging risks due to coupling effect, which have not been systematically analysed by the existing method. So, there is an essential need for a coupling risk assessment (CRA) model to tackle coupling effects and corresponding coupling accidents in utility tunnels quantitatively. A clear definition and classification of coupling effect, synergistic effect, and cascading effect are proposed in this work. By introducing the energy transfer and out-of-control theory, it is feasible to identify interacted hazards systematically and coupling accidents in utility tunnels. Natural gas explosion, cable fire, and rain-triggered ponding are identified as typical coupling accidents to perform CRA. The results indicate that the risks of the 3 coupling accidents are considerable, and fatality is possible in the case of gas explosion and ponding. It can be concluded that the current firefighting systems and drainage systems are not sufficient for risk mitigation of utility tunnels with coupling effect.

Probabilistic Method to Fuse Artificial Intelligence-Generated Underground Utility Mapping.

Utility as-built plans, which typically provide information about underground utilities' position and spatial locations, are known to comprise inaccuracies. Over the years, the reliance on utility investigations using an array of sensing equipment has increased in an attempt to resolve utility as-built inaccuracies and mitigate the high rate of accidental underground utility strikes during excavation activities. Adapting data fusion into utility engineering and investigation practices has been shown to be effective in generating information with improved accuracy. However, the complexities in data interpretation and associated prohibitive costs, especially for large-scale projects, are limiting factors. This paper addresses the problem of data interpretation, costs, and large-scale utility mapping with a novel framework that generates probabilistic inferences by fusing data from an automatically generated initial map with as-built data. The probabilistic inferences expose regions of high uncertainty, highlighting them as prime targets for further investigations. The proposed model is a collection of three main processes. First, the automatic initial map creation is a novel contribution supporting rapid utility mapping by subjecting identified utility appurtenances to utility inference rules. The second and third processes encompass the fusion of the created initial utility map with available knowledge from utility as-builts or historical satellite imagery data and then evaluating the uncertainties using confidence value estimators. The proposed framework transcends the point estimation of buried utility locations in previous works by producing a final probabilistic utility map, revealing a confidence level attributed to each segment linking aboveground features. In this approach, the utility infrastructure is rapidly mapped at a low cost, limiting the extent of more detailed utility investigations to low-confidence regions. In resisting obsolescence, another unique advantage of this framework is the dynamic nature of the mapping to automatically update information upon the arrival of new knowledge. This ultimately minimizes the problem of utility as-built accuracies dwindling over time.

Investigating the response of Urban Underground Utilities (3U) within an elastic and elastoplastic geological formation: Employing numerical and analytical techniques

Investigating the response of Urban Underground Utilities (3U) within an elastic and elastoplastic geological formation: Employing numerical and analytical techniques

Erratum to: Crack Detection of the Urban Underground Utility Tunnel Based on Residual Feature Pyramid Attention Network

Erratum to: Crack Detection of the Urban Underground Utility Tunnel Based on Residual Feature Pyramid Attention Network

Underground utility inspection using ground penetrating radar

Underground utility inspection using ground penetrating radar

LESSONS LEARNT FROM SOIL IMPROVEMENT CASE STUDIES

In Saudi Arabia two methods of soil improvement have been customarily employed. They are soil improvement by means of stone columns, and soil improvement by means of controlled modulus columns, that is CMC. Each of these methods have their own challenges to offer. Experience has shown that the sub-surface geology of the coastal areas of Saudi Arabia are marked with deep layers of poor soil termed locally as sabkha soil. Test results have determined that sabkha soil is known to have low shear strength, high soil compressibility, and high concentration of chlorides and sulphates which are corrosive to concrete, steel, and other construction materials. Design of foundations over a sabkha deposit remains a challenge and requires soil improvement. The CMC installation utilizes reverse flight augers, which displaces the soil laterally. However, it offers a huge challenge of post-operation trimming and cutting of CMCs. for stone columns, soil is removed during the drilling operation creating environmental issue. It also offers challenges as the huge impact during its operation are likely to damage the underground utilities. The environmental issues thus created can pose yet other challenge. This research paper is a case study that collates the experiences of soil improvement methods employed on a project in Saudi Arabia – vis-à-vis their advantages and the challenges encountered.