Underground System Research Articles

Deep learning-based detection of qanat underground water distribution systems using HEXAGON spy satellite imagery

Qanats are a remarkable type of ancient hydraulic structure for sustainable water distribution in arid environments that use subterranean channels to transport water from highland or mountainous areas. The presence of the qanat system is marked by a line of regularly spaced shafts visible from the surface, which can be used to detect qanats using satellite imagery. Typically, qanats have been documented by field mapping or manual digitisation within a Geographic Information System (GIS) environment. This process is time-consuming due to the numerous shafts within each qanat line. However, several automated methods for detecting qanat structures have been explored, using techniques such as morphological filters, custom convolutional neural networks (CNN) and, more recently, YOLOv5 and Mask R-CNN. These approaches used high-resolution RGB images and CORONA images. However, the use of black and white CORONA in CNNs has been limited in its applicability due to a high rate of false positives.This paper explores the potential of YOLOv9 in processing the black and white HEXAGON (KH-9) high-resolution spy satellite system launched in 1971. Two areas in Afghanistan (Maiwand) and Iran (Gorgan Plain) were selected to train the system images extracted from HEXAGON imagery and artificial synthetic data. The training dataset was augmented using the Albumentation library, which increased the number of tiles used. The model was tested using two types of HEXAGON imagery for selected areas in Afghanistan (Maiwand), Iran (Gorgan Plain) and Morocco (Rissani), and CORONA imagery in Iran (Gorgan Plain).Our study provided a model capable of predicting the location of qanat shafts with a precision of over 0.881 and a recall of 0.627 for most of the case studies tested. This is the first case study aimed at detecting qanats in different landscapes using different types of satellite imagery. Using real, augmented, and artificial data allowed us to generalise the representation of qanats into lineal groups of circular features. Thanks to applying labelling for individual qanats and their pairs as separate classes, our approach eliminated most of the isolated and clustered false positives.

Construction simulation and scheme optimisation of complex underground cavities

Underground cavities have complex spatial structures and geological settings, their arrangement is dense and crisscrossed. The construction system involves multiple work surfaces, levels, and processes. The close integration of construction simulation with actual production conditions is crucial for enhancing the guidance that simulation results provide for practical engineering. Therefore, from the perspective of optimizing construction organization and management, this article comprehensively considers various factors in the construction process, innovatively introduces the principle of production line balance and the concept of rule cycle, and combines technology and management, an underground cavities construction simulation system (UCCSS) is developed. In UCCSS, a hierarchical model is built and calculation are performed on models with different construction methods by modifying the parameters as per the actual engineering characteristics. The simulation results are comprehensively analysed to determine the optimal construction programme. An application case is proposed based on the construction organisation design of the long and parallel diversion tunnels at the CB Hydropower Station. The results show that the system has good practicality and credibility and can provide guidance for the construction organisation design of underground cavities with various features.

A study of XLPE insulation failure in power cables under electromagnetic stress

Underground cables with cross-linked polyethylene (XLPE) insulation are integral to medium voltage (MV) power transmission systems, ensuring continuous electricity supply amidst operational challenges and environmental conditions. However, the reliability of these cables can be compromised over time due to aging and installation-related factors, particularly at joints and terminations. This study offers a comprehensive analysis of how various defects, including spherical air voids, pinholes, and irregularities in semiconducting layers, affect electric field and potential distributions within cable end terminations using COMSOL Multiphysics software. Through detailed simulations, the study identifies significant variations in electric field strength caused by these defects, highlighting critical stress concentration areas. In this study, it assumed that the cable and termination have the same cross-section. By analyzing these simulations, the study provides insights into optimizing cable design and installation practices to enhance the reliability and lifespan of underground power transmission systems. This study introduces a novel approach by combining advanced COMSOL Multiphysics simulations with a detailed analysis of defect impacts on electric field distributions, offering new insights into stress concentrations and degradation at cable terminations. Simulation outcomes reveal significant variations in electric field strengths due to air voids and pinholes in cables and terminations: for 2 mm voids, up to 2.45×106 V mm−1 near the conductor and 56.5 V mm−1 at termination. These findings enhance the understanding of XLPE-insulated cable behavior under electromagnetic stress, providing a basis for mitigating failures and improving overall system performance.

Analysis of Underground Distribution System Models for Secondary Substations

Analysis of Underground Distribution System Models for Secondary Substations

Development of underground communication system for data transmission using Wi-Fi direct and power line communication

Safety and productivity are of utmost concern to companies in the underground mining industry. To improve safety and productivity, it is important to understand the underground environment using sensing methods. Such sensors obtain important measurement factors such as temperature, humidity, and gas concentration that assist with accurate decision making. However, it still remains challenging to develop a communication system that can transmit data obtained by the sensors from the underground to the surface. In addition to that, the cost of maintaining a wireline communication system in an ever-expanding underground mine is high and there is a high risk of wire breakage. Hence, the introduction and use of wireless communication networks (WSNs) in underground communication systems. This study proposes a data transmission system for an underground communication system in which Wi-Fi Direct and power line communications (PLC) are selected as part of the system. The purpose is to conduct a demonstration experiment and analyze the performance of the system based on the conditions of the mine.In this study, it was developed a data transfer system with minimum cost by using PLC and Wi-Fi Direct as a means of communication as well as Wi-Fi Ad hoc. The result of the Wi-Fi Direct system was that the distance from a data logger to a smartphone was 140 m in a straight line. At this time, the communication speed was 9.1MB/s, which means that the miner could recover 230MB of data before the data loggers pass the data to the miner’s smartphone. The distance between smartphones was 130 m in a straight line, and they were able to communicate at 5.7MB/s. By the time the data is shared from one smartphone to another, 72MB of data can be shared. The necessary monitoring data in the underground mine can be transmitted reliably as text and image files.Moreover, based on the results of performance analysis, a design of a data transfer system for the underground mine is demonstrated. The costs of the proposed system are estimated and compared with the most common communication system (leaky feeder). The proposed system can achieve communication for only 3% of its cost and 2% of the maintenance cost. The proposed data transfer system can be installed in a complex underground mine including a dwarf space with low cost and can be easily expanded. This data transfer system can be diverted to other mines with the installation of equipment, making it the data transfer system that underground mining companies are looking for.

Reshaping port-city relationships through underground logistics system: A mixed qualitative approach

Against the backdrop of explosive growth in freight demand, the negative impacts of the traditional road-system-based port-city logistics mode on urban transportation, environment and safety have become prominent livelihood issues, as well as significant economic and social problems. Port-city underground logistics system (PC-ULS) has been widely recognized as an innovative way to ensure the sustainable development of port cities. However, the influence mechanism of PC-ULS on the port-city relationships is still unclear. Thus, this paper attempts to explore the PC-ULS-based port-city relationships formation process and the main influencing factors using a mixed qualitative approach. The social, economic and environmental impacts of PC-ULS on the development of port cities were systematically analyzed using the Shanghe Port ULS and Shanghai Port ULS as the case studies. The results show that the impacts generated by PC-ULS are positive and widely distributed across the economic sphere, port-city traffic, logistics governance, urban equity, stakeholders, ports, and urban spaces, as well as ecological sustainability. Furthermore, the urban planning, technology compatibility and engineering risk related factors have a strong impact on the PC-ULS implementation. A set of incentive policies has been designed to promote the effectiveness of PC-ULS. The findings provide a unique perspective on underground space development and utilization to address port-city conflicts, as well as a reasonable implementation pathway for PC-ULS application.

Intelligent underground garage drainage system based on informatized surveying technology

In recent years, with the impact of environmental factors such as global warming, floods and waterlogging disasters have occurred frequently in China. The traditional drainage devices in underground garages have poor water-blocking effects, which can easily result in sewage entering the garage along with vehicles during severe weather or sudden floods. To address the issue of water accumulation outside underground garages, which prevents vehicles from entering, we propose a set of drainage devices for underground garages to complement the shortcomings of existing market products. This device, controlled by an automated intelligent control system, can effectively control each device to achieve automatic water-blocking and drainage operations in underground garages, as well as car washing. During extremely heavy rainfalls, it can completely seal off the garage and enter flood prevention mode to protect vehicles inside from being submerged. Additionally, as the device is semi-underground, it can save a significant amount of above-ground space without affecting surface traffic or existing facilities, demonstrating practicality and having the potential for widespread adoption.

Geophysical study of the Salto–Arapey Aquifer System in Salto, Uruguay

The Salto–Arapey Aquifer System (SAAS) represents a complex hydrogeological framework composed of a detrital aquifer that lays over a fissured one in the Chaco-Paraná Basin. To enhance our understanding of this underground system, an initiative was undertaken to characterize a specific sector of the SAAS utilizing a geophysical methods known as Audiomagnetotelluric sounding. The primary outcomes of this endeavor include the geoelectrical characterizations of key formations and the development of a 2.5D geological-geophysical model. This endeavor significantly advances our geological and geophysical comprehension of the targeted sector, thereby offering substantial societal and economic benefits. Although the method did not allow differences between sedimentary formations, it did allow the recognition of altered basalts, which would facilitate the identification of areas with considerable potential for the productive development of water wells. Notably, this investigation holds significant local relevance as it presents a replicable methodology to characterize the rest of the system, or even aquifers sharing similar characteristics.

Evaluation of robustness in underground networks

Since the development of urban public mass transport in cities, transport infrastructures are a milestone for the economies of the cities and those of their respective regions. The construction of underground systems has seen impressive growth in many transport networks in the past few years, becoming the hinge of mobility in many of the principal cities of the world. Due to the latter and because of the possibility of disruptive events (natural disasters, random failures, and intentional attacks), many scholars and governments have worried about how robust the networks are. For this reason, in this paper we reviewed the robustness of networks by using graph theory tools to analyze and measure them through a new centrality index, called Sum of Weighted Distances Index (SWDI). The index measures the percentage of changes in traveled distances in the event that the node and all edges containing it are disrupted. To evaluate the robustness of a network, we compare the outcomes of SWDI at a standard working configuration and at a degraded one, modeled as a reduction of performance at a certain edge, edge by edge. SWDI is able to show at what edges and nodes of the network the degradation will have the highest impact. Summing up the normalized SWDI outcomes for all the nodes and edges, the final evaluation of the robustness of the network is obtained. Applications to the two case studies of Boston and Barcelona are developed, compared, and discussed, limited to their topology.

A Data Analytics and Machine Learning Approach to Develop a Technology Roadmap for Next-Generation Logistics Utilizing Underground Systems

The increasing density of urban populations has spurred interest in utilizing underground space. Underground logistics systems (ULS) are gaining traction due to their effective utilization of this space to enhance urban spatial efficiency. However, research on technological advancements in related fields remains limited. To address this gap, we applied a data-driven approach using patent data related to the ULS to develop a technology roadmap for the field. We employed Latent Dirichlet Allocation (LDA), a machine learning-based topic modeling technique, to categorize and identify six specific technology areas within the ULS domain. Subsequently, we conducted portfolio analytics to pinpoint technology areas with high technological value and to identify the major patent applicants in these areas. Finally, we assessed the technology market potential by mapping the technology life cycle for the identified high-value areas. Among the six technology areas identified, Topic 1 (Underground Material Handling System) and Topic 4 (Underground Transportation System) showed significant patent activity from companies and research institutions in China, the United States, South Korea, and Germany compared to other countries. These areas have the top 10 patent applicants, accounting for 20.8% and 13.6% of all patent applications, respectively. Additionally, technology life cycle analytics revealed a growth trajectory for these identified areas, indicating their rapid expansion and high innovation potential. This study provides a data-driven methodology to develop a technology roadmap that offers valuable insights for researchers, engineers, and policymakers in the ULS industry and supports informed decision-making regarding the field’s future direction.

Research and application of rough set attribute reduction algorithm based on genetic algorithm in pipeline network

Abstract Explosion accidents often occur in urban underground pipeline network systems, which has caused safety issues in public life and industrial production. GIS technology can visually manage pipeline equipment and solve the problem of valve closure analysis in the event of current accidents, avoiding the escalation of the situation, but it cannot make predictions. Attribute reduction is one of the core contents of rough set theory and is an NP-hard problem. This article proposes a custom attribute reduction algorithm based on an algorithm and uses the algorithm in the historical burst pipeline dataset of the water supply pipeline industry. The results have shown that this method combined with a decision tree can make predictions before water pipe leakage. The algorithm provides the best result of attribute reduction for decision tree methods, which will improve the speed and accuracy of decision-making.

An underground pipeline relocation decision support system based on BIM and GIS integration

An underground pipeline relocation decision support system based on BIM and GIS integration

Inspection prioritization of gravity sanitary sewer systems using supervised machine learning algorithms

Underground wastewater collection systems degrade with time, necessitating utility owners to engage in ongoing evaluations and enhancements of their asset management frameworks to preserve the performance of their assets. The inspection and condition assessment of sewer pipes are crucial for the effective operation and maintenance of sewer systems. The closed-circuit television (CCTV) is frequently employed to examine sewer pipes in the United States. This procedure is both costly and laborious because of the extensive number of pipes in a metropolis. Prioritisation of inspection for sanitary sewage pipe segments requiring repair or maintenance can be done in advance depending on their past performance. Hence, the aim of this study is to construct a predictive model for the state of sanitary sewer pipes, utilising data collected from a city located in the southcentral region of the United States. The main contribution is that this study used multiclass classification and predicted PACP scores of the pipes. Condition prediction models were developed using extensively utilised supervised machine learning algorithms including logistic regression (LR), k-nearest neighbors (k-NN), and random forest (RF). However, the bulk of the constructed models were assessed using a limited number of assessment measures, such as the receiver operator characteristic (ROC) curve and the area under the curve (AUC) value. This paper asserts that the assessment of the predictive capacity of these models cannot be determined only by relying on ROC and AUC values. Out of the three models evaluated in this study, the LR model had an AUC value of 0.76. However, this model had a higher number of misclassifications or inaccurate predictions compared to the other models. Consequently, these models were assessed using additional assessment measures, including precision, recall, and F-1 scores (which represent the harmonic mean of precision and recall). Curiously, the LR model achieved an F1-score of 0.28 on a scale ranging from 0 to 1. The RF model yielded an F1-score of 0.45 and an AUC value of 0.86. The existing model can be enhanced before it is employed by asset managers during the inspection phase to assess the state of their sanitary sewers and identify essential sewers that require immediate care.

Review of the experience in utilising waste heat from the metro

The exhaustibility of traditional fossil energy sources is leading to the increasing use of unconventional energy sources. One of the most promising areas of alternative energy is the use of low-potential ground energy to heat buildings and structures for various purposes using a heat pump. The subway generates a significant amount of heat, especially when trains are braking, stopping on platforms and picking up speed when they start moving from the station. Thus, to combat the rise in temperature in tunnels and stations, a complex ventilation system is designed, including shafts, fans, and under-platform exhaust. In modern Ukrainian subways, the ventilation system is designed to cope with the rising temperatures in tunnels and stations. This traditional approach results in high energy consumption for running fans and ignores the possibility of using the extracted heat above ground in buildings. Techniques such as lining underground railway tunnels with heat exchanger segments, installing a heat exchanger in a subway ventilation shaft, installing geothermal heat pumps next to a subway tunnel, installing energy piles, energy baffle walls, energy platforms, and introducing absorption pipes into tunnel segments can provide an alternative solution to cool tunnels and the surrounding ground, and transfer the resulting heat to neighbouring buildings for heating. This would also have the benefit of reducing energy consumption for tunnel ventilation. This article discusses the possibility of using waste heat from underground railway systems as a source of low-potential energy to provide heat to, for example, adjacent buildings. Various technologies for utilising waste heat from underground railway tunnels that have already been implemented or whose models are technically and economically feasible are presented.

Investigation into Effects of Coating on Stress Corrosion of Cable Bolts in Deep Underground Environments.

Due to the intricate and volatile nature of the service environment surrounding prestressing anchoring materials, stress corrosion poses a significant challenge to the sustained stability of underground reinforcement systems. Consequently, it is imperative to identify effective countermeasures against stress corrosion failure in cable bolts within deep underground environments, thereby ensuring the safety of deep resource extraction processes. In this study, the influence of various coatings on the stress corrosion resistance of cable bolts was meticulously examined and evaluated using specifically designed stress-corrosion-testing systems. The specimens were subjected to loading using four-point bending frames and exposed to simulated underground corrosive environments. A detailed analysis and comparison of the failure patterns and mechanisms of specimens coated with different materials were conducted through the meticulous observation of fractographic features. The results revealed stark differences in the stress corrosion behavior of coated and uncoated bolts. Notably, epoxy coatings and chlorinated rubber coatings exhibited superior anti-corrosion capabilities. Conversely, galvanized layers demonstrated the weakest effect due to their sacrificial anti-corrosion mechanism. Furthermore, the effectiveness of the coatings was found to be closely linked to the curing agent and additives used. The findings provide valuable insights for the design and selection of coatings that can enhance the durability and reliability of cable bolts in deep underground environments.

Investigation of the impact of Gadon Kaya gate dumpsite on the underground water system in Kano Metropolis using the passive electrical resistivity profiling

Investigation of the impact of Gadon Kaya gate dumpsite on the underground water system in Kano Metropolis using the passive electrical resistivity profiling

Two-Dimensional Hydrodynamic Simulation of the Effect of Stormwater Inlet Blockage on Urban Waterlogging

The drainage capacity of stormwater inlets, which serve as the connection between the surface and the underground drainage system, directly affects surface runoff and the drainage capacity of underground drainage systems. However, in reality, stormwater inlets are often blocked due to the accumulation of leaves, human waste disposal and other factors, resulting in a greatly reduced drainage capacity of the drainage network and, in turn, urban waterlogging disasters. In view of the problem of stormwater inlet blockage, employing a typical waterlogging point in the Lianjiang Middle Road area of Fuzhou city as the research object, the stormwater inlet equivalent drainage method was adopted in this paper to characterize the drainage capacity of the pipe network and enable the control of the stormwater inlet blockage state. Coupled with the stormwater inlet drainage equation, an improved ITF-FLOOD two-dimensional hydrodynamic model was constructed, and the influence of stormwater inlet blockage on urban waterlogging under different rainfall return periods was simulated and analyzed. With increasing rainfall return period, the influences of stormwater inlet blockage on both the maximum area and the depth of accumulated water in the study area gradually decreased compared with those of a nonblocked stormwater inlet, and the growth proportions decreased from 43.35% and 34.58% under the 1-year rainfall scenario to 3.34% and 9.76% under the 50-year rainfall scenario, respectively. However, in terms of the change in the accumulated water level, stormwater inlet blockage will cause an increase, and the influence will always be significant. Overall, stormwater inlet blockage aggravated the waterlogging risk and the extent of waterlogging. Therefore, the results provided a reference for the construction of an urban waterlogging model and have certain guiding significance for waterlogging prevention and control in the study area prone to stormwater inlet blockage.

Numerical Simulation of Geothermal Energy Development at Mount Meager and Its Impact on In Situ Thermal Stress

The Meager Mountain Geothermal Project stands as one of the pioneering geothermal energy initiatives in its early stages of resource development. Despite its abundant geothermal heat resources, no prior studies have systematically evaluated the potential of implementing coaxial borehole heat exchangers on site. This study addresses this research gap by presenting a comprehensive heat transfer model for an underground closed-loop geothermal system utilizing a single coaxial well. Finite element analysis incorporated fluid and solid heat transfer, as well as solid mechanics. The results obtained facilitated the construction of the temperature and thermal stress profiles induced by the cooling effects resulting from years of heat extraction. After 25 years of operation, the outlet temperature has reached approximately 74 °C, and the maximum radial tensile thermal stress amounts to ~47 MPa. Furthermore, the analysis demonstrates that higher fluid velocities contribute to more perturbed temperature and stress distributions. The study attained maximum thermal and electric power outputs of 208 kW and 17 kW, respectively. This research also underscores the significant impact of geothermal gradient and well length on BHE design, with longer wells yielding more power, especially at higher injection velocities.

Important insights into steady-state calculations of voltages and currents in complex sheath bonding configurations of single-core cables

Ensuring effective sheath bonding holds paramount importance within underground single-core cable systems, as a misjudged selection can precipitate cable failures or jeopardize human safety. The foundation of a sound bonding design rests upon a meticulous examination of induced voltages and currents on the cable sheaths. To address this, guidelines and numerical techniques have been introduced, applicable to both handheld calculators and sophisticated software tools. However, their precision hinges on specific features and solving techniques, aspects that remain unclarified in current literature. This paper delves into a comprehensive exploration of sheath current and voltage calculations at steady-state in single-core cable systems. A rigorous benchmarking exercise is undertaken, comparing bonding-design simulation results derived from various computation methods. Moreover, the study scrutinizes the impact of several parameters, shedding light on crucial insights. Building upon this, the paper proposes modelling recommendations for the design and assessment of sheath bonding configurations in complex power cable installations.

Experimental study of an underground pipe gallery pre-cooled chimney ventilation system for a computer room

Natural ventilation is crucial for reducing the energy consumption and carbon emissions of buildings. However, it is often impossible to meet indoor thermal requirements in hot climates. In this study, an integrated natural ventilation system with an underground pipe gallery for pre-cooling and a built-in chimney to enhance the thermal pressure was proposed to cool a computer room. A full-scale experimental platform was constructed to confirm the feasibility of the system. The system performance was investigated by comparing two experimental scenarios, thermal pressure-driven natural ventilation and fan-assisted ventilation, during the transition season in a hot outdoor environment. The underground pipe gallery pre-cooled chimney ventilation system effectively provided a suitable indoor environment for the occupied area, with a mean temperature of 29.1 °C and relative humidity of 57.6 %. The proportion of hours in which the hourly average temperature around the server rack meets the Class C level for computer rooms specified in the national standard is 66.7 %. The maximum pre-cooling capacity of the underground pipe gallery was 3.5 kW. When the assisted fan was operated, the environmental stability of the equipment area further improved, and the system had the potential to operate continuously for 24h to provide a suitable indoor environment.This study provides a strategic solution to passive building design by demonstrating the viability of using an underground pipe gallery for pre-cooling in natural ventilation systems.