Underground System Research Articles

Statistical analysis of heat-induced rock physics and mineralogical alteration processes of monzogranite samples from Bátaapáti, Hungary

Heat-induced physical changes of rocks, as would happen in fire accidents, have crucial importance in the long-term stability of underground openings such as tunnels or radioactive waste disposal chambers. The thermal behaviour of monzogranite from the Radioactive waste repository of Bátaapáti (Hungary) was studied in that context. Room temperature (22 °C) and a series of high temperature (250 °C, 375 °C, 500 °C, 625 °C, 750 °C) heat-treated samples were tested. P and S- ultrasound pulse velocity, bulk density, Duroskop rebound, uniaxial compressive strength, and modulus of elasticity were measured and compared, detecting temperature-related changes. Descriptive statistics and non-parametric Kruskal–Wallis and Median tests were carried out to analyze the heat-induced rock mechanical and mineralogical alteration processes. Based on these results using the data set of physical parameters, it is possible to predict the heating temperature of granitic rocks when the firing or heat stress conditions are unknown. Additionally, the data could be utilized for design and monitoring systems in underground repositories or tunnel systems constructed in granitic rock settings globally. The study demonstrated that significant alteration occurs above 500 °C; all studied rock-mechanical parameters decreased rapidly. These changes are linked to the thermal expansion, micro-cracking in micro-fabric, and volumetric increase and fragmentation of quartz inversion. Consequently, the propagation velocities of P- and S-waves also decreased significantly. Bulk density and Duroskop surface strength significantly decreased above 375 °C, while uniaxial compressive strength and modulus of elasticity dropped drastically at 750 °C after a linear decrease.

Influence of Temperature and Long-Term Operation on Metal Durability of Pipelines of Hydrotechnical Structures

The paper considers the issue of the influence of ambient temperature and service life on the endurance of pipe steels of underground pipelines. The results of numerous experimental studies allowed us to draw the following conclusions. An analysis of the experimental data indicates that for all the studied steels, the endurance decreases with decreasing air temperature, mainly down to-20... -30 °C. This can be explained by the embrittlement of the metal, i.e. a decrease in the plastic properties of the pipeline metal structure. In addition, it can be seen from the given data that low-alloy steels 48KhN, 09G2S, 10GS have the highest endurance. Weak endurance is mainly typical of grade 20 carbon steel. Experimental studies show that with an increase in the service life of pipes, their endurance decreases, and this tendency is inherent in all the studied steels. Studies of the endurance of pipe steels under complex stress states show that static torsional stresses close to the yield strength, when tested in the air, do not reduce fatigue life. Although the corrosive environment significantly reduces the cyclic strength of steel under shear stresses up to τcr=05τY, the conditional limit of corrosion fatigue is not lower than when tested for corrosion fatigue under the action of only alternating stresses in a symmetrical cycle. It could be considered that the torsional stress in the pipeline system does not exceed 10 MPa. In that case, their influence on practical calculations on the endurance of pipes of underground pipeline systems can be neglected.

A study of the underground banking system in Sri Lanka – a phenomenon of Boyle’s law

PurposeThe purpose of the study is to examine the available literature to comprehend what the underground banking system is, for what purposes this method is used and how policymakers should proceed to address this issue.Design/methodology/approachThe approach involved conducting this study and combining it with a critical analysis of the available literature as well as the available historical data. The sources the study has explored include government documents, public hearings, academic articles, case studies and articles available on the internet.FindingsThe study revealed prevention of illegal proceeds is critical, still regulating one entity, is a phenomenon of Boyle’s law, “squeezing the balloon”. If one end of the balloon is squeezed, making the volume smaller, the pressure inside increases, making the un-squeezed part of the balloon expand out. The real issue is not how criminals transfer their illegal earnings; it is the criminals themselves. Hence, the policy decision on this issue needs to be carefully considered.Research limitations/implicationsDue to the complexity of the operating system of Undiyal, this study had a number of limitations, as do many others. Firstly, there are no records of the Undiyal agents or the volumes of transactions publicly available. However, comprehending the scope of the underground operation that exists in the country is quite difficult.Practical implicationsThe study contributes to the academic researchers grasping what type of future research should be focused on in this area according to the study.Social implicationsFrom the point of view of its practical application, the study seeks to resolve social issues that the middle-class population experiences on a daily basis and that have a huge and adverse impact on GDP.Originality/valueTo the best of the authors’ knowledge, this is an original contribution.

Multi-sensor fusion method based on FFR-FK for 3D trajectory measurement of underground pipelines

The three-dimensional (3D) trajectory measurement of underground pipelines is the basis for establishing an underground pipeline network system. Mastering the trajectory of underground pipelines can reduce damage to old pipelines during construction. Traditional pipeline measurement methods have limitations in terms of depth and environment, leading to the inability to obtain accurate information on the pipeline trajectory. In this study, a forward and reverse Kalman filtering fusion measurement algorithm based on MEMS-IMU, MEMS magnetometer, and the odometer was proposed. First, a 16-dimensional Kalman filtering model was established according to the motion mode and working environment of the pipeline measurement instruments; Secondly, based on the 16-dimensional Kalman filtering model, the data of multi-sensors were fused according to the forward and reverse time order respectively. Thus, two kinds of 3D trajectories of the pipeline were obtained. One is the time order, the other one is the reverse time order. Thirdly, in order to get the optimal measurement results of the 3D trajectory of the pipeline, the forward and reverse measurement results were fused according to the covariance matrix of the forward and reverse Kalman filter. Finally, a ground simulation experiment and an underground pipelines experiment with a MEMS sensor (PA-IMU488B) were performed to verify the feasibility of the method. In the ground simulation experiment, the maximum relative error in the plane is 0.14%, and the maximum relative error in the vertical is 0.28%. In the experiment of underground drainage pipelines, the maximum relative error in the plane is 0.22%, and the maximum relative error in the vertical is 0.12%. This method proposed by this study uses one set of data twice which can make the measurement results more accurate. Above all, the sensors used in this method are all cheap and low precision. Moreover, the measuring equipment only needs to travel through the pipe from the entrance to the exit and doesn’t need to go back from the exit to the entrance. Therefore, the method proposed by this study is a high-precision, low-cost, and low-time-consuming method for 3D trajectory measurement of underground pipelines.

Specific heat and excess heat capacity of grout with phase change materials using heat conduction microcalorimetry

Microencapsulated phase-change-materials (PCMs) incorporated in cementitious grout can be used as a source of energy in an underground thermal energy storage system. Differential scanning calorimetry (DSC) is a widely used technique to measure the latent heat or specific heat of PCM-embedded cementitious materials. However, using milligram sample sizes (as required by DSC) of a cementitious material fails to represent the actual scale of cementitious components. This is the reason why, in the present paper, non-isothermal heat conduction microcalorimetry (MC) was evaluated as a tool for determining the thermal properties of PCM-embedded grout as well as pure PCM (three PCMs were used). An MC experimental protocol (using both single and 5–6 temperature cycles) was developed and used to measure latent heat and melting and crystallization temperatures, which were in good agreement with those reported for pure PCMs by the producers. In addition, the specific heats of the PCM-containing grout also agreed with measurements using the hot disk technique. Overall, the results show that the MC technique can be used as a potential standard method in determining thermal processes in complex systems, such as in PCM-embedded cementitious systems, where a large sample size is needed to represent the material.

Mission invisible? Managing boundaries for flood protection

Although boundaries are typically seen as hampering inter-organizational collaboration, a lack of clear boundaries does not kindle collaboration either. This paper investigates how boundary spanners manage boundaries in inter-organizational collaboration. I draw on data from a 12-month ethnography of an inter-organizational innovation pilot between water authorities and utility owners in the Netherlands. The aim of this pilot was to improve the logistical and budgetary efficiency of renovations on dykes with underground utility systems, through collaboration between utility companies and water authorities. Findings show how pilot staff and participants were challenged by the invisibility of collaborative work: collaboration was undervalued, seen as a nuisance, and not as a core responsibility. Within the pilot potential measures of collaborative success and action were formulated, and participants learned about potential obstacles. This helped participants to see the potential of collaborative work clearer, and formulate collaborations that could move forward in acknowledgement of limitations. This paper contributes to the boundary work literature by proposing that managing the (in)visibility of boundaries is substantial to the competency of boundary spanners.

Numerical simulation of the impact of different cushion gases on underground hydrogen storage in aquifers based on an experimentally-benchmarked equation-of-state

Underground hydrogen storage (UHS) in geological formations is a promising technology for large-scale hydrogen energy storage. In this study we focus on UHS in saline aquifers. Although lessons were learned from similar studies, including geological carbon sequestration and underground gas storage, the unique thermodynamic and physical properties of hydrogen distinguish UHS from the other subsurface storage projects. We developed a two-phase, three-component reservoir simulator, which incorporated essential physics based on the fully coupled multi-physics framework of the Delft Advanced Reservoir Simulation (DARSim). Properties of fluid mixtures were computed using the GERG-2008 equation of state (EoS), in which the parameters were determined by fitting laboratory data. The simulation results demonstrated the impact of different cushion gases (CO2, CH4, and N2) on UHS. Most hydrogen stayed in the gaseous phase at the top of the aquifer when CH4 and N2 were used as the cushion gas. Conversely, hydrogen-rich fingers were observed in the aqueous phase when CO2 was used as the cushion gas, because dissolved CO2 increased brine density, leading to density-driven downward convection which was favorable for hydrogen dissolution into the aqueous phase. The highest purity of produced hydrogen was observed when CO2 was used as the cushion gas, whereas using CH4 and N2 as the cushion gas was favorable for the hydrogen production rate and mobility. This work is the first study that utilizes an EoS-based reservoir simulator to investigate hydrogen's flow patterns and interactions with cushion gases in an underground storage system. Specifically, the productivity and retrievability of hydrogen in a two-phase, three-component UHS system were analyzed in detail. The developed reservoir simulation tool and research findings from this study will be valuable to support decision making in practical UHS projects.

Development and assessment of an integrated underground gasification system for cleaner outputs

In this study, an underground coal gasification-based integrated multigenerational system is developed to generate multiple useful outputs, including electricity, heating, cooling, hydrogen, ethanol and sulfuric acid, for achieving cleaner applications and meeting the community needs. An application of this conceptually developed system is considered for a community as identified in Kutahya, Turkey. The proposed system is developed, modelled, and analyzed using thermodynamic-based, sensitive modeling tools and software packages. The effects of operating conditions such as oxygen, steam, as well as lignite feed rate, reference temperature, and gasifier temperature are investigated to evaluate the performance of the integrated underground coal gasification system. This research further aims to analyze the influence of varying system parameters and operational conditions on ethanol and hydrogen generation and increase energetic and exergetic efficiencies while reducing harmful product gas emissions. In this regard, many parametric studies of the underground coal-powered multigeneration system are conducted. According to the results, the integrated underground lignite gasification combined system's overall system energetic and exergetic efficiencies are found to be 68.8% and 66.56%, respectively.

Towards a Regenerative Role of Cultural Heritage in Climate Resilience; the Case of the Indian Water Infrastructure Heritage

Despite great efforts in facing climate change challenges—especially by the UN Paris Agreement, the 2030 Agenda for Sustainable Development, and companion documents (Sendai Framework for Disaster Risk Reduction and the New Urban Agenda)—generally speaking, current policies on climate change and Disaster Risk Reduction at both national and international levels have not yet been centrally positioned in respective plans for heritage, and cultural heritage still does not have a central role in such policies. The main aim of this paper is to explore the culture/cultural heritage’s complex interrelationship with climate change by delving into critical issues/gaps and recommendatory encounters of heritage framework in climate change framework and vice versa at the international level and an example in India. Accordingly, this paper showcases a type of Indian Water Infrastructure Heritage; Stepwells, traditional underground water management systems in arid western India which, unfortunately, with modernization, lost their original function and hence, nowadays, most are abandoned. Thus, by the situational analysis of such an Indian urban-scale type of heritage, this paper concludes with critical reflections on the necessity of the systemic relationship among sustainability, conservation, and development, especially in practice and the need to recall the notion of sustainability again.

A survey on channel measurements and models for underground MIMO communication systems

A survey on channel measurements and models for underground MIMO communication systems

Sustainable Design and Operations Management of Metro-Based Underground Logistics Systems: A Thematic Literature Review

Sustainable urban development relies on forward-looking infrastructure development. As an emerging infrastructure system that incorporates green technologies, the Metro-based Underground Logistics System (M-ULS) enables sustainable transportation of passengers and freight within cities collaboratively by sharing rail transit network facilities. M-ULS can effectively save non-renewable energy and reduce pollution to the ecological environment, and the comprehensive benefits of the system make an outstanding contribution to sustainable urban development. The purpose of this study is to provide a systematic review of M-ULS based on different perspectives and to present the development of the M-ULS network integration concept. By employing bibliometric analysis, the four dimensions of M-ULS related literature are statistically analyzed to discover the knowledge structure and research trends. Through thematic discussions, a development path for developing the concept of M-ULS network integration was established. The main findings of this study are summarized as follows: (i) A comparative analysis shows that the metro system has a high potential for freight use; (ii) Improvements in metro freight technologies are conducive to urban economy, environment, and social sustainability; (iii) Network expansion is an inevitable trend for implementing underground logistics based on the metro; (iv) The interaction among public sectors, metro operators, logistics corporations, and users plays a critical role in promoting the development of M-ULS. (v) It is worth mentioning that the planning of green infrastructure should fully consider its comprehensive contribution to the sustainable development of the city. This study visualizes the current status and hotspots of M-ULS research. It also discloses frontier knowledge and novel insights for the integrated planning and operations management of metro and urban underground freight transportation.

Legacies Matter: Exploring Social Acceptance of Pumped Storage Hydro in Michigan’s Upper Peninsula

Using electrical energy for an increasingly wide range of energy services (including lighting, heating, cooling, food storage, communications, and transport) requires grappling with the impacts of these systems on ecologies and societies. Renewable energy can provide less ecologically damaging electrical energy, but intermittency—the fact that solar requires the sun to shine and wind requires a breeze for energy to be produced—means having to create a way to store electrical energy to balance production and demand effectively. Underground storage hydro energy systems offer one way to achieve this, and one innovative approach involves repurposing abandoned underground mine shafts for pumped underground storage hydro (PUSH) systems. In this article, we present an initial foray into the social acceptance (SA) of the potential development of a PUSH facility. The article looks at the case of SA of a PUSH facility in a post-mining community in the Upper Peninsula of Michigan through its three pillars: community acceptance, sociopolitical acceptance, and market acceptance. This case study reveals that community input into design considerations and economic participation are the primary drivers and may be required to achieve community acceptance. The study provides insights regarding the importance of engaging the community in discussions while planning for large energy infrastructure to spur renewable energy transition. The case study will further engage the audience in understanding the SA of energy storage systems when developed in brownfield sites (abandoned mines) instead of greenfield sites.

Reduced commuter exposure to PM2.5 and PAHs in response to improved emission standards in bus rapid transit systems in Mexico

We evaluated impacts of progressive technological updates to bus rapid transit (BRT) systems on in-cabin concentrations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5), and the various polyaromatic hydrocarbons (PAHs) to which commuters were exposed. PM2.5 samples were collected and real-time concentrations measured from October 2017 to March 2020 inside cabins of BRT buses equipped with Euro IV, V and VI diesel emission standards in the Mexico City Metropolitan Area (MCMA). For effective comparison, similar samplings and measurements were carried out on trains in the MCMA underground (MCU) system. Peak in-cabin PM2.5 concentrations decreased significantly (p < 0.05) by 35% from Euro IV to Euro V buses, and by 80% from Euro IV to Euro VI buses. PM2.5 concentrations inside Euro VI buses were significantly lower (p < 0.05) than in Euro IV and Euro V buses and in underground trains. The in-cabin excess (ICE) of PM2.5 relative to ambient concentrations was significantly (p < 0.05) higher for Euro IV than for Euro V buses during morning the traffic peak, and consistently higher than for Euro VI buses. Indeed, ICEs calculated for Euro VI buses were always lower than those for electricity-powered underground trains. The frequency of hotspots decreased from Euro IV to Euro VI buses due to the combined effect of low emissions and closed, air-conditioned cabins. Concentrations of total PAHs including carcinogenic species also decreased from Euro IV to Euro V buses and were below limits of detection aboard Euro VI buses. This work shows that in real-life conditions, advanced diesel technologies and cabin design significantly reduce commuters’ exposure to PM2.5 and to toxic PAH compounds.

Characterizing the bending behavior of underground utility tunnel roofs in a fabricated composite shell system

The traditional underground utility tunnel system is characterized by a lengthy construction period, material waste, and poor engineering quality. This study proposes the prefabricated composite shell system underground utility tunnel as a new type of prefabricated underground utility tunnel system. This system uses 20 mm thick high-performance cement-based materials as permanent templates, with steel reinforcement skeletons placed in the cavity between the two side molds, and concrete can be poured after on-site hoisting and positioning to form an integrated tunnel. This study first systematically introduces the system design method of the prefabricated composite shell system underground utility tunnel and clarifies its component and connection structures. Then, bending tests are conducted on the composite shell tunnel top plate specimens, and a cast-in-place top plate specimen is selected as a control group. A suitable bearing capacity calculation formula for composite shell top plates is derived and proposed based on test phenomena and results analysis. The results showed that the prefabricated outer template and internal cast-in-place concrete of the composite shell top plate specimen have good collaborative performance. Its bearing capacity, stiffness, and failure phenomena are consistent with those of cast-in-place components, as are its mechanical properties. In addition, the proposed bearing capacity calculation formula for a composite shell top plates is highly accurate and can guide the design of such components.

Historiographic Aspects of the NKVD (MVD) of the USSR Fight against the Nationalist Underground in the Estonian SSR (1940-1953)

The topic under study has an actual historical and political orientation. It is necessary to shed light on the events that took place during the Second World War, in the pre-war and post-war periods of the Estonian SSR. The activities of Estonian nationalists aimed at fighting the Soviet regime began to gain momentum after the Baltic States had joined the USSR and its peak was the June 1941 deportation. It was during this period that the nationalist underground system of Estonia, later called the “Forest Brothers”, began to form. It was aimed at undermining the authority of the Soviet governing bodies and the fight against the Soviet regime. The first open clashes began in the post-war period of 19441947, after the influence of the German propaganda apparatus on the minds of the population. It was then that the activities of the Soviet NKVD became a significant component in the fight against the nationalist movement in the Baltic States. In 1947, the activities of the Soviet NKVD organs and troops made it possible to discover and destroy the officer school that trained the Estonian partisans. This scientific work proves that the service of the Soviet security forces against the nationalist movement in Estonia in the period 1940-1953 was an important element that affected in their activities for the stabilization of the social and political situation in Estonia during the period under study.

Rapid quantification of the surface overflow and underground infiltration in sewer pipes based on computer vision and continuous optimization

The overloading of the sewer network caused by unwarranted infiltration of stormwater may lead to waterlogging and environmental pollution. The accurate identification of infiltration and surface overflow is essential to predict and reduce these risks. To retrieve the limitations of infiltration estimation and the failure of surface overflow perception using the common stormwater management model (SWMM), a surface overflow and underground infiltration (SOUI) model is proposed to estimate the infiltration and overflow. First, the precipitation, water level of the manhole, surface water depth and images of the overflowing point, and volume at the outfall are collected. Then, the surface waterlogging area is identified based on computer vision to reconstruct the local digital elevation model (DEM) by spatial interpolation, and the relationship between the waterlogging depth, area and volume is established to identify the real-time overflow. Next, a continuous genetic algorithm optimization (CT-GA) model is proposed for the underground sewer system to determine the inflow rapidly. Finally, surface and underground flow estimations are combined to perceive the state of the urban sewer network accurately. The results show that, compared with the common SWMM simulation, the accuracy of the water level simulation is improved by 43.5% during the rainfall period, and the time cost of the computational optimization is reduced by 67.5%. The proposed method can effectively diagnose the operation state and overflow risk of the sewer networks in real time during rainfall seasons.

Towards inclusive underground public transportation: Gender differences on thermal comfort

As urbanization and societal needs grow, the demand for inclusive, efficient, and sustainable underground public transportation has increased, necessitating a greater focus on enhancing passengers' thermal comfort. However, limited research has addressed the subway station environment, and restricted datasets are challenging to build an accurate nonlinear model. Therefore, this study proposes a thermal comfort data generation algorithm based on 5161 measured data via the Variational Autoencoder (VAE) framework to break data collection constraints and increase thermal comfort model accuracy. By employing a gradient boosting algorithm on the extensively generated dataset, this study investigated factors influencing thermal comfort in subway stations, emphasizing individual gender differences and dynamic environmental variables. The VAE model enhanced the thermal comfort dataset, resulting in a 29% and 35% increase in male and female test set accuracy, respectively. The study suggests that males with a BMI over 27 were more sensitive to temperature. As for the gender-friendly environmental features, people feel most comfortable at temperatures between 24 and 29 °C and relative humidity levels between 20% and 70%. Additionally, the study reveals that a stable environment promotes enhanced thermal comfort for passengers. These insights contribute to developing sustainable, equitable, and user-friendly underground public transportation systems.

The DarkSide-20k TPC and underground argon cryogenic system

DarkSide-20k (DS-20k) will exploit the physical and chemical properties of liquid argon (LAr) housed within a large dual-phase time project chamber (TPC) in its direct search for dark matter. The TPC will utilize a compact, integrated design with many novel features to enable the 20t fiducial volume of underground argon. Underground Argon (UAr) is sourced from underground CO_22 wells and depleted in the radioactive isotope ^{39}39Ar, greatly enhancing the experimental sensitivity to dark matter interactions. Sourcing and transporting the \mathcal{O}𝒪(100t) of UAr for (DS-20k) is costly, and a dedicated single-closed-loop cryogenic system has been designed, constructed, and tested to handle the valuable UAr. We present an overview of the (DS-20k) TPC design and the first results from the UAr cryogenic system.

Microbial risk assessment for underground hydrogen storage in porous rocks

Geological hydrogen storage, e.g. in depleted gas fields (DGF), can overcome imbalances between supply and demand in the renewable energy sector and facilitate the transition to a low carbon emissions society. A range of subsurface microorganisms utilise hydrogen, which may have important implications for hydrogen recovery, clogging and corrosion. We gathered temperature and salinity data for 75 DGF on the UK continental shelf and mapped their suitability for hydrogen storage in terms of the risk of adverse microbial effects, based on a novel collection of microbial growth constraints. Data on wind and solar operational capacities as well as offshore gas and condensate pipeline infrastructure were overlaid on the microbial risk categorization to optimize geographical centers of green hydrogen production, transport infrastructure and underground storage. We recommend storing hydrogen in 9 DGF that are at no microbial risk due to temperatures > 122 °C, or in the 35 low-risk DGF with temperatures > 90 °C. We recommend against utilising high-risk DGF with temperatures < 55 °C (9 DGF). Alignment with centers for renewable energy production and out-of-use pipelines suitable for repurposing to transport hydrogen suggests that no-risk and low-risk DGF in the Southern North Sea are the most suitable candidates for hydrogen storage. Our results advise site selection choices in geological hydrogen storage in the UK. Our methodology is applicable to any underground porous rock system globally.

Influence of plasticity and vibration isolators on an underground floating slab track using finite element analysis

The floating slab track (FST) is largely viewed as the most efficient structure for mitigating the vibrations caused by underground railway systems. This paper presents a study on the dynamic behavior of the FST subjected to train-induced vibrations using a finite element approach. A three-dimensional simulation model of an FST was analyzed under a moving load. The effects of material plasticity of underground strata and concrete damaged plasticity of the floating slab were analyzed. A comparison between the vibration attenuation of the steel-spring isolator (SSI) and polyurethane pad (PUP) was performed. The load was moved at constant speeds ranging from 90 to 324 km/h using a pressure-loaded moving block. The results were analyzed in the form of four general output parameters. A slight vibration attenuation was observed when plastic material properties were included in the simulation model. The PUP was more effective in reducing vibrations at FST than SSI by a vibration transfer mechanism.