Underground Installations Research Articles

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.

Improving construction site efficiency through automated progress monitoring of underground pipe installation sites using image color analysis of iPhone LiDAR camera data

This study presents an innovative method utilizing smartphone for automated progress monitoring at underground pipe installation sites. Leveraging the LiDAR iPhone camera, the method captures detailed point cloud data of construction sites. Sophisticated color analysis of images accurately distinguishes between areas with and without pipes within excavations. Key aspects of the proposed workflow include segmentation of the excavation area, differentiation between main and side excavations, and application of an earth color mask in the RGB space to isolate pipes. The research focuses on enhancing measurement precision for excavation width, depth, and pipe burial depth, significantly reducing the manual labor traditionally required at construction sites, thereby offering an efficient and cost-effective solution. We further demonstrated the robustness of the proposed algorithm by applying it to two types of data acquired at actual construction sites. This approach is expected to contribute significantly to the digital transformation in the construction industry.

ОПРЕДЕЛЕНИЕ ОПТИМАЛЬНЫХ ПАРАМЕТРОВ КАПЕЛЬНОЙ ЛЕНТЫ ДЛЯ МЕХАНИЗИРОВАННОЙ УКЛАДКИ

The introduction of drip irrigation systems in irrigated areas is impossible without the creation of special machines for laying drip tape. The advantage of in-soil laying of the tape is the absence of losses due to evaporation of irrigation water and the inadmissibility of its heating to temperatures dangerous for the plant in the hot season. To ensure high-quality laying of the drip tape in the soil, constant tension of the tape is required when the speed of the machine fluctuates or it suddenly stops. The absence of constant tension will lead to jamming of the tape in the laying pipe or its twisting, which will make further operation of the drip irrigation system impossible and will require repair work that requires additional labor costs. Constant tension of the tape ensures its precise location in the soil, which will eliminate additional pressure losses when the position of the tape changes during operation of the drip irrigation system. To maintain constant tension, a permanent brake is required. This creates additional tensile forces applied to the tape. The tape is also affected by the resistance of laying it in the soil. The research was aimed at establishing the numerical values of the forces acting on the drip tape to assess their impact. The most popular tapes on farms are those with a thickness of 0.15...0.25 mm due to their low cost. Research has established that for underground installation it is desirable to use a tape with a thickness of at least 0.2 mm. When using a tape with a thickness of 0.15 mm, tensile forces can lead to dangerous deformations of the tape, making it impossible to further use

Analisis Perbandingan Biaya dan Waktu pada Penggunaan Duct Spacer dengan Prefabricated dan Hollow Baja Ringan Untuk Pekerjaan Underground Ducting

The Kediri Airport development project encountered challenges related to underground ducting work. The design of Kediri Airport adheres to international standards, which led to the use of materials not readily available in Indonesia, specifically pipes and duct spacers. Duct spacers are tools used to arrange ducting pipes according to their formation and prevent them from floating during concrete pouring due to buoyancy. The SKEP/114/VI/2002 serves as a reference for underground cable installation, involving direct burial of cables at a depth of 70 cm, covered with a 5 cm layer of sand above the cable surface. These two approaches significantly differ, necessitating problem-solving solutions. To address this issue, research was conducted to find suitable duct spacers in Indonesia. Two alternative materials were considered: PVC and lightweight hollow steel. The study compared costs and time associated with these materials. PVC duct spacers would be imported and be fabricated in Indonesia, while hollow steel duct spacers would be fabricated on-site. The research focused on three aspects: ducting work methods, duct spacer design, and cost-time analysis. Given tight installation spaces and busy schedules, duct spacers needed to be compact, simple, and adaptable to various pipe formations. The design for hollow steel duct spacers aimed for simplicity to reduce on-site construction work. However, care was taken to avoid potential injuries from exposed bolts on the hollow steel frame. The PVC duct spacer design utilized Polytam PF 1000 material, with a nominal shear strength of 399 kg and a nominal moment of 266 kg·cm—sufficient to withstand saturated soil loads up to 162 cm but not vehicular loads. Analyzing procurement time, PVC duct spacers from Indonesian manufacturers were the quickest, taking only 56 days due to no port clearance delays. The fastest completion time for the project was achieved using PVC duct spacers, taking 122 seconds—three times faster than hollow steel duct spacers. While lightweight steel was the most cost-effective option for on-site procurement, combining cost and time analysis favored PVC duct spacers. The minimal cost difference allowed for accelerated production, minimizing the risk of delays

Finite Element Analysis of Polyethylene Pipe with Elliptical Hole Supported by Saddle Fusion Patch with Fin

Underground pipe installation is one of the crucial components in supporting industrial activities. Damage to the underground pipe is typical and usually done by patching repair. Analysis of the stress distribution on pipe with patch has been done previously. An analysis needs to be done to determine the effectiveness of the patches and the effect of the growth of the damage. The purpose of this paper is to know the effect of the application of fins on the saddle fusion patch with variations in the number of fins, fin angle orientation, and fin height on the stress distribution on the PE 80 pipe. The research was carried out on a polyethylene pipe with elliptical defects that have been repaired with a saddle fusion patch with a fin as a stiffener. The pipe is a medium-density polyethylene pipe (MDPE80), and the patched is high-density polyethylene (HDPE100). The variation in the research is the fin’s height, the fin’s number and orientation of the fin, and the variation of defect dimension as representative of crack growth. The study was carried out using a finite element analysis tool, ANSYS 2020. The simulation results showed that the addition of fins and the difference in given height on the saddle fusion patch could reduce the stress acting on the cracked pipe. The stress drop that occurs in the addition of the number of fins is not only influenced by the number of fins but also influenced by the orientation of the added fins. The results of this study will provide an overview of the optimal patch thickness after being given reinforcement by fins added to the patch. The hole variations carried out aim to simulate so that the damage that occurs does not repeat itself after being given a patch. Information regarding the optimal and efficient patch thickness becomes an input that is used as a consideration in determining effective and economical repair steps.

Wind Farm Layout Optimization Subject to Cable Cost, Hub Height, and a Feasible 3D Gaussian Wake Model Implementation

We address the Wind Farm Layout Optimization (WFLO) problem and tackle the optimal placement of several turbines within a specific (wind farm) area by incorporating additional aspects of an economically driven target function. With this, we contribute three refinements for WFLO research: First, while many research contributions optimize the turbines’ locations subject to maximum energy production or energy efficiency, we instead pursue a strategy of maximizing a profit objective. This enables us to incorporate inner-farm wiring costs (underground cable installation). For this, we explore the impact of using MSTs (Minimum Spanning Trees) and adding junction (so-called “Steiner”) points to the terrain plane. Second, while most research focuses on finding optimal x and y coordinates (i.e., address two-dimensional turbine placement), we also optimize the turbines’ hub heights z. Third, we also provide a software implementation of the Gaussian wake model. The latter finds entrance to the open-source WFLO research framework that comes as package <strong>wflo</strong> for statistical software R. We find that taking wiring cost into account may lead to very different turbine placements, however, increasing overall profit significantly. Allowing the optimizer to vary the hub heights may have an ambiguous impact on the wind farm profit.

EXPERIMENTING TIN DATA STRUCTURE FOR REPRESENTING PLANE SURFACE AND SUBSURFACE SPATIAL OBJECTS - PRELIMINARY WORK

Abstract. Understanding and analyzing complex spatial objects involves the integration of surface, terrain, and subsurface data into 3D spatial models. However, describing and efficiently analyzing the connections between these data model is particularly challenging. This study aims to generate TIN data structure that enable the 3D representation of surface terrain subsurface integration. Furthermore, to ensure accurate representation within a unified 3D model, spatial relationships between the TIN data model could be obtained. Consequently, three – dimensional Triangular Irregular Networks (3D TIN) mesh of spatial objects representations and indexing structures were created. The integration of spatial objects, encompassing surface, terrain, and subsurface elements, is realized through a unified model. This synergy is achieved by combining the distinct 2D and 3D topology structures of each component. The resulting comprehensive model captures the intricate relationships and interactions within the spatial environment. This study provides additional insight into the representation and analysis of surface, terrain, and subsurface management in 3D spatial models. Hence, better decision making, resource management, underground utility installations, and evaluation of spatial objects will be made possible in our future work.

Optimization of Ampacity in High-Voltage Underground Cables with Thermal Backfill Using Dynamic PSO and Adaptive Strategies

This article addresses challenges in the design of underground high-voltage transmission lines, focusing on thermal management and cable ampacity determination. It introduces an innovative proposal that adjusts the dimensions of the backfill to enhance ampacity, contrasting with the conventional approach of increasing the core cable’s cross-sectional area. The methodology employs a particle swarm optimization (PSO) technique with adaptive penalization and restart strategies, implemented in MATLAB for parameter autoadaptation. The article emphasizes more efficient solutions than traditional PSO, showcasing improved convergence and precise results (success probability of 66.1%). While traditional PSO is 81% faster, the proposed PSO stands out for its accuracy. The inclusion of thermal backfill results in an 18.45% increase in cable ampacity, considering variations in soil thermal resistivity, backfill properties, and ambient temperature. Additionally, a sensitivity analysis was conducted, revealing conservative values that support the proposal’s robustness. This approach emerges as a crucial tool for underground installation, contributing to continuous ampacity improvement and highlighting its impact on decision making in energy systems.

The Effect of the Vertical Layout on Underground Cable Current Carrying Capacity

Underground cable installation in historical areas, natural protected areas, narrow streets, or residential areas with high traffic flows is very difficult due to both legal permits and the conditions of the work sites. The trefoil layout requires a smaller channel than the flat layout. However, the trefoil layout carries some risks, such as damage to the cables together in the event of short circuit faults and reduced ampacity in single-side-bonded systems. This study’s scope examines the current carrying capacities and thermal effects of directly buried underground cables in trefoil and vertical layouts using CYMCAP power cable analysis software. A field investigation was also carried out to verify the analysis results. The performance of the recommended method was evaluated by considering current and temperature measurements from the fieldwork and analysis. According to the studied cable design, the current carrying capacities of the cables in flat and vertical layouts are similar and higher than in the trefoil layout. However, it should be taken into consideration that these results will vary depending on a cable system’s design parameters. As a result, this article emphasizes that a vertical layout can be considered as a layout option in certain areas.

ПАРАМЕТРИЧЕСКИЕ КОЛЕБАНИЯ ПОДЗЕМНОГО И НАДЗЕМНОГО НЕФТЕПРОВОДА

Based on the use of the assumptions of the theory of closed cylindrical shells by Vasiliy Z. Vlasov, the authors suggested an analytical method for the study of dynamic instability of pipelines. The nonstationary internal pressure induced by the pumping equipment of the pumping stations is considered as the stimulation source. This pressure excites the longitudinal compressive force, the elastic soil resistance reaction, and the velocity of the flowing fluid. The result of the proposed method is inequalities that take into account the damping properties of the ground and the above factors. By means of these inequalities, it can be determined the upper and lower limits of the region depending on the excitation frequency of the pumping station. And the estimation of the stability loss is reduced to the determination of the value of the natural pipeline frequency. If a point falls into the constructed region, the appearance of parametric resonance is inevitable. Comparison of the instability areas for elevated and underground installation depending on the longitudinal force parameter showed that the shift of the area for the underground method is towards the increase of the longitudinal force parameter.

Determining and Verifying the Operating Parameters of Suppression Nozzles for Belt Conveyor Drives

Drives in belt conveyors are critical components of the conveyor system, susceptible to various factors that can cause disruptions and energy losses. In underground mining conditions, the risk of drive fires is particularly hazardous. Therefore, it is necessary to develop highly effective fire suppression systems. However, there are no guidelines for designing such systems. This study presents a methodology for selecting and verifying the fire suppression systems for belt conveyor drives. The proposed AMIGA system for extinguishing fires on underground coal mine conveyor belts, incorporating spraying and water mist installations, is supported by a theoretical calculation methodology. This enables determining the number of required nozzles and flow rate for complete fire suppression. The development of a methodology for the selection and verification of the sprinkler system components utilized guidelines provided in the standard VdS 2109:2002-03 and the PN-EN 12845+A2 standard from 2010, while a novel approach is proposed for water mist parameters that has not been previously applied anywhere else, and is based on assessing the fire’s intensity and the persistent disruption of the energy balance of the combusted coal. The theoretical calculations for potential fire power facilitate the determination of the appropriate water flow rate for the spraying system to protect the upper belt drive. For the proposed AMIGA system, the potential fire power was calculated to be 10.33MJ/min. Based on this, the water flow rate for the spraying installation to protect the upper drive belt of the conveyor was established to be a minimum 37.5dm3/min, and 21.4dm3/min for the mist installation used to protect the space below the conveyor drive. In order to verify the developed methodology for parameter selection, on-site tests were conducted to verify the results. Tests were conducted on an AMIGA prototype suppression system integrated into a conveyor drive. The results demonstrate that the developed system is effective in extinguishing fires on the belt using the spraying installation, as well as under the conveyor belt drive using the water mist installation, within the entire supply pressure range ( 0.4MPa to 1.6MPa ).

An experimental study of Horizontal Directional Drilling (HDD) in sand in a large flexible calibration chamber

Horizontal Directional Drilling (HDD) is a trenchless technique for underground infrastructure installation that uses pressurized drilling fluid. Excessive loss of fluid to the formation can cause problems not only for the execution of HDD but also to nearby structures and must, therefore, be avoided. Hydraulic fracture is one of the possible causes and theories to predict the ultimate pressure have been developed, mostly for clays. Luger and Hergarden (1988, apud Keulen, 2001) developed a hydraulic fracture model particularly for HDD. The present study presents an experimental program carried out on a large flexible calibration chamber in sand using drilling fluid and confining pressures compatible with HDD field conditions. Results show that while local fracturing may occur, causing injection pressure to decrease for a while, permeability is still the dominating factor.

The CYGNO/INITIUM experiment

The CYGNO project for the development of a high precision optical readout gaseous TPC for directional Dark Matter search and solar neutrino spectroscopy will be presented. It is to be hosted at Laboratori Nazionali del Gran Sasso. CYGNO peculiar features are the use of sCMOS cameras and PMTs coupled to GEMs amplification of a helium-based gas mixture at atmospheric pressure, in order to achieve 3D tracking with head tail capability and background rejection down to O(keV) energy, to boost sensitivity to low WIMP masses. The latest R&D results within the CYGNO project will be discussed along with the underground installation and operation of a 50 l prototype, soon to be followed by a O(1) m3 experiment demonstrator in 2024-2026. The latest results on the negative ion drift operation at atmospheric pressure within CYGNO optical readout approach will be illustrated, which is the aim of the ERC Consolidator Grant project INITIUM.

Расход тепловой энергии на временное отопление законченных вчерне станций метрополитена

Introduction. During construction of underground facilities, architectural, finishing and installation works begin before the completion of the main structures. At that time, there is no permanent heating network connection and therefore temporary heat sources must be used to ensure compliance with the works technology. The lack of specific information about the required capacity of such sources makes it impossible to forecast the financial costs, which is essential for contractors. The purpose of the study is to determine the specific value of heat energy consumption for heating underground stations, construction of which is carried out by open method, depending on different outdoor temperatures, construction completion, depth of station installation, as well as the construction volume of the station. Materials and methods. Heat flows have been calculated by means of mathematical modelling of a stationary thermal regime. Analyses of calculation results and normative data have been performed in accordance with the provisions of probability theory and mathematical statistics. Calculation of coefficients and loads are carried out according to generally accepted equations and laws of heat and mass exchange. Climatic data and material parameters are taken according to current normative documents. Results. The values of specific thermal performance of open-cut metro stations depending on space-planning and design solutions, composition of external envelopes, as well as the stage of construction completion (including the presence or absence of backfill) are calculated. Estimated rate of heat energy consumption for temporary heating of open cut metro station is 3.87 Gcal/(1,000 m 3 · month). Conclusions. Temporary heating norms (amount of heat energy) for open-circuit metro stations have been proposed. Heat costs for ensuring the specified air parameters, referred to a unit volume and required for construction and installation works inside the stations during the heating period, are determined.

ЕФЕКТИВНІСТЬ ЗАСТОСУВАННЯ МАКСИМАЛЬНОГО СТРУМОВОГО ЗАХИСТУ В ПІДЗЕМНИХ МЕРЕЖАХ

The article considers the use of maximum current protection in underground mine electrical networks, which disables short-circuit currents with an absolute value greater than the starting currents of powerful electric motors. It was determined that these protections have a number of disadvantages. The article reveals that the protection with the current-time characteristic is more perfect than the maximum current protection, but in the case of arcing short circuits, the values of which can be less than the starting ones in absolute value, the protection activation time significantly exceeds the permissible value. Protection with filters of symmetrical components of currents and voltages reduces the sensitivity to two-phase short circuits with a connected load, protection at the level of the third harmonic in the event of a short circuit has a limited range of action and requires duplication. It was investigated that with the use of valve converters and thyristor schemes for controlling the drives of lifting installations and conveyor transport in underground networks, the level of higher harmonic currents increased. In the practice of work of domestic and foreign enterprises, it has been proven that capacitor banks, which are installed to compensate for reactive power, have protection against overcurrents and shortcircuit currents, but with non-sinusoidal voltage, in a number of cases, they quickly fail because they are overloaded with higher harmonics. The article shows that with the increase in the power of the engines of the underground district networks and the manifestation of the asymmetry of the air gap, the higher harmonics given exceed the permissible values. Therefore, the article presents the most promising directions for the construction of systems for the protection of mine distribution underground networks and electrical installations

Study on positioning of trenchless drill bits based on the principle of acoustic resonance

Trenchless Technology is widely used in underground pipelines installation for communication, energy, and other applications. To avoid accidents such as the drill bits’ sliding and deviating to obtain the pilot path, the typical positioning method depended on electromagnetic signals requires an inner probe and is easily disturbed in the urban electromagnetic environment. This paper introduces a new method for positioning metal drill bits at shallow depth based on the principle of acoustic resonance. In a simulated trenchless experiment, the hammering method and the fast Fourier transform algorithm were used to analyze the resonant characteristics of the underground drill bit. Measured by acoustic sensors set on the surface, the resonant wave was analyzed by acoustic spectrum and spectral analysis to obtain its capability to position. It is found that the underground drill bit is an oscillation system whose resonance could be excited by an aboveground acoustic generator at the resonant frequency, and the resonant sound intensity can be used to position. The calculation model was proposed with the linear algorithm and the least square method, which was studied on the lab scale simulation. The average positioning error is less than 0.083 m, which can meet the accuracy at the operational depth of urban trenchless projects. This pioneer method is based on the resonance principle to eliminate the inner probe and remedy the weak robustness of electromagnetic signals in urban mini trenchless projects, which provides a new way to design positioning systems for underground space.

Multi-Source Ensemble Learning With Acoustic Spectrum Analysis for Fault Perception of Direct-Buried Transformer Substations

The tremendous growth of electrical loads results in the capacity increase and underground installation of power distribution infrastructures due to the shortage of urban land resources. However, the closed and narrow underground space of direct-buried transformer substation (DBTS) brings great challenges to its fault perception. This article proposes an adaptive acoustic spectrum analysis method with refined composite multiscale dispersion entropy to extract informative fault-related time-frequency vocal features using the singular-value thresholded variable mode decomposition for facilitating fault diagnosis of DBTS. Then, a time-series generative adversarial network based fault data augmentation model is presented to enrich the training dataset while preserving temporal dynamics of the original fault data for boosting the generalization ability of DBTS fault perception. Furthermore, a multi-source ensemble learning strategy is developed to integrate heterogeneous sub-classifiers based on the dynamic weighted fusion of electrical monitoring data and acoustic signals for promoting fault diagnosis accuracy of DBTS. Comparative studies have been investigated to demonstrate the superior performance of the proposed multi-source ensemble learning strategy in improving the fault diagnosis accuracy of DBTS.

Investigations of the Wireless M-Bus System Resilience under Challenging Propagation Conditions

Wireless M-Bus is a short-range wireless telemetry system that plays a vital role in the capillary sector of the Internet of Things (IoT) ecosystem. Similar to any other IoT technology, it is meant to operate in harsh environmental conditions such as production plants, cellars, or other under-ground or indoor metering installations. This paper describes the methodology and outcomes of a carefully designed measurement campaign targeted at investigating this system’s immunity to jamming and extremely fading channels. The former was carried out in an anechoic chamber and the latter in a reverberation chamber, both specifically adapted for these types of measurements. The presented methodology allows for reproducible research. The article demonstrates PER measurements results as a function of CNIR for all throughput modes offered by the tested devices (ranging from 4.8 kb/s to 100 kb/s). The threshold CNIR values are universal and may prove useful in an IoT network design that is based on the Wireless M-Bus technology.

Soil degradation and crop yield declines persist 5 years after pipeline installations

AbstractDegradation of natural resources, including increased soil compaction, soil horizon mixing, and decreased crop yields have been common outcomes of underground pipeline installation. However, most of the research documenting the impacts of pipeline installation on soil and crops was conducted before contemporary best management practices were developed and implemented. The objective of this study was to evaluate the impact of pipeline installation on soils and field crops after a 4‐ to 5‐year remediation period, coinciding with the end of landowner compensation and when sites are considered fully remediated by pipeline companies. We report soil properties and corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yields from three independently operated pipelines at 29 sites across 8 Ohio counties. We observed significant degradation in soil physical properties, such as surface penetration resistance (15.3% increase) and mean weight diameter of soil aggregates (13.6% decrease) in right‐of‐way (ROW) areas compared with adjacent (ADJ) areas, respectively. Soils in ROW showed evidence of soil horizon mixing, with 25.0 g kg−1 higher clay compared with ADJ areas. Soil degradation resulted in decreases of 23.8% and 19.5% in corn yields and 7.4% and 12.5% in soybean yields during 2020 and 2021, respectively. Widespread disturbance persisted 5 years following pipeline installation in soil physical, chemical, and biological properties. Current best management practices of pipeline installation and remediation employed by three companies were insufficient to combat widespread soil degradation and crop yield loss.

Investigating the impacts of high voltage powerlines on ground current fields

Stray currents are a typical problem of areas crossed by electric railways. This well-known phenomenon can cause significant damage to all underground metallic installations, especially in case of DC stray currents. In areas close to the railway, the presence of stray currents is expected, and protective measures are applied to all sensitive installations like pipelines. However, field measurements have shown that the presence of high voltage power lines can significantly affect the ground current field due to the well-grounded ground wire representing an excellent alternative path for ground currents. This way, stray currents can appear in areas where the presence of ground current field from DC traction is normally not expected. Preliminary simulations have confirmed that high voltage power lines are a significant element affecting the spreading of ground current and the presence of high voltage power lines must be considered when investigating the ground current field of an area. However, these simulations were performed only for a limited area with a very simplified geometry of railway truck and a single power line. This paper presents results of a more complex simulation involving a large area crossed by a DC railway traction system and a complex high voltage network. The simulation is based on real topology representing an area around the town of Zilina, an industrial area with a complex high voltage network and an important railway hub.