Search Results (150)

This study investigates the behavior and performance of a newly proposed cone-top pile foundation designed to improve stability in layered, deformable, or strain-sensitive soils. Traditional shallow and uniform conical foundations often suffer from excessive settlement and reduced capacity when subjected to vertical loads and horizontal soil deformations. To address these limitations, a hybrid foundation was developed that integrates an inverted conical base with a central pile shaft and a rolling joint interface between the foundation and the superstructure. Laboratory model tests, full-scale field loading experiments, and axisymmetric numerical simulations using Plaxis 2D (Version 8.2) were conducted to evaluate the foundation’s bearing capacity, settlement behavior, and load transfer mechanisms. Results showed that the cone-top pile foundation exhibited lower settlements and higher load resistance than columnar foundations under similar loading conditions, particularly in the presence of horizontal tensile strains. The load was effectively distributed through the conical base and transferred into deeper soil layers via the pile shaft, while the rolling joint reduced stress transmission to the structure. The findings support the use of cone-top pile foundations in soft soils, seismic areas and areas affected by underground mining, where conventional designs may be inadequate. This study provides a validated and practical design alternative for challenging geotechnical environments. Full article

With the rapid advancement of urban underground space development, shield tunnel construction has seen a significant increase. However, at the initial launching stage of shield tunnels in shallow-buried weak strata, engineering risks such as face instability and sudden surface settlement frequently occur. At present, there are relatively few studies on the reinforcement technology of the initial section of shield tunnel in shallow soft ground and the evolution law of ground disturbance. This study takes the launching section of the Guanggang New City depot access tunnel on Guangzhou Metro Line 10 as the engineering background. By applying MIDAS/GTS numerical simulation, settlement monitoring, and theoretical analysis, the reinforcement technology at the tunnel face, the spatiotemporal evolution of ground settlement, and the mechanism of soil disturbance transmission during the launching process in muddy soil layer are revealed. The results show that: (1) the reinforcement scheme combining replacement filling, high-pressure jet grouting piles, and soil overburden counterpressure significantly improves surface settlement control. The primary influence zone is concentrated directly above the shield machine and in the forward excavation area. (2) When the shield machine reaches the junction between the reinforced and unreinforced zones, a large settlement area forms, with the maximum ground settlement reaching −26.94 mm. During excavation in the unreinforced zone, ground deformation mainly occurs beneath the rear reinforced section, with subsidence at the crown and uplift at the invert. (3) The transverse settlement trough exhibits a typical Gaussian distribution and the discrepancy between the measured maximum settlement and the numerical and theoretical values is only 3.33% and 1.76%, respectively. (4) The longitudinal settlement follows a trend of initial increase, subsequent decrease, and gradual stabilization, reaching a maximum when the excavation passes directly beneath the monitoring point. The findings can provide theoretical reference and engineering guidance for similar projects. Full article

Urbanization always leads to increasing challenges to the groundwater resources in karst regions due to intensive land use, infrastructure development, and the rapid transmission potential of pollutants. This study proposed an improved groundwater vulnerability assessment (GVA) framework by modifying the widely used COP (Concentration of flow, Overlying layers, and Precipitation) model, through the integration of three additional indicators: urban underground rail transportation (UURT), land use and cover (LULC), and karst development (K). Guiyang, a typical urbanized karst city in southwest China, was selected as the case study. The improved COP model, namely the COPK model, showed stronger spatial differentiation and a higher Pearson correlation coefficient ($r$) with nitrate concentrations ($r$ = 0.4388) compared to the original COP model (R = 0.3689), which validates the effectiveness of the newly introduced indicators. However, both R values remained below 0.5, even after model modification, suggesting that intensive human activities play a role in influencing nitrate distribution. The pollution load index (PI) was developed based on seven types of pollution sources, and it was integrated with the COPK vulnerability index using a risk matrix approach, producing a groundwater risk map classified into five levels. Global Moran’s I analysis (0.9171 for COP model and 0.8739 for COPK model) confirmed strong and significant spatial clustering patterns for the two models. The inclusion of UURT and LULC improved the model’s sensitivity to urban-related pressures and enhanced its capacity to detect local risk zones. It is a scalable tool for groundwater risk assessment in urbanized karst areas and offers practical insights for land use planning and sustainable groundwater management. Full article

Swift urbanization and technical progress in Cambodia, specifically in Phnom Penh, require underground transmission lines (UGTL) as a viable substitute for overhead transmission lines (OHTL). However, the substantial cost of UGTL has prevented its extensive integration. In this respect, we identified the most cost-effective technological route for an underground transmission line between substations. Using geographic information system (GIS) data, we generated algorithms to define the optimal route for the installation of a UGTL and minimize the costs of the material and labor required. The research results presented an automated tool for route optimization which simplifies the planning of energy projects and partially relieves the financial burden of UGTL integration. The proposed method radically changes the planning of urban energy infrastructure, as it provides a technology-based, cost-efficient, and environmentally favorable decision for UGTL routing. It also fosters the development of sustainable and resilient urban energy systems in similar urban locations. Full article

Background/Objectives: Subterranean mole-rats live in an intricate system of underground tunnels, a unique acoustic environment that has led to adaptations to their hearing. Most experimenters have concluded that mole-rats have poor hearing thresholds, perhaps 20–40 dB less sensitive than rodents living on the surface. The potential problem identified here is that mole-rat thresholds have all been measured in air, whereas there is some evidence—theoretical and observational—to suggest that these animals may hear more sensitively via bone conduction. Methods: A wide-ranging review of the literature surrounding mole-rat hearing is undertaken and then interpreted in terms of the ways air conduction and bone conduction thresholds are measured. The important factor, often overlooked, is that the detection of an acoustic signal is most sensitive when there are matching impedances all along the transmission path, and the argument is made that, for subterranean mole-rats, more energy may be transmitted to their cochlea when the head is directly in contact with the earth than when an acoustic signal must propagate from the earth to the air and then reach the cochlea via the external and middle ear. Results: Based on observational evidence, theoretical considerations, and inferences from related species, the suggestion is made that, for African mole-rats, high bone conduction sensitivity could make up for their relatively poor air conduction thresholds. Conclusions: Bone conduction audiograms are needed for mole-rats, similar to those for other animals sensitive to substrate vibration such as snakes or amphibians. It is possible that the hearing thresholds of mole-rats may, when measured appropriately, be comparable to those of other rodents. Full article

Electrical and seismic exploration are two widely used geophysical methods in geological surveys. They reflect different geophysical properties of underground rocks, but each method can only provide information from a single perspective of the rock structure’s physical parameters. As a result, relying on a single geophysical method can lead to ambiguous interpretations. To address this issue, this paper presents the development of a multi-functional, high-power, multi-channel, rolling, fast measurement system for combined electrical and seismic exploration. The system features the following capabilities: it can be used simultaneously for both electrical and seismic exploration; it supports high-power operation, with a transmission power of up to 10 kW during electrical exploration; it includes multiple measurement channels for rolling measurement and data acquisition, with a sampling rate of up to 100 ksps, significantly improving work efficiency and expanding the frequency range. The distance between channels can be selected from 1 to 20 m, greatly enhancing the system’s adaptability to various environments. Additionally, we have designed accompanying upper-level software that not only stores data internally but also displays waveforms in real-time on a computer for monitoring and control. The experimental results demonstrate that the instrument operates stably and meets the requirements for field exploration. Full article

Aiming to solve the problems of communication interruption caused by the collapse of underground space, this study constructs a strong penetration information transmission system and proposes a centroid localization method based on the received signal strength indication (RSSI) in an underground space ground electrode current field. This is applicable to localization in underground space such as subways, mines, tunnels, etc., as well as under the environment of collapse. First, the propagation characteristics of the ground current field signal in underground space are analyzed, and the attenuation model of the ground current field signal is constructed by combining the RSSI ranging method. On this basis, an improved weighted centroid localization algorithm is introduced to improve the localization accuracy and reliability by optimizing the algorithm parameters to cope with the fluctuations and instabilities generated in the signal propagation process. The experimental results show that the proposed localization method achieves an average positioning error of 7.47 m in an underground environment of 10,000 square meters, which is 32.32% less compared with the weighted centroid localization algorithm, and 62.74% less compared with the traditional centroid localization algorithm. This method presents a positioning technology that operates independently in underground spaces, overcoming the limitation of traditional wireless positioning systems, which rely on external transmission links. Its application will provide crucial technical support for life-saving operations in underground environments, acting as the ‘last line of defense’ in rescue missions. By completing the emergency response chain, it will enhance disaster rescue capabilities, offering substantial practical value and promising prospects. Full article

A 3D visual presentation provides a wide spectrum of interpretive and collaborative possibilities. Building Information Modeling (BIM) is becoming increasingly popular in the AEC (Architecture, Engineering, Construction) sector. However, it mainly applies to cubic (building structures) and infrastructure projects. BIM is rarely used in the digitization of aboveground or underground networks. The purpose of this article is to fill this research gap and to demonstrate, through a case study, the real benefits of processing integrated 3D data covering civil structures, technical infrastructure and networks. The methodology of this paper included all steps towards the creation of an integrated model of a district heating network and the infrastructure located in its vicinity. The results show that integrated BIM models can help minimize or prevent design and execution collisions. This article undertakes critical inquiry and presents a unique approach to modeling urban spaces. The integrated BIM model enables management of the life cycle of a district heating network using a wide range of applications depending on the nature of the data, analysis and simulation. This article contributes to the discussion on modeling transmission infrastructure and integrating it with existing spatial models and databases. This paper presents innovative and significant interdisciplinary research. Full article

In the study of underground gas diffusion, traditional methods often emphasize diffusion while neglecting the potential impact of convection. This research constructs a coupled model of diffusion and convection to investigate gas transmission characteristics in complex underground environments. The model is validated and calibrated using field measurement data. The results indicate that the coupled model provides a more accurate representation of gas concentration distribution and diffusion time compared to models that consider only diffusion. Furthermore, this study examines the influence of horizontal well inclination angle on gas diffusion time within the framework of convection–diffusion coupling, revealing its underlying variation patterns. This analysis offers a theoretical foundation for enhancing efficiency and safety in oil and gas production as well as related operations. Under the convection–diffusion coupling mechanism, it is found that the inclination angle of horizontal wells significantly affects gas diffusion time; specifically, larger inclination angles result in shorter durations for gas to diffuse from the bottom to the wellhead. Understanding these variation patterns can facilitate optimization in horizontal well design, rational arrangement of production processes, precise prediction of diffusion times, enhancement of existing safety measures, and provision of forward-looking methodologies and technical support for addressing potential risk events within the oil and gas industry. This has substantial practical implications for engineering applications. Full article

Based on the engineering context of prefabricated underground station structures, this paper proposed a novel diaphragm wall–beam joint based on post-poured ultra-high-performance concrete (UHPC) and non-contact lap-spliced steel bars. This research study designed and conducted a full-scale experiment on the diaphragm wall–beam joints. The failure modes, bearing capacity, overall stiffness, crack resistance performance, and force transmission mechanism of the new diaphragm wall–beam joint were investigated. Additionally, a three-dimensional finite element model (FEM) of the wall–beam joint was developed using the software ABAQUS 2020. The model was validated against experimental results and used for further analysis. The results showed that the tensile through-cracks at the UHPC-diaphragm wall interface characterize the final failure process. The proposed UHPC joint could satisfy the structural design requirements in terms of crack resistance and bearing capacity. No rebar pulled-out damage was observed, and the non-contact lap-spliced length of 10d in the UHPC joint was sufficient. Compared with the traditional cast-in-place concrete joint, the cracking moment and yield moment of the proposed UHPC joint increased by 8.7% and 5.4%, respectively. Full article

In Europe, renewable energy sources such as photovoltaic panels and wind power plants are developing dynamically. The growth of renewable energy is driven by rising energy prices, greenhouse gas emission restrictions, the European Union’s Green Deal policy, and decarbonization efforts. Photovoltaic farms generate energy intermittently, depending on weather conditions. Given the increasing number of new installations, ensuring the power balance and transmission capacity of the electrical grid has become a major challenge. To address this issue, the authors propose a technical solution that allows the energy generated by photovoltaic systems to be stored in the form of heat. Thermal energy from solar power and wind energy offers significant potential for energy storage. It can be accumulated during summer in specially designed sand-based heat storage systems and then used for heating purposes in winter. This approach not only reduces heating costs but also decreases greenhouse gas emissions and helps balance the power grid during sunny periods. Post-industrial areas, often located near city centers, are suitable locations for large-scale heat storage facilities supplying, among others, public utility buildings. Therefore, this article presents a concept for utilizing high-temperature sand-based heat storage systems built in decommissioned underground mining excavations. Full article

Artificial intelligence (AI)-based fault diagnosis methods have been widely studied for power grids, with most research focusing on fault interval localization rather than precise fault point identification. In cases involving long-distance transmission lines or underground cables, merely locating the fault interval is insufficient. This paper presents a novel fault diagnosis and precise localization method for power systems utilizing the Graph Sample and Aggregated (GraphSAGE) algorithm. A fault diagnosis and interval localization model are developed based on the system topology, identifying k-order adjacent nodes at both ends of the fault interval. This information is then used to construct an accurate fault point localization model. Leveraging the strong inductive learning capability of GraphSAGE, the proposed method effectively captures the impact of the fault point on surrounding nodes, enabling precise fault point localization. Experimental results demonstrate that the proposed method offers high fault diagnosis accuracy, precise localization, and robust performance. The model shows significant applicability in real-world fault scenarios, maintaining strong performance and economic value across varying network topologies and incomplete data collection. Full article

The UK net zero strategy aims to fully decarbonize the power system by 2035, anticipating a 40–60% increase in demand due to the growing electrification of the transport and heating sectors over the next thirteen years. This paper provides a detailed technical and economic analysis of the role of energy storage technologies and transmission lines in balancing the power system amidst large shares of intermittent renewable energy generation. The analysis is conducted using the cost-optimizing energy system modelling framework REMix, developed by the German Aerospace Center (DLR). The obtained results of multiple optimization scenarios indicate that achieving the lowest system cost, with a 73% share of electricity generated by renewable energy sources, is feasible only if planning rules in England and Wales are flexible enough to allow the construction of 53 GW of onshore wind capacity. This flexibility would enable the UK to become a net electricity exporter, assuming an electricity trading market with neighbouring countries. Depending on the scenario, 2.4–11.8 TWh of energy storage supplies an average of 11% of the electricity feed-in, with underground hydrogen storage representing more than 80% of that total capacity. In terms of storage converter capacity, the optimal mix ranges from 32 to 34 GW of lithium-ion batteries, 13 to 22 GW of adiabatic compressed air energy storage, 4 to 24 GW of underground hydrogen storage, and 6 GW of pumped hydro. Decarbonizing the UK power system by 2035 is estimated to cost $37–56 billion USD, with energy storage accounting for 38% of the total system cost. Transmission lines supply 10–17% of the total electricity feed-in, demonstrating that, when coupled with energy storage, it is possible to reduce the installed capacity of conventional power plants by increasing the utilization of remote renewable generation assets and avoiding curtailment during peak generation times. Full article

The electro-hydraulic composite intelligent completion technology is one of the most effective ways to solve the efficient development of oil and gas. The development of an electro-hydraulic composite wet joint tool that is compatible with the electro-hydraulic composite intelligent completion system can achieve intelligent control between the upper and lower pipe columns of deepwater oil and gas wells and the pluggable transmission of monitoring signals. This article proposes a new type of electromagnetic coupling electro-hydraulic composite wet joint designed to address the defects of friction damage and poor contact in current wet joint direct contact power transmission. The joint uses claw docking and wireless energy transmission to achieve the composite transmission of hydraulic and electric power. Firstly, we independently designed a DC power supply inverter circuit, rectification circuit, and wireless power transmission coil assembly to form a wireless power transmission system. We also conducted testing and analysis on the wireless power transmission efficiency, which exceeded 60%. When the input voltage was above 80 V, the output power was greater than 60 W, meeting the design requirements. Secondly, the mechanical structure of the new electro-hydraulic signal wet joint tool was optimized and its strength was verified. The simulation results showed that the maximum stress was 891.8 MPa, and the maximum deformation of the wet joint docking overall structure was 0.123 mm. The strength and deformation met the design requirements. The hydraulic and electrical connectivity indoor tests were conducted on the electromagnetic coupling wet joint, and all aspects of transmission were normal, thus forming a design scheme for the underground electromagnetic coupling electro-hydraulic signal wet joint. The wireless transmission type electro-hydraulic signal wet joint designed in this article is of great significance for accelerating the promotion and application process of deepwater intelligent completion systems. Full article

Underground and submarine power cables are subjected to mechanical stress during installation and operation, which degrades the cable insulation and reduces the reliability of power transmission. Therefore, tests that can evaluate the mechanical properties of power cable insulation are very important. The purpose of this paper is to introduce an improved sampling method for the test sample, the peeling, for mechanical testing of power cable insulation and to evaluate the reliability of the method. The influence of the sampling method of the test sample on the mechanical property values was analyzed. The tensile strength and elongation of XLPE (cross-linked polyethylene) and PP (polypropylene) insulation prepared by the slice method and the peeling method were measured, and the surface of the test samples according to the sampling methods was photographed by SEM. The results show that the mechanical property of the cable insulation increased by more than 10% when the improved peeling method was used, and the precision of the peeling method was relatively better. The SEM analysis showed that the surface of the sliced test sample was rougher than the peeled test sample and was physically damaged. Therefore, the high reliability of the peeling method for mechanical testing of cable insulators was demonstrated. Full article