Deep Underground Science and Engineering最新文献

Due to the invisibility and complexity of the underground spaces, monitoring the propagation and filling characteristics of the grouting slurry post the water–sand mixture inrush in metal mines is challenging, which complicates engineering treatment. This research investigated the propagation law of cement-sodium silicate slurry under flowing water conditions within the caving mass of a metal mine. First, based on borehole packer test results and borehole TV images, the fractured strata before grouting were classified into four types: cavity, hidden, fissure, and complete. Second, an orthogonal experimental design was employed to evaluate the impact of four key factors—stratigraphic fragmentation, water flow rate, grouting flow rate, and water-cement ratio—on the efficacy of grouting within a caving mass at the site. The results indicate that the factors influencing grouting efficacy are ranked in the following order of importance: stratigraphic fragmentation > water flow rate > water–cement ratio > grouting flow rate. Ultimately, five propagation filling modes—pure slurry, big crack, small crack, small karst pore, and pore penetration—were identified by examining the propagation filling characteristics of slurry in rock samples, incorporating microscopic material structure analysis through scanning electron microscopy and energy spectrum analysis. The findings of this study provide valuable insights into selecting engineering treatment parameters and methodologies, serving as a reference for preventing and controlling water–sand mixture inrush in metal mines, thereby enhancing treatment efficacy and ensuring grouting success.

CO₂-enhanced oil recovery (CO₂-EOR) is an economically viable carbon capture, utilization, and storage (CCUS) technique that is widely practiced and greatly contributes to the achievement of carbon-neutral cities. However, studies on CO₂-EOR source–sink matching involving different emission sources, different carbon capture rates, and stepwise CO₂ pipeline construction are scarce. Considering four types of carbon sources, including coal-fired power, iron and steel, cement, and chemical plants, with different CO₂ capture rates (85%, 90%, 95%, and 100%, respectively), and using a five-phased construction plan with a 25-year build-up period, we developed a method for quantifying carbon emissions from different sources, calculating the effective storage of carbon in CO₂-EOR and optimizing CO₂-EOR source–sink matching to reduce project costs. Using the Subei Basin in the Jiangsu Province, China, as a case study, we calculated the theoretical CO₂-EOR storage to be 1.7408 × 10⁸ t and the effective CO₂-EOR storage to be 0.435 × 10⁸ t. We analyzed the completion rate of transportation pipelines, the number of connected carbon sources, and the mass of CO₂ stored, as well as the cost-effectiveness and sensitivity. Implementation of CO₂-EOR effectively reduced the total cost of source–sink matching in the five-stage 25-year construction approach. The reduction of CO₂ capture rates had no effect on the value of oil repelling. The capture cost significantly affected the total cost of source–sink matching, and the impacts of the carbon sources on the total cost were in the order coal-fired power > iron and steel > cement > chemical plants. This study provides an innovative tool for evaluating the CO₂ storage potential of CO₂-EOR and provides an important framework for implementing CO₂-EOR and planning CCUS projects in the Subei Basin and similar regions.

Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonite-based buffer, backfill, and sealing systems in deep geological disposal of high-level radioactive wastes. Motivated by such applications, most past experimental studies were focused on highly compacted and high-quality bentonite. Such degrees of dry densities may not be economically or technically feasible for other emerging applications, including as an alternative material to cement in plugging and abandonment of wells. A bespoke high-pressure high-temperature constant rate of strain (CRS) apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro-mechanical response of compacted bentonite to elevated temperatures. Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities (1.1, 1.4, and 1.7 Mg/m³) and temperatures between 20 and 80°C. The results show that temperature increase leads to the decrease of swelling pressure for all studied densities. Larger reductions of swelling pressure were observed with increasing dry densities, suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay. The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high-density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.

Groundwater inrush is a hazard that always occurs during underground mining. Grouting is one of the most effective processes to seal underground water inflow for hazard prevention. In this study, grouting experiments are conducted by using a visualized transparent single-fracture replica with plane roughness. Image processing and analysis are performed to investigate the thermo–hydro–mechanical coupling effect on the grouting diffusion under coal mine flowing water conditions. The results show that higher ambient temperature leads to shorter initial gel time of chemical grout and leads to a better relative sealing efficiency in the case of a lower flow rate. However, with a higher water flow rate, the relative sealing efficiency is gradually reduced under higher temperature conditions. The grouting pressure, the seepage pressure, and the temperature are measured. The results reveal that the seepage pressure shows a positive correlation with the grouting pressure, while the temperature change shows a negative correlation with the seepage pressure and the grouting pressure. The “equivalent grouting point offset” effect of grouting shows an eccentric elliptical diffusion with larger grouting distance and width under lower temperature conditions.

In this study, the design and development of a sensor made of low-cost parts to monitor inclination and acceleration are presented. Α micro electro-mechanical systems, micro electro mechanical systems, sensor was housed in a robust enclosure and interfaced with a Raspberry Pi microcomputer with Internet connectivity into a proposed tilt and acceleration monitoring node. Online capabilities accessible by mobile phone such as real-time graph, early warning notification, and database logging were implemented using Python programming. The sensor response was calibrated for inherent bias and errors, and then tested thoroughly in the laboratory under static and dynamic loading conditions beside high-quality transducers. Satisfactory accuracy was achieved in real time using the Complementary Filter method, and it was further improved in LabVIEW using Kalman Filters with parameter tuning. A sensor interface with LabVIEW and a 600 MHz CPU microcontroller allowed real-time implementation of high-speed embedded filters, further optimizing sensor results. Kalman and embedded filtering results show agreement for the sensor, followed closely by the low-complexity complementary filter applied in real time. The sensor's dynamic response was also verified by shaking table tests, simulating past recorded seismic excitations or artificial vibrations, indicating negligible effect of external acceleration on measured tilt; sensor measurements were benchmarked using high-quality tilt and acceleration measuring transducers. A preliminary field evaluation shows robustness of the sensor to harsh weather conditions.

Deep Underground Science and Engineering (DUSE) launched its first issue in September 2022 as a quarterly journal. So far, it has published 106 articles with nine issues and online early view. The volume of received manuscripts increases by 50% each year and over 200 manuscripts were received by 28th of November 2024. In the early period, DUSE authorship came from five countries and now reaches 29 countries. DUSE articles have been downloaded over 97 000 times by readers from 170 countries/regions. It is indeed encouraging to note that DUSE has been admitted to different indices, including ESCI (August 2024), EI (March 2024), Scopus (July 2023), and DOAJ (May 2023). Its CiteScore in Scopus was 2.2 in 2023 and increased to 5.1 at the mid-November 2024. Its first impact factor from the Web of Science will be available in 2025. DUSE is growing to be a rapidly recognized international journal by readers in deep underground research and practice.

DUSE is making its best efforts to trace and shape a full-chain deep underground science and engineering through its six directions. Direction 1: Exploration and extraction of geo-resources. The geo-resources refer to minerals, energy sources, and water. DUSE makes efforts to streamline research studies in geo-resources from the initial geological analysis of source location, geo-resource volume estimation, and hot sweat point identification. These processes involve geology, geophysics, rock mechanics, and related material science and technology. After the identification of geo-resources, the next step is to extract these geo-resources from (deep) ground. This step involves engineering science and technology, such as rock mechanics, hydraulic fracturing technology, blasting, and so on. The key outcome is the extraction of these identified geo-sources from the deep ground with technical feasibility and economic benefit. Direction 2: Energy extraction and storage. Deep underground has abundant fuel matter, which was generated through long-term geological actions. Deep underground also has abundant space for the storage of energy and materials. This direction involves branches of engineering science, such as petroleum, engineering science and technology, material science, and environment science. Direction 3: Underground infrastructures. This direction focuses on the excavation and utilization of underground spaces, such as cavern construction, tunneling, and other pore space use. Direction 4: Geo-environments and waste geological disposal, which deals with the solutions to environmental problems in deep underground. The environmental problems have two types: The first one refers to the environmental problems induced by the exploitation of underground resources. The second one refers to the utilization of underground space (including pore space) to solve the environmental problems that are difficult to tackle on the ground surface, such as geological disposal of nuclea

Coal mining induces changes in the nature of rock and soil bodies, as well as hydrogeological conditions, which can easily trigger the occurrence of geological disasters such as water inrush, movement of the coal seam roof and floor, and rock burst. Transparency in coal mine geological conditions provides technical support for intelligent coal mining and geological disaster prevention. In this sense, it is of great significance to address the requirements for informatizing coal mine geological conditions, dynamically adjust sensing parameters, and accurately identify disaster characteristics so as to prevent and control coal mine geological disasters. This paper examines the various action fields associated with geological disasters in mining faces and scrutinizes the types and sensing parameters of geological disasters resulting from coal seam mining. On this basis, it summarizes a distributed fiber-optic sensing technology framework for transparent geology in coal mines. Combined with the multi-field monitoring characteristics of the strain field, the temperature field, and the vibration field of distributed optical fiber sensing technology, parameters such as the strain increment ratio, the aquifer temperature gradient, and the acoustic wave amplitude are extracted as eigenvalues for identifying rock breaking, aquifer water level, and water cut range, and a multi-field sensing method is established for identifying the characteristics of mining-induced rock mass disasters. The development direction of transparent geology based on optical fiber sensing technology is proposed in terms of the aspects of sensing optical fiber structure for large deformation monitoring, identification accuracy of optical fiber acoustic signals, multi-parameter monitoring, and early warning methods.