Tạp chí của Trường Đại học Mỏ - Địa chất
Publishing Office - Hanoi University of Mining and Geology
Determination of density value in the Nong Son - Da Nang by Petrov's 3D gravity inversion
The paper presents the results of Petrov’s 3D inversion applied to gravity data to determine the continuous distribution of rock density from the surface down to a depth of Z = 7250 m in the Nong Son - Da Nang area, supporting the delineation of potential zones associated with ore-forming processes. The inversion method was performed continuously on the residual gravity field using a two-dimensional “live-window” energy filter, with window sizes varying from 600÷8600 m. The reliability of the inversion results strongly depends on the accurate determination of residual gravity anomalies. Therefore, in this study, we apply a statistical-probabilistic approach to identify adaptive filter-window geometries that are consistent with the regional anomaly trend, thereby enhancing the accuracy of residual gravity anomaly separation. The results show that, at the southwestern ore-point locations, the subsurface rock density is heterogeneous, forming blocks with positive residual-density values ranging from 0.1÷0.35 g/cm³, corresponding to residual gravity anomalies of 1÷3.5 mGal. The residual density anomalies within local block structures at the ore-point sites extend to depths of approximately 4000 m. The density increases from about 2.25 g/cm³ at the surface to 3.05 g/cm³ at a depth of 7250m. In the ore-bearing zones, the density varies from 2.8 g/cm³ near the surface to 3.0 g/cm³ at depths of around 4000 m, forming a continuous band extending upward from depth toward near-surface levels. The interpretation results indicate potential mineralized zones associated with the upward migration and near-surface accumulation of magma-derived materials.
Copyright (c) 2026 Journal of Mining and Earth Sciences
Analysis of Vietnam coal mining pressure under competent strata using field measurement
This paper presents an analysis of Vietnam coal mining pressure under competent roof strata. Using classical ground pressure theories, the pressure law around longwall mining from setup entry to first strata caving and cyclic strata caving is strongly confirmed to follow pressure arch, voussoir beam and cantilever beam theories, respectively. Through analysis of shield pressure and shield convergence from a typical longwall mining under competent strata in Vietnam, the study clearly demonstrates the pressure law caused by progressive mining. The pressure change is proved to have a close relationship with roof strata movement and classical pressure theories. The pressure magnitude increases significantly and decreases rapidly when competent roof strata rupture. The difference in pressure and piston displacement between front leg and rear leg is an indicator for the stability of coal face and roof. The shield behaviours at T-junction are found to be less severe than those at the mid-panel width. The study proposes solutions to improving shield capability by increasing maximum support force and using multi-level face guard. The results from this study assist mining engineers in Vietnam in better understanding ground pressure on coal face and properly designing face support. The sustainable mining under unfavourable conditions can be better achieved for the national coal industry
Numerical analysis of stability of sea dikes: a case study at An Bien - An Minh coastline
In response to increasing coastal hazards driven by climate change and sea level rise, this study investigates severe shoreline erosion and instability of the An Bien - An Minh sea dike system in An Giang Province, Vietnam, located in the western Mekong Delta. The research aims to evaluate the existing geological, geotechnical, and hydrodynamic conditions of the study area and to assess their combined influence on the stability and structural performance of the sea dike system. Field investigations and monitoring programs were conducted to collect data on wave characteristics, coastal currents, sediment conditions, and subsurface soil properties. These datasets were integrated into a numerical modeling framework using PLAXIS 3D based on the finite element method to analyze soil-structure interaction, deformation behavior, and stability of the dike system under representative design loading conditions. The numerical analysis focused on stress distribution, displacement patterns, and potential failure mechanisms associated with soft soil foundations and wave-induced loading. Based on the modeling results, an integrated coastal protection solution is proposed, combining offshore wave attenuation structures, reinforced concrete revetments, and mangrove forest restoration. Simulation results demonstrate that the proposed measures significantly reduce wave energy transmitted to the dike toe, mitigate shoreline erosion, and enhance the overall stability and resilience of the sea dike system. In addition to technical effectiveness, the integrated solution supports environmental sustainability by promoting ecosystem-based coastal protection and reducing long-term maintenance requirements. The findings provide a robust scientific basis for climate-resilient coastal infrastructure planning and management in the Mekong Delta and offer practical guidance for the design and upgrading of sea dike systems in other low-lying coastal regions facing similar climate-related challenges.
Quantitative evaluation of geosites in the Lang Son UNESCO global geopark
A quantitative evaluation of geosites in the Lang Son UNESCO Global Geopark (Vietnam) is urgently needed to provide objective evidence for conservation prioritization and sustainable geotourism planning. This study aims to quantitatively assess the geotourism value of 19 selected geoheritage sites within the Lang Son UNESCO Global Geopark. By integrating secondary data, spatial distribution analysis, and primary data collected through expert interviews and field surveys conducted within the geopark, the research applies the Geosite Assessment Model (GAM). The model is structured as a 9-field matrix, allowing the classification of geosites according to appropriate development orientations based on two main groups of values: (1) Main Values (maximum 12 points), including scientific/educational value (VSE), aesthetic/landscape value (VSA), and protection level (VPr); and (2) Additional Values (maximum 15 points), including functional value (VFn) and touristic value (VTr). The results indicate that the Main Values (VSE + VSA + VPr) of the evaluated geosites are relatively uniform (average ≈ 8.0 points), while the Additional Values (VFn + VTr) exhibit a wider variation (3.75÷13.75 points), which plays a decisive role in distinguishing between the Z33, Z32, and Z21 groups. This demonstrates that, beyond their inherent geological and scientific significance, factors such as infrastructure, promotional activities, and community-based tourism management are crucial in enhancing the overall value of geosites within the context of sustainable geotourism development. The GAM results not only help identify the geosites that should be prioritized for conservation and development (Z33, Z32) but also highlight the groups requiring functional and touristic enhancement (Z23, Z22, Z21). These findings provide a scientific foundation for local authorities and tourism enterprises to design more effective strategies for the sustainable utilization of geoheritage resources within the Lang Son UNESCO Global Geopark, thereby contributing to the socio-economic development of Lang Son Province.
Study and proposal of a flotation technology for Zinc Oxide Ore from the Cho Dien deposit
In recent years, the rapid decline in both reserves and quality of domestic zinc sulfide ores-the primary raw material for zinc metal production in Vietnam-has posed significant challenges for the industry. This has made the development of alternative processing technologies for low-grade zinc oxide ores (5÷10% Zn) increasingly urgent. The Cho Dien deposit (Thai Nguyen province) hosts such ores, which are strongly weathered, fine-grained, and mineralogically complex, containing smithsonit, hemimorphit, and chalcophanite with goethite, clays, and carbonates as major gangue minerals. This study investigates flotation performance under different processing regimes, including desliming versus non-desliming, reagent schemes, and flotation machine types. Experimental results demonstrate that a reagent combination of Na₂S_Tan-X_Sep-X, combined with non-desliming, is more effective than conventional depressants and dispersants. Moreover, a comparison between conventional mechanical flotation and forced-air flotation cells (TankCell) shows that TankCell achieves a zinc concentrate grading 21.75% Zn with a recovery of 62.7% after a single cleaning stage, whereas mechanical flotation requires two cleaning stages to obtain a concentrate of 21.18% Zn at 62.5% recovery. These findings confirm that flotation is a technically feasible route for complex low-grade zinc oxide ores in Vietnam and provide a practical basis for industrial application
New points in TCVN 5575:2024 and the use of bi-moment in the strength verification of flexural members
In countries with advanced science and technology, important standards in the field of structural design for buildings and civil structures - particularly in steel and reinforced concrete structures - are constantly monitored, revised, or updated. The Vietnamese standard TCVN 5575:2012 - Steel Structures - Design Standard has been in effect for 13 years since its issuance and has now been replaced by the new version TCVN 5575:2024. This paper focuses on analyzing and presenting several notable updates introduced in TCVN 5575:2024, including: the structure of the standard, its scope of application, classification of structural members and structural groups, design strength of materials and steel structural connections, as well as reliability factors. In the structural design section, several updated aspects in the calculation of flexural members are analyzed with consideration of the bi-moment component. The application of TCVN 5575:2024 also emphasizes critical updates concerning material grades, reliability factors, and the effect of bi-moment forces in conducting strength checks and connection calculations for a Grade 1 steel beam with a closed rectangular hollow section and an open-section thin-walled C - beam. The analysis demonstrates that the updates in TCVN 5575:2024 - Steel Structures - Design Standard are harmonized with international standards, enhance structural safety, optimize design efficiency, and improve constructability in the field of steel structures
Correlation between P-wave modulus (M) and Uniaxial compressive strength (UCS) derived from hydraulic flow units (HFU)
Uniaxial compressive strength (UCS) is one of the most important geomechanical parameters for evaluating rock strength along the wellbore. It is essential for ensuring drilling safety and optimizing drilling operations, particularly in determining the appropriate mud weight window to maintain well stability and improve the rate of penetration. Additionally, the UCS parameter plays a significant role in predicting sand production. Typically, UCS is determined through core sample tests in the laboratory, but this method is costly and time-consuming and provides either scattered data nor continuous log profile. Therefore, many studies around the world have proposed correlation between cored UCS and well log. However, these models often exhibit significant errors when applied to field X, Block Y in the Northern area of Cuu Long basin. In this paper, we propose a correlation between P-wave modulus (M) and Uniaxial compressive strength (UCS) derived from hydraulic flow units. Consequently, the correlation coefficient between cored UCS and log-derived UCS values is very high, with an overall value of 0.82 for all wells. In particular, the mean absolute error (MAE), mean absolute percentage error (MAPE), and root mean square error (RMSE) are as follows: for well A-1X — MAE: 426.3 psi, MAPE: 10.4%, RMSE: 582.5 psi; for well A-2X — MAE: 843.17 psi, MAPE: 16%, RMSE: 1115.5 psi; for well A-3X — MAE: 321.9 psi, MAPE: 7%, RMSE: 385.6 psi; and for well A-4X — MAE: 286.46 psi, MAPE: 10%, RMSE: 438.76 psi. The blind-test well B-1X shows acceptable errors, with MAE: 335.5 psi, MAPE: 14%, and RMSE: 383.37 psi. This model enhances the efficiency and safety of drilling and production operations in Field X, Block Y, located in the northeastern part of the Cuu Long Basin
Standardization and the Development of a Database in the General Urban Planning Scheme of Phu Thong Town
Developing a planning database is a crucial task to ensure publicity, transparency, and accessibility of information for state agencies, organizations, and the public. This contributes to improving the effectiveness of urban and rural planning, as well as supporting the implementation of the National Digital Transformation Program and realizing Resolution No. 06-NQ/TW dated January 24, 2022, issued by the Politburo. However, in many localities, the implementation of this work still faces challenges and difficulties. Continued research is necessary to make the standardization and construction of planning databases more convenient and widely adopted. This article introduces the process, design method, and experimental results of developing a planning database for the Master Plan for Construction of Phu Thong Town, Bach Thong District, Bac Kan Province, for the period 2021-2030, with a vision toward 2050. The input data include current drawings, plans, and diagrams approved by competent authorities; explanatory reports, tables, and attached miniature drawings; as well as decisions and submissions. The results show that by applying GIS tools, the Master Plan for Construction of Phu Thong Town database is developed in compliance with current regulations, is simple to implement, and effectively supports state management agencies in planning activities, while also facilitating access to planning information for residents and businesses
Assessment of the potential use of the Radar Vegetation Index (RVI) using Sentinel-1 imagery for monitoring vegetation cover: A case study in Thanh Hoa province, Vietnam
Changes in the surface vegetation cover occur continuously over time as a result of the influence of anthropogenic activities, natural hazards, and the dynamics of vegetation development. The Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) are two examples of optical remote sensing indices that are routinely used to monitor vegetation cover at the present time. The optical indices, on the other hand, are frequently constrained by the weather conditions, which results in the collecting of data being interrupted. In order to overcome this constraint, the authors propose the utilization of the Radar Vegetation Index (RVI), which is produced from Synthetic Aperture Radar (SAR) data obtained from Sentinel-1A, for the purpose of monitoring landscape vegetation cover. The research findings show that RVI values follow a pattern of variation that corresponds to the stages of paddy rice growth. Additionally, the Pearson correlation coefficient (r) and p-value were employed to examine the correlation between the RVI (provided by Sentinel-1) and the NDVI (provided by Sentinel-2) for various vegetation categories. Perennial crops, industrial crops, and paddy rice demonstrated correlation coefficients of 0.675, 0.700, and 0.563, respectively, with p-values at or below 0.05. In particular for industrial and perennial crops, our results show that RVI often varies in correlation with NDVI. It is confirmed that the RVI is sensitive to the dynamics of vegetation, which is comparable to that of standard optical indices such as the NDVI. This study contributes to the enhancement of the usefulness of RVI in vegetation cover monitoring.
Zoning debris flow risk in Than Uyen region, Lai Chau province through machine learning models
Debris flows are one of the most common and hazardous types of natural disasters in mountainous regions of Vietnam, particularly in the Than Uyen region, Lai Chau Province. This region is characterized by steep terrain, high rainfall, degraded vegetation cover, and weak soil structure, all of which contribute to the frequent triggering of debris flows. This study aims to assess debris flow susceptibility using Linear Regression and the Random Forest (RF) model, integrating remote sensing data, GIS, and field surveys. A total of ten input variables were selected to train the models using 422 sample points. The RF model demonstrated superior performance, achieving an accuracy of 86% and an AUC of 0.91, compared to 74% accuracy and an R² of 0.65 from the regression model. Given its higher reliability and practical relevance, the RF model was used to generate a debris flow susceptibility map for the entire region. Field validation conducted in Khoen On, Ta Mung, and Muong Cang communes confirmed a strong spatial agreement between high-susceptibility zones and actual debris flow events. The study recommends implementing early warning systems, continuous monitoring, and resettlement planning in high- susceptibility areas. It also emphasizes integrating the model outputs into spatial planning frameworks to enhance climate change adaptation and disaster risk reduction in mountainous areas
Application of deep learning model and DSAS in assessing coastline changes of Da Nang Bay
The effects of climate change and the rapid increase of urbanization are exerting pressure on coastal areas. Meanwhile, coastal accretion and erosion are natural hazards that affect coastal communities, particularly in Da Nang Bay, where both processes are influenced by natural dynamics and anthropogenic activities. The study aims to assess coastline changes in Da Nang Bay under the influence of storms and urbanization. The authors used DSAS and the deep learning UNet model on high-resolution UAV images to analyze coastline change during the period from 2002 to 2024. The results show that the UNet model achieved an overall accuracy of 98.5% with a Kappa coefficient of 0.97, demonstrating the effectiveness of the combined UNet–DSAS approach in shoreline change analysis. The southern area of the Cu De River tends to experience severe erosion, with a maximum rate of 3.43 m/year. In contrast, the Cu De River mouth shows a tendency toward accretion, which prevented transportation there. Land reclamation has caused the Da Phuoc urban area to grow quickly, with a maximum pace of 22.78 m/year. The study showed that the UNet model improved the accuracy of coastline detection. The results provide an effective methodological framework for coastal planning and management, and offer scientific evidence to support sustainable coastal planning and protection in Da Nang Bay.
Using red mud for flue gas storage and treatment: A green solution for the alumina industry
The production of alumina by the Bayer process invariably generates two types of hazardous waste: red mud and greenhouse gas emissions. Red mud is a voluminous solid residue consisting primarily of 30÷60% Fe₂O₃, 10÷20% Al₂O₃, 3÷50% SiO₂, 2÷10% Na₂O, 2÷8% CaO, and approximately 10% TiO₂. Due to its high alkalinity (pH 10÷13), red mud is not only difficult to manage but also poses potential risks of soil, water, and ecosystem contamination if improperly handled. In parallel, the combustion of fossil fuels during alumina production releases greenhouse gases along with other pollutants such as CO, CO₂, SO₂, NOₓ, and fine particulate matter, thereby contributing to climate change and deteriorating air quality. Nevertheless, the strong alkalinity of red mud makes it a promising material for adsorption and neutralization of acidic wastes, particularly flue gases from fossil fuel–fired power plants. Thus, utilizing red mud for greenhouse gas capture and treatment offers dual environmental benefits: mitigating gaseous emissions while providing a sustainable waste management strategy for the alumina industry. This paper reviews international research and practical applications of red mud for greenhouse gas storage and treatment. Building on these findings, it proposes technological directions for the simultaneous management of red mud and gaseous emissions generated during alumina production in Vietnam. Such an integrated approach is expected to enhance environmental performance while supporting the sustainable development of Vietnam’s bauxite and alumina industry.
3D numerical simulation of interaction between aligned Vertical-Axis Turbines within a farm: The case of Tidal Turbines
Vertical Axis Turbines (VATs) are devices used to extract kinetic energy from natural flows and convert it to electricity. In the past, VATs received less attention than Horizontal Axis Turbines (HATs). Recently, considerable research has focused on this type of turbine for applications in both wind and tidal power due to their distinct advantages over HATs. Understanding the interaction between the VATs within an array remains a complex issue, particularly regarding wake interactions and flow recovery downstream of each turbine. This paper presents the results of research on the interaction between Vertical Axis Tidal Turbines (VATTs) within an array. Turbines are modeled using the Actuator Cylinder theory. Simulations are conducted in ANSYS Fluent employing the standard k–ε turbulence model. First, a single turbine model is validated by comparing the normal and tangential forces acting on its blades with experimental data from Strickland’s study. Then, the interaction between two aligned turbines is analyzed. The distances considered are 3D, 7.5D, 15D, and 20D (where D represents the turbine diameter). The research results show that increasing the distance between turbines leads to faster recovery of flow energy for the downstream turbine. The flow velocity recovers to 42% of the free-stream velocity at a distance of 7.5D, and reaches 70% at 15D. The results of the research indicate that a 15D spacing is an appropriate distance for enhancing flow energy recovery for the downstream turbine. These findings are important for determining the optimal spacing between aligned VATTs within an array to ensure maximum efficiency in energy extraction from the flow
Tunnel–pile interaction is a key concern in geotechnical research due to the significant impact of tunnelling on the stress and deformation of the soil, as well as on surface structures. Tunnel excavation, especially at shallow depths, often causes ground settlement or heave, which affects the stability of existing structures and their pile foundations. Research on tunnel–pile interaction is conducted through analytical, numerical, and experimental methods. In analytical approaches, a two-step procedure is commonly applied: first, the ground displacement without piles is determined, followed by the analysis of the pile response. Experimental methods include physical modeling under 1g and centrifuge conditions, as well as full-scale prototypes. Full-scale models and field measurements provide real data on pile and soil deformation, which are essential for validating numerical and analytical models. Numerical modeling is widely used due to its ability to fully simulate the tunnelling process using a shield machine and the complex tunnel-pile interactions. It provides a balance between cost, accuracy, and flexibility, making it a powerful tool in both research and design. This paper reviews existing research methods and identifies potential research directions to enhance the accuracy of analysis and design of pile foundation structures.
Surface settlement caused by twin stacked tunnels excavated beneath buildings
Underground construction plays a crucial role in the development of megacities by addressing key urban transportation challenges such as traffic congestion and limited parking. One of the most effective solutions to the growing global demand for efficient transportation systems is the development of underground public transit networks, particularly subways. To support the rapid expansion of such infrastructure, this study investigates the impact of twin stacked tunnel excavation on ground surface settlement through three-dimensional (3D) numerical modeling. The models were developed under various excavation scenarios, considering factors such as groundwater level, soil conditions, face pressure, and grouting pressure applied by the Tunnel Boring Machine (TBM). The Ben Thanh - Suoi Tien metro line in Ho Chi Minh City was used as a reference case study, with settlement data from the tunnel site employed to validate the numerical model. The results show that all investigated parameters significantly influence ground settlement above twin stacked tunnels. In particular, variations in water level, soil conditions, face pressure, and grouting pressure have significantly influenced the surface settlement when the upper tunnel is excavated. This indicates their critical role in ensuring ground stability and must be carefully considered during the construction process
Copyright (c) 2025 Journal of Mining and Earth Sciences
U-Pb age and Lu-Hf isotopic characteristics of S-type granite in the Bac Tra My area, Quang Nam and their regional tectonic implications
The Kon Tum Massif (KTM) in central Vietnam is a key part of the Indochina Block, where Early Paleozoic magmatism is attributed to subduction and subsequent collision between the KTM and the Truong Son Belt (TSB). However, the timing, source and tectonic setting of S-type granites of the Chu Lai Complex, especially near Bac Tra My area, remain unclear. This study presents new zircon U-Pb geochronological and Lu-Hf isotopic data from two granitic gneiss samples of the Chu Lai Complex in the Tra My area to better constrain their formation age, magma source and tectonic implications. Zircon U-Pb dating by MC-LA-ICP-MS yields concordant crystallization ages of 438.7 ± 2.9 Ma and 441.7 ± 1.9 Ma, corresponding to the Late Ordovician. Inherited zircon core ages (1.45÷2.62 Ga) indicate that the magma was derived from partial melting of Paleoproterozoic-Mesoproterozoic metasedimentary sources. Zircon εHf(t) values from -11.1to -2.4 support derivation from ancient crustal materials. Petrographic features, including muscovite, garnet and tourmaline, further indicate an S-type peraluminous affinity. Integrating these data with previous results suggests that Chu Lai magmatism (455÷426 Ma) represents a syn- to post-collisional episode following the closure of the Proto-Tethys Ocean and the collision between the KTM and the TSB. This event, likely during the Middle to Late Ordovician, marks the termination of subduction beneath the KTM and the onset of a widespread post-collisional thermal regime across the Indochina Block. The study refines the timing of Early Paleozoic orogenesis in central Vietnam, provides new isotopic evidence for the crustal evolution of the KTM and contributes to a better understanding of the tectonic assembly of the eastern Indochina Block during the Paleozoic
Identification of well breathing phenomena in HPHT wells and technical solutions to enhance drilling efficiency in the Nam Con Son Basin
The Nam Con Son Basin is considered the most technically challenging area for drilling operations in Vietnam and ranks among the most complex globally. Its central region, dominated by high-temperature, high-pressure (HPHT) conditions, accounts for approximately 70÷80% of the basin’s total gas production. This area is geologically characterized by heterogeneous stratigraphy, abnormally high formation pressures and temperatures, and a narrow margin between pore pressure and fracture gradient-commonly referred to as the “narrow pressure window.” Under such conditions, even minor variations in mud weight can lead to wellbore instability or formation damage. One of the most critical drilling challenges in this environment is wellbore breathing - a transient loss and subsequent return of drilling fluid-typically observed in formations within the Miocene formation. These formations exhibit low porosity, low permeability, and elastic rock behavior, which can result in misleading well control indications, non-productive time, and potential well control incidents if not identified and managed appropriately. This study presents a novel diagnostic framework for recognizing and managing wellbore breathing in HPHT wells of the Nam Con Son Basin. It systematically evaluates operational data from recent wells using four key indicators: (i) loss circulation behavior during circulation, (ii) mud-volume return after pump stoppage, (iii) downhole pressure variations, and (iv) changes in total gas and gas-peak composition in returns. The combined indicators reliably identified early breathing onset and severity, distinguishing it from other circulation anomalies. Field validation confirmed the method’s robustness across multiple well sections. Applying the proposed framework, along with mud-weight optimization, real-time monitoring, and wellbore strengthening, reduced non-productive time and minimized well-control false alarms. These outcomes demonstrate significant practical value for improving safety, integrity, and efficiency in complex HPHT drilling environments worldwide HPHT.
Enhancing wind turbine efficiency: characteristics of cylindrical-conical hydrodynamic fluid friction bearings
One of the main causes of energy loss in wind turbine systems is friction between moving parts, particularly the multiplier, braking system and shaft supports. Conical- cylindrical plain bearings with a friction-reducing design help reduce energy consumption during turbine operation. Conical-cylindrical hydrodynamic bearings play a crucial role in wind turbines, reducing friction and energy losses, and effectively transmitting mechanical energy from wind blades to generators, thereby enhancing the overall efficiency of wind turbines. The research has developed a mathematical model to analyze the load-bearing capacity and energy losses due to friction. Using the calculation program developed on the basis of mathematical modeling and algorithms, a set of calculation experiments was performed to calculate the load-carrying capacity, moment and frictional power loss in a combined angular contact bearing depending on the shaft speed, lubricating oil supply pressure, radial clearance and relative eccentricity. This study investigates the characteristics of cylindrical-conical hydrodynamic fluid friction bearings and their critical role in optimizing the performance of wind turbines. By analyzing the load-carrying capacity, friction torque, and power losses under varying geometric and kinematic conditions, the research highlights how these bearings contribute to the overall efficiency and reliability of wind energy systems. The findings provide valuable insights into the design and operation of hydrodynamic bearings in highly loaded wind turbine applications, supporting the development of more sustainable and efficient wind energy technologies
Research on the material composition of Ta-Phoi copper tailings and accompanying gold recovery orientation
Drought risk prediction using remote sensing data and machine learning: A case study in Quang Tri province
Quang Tri Province was located in Vietnam’s North Central Coast, frequently experiences severe climatic conditions including prolonged droughts. These conditions adversely affect agricultural production and local livelihoods. This study proposes a drought risk prediction model by integrating remote sensing data with machine learning techniques to support water resource management and mitigate drought-related damages.​ Remote sensing data from Landsat and Sentinel-2 satellites covering the period from 2016 to 2025 were collected and processed using the Google Earth Engine (GEE) cloud platform. Drought indices including NDVI, LSWI, NDWI, MSI, NDDI, SAVI, VCI, TCI, TVDI, and VHI were computed to assess temperature conditions, soil moisture, and vegetation health. Based on the TVDI index, data were categorized into five drought severity levels: no drought, mild drought, moderate drought, severe drought, and extreme drought. A training dataset was constructed by randomly selecting pixel samples representing each drought level. Three machine learning models including Random Forest (RF), Support Vector Machine (SVM), and Gradient Tree Boosting (GTB) were employed to classify and predict drought risk.​ The GTB model achieved the highest accuracy with an overall accuracy of 91.67% and a Kappa coefficient of 0.89, outperforming both SVM and RF models. The drought risk distribution map generated using the GTB model clearly highlights areas with high drought risk, particularly in the eastern and central regions of Quang Tri Province. In addition, 2019 and 2022 recorded severe and extreme drought areas exceeding 90% of the total area of ​​the region
Optimizing axial bearing capacity estimation of pre-bored grouted planted nodular (PGPN) pile: Enriched dataset and genetic algorithm approach
This study introduces a practical and efficient methodology to improve the estimation of the ultimate axial bearing capacity of Pre-bored Grouted Planted Nodular (PGPN) piles, addressing a critical need in geotechnical engineering. By enhancing the dataset with 98 additional case histories and pile load test data from various projects across Vietnam, we have developed a more reliable predictive tool for engineers. The use of genetic algorithms has refined existing empirical formulas, significantly improving their accuracy while remaining simple enough for hand calculations. The proposed formula achieves a correlation coefficient of 0.907, a 7.2% improvement over previous methods. This research offers a valuable solution for the challenges faced in predicting the load-bearing capacity of PGPN piles, providing a more dependable method that can streamline design and construction practices
Copyright (c) 2024 Journal of Mining and Earth Sciences
The initial research results on the improvement of offshore axial pile capacity calculation using CPTu data at block A, offshore Vietnam
This paper presents the use of CPTu data in calculation of offshore axial pile capacity based on the CPT-based methods recommended in Appendix C of API RP 2GEO (2014) which are the Simplified ICP-05 Method (Method 1); Offshore UWA-05 Method (Method 2); Fugro-05 Method (Method 3); and NGI-05 Method (Method 4). Formerly, the strength values of cohesionless layers were usually taken from onshore laboratory results or if there were none done, the values were generally assumed based on recommendations of API RP 2A-WSD (2000) standard which often resulted in unconservative axial pile capacity. With the availability of CPTu data which better reflects the in-situ soil conditions, the selection of design parameters for cohesionless layers is improved and consequently, the improved axial capacity calculation both in tension and compression. The improvement in predicted axial pile capacity allows better pile design (for example, choice of pile length, optimization of pile diameter) and hence the economical aspects of the final design at a later design stage. Results from the analyses by CPT-based methods indicate that Method 1, 2 and 3 produce comparable results of capacities in both compression and tension, whereas Method 4 shows somewhat a deviation from the other 3 methods. Hence, a conservative approach to using the capacities calculated by method 4 and especially the API RP 2A-WSD (2000) method should be exercised properly by applying appropriate safety factors
Potential using of marine sand in coastal areas of Vietnam to create concrete for rural roads
In Vietnam, there is not enough sand from the river for the construction operation, and it is necessary to find other resources to replace it. Marine sand was distributed in large areas in the coastal area of Vietnam and was not used for rural roads. This paper presents experimental results on the workability and compressive strength of concrete which was made from Nghe An and Ha Tinh marine sand. The particle size of two marine sands is not fully suitable for use as fine aggregates in concrete according to TCVN 7570:2006. The Ha Tinh sand was more suitable for use as fine aggregates in concrete than Nghe An sand. Three grades of concrete (M20, M25, M30) were designed for testing. Fifty-four samples of concrete were mixed and cured for 3, 7, and 28 days. Results showed that the compressive strength of Ha Tinh concrete achieved the requirements of M20, M25, and M30 grade - concrete. Otherwise, the compressive strength of Nghe An concrete has only achieved the requirements of M10, M15, and M20 grade – concrete. The research results also showed that the concrete made from Ha Tinh sand can be used for the A, B, C, and D grades of rural roads and the concrete made from Nghe An sand can only be used for the C, D grades of rural roads. The workability of all concrete mixtures met the requirements of Vietnamese standards. The sea sand in the coastal area of Vietnam has enormous potential to produce concrete for rural roads
Landslide hazard assessment for the Batxat area of Vietnam using GIS-based spatial prediction models
Located in the northwest of Laocai province, Batxat district has been frequently affected by natural disasters, including landslides and debris flows. Therefore, landslide hazard assessment (LHA) has been a significant task for planning, economic development, and minimizing human and property damage. For this purpose, landslide hazard maps were established in this study using the Analytic Hierarchy Process (AHP) and the combined Analytic Hierarchy Process - Frequency Ratio (AHP&FR) models. Ten landslide-related factors were selected, including elevation, slope, distance to road, distance to drainage, land use and land cover (LULC), average monthly rainfall, lithology, aspect, distance to fault, and relative relief. Afterwards, the weighted value of landslide-related factors and the landslide susceptibility index (LSI) were determined using the Analytic Hierarchy Process. The Frequency Ratio method was used to calculate the weighted value of factor classes. Two landslide hazard maps were established, and the study area was divided into five hazard zones: very low, low, moderate, high, and very high. The performance of the models was determined using the area under the curve (AUC) of the receiver operating characteristic (ROC), the seed cell area index (SCAI), and the precision of the predicted results (P). The AUC values for the success rate of these models were 0.72 and 0.75, and for the prediction rate were 0.67 and 0.70, respectively. The evaluation results of the models showed that, although both the AHP and combined AHP&FR models have good performance for landslide hazard mapping, the AHP&FR model produces more accurate outcomes than the AHP model
Geological setting and gold mineralisation characteristics at the Me Xi, Vinh Linh, Quang Tri, Vietnam
The Me Xi gold deposit is located in Vinh Linh, Quang Tri, Truong Son Fold Belt, Vietnam, about 45 km to the east of the Sepon Mineral District, Laos PDR. Gold mineralisation at Me Xi is predominantly hosted in siltstone and subordinate calcareous siltstone, sandstone, shale, black shale and calcareous shale of Ordovician - Early Silurian Long Dai formation that were metamorphosed at greenschist facies. The igneous rocks that are closest to Me Xi deposit include undated porphyritic dolerite and mafic dykes. Two gold mineralisation zones consisting of eight mineralised bodies have been recorded, in which the main zone is ~ 640 m long and ~10÷60 m wide. The largest gold mineralisation body has a length of ~220 m and a width of ~0.5÷3 m. Gold mineralisation occurred mainly as stockwork quartz-sulphide veins that were typically characterised by the brittle deformation of host rocks. At least four hydrothermal stages were observed at the deposit, of which gold was accumulated in the stage 2 veins and possibly stage 3 veins that has similar mineralogical assemblage and alteration patterns to those of the stage 2. These stockwork stages 2 and 3 veins predominantly consist of pyrite and minor chalcopyrite, gold, arsenopyrite, pyrrhotite and galena in association with strong silicification, chloritisation, sericitisation and subordinate decalcification. The pre-Au stage 1 veins are rarely observed, but this hydrothermal stage records an initial deformation of the host sequence. The post-Au stage 4 is characterised by carbonate-rich quartz stockwork veins with local patches of sulphides
Prediction of Poisson's ratio for hydraulic fracturing operations in the Oligocene formations in the Bach Ho field
In rock geomechanics analysis, Poisson's ratio is one of the critical factors that affect mechanical properties of rocks and soils, wellbore stability, in situ stress, drilling efficiency, and hydraulic fracturing design. There are two conventional methods for measuring Poisson's ratio, they are called acoustic wave method and compression testing of core sample. In the first, the Poisson's ratio is determined based on well-log data known as dynamic values. Conversion formulas need to be established for different geological conditions to obtain reliable computational results. However, the determination of each suitable conversion formula is time and money-consuming, as well as the process, is relatively complicated. The latter method must be performed in the laboratory with high accuracy equipment and requires the availability of core samples obtained through the coring process with high expenditure. To overcome the limitations of these two methods, the authors used the Artificial Intelligence technique to establish correlations between the value of Poisson's ratio and drilling parameters (e.g., weight on bit, flow rate, torque, annulus velocity, pressure losses) in the Oligocene formation of the Bach Ho field. Two machine learning algorithms including Random Forest (RF) and Decision Tree (DT) were applied in this study. On the other hand, the offset data from Well A and Well B penetrated through the Oligocene formation of the Bach Ho field were used to build, train, and verify the accuracy of the artificial intelligence simulations. Both wells have similarities in lithological characteristics and composition. The results indicated that the Artificial Intelligence models are highly accurate in predicting the value of Poisson's ratio, with correlation coefficient results for the RF model and the DT model being at 0.79 and 0.76 respectively
Research on the application of wellbore strengthening methodology and managed pressure drilling for HTHP wells in highly depleted reservoirs at the Nam Con Son basin
The gas production in high-temperature, high-pressure (HTHP) projects in the Nam Con Son basin is entering a declining production phase, the production duration almost reaching the final phase of the designed field life. Therefore, the need to build a development plan for maintaining and supplementing gas production is the most important in the current phase. Evaluation of gas field conditions, drilling infill wells to expand existing prospects is considered a feasible solution both technically and economically. However, the physical characteristics of the production reservoirs have changed after a long production time, including a decrease in pore pressure at the production reservoirs, posing a significant technical challenge during the drilling operations. The infill wells are required to penetrate through the shale formations interbedded with sand formations. In there, the cap rock shale layer remains at or close to virgin pressure and the sand reservoir with pore and fracture pressures has largely decreased due to production activities. There is no mud-weight window that exists any more at the transition between cap rock and reservoirs which leads to drilling problems such as loss circulation, gas kicks and especially, the well could not reach the total desired depth or production targets which impact to overall development project. This article evaluates the applicability of a combination of technologies, including utilizing special lost circulation materials to seal the fractures due to changes in reservoir properties and the application of managed pressure drilling methodologies while drilling through infill wells in HTHP conditions. The goal is to minimize the risks of well problems and provide the management of uncertainties during the drilling which improves project efficiency.
A study on identifying and analyzing road traffic incident hotspots on National Highway 1A, Thanh Hoa province, Vietnam, employing Statistical and GIS Techniques
The study focuses on the prevalence of road traffic accidents in Vietnam, particularly along national highways, which are frequent and severe. Specifically, it examines National Highway 1A passing through Thanh Hoa province, utilizing statistics and geographic information systems (GIS) to identify high-risk areas. Data from road traffic incidents spanning from 2020÷2023 were used to analyze spatial autocorrelation, kernel density estimation (KDE), and Getis-Ord Gi* hotspot analysis. Spatial autocorrelation assessed the autocorrelation of incidents, while KDE visualized hotspot clusters. Meanwhile, Getis-Ord Gi* hotspot analysis determined the statistical significance of incident hotspot locations. The analysis revealed a higher concentration of hotspots in the northern section of the national highway compared to the southern section. Notably, the section passing through Thanh Hoa city center, Hau Loc, and Hoang Hoa districts exhibited very high traffic density. Hotspots identified through Getis-Ord Gi* statistics aligned with those detected using KDE. Furthermore, several hotspots were concentrated at bends in the national highway, often lacking warning signs despite high traffic density. The study’s findings serve as valuable references for authorities, enabling them to implement timely intervention measures such as infrastructure improvements or enhanced law enforcement to address issues and provide warnings regarding road traffic incident risks
Evaluate the influence of steel fiber on the propagation time of ultrasonic waves in high-strength concrete
In modern high-strength concrete, steel fibers are commonly added to the concrete mix to improve its mechanical properties and structure. The steel fibers typically have a specific length and are randomly distributed to increase the tensile and bonding strength of concrete structures. However, the presence of steel fibers can impact the propagation of ultrasonic waves in concrete, causing alterations in ultrasonic wave transmission characteristics and potentially affecting the ability to assess the quality and safety of construction projects. A successfully produced high-strength concrete (> 60 MPa) from cement, sand, silica fume, and superplasticizer. Using this concrete mix, the authors fabricated beam specimens with dimensions of 150 × 150 × 600 mm for both cases with and without steel fiber reinforcement. Based on the Time-of-Flight Diffraction (TOFD) ultrasonic testing method, the authors conducted a series of experiments on high-strength concrete beam specimens. The results of ultrasonic wave propagation experiments indicated that the presence of steel fibers at a 2% content increased the time of wave propagation. On the other hand, curing conditions, specimen maintenance time, and transmission path distance affected the ultrasonic wave propagation time in high-strength concrete. Understanding the influence of steel fiber content on the propagation time of ultrasonic waves in high-strength concrete can contribute to improving the inspection and quality assessment processes of construction projects. Additionally, it helps enhance the understanding of the properties of high-strength concrete reinforced with steel fibers
Solutions to improving the efficiency of production organization at semi-mechanized longwall face I-6-2, Bac Quang Loi coal mine
Dong Bac Corporation is the second largest coal producer in Vietnam with output accounting for more than 14% of the country's total production. According to the plan, coal production from underground mines is expected to increase to 60%of the total Corporation’s production by 2025. To increase coal production in longwall mining, Dong Bac Corporationapplies advanced technological solutions to modernize production stages, with the notable implementation of the semi-mechanized longwall mining technology. This technology usesa single-drum shearer and mobile hydraulic supports. The use ofthe technologyhas encountered challenges and difficulties, resulting in low production efficiency. The highest output achieved in the longwall face only reached 70% of the initial design capacity. The article presents the current status of technological innovation in underground coal mining of Dong Bac Corporation. The primary research subject is the semi-mechanized longwall face I-6-2 at Bac Quang Loi coal mine of Company 790,Dong Bac Corporation.Based on analysingthe causes of difficulties, the authors provide solutions to improvingproduction efficiency, safety, and the environment. Some solutions have been used in practice and have achievedpositive and promising effects. Adjustment of production cycle organization chart to align with mining conditions has resulted in an increase in effective working time and a 17% rise in coal output.Accordingly, the authors propose technological orientations for the development of underground coal mining at Dong Bac Corporation