Rock Fragments Research Articles

Open-Pit Bench Blasting Fragmentation Prediction Based on Stacking Integrated Strategy

The size distribution of rock fragments significantly influences subsequent operations in geotechnical and mining engineering projects. Thus, accurate prediction of this distribution according to the relevant blasting design parameters is essential. This study employs artificial intelligence methods to predict the fragmentation of open-pit bench blasting. The study employed a dataset comprising 97 blast fragment samples. Random forest and XGBoost models were utilized as base learners. A prediction model was developed using the stacking integrated strategy to enhance predictive performance. The model’s performance was evaluated using the coefficient of determination (R2), the mean square error (MSE), the root mean square error (RMSE), and the mean absolute error (MAE). The results indicated that the model achieved the highest prediction accuracy, with an R2 of 0.943. In the training set, the model achieved MSE, RMSE, and MAE values of 0.00269, 0.05187, and 0.03320, while in the testing set, these values were 0.00197, 0.04435, and 0.03687, respectively. The model was validated using five sets of actual blasting block data from a northeastern mining area, which yielded more accurate prediction results. These findings demonstrate that the stacking strategy effectively enhances the prediction performance of a single model and offers innovative approaches to predicting blasting block size.

Study on the Mechanical Characteristics and Degradation Response of Unloading Rocks Surrounding Tunnels in Cold Regions

The excavation of the rock mass at the tunnel entrance in regions characterized by high altitudes and elevated stress levels results in the direct exposure of the surrounding rock to atmospheric conditions. This surrounding rock is subjected to the compounded effects of excavation-induced unloading damage and freeze–thaw erosion, which contribute to the degradation of its mechanical properties. Such deterioration has a negative impact on production and construction operations. Following tunnel excavation, the lateral stress exerted by the surrounding rock at the tunnel face is reduced, leading to a predominance of uniaxial compressive stress. As a result, the failure mode and mechanical behavior of the rock exhibit characteristics similar to those observed in uniaxial loading tests conducted in controlled laboratory environments. This study conducts laboratory-based uniaxial loading and unloading tests, as well as freeze–thaw tests, to examine the strength, deformation characteristics, and fracture attributes of unloading sandstone subjected to freeze–thaw erosion. A damage deterioration model for unloading sandstone under uniaxial conditions is developed, and the patterns of damage response are further analyzed through the identification of compaction points and the definition of damage response points. The results indicate that (1) as the degree of freeze–thaw erosion increases, the failure threshold of the sandstone significantly decreases, with the residual rock fragments on the fracture surface transitioning from hard and sharp to soft and sandy; (2) freeze–thaw erosion has a pronounced negative impact on the cohesion of the sandstone, while the reduction in the internal friction angle is relatively moderate; and (3) the strain induced by damage following three, six, and nine freeze–thaw cycles exhibits a gradual decline and appears to reach a state of stabilization when compared to conditions without freeze–thaw exposure. Investigating the mechanical properties and deterioration mechanisms of the rock in this specific context is crucial for establishing a theoretical foundation to assess the stability of the tunnel’s surrounding rock and determine the necessary support measures.

Non-ideal Detonation Performance of Engineering Explosive and Its Influence on Rock Fragmentation Under Different Blasting Conditions

Non-ideal Detonation Performance of Engineering Explosive and Its Influence on Rock Fragmentation Under Different Blasting Conditions

Three‐dimensional characterization of particle morphology in natural gravel and blasted rock fragments using SfM‐MVS photogrammetry

AbstractThis study aims to develop a high‐precision and cost‐efficient method for the three‐dimensional reconstruction of large particles in natural gravel and blasted rock fragments, utilizing Structure from Motion (SfM) and Multi‐View Stereo (MVS) techniques. The proposed approach was applied to characterize the three‐dimensional morphology of rockfill dam materials at a real construction site. Particle shape was quantitatively analyzed using shape indices of sphericity, convexity, and angularity. The predominant morphology of natural gravel is characterized as slightly elongated and slightly flat, while rock fragments are slightly elongated and not flat. Probability density distributions of shape indices follow a skewed normal distribution: sphericity and convexity show leftward skewness, whereas angularity is right‐skewed. Skewness parameters of sphericity and angularity are consistent between natural gravel and blasted rock fragments, indicating comparable shape asymmetry. Convexity skewness is significantly higher in natural gravel compared to rock fragments, by approximately an order of magnitude. The relationship between size and particle shape shows that form ratios and associated shape descriptors change linearly with the logarithm of size; larger particles approach spherical or cubic forms. The innovative measurements contribute to the particle shape data set of rockfill dam materials, providing valuable insights into the three‐dimensional and statistical morphological characteristics of relatively large particles in natural gravel and blasted rock fragments. This approach enhances understanding of particle morphology's impact on the mechanical behavior of granular materials.

Terminal Fan Deposition and Diagenetic Control in the Lower Paleogene of the Shahejie Formation, Bonan Sag, Bohai Basin, China: Insights into Reservoir Quality

In the Bonan area, the lower fourth member of the Shahejie Formation (Es4x) is buried beneath a sedimentary pile ranging from 2500 to 5000 m. Understanding the impact of diagenetic alterations on these deeply buried reservoirs is crucial for effective hydrocarbon exploration and production. This study employs a terminal fan sedimentation model, encompassing depositional environments such as feeder channels, distributary channels, floodplains, and basinal zones, to provide insights into the spatial distribution of reservoir properties and their influence on the localization of optimal reservoirs within the sag. The analysis integrates diagenetic facies with well log responses, subsurface porosity trends, and permeability variations across the formation. The petrographic analysis indicates that the sandstone is composed primarily of litharenite, feldspathic litharenite, lithic arkose, and minor amounts of arkose. The dominant clay cement is illite, accompanied by mixed-layer smectite/illite, chlorite, and kaolinite. Thin section observations reveal secondary porosity formed through the dissolution of quartz grains, volcanic rock fragments, and feldspar, along with their associated cements. These sandstones exhibit relatively good sorting, with average porosity and air permeability values of 14.01% and 12.73 mD, respectively. Diagenetic alterations are categorized into three processes: porosity destruction, preservation, and generation. Key diagenetic mechanisms include compaction, cementation, replacement, and dissolution, with compaction exerting the most significant control on reservoir porosity reduction. Statistical analysis indicates that the average porosity loss due to compaction is approximately 13.3%, accounting for about 38% of the original porosity. The detrital rock cement predominantly comprises quartz (42%), feldspar (32%), clay minerals (14%), and carbonate (12%). Under the prevailing depositional conditions, porosity is enhanced by dissolution and fracturing, while late-stage diagenetic cementation by clay and carbonate minerals—excluding chlorite—adversely affects reservoir quality. Consequently, the distributary zone is identified as the primary target for exploration.

Remote Mapping of Bedrock for Future Cosmogenic Nuclide Exposure Dating Studies in Unvisited Areas of Antarctica

Cosmogenic nuclide exposure dating is an important technique for reconstructing glacial histories. Many of the most commonly applied cosmogenic nuclides are extracted from the mineral quartz, meaning sampling of felsic (silica-rich) rock is often preferred to sampling of mafic (silica-poor) rock for exposure dating studies. Fieldwork in remote regions such as Antarctica is subject to time constraints and considerable logistical challenges, making efficient sample recovery critical to successful research efforts. Remote sensing offers an effective way to map the geology of large areas prior to fieldwork and expedite the sampling process. In this study, we assess the viability of multispectral remote sensing to distinguish felsic from mafic rock outcrops at visible-near infrared (VNIR) and shortwave infrared (SWIR) wavelengths using both the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and very high-resolution Worldview-3 (WV-3) imagery. We applied a combination of spectral mapping and ground truth from spectral measurements of 17 rock samples from Mount Murphy in the Amundsen Sea sector of West Antarctica. Using this approach, we identified four dominant rock types which we used as a basis for felsic–mafic differentiation: felsic granites and gneisses, and mafic basalts and fragmental hydrovolcanic rocks. Supervised classification results indicate WV-3 performs well at differentiating felsic and mafic rock types and that ASTER, while coarser, could also achieve satisfactory results and be used in concert with more targeted WV-3 image acquisitions. Finally, we present a revised felsic–mafic geological map for Mt Murphy. Overall, our results highlight the potential of spectral mapping for preliminary reconnaissance when planning future cosmogenic nuclide sampling campaigns in remote, unvisited areas of the polar regions.

Study on Construction Optimization Method of Tunnel Crossing Fault Fracture Zone

When a highway tunnel intersects a fault fracture zone, the excavation process disrupts the surrounding weak and fragmented rock mass, compromising the stability of the fault zone. This study compares the deformation and stress distribution of the surrounding rock using the reserved core soil method, central diaphragm (CD) method, and cross diaphragm (CRD) method during tunnel excavation through fault fracture zones. Among these, the CRD method is identified as the safest construction technique. Additionally, to address the significant deformation of the surrounding rock when tunneling through fault zones, the impact of various pre-support and advance reinforcement techniques on rock mass deformation is analyzed. By comparing the full-ring grouting method with the optimized reinforcement zone approach, the findings demonstrate that optimized grouting significantly reduces disturbance to the fault fracture zone during excavation, thereby enhancing the overall stability of the surrounding rock mass.

Automatic determination of 3D particle morphology from multiview images using uncertainty‐evaluated deep learning

AbstractParticle morphology is a crucial factor influencing the mechanical properties of granular materials particularly in infrastructure construction processes where accurate shape descriptors are essential. Accurately measuring three‐dimensional (3D) morphology has significant theoretical and practical value for exploring the multiscale mechanical properties of civil engineering materials. This study proposes a novel approach using multiview (two‐dimensional [2D]) particle images to efficiently predict 3D morphology, making real‐time aggregate quality analysis feasible. A 3D convolutional neural network (CNN) model is developed, which combines Monte Carlo dropout and attention mechanisms to achieve uncertainty‐evaluated predictions of 3D morphology. The model incorporates a convolutional block attention module, involving a two‐stage attention mechanism with channel attention and spatial attention, to further optimize feature representation and enhance the effectiveness of the attention mechanism. A new dataset comprising 18,000 images of 300 natural gravel and 300 blasted rock fragment particles is used for model training. The prediction accuracy and uncertainty of the proposed model are benchmarked against a range of alternative models including 2D CNN, 3D CNN, and 2D CNN with attention, in particular, to the influence of the number of input multiview particle images on the performance of the models for predicting various morphological parameters is explored. The results indicate that the proposed 3D CNN model with the attention mechanism achieves high prediction accuracy with an error of less than 10%. Whilst it exhibits initially greater uncertainty compared to other models due to its increased complexity, the model shows significant improvement in both accuracy and uncertainty as the number of training images is increased. Finally, residual challenges associated with the prediction of more complex particle angles and irregular shapes are also discussed.

Automated Scene-Adaptive Rock Fragment Recognition Based on the Enhanced Segment Anything Model and Fine-Tuning RTMDet

Automated Scene-Adaptive Rock Fragment Recognition Based on the Enhanced Segment Anything Model and Fine-Tuning RTMDet

Dynamic response of aerodynamic flutter of blooie line during gas drilling in mountain areas

Gas drilling technology remains a superior method for discovering and protecting oil and gas reservoirs in the petroleum exploration and development industry. However, its widespread application and further advancement have been significantly hindered by safety risks associated with surface equipment. Owing to the constraints of mountainous terrain, the connection of the blooie line inevitably adopts multiple elbow connections. As a result, aerodynamic flutter will occur when high-speed gas flow enters the blooie line, which threatens drilling safety. In this study, a series of comprehensive two-way fluid–structure interaction numerical simulations are conducted on the blooie line with multiple bends to determine its structural responses of the aerodynamic flutter induced by a sudden high-speed gas flow during gas drilling. The results suggest that a large quantity of rock cuttings and rock fragments, suddenly ejected when a high-production reservoir was unexpectedly encountered during drilling, tends to accumulate at the bends, leading to blockages and a reduction in the circulation area. This blockage is found to expose the blooie line to a significant risk of fracture, thereby threatening its structural integrity. The higher the gas production, the more severe the aerodynamic flutter of the blooie line. To address the challenge of blockage on the flutter, novel tank equipment is designed to effectively manage the sudden ejection of massive cuttings, aiming to prevent abrupt blockages in the blooie line during the drilling process. The application of this equipment, integrated into the blooie line, ensures the safety of gas drilling operations.

A theory-data-integrated intelligent framework for prediction of blasting-induced rock fragment size

A theory-data-integrated intelligent framework for prediction of blasting-induced rock fragment size

Effects of Rock Fragment Cover on the Sediment Transport Capacity of Overland Flow

Effects of Rock Fragment Cover on the Sediment Transport Capacity of Overland Flow

Study on the mechanism of rock fragmentation of bionic integrated high working layer impregnated diamond bit

Study on the mechanism of rock fragmentation of bionic integrated high working layer impregnated diamond bit

Evaluating the Influence of Blast Design in Quarrying Operations on the Environment

Blasting operations in quarrying have significant environmental impacts that must be managed carefully. Ground vibrations, air blasts, and dust generation are primary concerns. Understanding blast design parameters' impact on fragmentation efficiency and environmental consequences is essential for advancing quarrying practices. The primary challenge in quarrying is to balance these competing demands: achieving optimal rock fragmentation while minimising adverse environmental effects. This research aims to evaluate the influence of blast design on the environment by providing a detailed assessment of how different parameters affect productivity and environmental impact. This research investigates how various blast design parameters—specifically charge weight, blast pattern, timing sequences, and explosive types—impact the environment. The results show that none of the selected quarries complied with the regulated standard. However, factors that promoted low blasting vibration effects on the environment were bench height of not more than 10 m, very low charge load density of approximately 2 tonnes, and consistent application of non-electric detonators and connectors. Locations with a high bench height of 13.8 m recorded noise levels of 105 to 110 dB, fly rocks within 225 to 280 m, and a backbreak of 3.5 to 6.0 m, while locations with a bench height of 10 m and below recorded noise levels of 79 to 91 dB at 300 m away from the centre of the blast, while the backbreak and the fly rock distances are within 1.6–2.2 and 170-216, respectively. Siting a residential building over 1000 meters away from the quarry is significant for the control and reduction of vibration effects to a negligible degree. Therefore, the government should contract quality control monitoring to private companies for effective monitoring.

Study of the Effects of Different Dielectric Environments on the Characteristics of Electro-Explosive Discharge of Metal Wires and Shock Waves

The electrical explosive fragmentation technique has attracted widespread attention due to its environmental friendliness and high efficiency. However, the mechanism by which dielectrics influence rock fragmentation remains unclear. This study innovatively selected seven types of environmentally friendly dielectrics to systematically investigate their roles in the metallic wire electrical explosive rock fragmentation process. By precisely characterizing the crack morphology of concrete blocks, shock wave–strain responses, and discharge signal characteristics, the diverse mechanisms by which different dielectrics modulate rock fragmentation were revealed. The results indicate that oxide dielectrics release energy continuously through thermochemical reactions, highly conductive solutions accelerate energy deposition, and reductant suspensions generate strong secondary shock waves—all significantly outperforming tap water in terms of rock fragmentation performance. Notably, the energy deposition efficiency shows a nonlinear relationship with fragmentation effectiveness, influenced by factors such as energy release modes, dielectric composition, and bubble dynamics. The energy conversion mechanism of the electrical explosive rock fragmentation process studied in this paper provides a theoretical foundation for the fine-tuning, customization, and greening of electrical explosive rock fragmentation strategies in engineering practice.

Deposit potential and distribution of cobalt and nickel in the sludge of chromite placer mining process at Nui Nua ultramafic massif area, Thanh Hoa province, Vietnam

Chromite placer is widely distributed in Quaternary sediments located around the Nui Nua ultramafic massif in Thanh Hoa province, Vietnam. The long-term mining works targeting chromite placer in this area have left a huge amount of waste sludge, up to tens of millions of tons. The paper aims to introduce a deposit potential and distribution of cobalt- and nickel- bearing minerals within the waste sludges generated from the chromite placer mining operations around the mines situated near the Nui Nua ultramafic massif in Thanh Hoa province, Vietnam. Based on field investigations and sample analyses, two groups of waste sludge have been identified: clay-sized sludges and debris waste sludges. The former group is plastic bentonite clay, distributed in depressions and low terrain, and has low contents of cobalt (0.06%) and nickel (0.67%), which is of impractical significance for the recovery purposes of cobalt and nickel. The latter group is usually distributed in relatively high terrain, forming waste sludge ranging from several thousand to hundreds of thousands of tons in volume. These deposits include rock fragments, mineral fragments derived from the Nui Nua ultramafic massif, along with dark spherical nodules rich in goethite, limonite, and Fe-Mn hydroxides, which contain relatively high contents of cobalt (up to 0.75%) and nickel (up to 2.43%) in the waste sludge and chromite placer mines. The cobalt and nickel are mainly concentrated in Fe-Mn nodules made up of goethite, limonite, todorokite, and other Fe-Mn hydroxides. Data from chromite placer explorations, combined with the study results, provide reliable insights into the distribution of cobalt and nickel resources within the waste sludges and chromite placer deposits in the Co Dinh area (northeast of Nui Nua ultramafic massif) and Mau Lam (southwest of Nui Nua massif), Thanh Hoa province. A preliminary estimation of potential resources of Co and Ni metals have been made for the debris waste sludges at Co Dinh and Mau Lam areas based on the ratios of debris particles in the sludges and their contents of Co and Ni along with published resources and reserves of chromite placer ores.

Energy optimization design for the driving source for rock fragmentation by high-voltage pulsed discharge (RHPD)

The energy parameter of the driving source for rock fragmentation by high-voltage pulsed discharge (RHPD) determines the effectiveness of rock fragmentation. The mapping relationship between the energy parameter of the RHPD driving source and the stress parameter is established, and an energy optimization design criterion for the RHPD driving source is proposed. The time-varying impedance of the plasma channel is simulated, and the spatial and temporal distribution of stress within the rock under the channel pressure loading is analyzed. A rock fragmentation criterion based on the stress impulse criterion is proposed, and a nonlinear constrained mathematical model for the energy optimization design for the RHPD driving source is developed. Using the existing driving source and load parameters as examples, the feasibility and accuracy of the proposed energy optimization design criterion for the RHPD driving source are verified, which provides theoretical guidance for the design of the RHPD driving source.

Rock-Breaking Mechanism and Application of Combined Long and Short Holes in Parallel Holes Cut in Small-Section Tunnels

In order to address the issue of limited excavation footage in the drilling and blasting of a water diversion tunnel with a cross-section of approximately 10 m2, which is unable to meet the demands of rapid construction, a blasting method combining long and short straight-hole cutting was proposed based on the theories of elastic mechanics, blasting craters, explosive gas and stress waves. A mechanical model was established to elucidate the parameter design method and cavity formation principle of the combined cutting. Numerical simulation and field tests were employed to analyze the rock-breaking process of combined cutting, with a view to comparing the blasting effect differences between the traditional inclined cutting method and the combined cutting method. The research results indicate that during the blasting process with combined long and short straight-hole cutting, the uncharged portion of the deep hole can serve as an empty hole during the subsequent blasting of the shallow hole. The concentration of stress at the wall of the empty hole and the superposition of reflected and incident waves serve to enhance the rock-breaking effect of the shallow hole, with the enhancement being influenced by the diameter of the hole and the distance between it and the empty hole. The preferential detonation of the shallow hole can provide a smaller resistance line and free surface distance for deep hole detonation, creating favorable conditions for rock fragmentation in deep hole blasting, making it easier for the rock in the cutting area to be thrown out and increasing the utilization rate of the blast holes. The shape of the formed cavity is a long strip-shaped cube, with its volume being influenced by the spacing between each group of deep and shallow holes. The rock mass damage is most severe in the vertical direction, while the rock mass damage at the center of the upper and lower edges is relatively weaker. In order to optimize the utilization of blasting energy, it is essential to select an appropriate spacing between each group of blast holes. In comparison to the utilization of traditional inclined cuts, the implementation of combined long and short holes has been observed to result in a greater extent of blasting footage and relatively lower explosive consumption. These research findings provide a reference point for the rapid and efficient construction of small-section tunnel engineering, as well as the design of straight-hole cut blasting with reduced consumption.

The occurrences, characteristics, and implications of chaotic rocks (accretionary rocks) within the Trans-Saharan orogenic belt in Nigeria

The present research paper reveals the occurrences of metachaotic rocks/accretionary sediments (mélange) in Igarra, southwest Nigeria. These metachaotic rocks are associated with schistose, marble, pegmatite, granitoid, and gneissose units. The mineral assemblage of the surrounding rocks shows garnet, biotite, staurolite, quartz, and chlorite assemblage, which suggest that the rocks were metamorphosed to the epidote–amphibolite facies grade. The chaotic rocks were classified into four groups based on major differences in color, grain size distribution, and stratigraphic and structural characteristics of observed blocks and matrices surrounding them. Group I metachaotic rocks are melanocratic in color, and form pockets of coarse lineation. They are highly deformed with mullions, rodding structures, and burrow-like cavities and show quartzite veins. Group II occurs as a leucocratic to melanocratic mixture of meta-siltstone and metapelite with greenish rock fragments trapped within the meta-siltstone layers. This unit has a cover of meta-siltstone layers occurring in pockets as striations forming mullion and rodding structures as well as ripple-like lineation. Group III metachaotic rocks occur as multiple benches of different strata tilted between 70 and 80º, with mild folding and burrow-like cavities at the base and well-preserved sedimentary structures. In Group IV, there are evidences of pre-metamorphic soft sediment deformational structures that are well-preserved in the metachaotic rocks, with discontinuous blocks of different units trapped within mixtures of metapelite and meta-siltstone. In this group, micro-faults and quartzite veins are scattered within the rocks. Meta-siltstone occurs as horizontal and vertical layers and web-like structures showing dendritic patterns. Overall, the field and petrographic characteristics suggest the Igarra metachaotic rocks are tectonic in origin and may have been formed within the trench basin of an outer accretionary complex.

Geostress-Adaptive Charge Structure Design and Field Validation for Machinery Room Excavation.

The application of blasting in modern engineering construction is prized for its speed, efficiency, and cost-effectiveness. However, the resultant vibrations can have significant adverse effects on surrounding buildings and residents. The challenge of optimizing blasting procedures to satisfy excavation needs while minimizing vibration impacts is a critical concern in blasting excavation. This research addresses this challenge through the development of a 3D simulation and analysis model for an underground pumped storage power plant in East China, utilizing the LS-DYNA finite element analysis software. To explore the influence of charging structures on rock fragmentation and vibration propagation, three distinct blasting programs were formulated, each featuring varied configurations within the machinery room. The analysis revealed that the adoption of an optimized charging structure can significantly decrease damage to the protective layer by approximately 40%, while also reducing the impact on the upstream and downstream side walls by 27.25% and 12.03%, respectively, without compromising the efficacy of the main blast zone. Moreover, the vibration velocities at the remote measurement point were found to be reduced across multiple directions, indicating effective control of the vibration effects. The post-implementation of the optimized blasting strategy at the site, the assessment of the retained surrounding rock integrity, and the impact on protected structures demonstrated that the proposed solution met satisfactory outcomes. This study underscores the potential of simulation-based optimization in managing vibration risks during blasting operations, offering a valuable tool for engineers and practitioners in the field of underground construction.