Search Results (1,022)

Conventional drilling pressure relief technology destroys the rock integrity of the roadway-surrounding rock and support system in the anchorage area of surrounding rock at the same time as roadway pressure relief. To overcome the incompatibility between roadway pressure relief and structural support, an integrated control strategy combining anchorage reinforcement with pressure release was established. The distribution characteristics of the deviatoric stress field under different internal borehole parameters were investigated through numerical simulations, and the influence degree of each parameter is discussed. We constructed a similar model to verify the reasonable key parameters of pressure relief and evaluate the pressure relief effect. The conclusions drawn are as follows. (1) The sensitivity ranking of factors affecting pressure relief in the surrounding rock was determined as internal hole-making position > internal hole-making length > internal hole-making spacing. At an internal hole-making depth of 10 m, the peak deviatoric stress migrated to deeper regions, accompanied by a notable reduction in its distribution range. Hence, the stress within the roadway-surrounding rock was effectively released. (2) The internal deviatoric stress peak (si) and its corresponding location were identified according to the internal borehole-creation position. As the internal hole-making length increased, the positional transfer effect became notably stronger. Appropriately extending the internal hole-making length can thus create a compensatory buffer zone that accommodates the volumetric expansion deformation of the roadway sides. (3) By appropriately determining the position and length of the internal boreholes, reducing the spacing between them can substantially release high deviatoric stress. When the spacing was ≤4 m, the rock surrounding the borehole exhibited a low-deviatoric-stress state, suggesting that the deviatoric stress between adjacent internal holes was largely dissipated without elevating the stress level in the shallow surrounding rock. (4) A comparable simulation approach confirmed the feasibility of implementing internal hole-making and pressure relief measures on both sides of a deep coal roadway. Field engineering applications further demonstrated that the proposed “anchorage + pressure relief” cooperative control system can effectively restrain the continuous large deformation of the surrounding rock along the sidewalls in soft and fractured deep chambers. These findings offer an effective strategy for controlling large-scale deformation and failure of surrounding rock in similar deep roadways and provide valuable engineering insights. Full article

Automated precision drilling is essential for aircraft skin manufacturing, yet current robotic systems face dual challenges: chatter-induced inaccuracies in hole quality and limited access to confined spaces such as air inlets. To overcome these limitations, this paper develops a compact drilling robot for drilling large-curvature skins of aircraft air inlets. Targeting the precision drilling requirements for complex-curvature aircraft air inlets, we present the robot’s overall design scheme, detailing each module’s composition to ensure precision drilling. In-depth analysis of the robot’s large-curvature adaptability precisely calculates the wheel assembly dimensions. To ensure high-precision drilling bit entry into guide mechanisms, a flexible drilling spindle mechanism is designed, with calculated and verified elastic ranges. An integrated intelligent control system is developed, combining vision recognition, real-time pose adjustment, and automated drilling workflow planning. Finally, traversability and drilling capabilities are validated using a simplified air inlet model. Test results confirm successful traversal on R200 mm curvature skins and automated drilling of Carbon Fiber-Reinforced Polymer (CFRP)/7075 aluminum stacks with a diameter of Φ4–Φ6 mm, achieving dimensional errors of less than 0.05 mm and normal direction errors of less than 0.65°. Full article

In aerospace manufacturing, laser welding of TC4/TA18 dissimilar titanium alloys in bottom-locking configurations is essential for lightweight design, yet the residual stress behavior of such joints remains insufficiently understood. This study systematically examines the influence of laser power on residual stress distribution in laser-welded TC4/TA18 bottom-locking tubular joints. Welded specimens were fabricated at three distinct laser power levels (600 W, 800 W, and 1000 W). Experimental characterization included macroscopic morphology analysis and residual stress measurement using the blind-hole drilling method, among other techniques. Concurrently, a three-dimensional thermo-elastic-plastic finite element model was established based on ABAQUS 2022 to simulate the transient temperature field and stress–strain field during the welding process. The results indicate that due to the differences in thermophysical properties between the two titanium alloys and the wall thickness effect, both the temperature field and residual stress distribution of the TC4/TA18 dissimilar titanium alloy bottom-locking joints exhibit significant asymmetry. Laser power exerts a selective influence on the residual stress field: within the parameter range of this study, increasing laser power can significantly reduce the peak hoop stress of TA18 thin-walled tubes and TC4 thick-walled tubes, as well as the peak axial stress of TC4 thick-walled tubes, while remarkably increasing the peak axial stress of TA18 thin-walled tubes. The numerical simulation results are in good agreement with the experimental data, verifying that the established finite element model is an effective tool for predicting welding outcomes. Full article

To reduce the computational cost associated with traditional moving heat source methods, a segmented approach is proposed for simulating the welding process of T-joints in large-scale infrastructure steel modules. Firstly, the hole-drilling method was employed to measure the welding residual stresses in a 2400 mm T-joint. Subsequently, a three-dimensional finite element model was established in ABAQUS, and a user-defined subroutine for the segmented moving heat source was developed in Fortran to calculate the welding residual stresses. The numerical simulation results were compared with experimental data, showing high consistency and further validating the accuracy of the finite element model. Furthermore, the distribution patterns of residual stresses along the thickness direction and the effects of different welding sequences on temperature, stress, and deformation were investigated to optimize the welding sequence. The results indicated that the residual stresses along the weld seam exhibited a compressive–tensile–compressive distribution, with the maximum tensile stress reaching approximately 347 MPa. Additionally, the simulation results demonstrated that the double-ellipsoidal heat source method was computationally intensive and failed to provide accurate results for long weld seams, whereas the segmented moving heat source approach reduced the computation time to only 38 h. Moreover, different welding sequences had a significant impact on residual stresses and deformation. Through comprehensive analysis, it was found that Case 1 (sequential welding in the forward direction) achieved the best performance in minimizing welding residual stresses and deformation. Full article

This study examines the influence of drilling parameters on thrust force, torque, active work, and axial residual stress formation in hot-forged and T6-treated AA7075, a critical high-strength aluminum alloy. A full factorial design was applied using three spindle speeds (800, 1000, 1200 rpm) and three feed rates (0.05, 0.10, 0.15 mm/rev). Cutting force and torque signals were measured using a dynamometer, and axial residual stresses were determined by X-ray diffraction at two locations along the hole depth, namely, the hole entrance (Point A) and the hole exit (Point B). The results show that feed rate is the dominant factor influencing drilling mechanics and residual stress formation, whereas spindle speed mainly affects the thermal and frictional conditions governing stress relaxation. A consistent asymmetry was observed between the two measurement locations, with the exit side exhibiting stronger stress relaxation behavior associated with breakthrough mechanics. Finally, the relationship between active work and axial residual stress is discussed using a qualitative, energy-based interpretation, highlighting active work as a physically meaningful indicator for drilling-induced residual stress evolution. Full article

The oxidation of sulfide minerals in the presence of oxygen and water, facilitated by microbes, is the principal cause of acid mine drainage (AMD). Static testing for the quantitative assessment of the acidic potential and acid-neutralizing capacity of mineral samples has been thoroughly investigated; the extent of its accuracy remains uncertain. This study involved 329 ore samples from 34 drill holes from abandoned mining sites and conducted laboratory static tests and mineralogical analysis. Static testing and mineralogical characterization identified a significant positive correlation between total sulfur and net acid generation (NAG), confirming that sulfide oxidation is the dominant mechanism for acid production. Furthermore, the strong positive correlation between calcium content and acid-neutralizing capacity (ANC) demonstrates that the buffering capacity stems mainly from carbonate dissolution, with negligible contribution from silicate weathering. The effectiveness of a detailed acid-generating potential discrimination chart was also assessed. Through the examination of acid drainage samples and groundwater from the research area, with their stable isotope and Deuterium excess (D-excess) properties, hydrochemical classifications were established, and sources of acid drainage were evaluated. This comprehensive method pinpoints the main “acid-generating sources” in the abandoned mining sites, elucidating the geochemical origins of acid drainage in the research area. It offers a case study and analytical framework for employing static test findings from abandoned mining sites to evaluate acid-generating potential in those areas. Full article

To improve the identification accuracy of leakage layer location in an open-hole well with a distributed fiber optic temperature system, a transient temperature field heat transfer numerical calculation model for bare hole wellbore leakage process was established based on process of the distributed fiber optic open-hole well temperature measurement technology, considering factors such as drilling fluid frictional pressure drop, casing section and bare hole section boundary conditions. The distributed fiber optic test data was compared with the calculation model, and the wellbore calculated temperature distribution was consistent with the test temperature curve, and the temperature characteristics of the leakage layer location were obvious, with a maximum error of less than 5.5%. The calculation results show that when using distributed fiber optic open-hole well leak detection, by extending the continuous injection time of drilling fluid to 30 min and increasing the injection flow rate of drilling fluid by 30 L/s, the temperature at the wellbore leak location reaches 2.7 °C and 6.6 °C, respectively, which can reduce the difficulty of identifying the leak location and improve the accuracy of leak location identification. However, after changing the type of drilling fluid, the calculated wellbore temperature distribution showed a difference of no more than 0.01 °C. When detecting the location of the leakage layer in open-hole wells with high temperature gradients, the temperature difference at the leakage layer is more pronounced, which can reduce the difficulty of leak location via distributed fiber optic system. Full article

This study addresses the issue of adapting the thermal drilling process for joining dissimilar thin-walled materials—sheets made of non-ferrous metal alloys and polymer composites with a thermoplastic matrix reinforced with glass and carbon fibers—without the use of connecting elements and without disrupting the continuity of the reinforcing fibers. An extensive metallographic study was conducted on bushings formed in thin metal sheets made of EN AW 6082 T6 aluminum alloy and AZ91 magnesium alloy obtained during separate drilling procedures. Experiments were also performed where the metal sheet and composite material overlapped, using both direct and sequential drilling above the melting point of the polymer matrix, applying various process parameters. The dimensions of the resulting bushings and the suitability of their profile for joining with composites were evaluated. The results suggest the possibility of joining metals and fiber composites through thermal drilling, and suitable joining process parameters and conditions are specified. To limit composite delamination, it is advisable to make a hem flange on the reverse side of the joints. CT scans confirmed the deflection of fibers around the hole in the composite without compromising their integrity. The load-bearing capacity of the joints and the possibility of creating hybrid mechanical–adhesive joints between these materials are the subject of Part Two of this study. Full article

Accurately and efficiently predicting bottomhole pressure (BHP) is of great importance for safe drilling in complex formations. Many researchers have conducted extensive investigations into intelligent BHP prediction techniques. However, the current intelligent models mostly focus on the data-driven relationship between logging parameters and BHP, and less on the influence of the correlation between the logging parameters on the BHP. This paper proposes a real-time prediction framework based on graph neural networks. Our model selects input features based on drilling mechanisms and statistical analyses, and utilizes adaptive learning of the graph based on multivariate time-series parameters to capture the relationship between multivariate logging parameters and BHP. Finally, the model performance is thoroughly analyzed based on field drilling datasets after optimizing model hyperparameters using the Bayesian optimization method. Results indicate that the proposed method performs better in terms of prediction accuracy, captures the inflection points of curve changes better, and is more robust under the new well section. The mean absolute percentage error of the method reaches 1.28% which is reduced by 25% compared with other traditional intelligent models. This study provides a solution for achieving accurate real-time predictions of bottom hole pressure, establishing a solid foundation for the realization of precise pressure control during drilling operations. Full article

Stick–slip vibration leads to accelerated wear of drilling tools and downhole tool failures, particularly in long horizontal sections. Existing drill-string dynamics models and control or digital-twin frameworks have significantly improved our understanding and mitigation of stick–slip, but most of them adopt simplified Newtonian or linear viscous damping and low-degree-of-freedom representations of the drill-string–fluid–BHA system, which can under-represent the influence of non-Newtonian oil-based drilling fluids and detailed BHA design in long horizontal wells. In this study, an n-degree-of-freedom torsional stick–slip vibration model for horizontal wells is developed that explicitly incorporates Herschel–Bulkley non-Newtonian rheological damping of the drilling fluid, distributed friction between the horizontal section and drill string, and bit–rock interaction. The model is implemented in a computational program and calibrated and validated against stick–slip field measurements from four shale-gas horizontal wells in the Luzhou area, showing good agreement in stick–slip frequency and peak angular velocity. Using the Stick–Slip Index (SSI) as a quantitative metric, the influences of rotary table speed, weight on bit (WOB), and bottom-hole assembly (BHA) configuration on stick–slip vibration in a representative case well are systematically analyzed. The results indicate that increasing rotary speed from 64 to 144 r/min progressively reduces stick–slip severity and eliminates it at 144 r/min, reducing WOB from 150 to 60 kN weakens and eventually removes stick–slip at the expense of penetration rate, drill collar length has a non-monotonic impact on SSI with potential high-frequency vibrations at longer lengths, and increasing heavy-weight drill pipe (HWDP) length from 47 to 107 m consistently intensifies stick–slip. Based on these simulations, SSI-based stick–slip severity charts are constructed to provide quantitative guidance for drilling parameter optimization and BHA configuration in field operations. Full article

Virtual planning and patient-specific surgical guides have become standard practice to achieve accurate mandibular reconstruction with fibula free flaps. Although these technologies have greatly improved surgical precision, slight deviations may still occur. To further minimize these inaccuracies, we focused on the drilling process and developed a novel drill-fitting hole guide (DFG) system. This in vitro study compared the DFG with two conventional guide designs—a drill-wide hole guide (DWG) and a trocar-fitting hole guide (TFG)—using 3D-printed resin models. Twenty oral and maxillofacial surgeons performed guided drilling with all three guide types, and drilling accuracy and subsequent plate positioning were evaluated using a fully digitized workflow in 3-matic software. Deviations in drill entry points and trajectories were quantified, along with plate overlap ratios (Dice coefficients) and plate angular discrepancies. The DFG achieved the highest accuracy, showing the smallest drilling point deviation (0.17 ± 0.08 mm) and angular deviation (2.41 ± 1.24°), the greatest plate overlap (0.90 ± 0.04), and the lowest plate angular misalignment (0.87 ± 0.59°). Although all guide types yielded clinically acceptable results, the DFG demonstrated significantly higher accuracy. These findings suggest that the drill-guide interface is a key factor in surgical precision that has received limited attention. Full article

Based on the characteristics and distribution patterns of collapsed holes in cast-in-place bored pile foundations in the typical coastal area of Guangdong Petrochemical Company, the deformation and collapse behavior of pile walls in the project zone were systematically monitored and measured using a specialized pore diameter detection system for cast-in-place bored pile quality assessment. A collapse rate parameter is proposed and established as an evaluation index for pile wall stability and collapse. Using the basic principles of Quantification Theory I and considering the collapse characteristics of pile walls in a cast-in-place bored pile project in Guangdong, the influencing factors and mechanisms of pile wall collapse are comprehensively analyzed and evaluated. A quantitative theoretical evaluation model for the influencing factors of pile wall collapse is then established. Focusing on the construction technology of cast-in-place bored piles, the proposed quantitative theoretical evaluation model is applied to quantitatively analyze and assess the factors contributing to pile wall collapse in the project area. The relationships between pile wall collapse rate in the Guangdong Petrochemical Company cast-in-place bored pile project and influencing factors such as stratum structure, soil properties, sand layer thickness, drilling depth, and drilling methods are systematically determined. The primary collapse factors and secondary influencing factors in the pile wall collapse of the cast-in-place bored pile engineering zone are identified, providing a theoretical basis for determining optimal prevention and control measures against pile wall collapse during the drilling process of cast-in-place bored piles. Full article

Slope failures frequently occur during rainfall, earthquakes, and long-term weathering, and reinforcing bar insertion is widely used worldwide to prevent such failures. In this method, steel bars are installed in pre-drilled holes and bonded to the ground with grout, with a pressure plate resisting deformation; however, tensile forces generated during slope movement may crack the hardened grout and reduce performance. To address this issue, we propose an Early-stage Prestressed Reinforcing Bar Insertion Method, in which tensile load is applied to the bar before grout hardening. Grout is injected while maintaining tension, allowing the bar to remain prestressed after construction and inducing compressive stress in the grout, which is expected to improve resistance against tensile loading. A field construction test and numerical finite-element analysis were conducted to verify performance. The test confirmed constructability within half a day and retained tensile force of 42 kN after 30 days. The numerical model reproduced measured axial forces and indicated that the hardened grout remained in compression, with an average compressive stress of 3680 kN/m². These results demonstrate that prestressing can enhance grout tensile resistance. The method shows promise for future application and potential extension to similar anchoring systems. Full article

The Cimabanshuo deposit, situated in the western Gangdese Belt, is a recently discovered porphyry Cu deposit formed in a post-collisional setting, approximately 10 km from the giant Zhunuo porphyry Cu deposit. Despite its proximity to Zhunuo, Cimabanshuo remains poorly studied, and the current exploration depth of 600 m leaves the potential for deeper resources uncertain. In this study, 840 samples from four drill holes along the NW-SE section (A-A′) were analyzed using portable X-ray fluorescence (pXRF). Based on the geochemical characteristics of primary halos, the deep mineralization potential of Cimabanshuo was evaluated. The results show that Co, Pb, and Ag are near-ore indicator elements; Zn, Cs, Hg, Sb, As, and Ba represent the frontal elements; and Te, Sn, and Bi occur as tail elements. Based on these distributions, a 14-element zoning sequence is defined along the A-A′ profile according to Gregorian’s zoning index, showing Mo-Co-Cu-Pb-Bi-Ag-Sn-Te-Sb-Hg-Cs-Zn-Ba-As from shallow to deep. This sequence shows a distinct reverse zonation pattern, in which tail elements occur in the middle and frontal elements appear at depth, suggesting the existence of a concealed ore body in the lower part of the deposit. Horizontally, the geochemical ratios Ag/Mo and Ag/Cu decrease from northwest to southeast along the profile, implying hydrothermal flow from southeast to northwest. Vertically, the ratios As/Bi, (As × Cs)/(Bi × Te), (As × Ba)/(Bi × Sn), and (As × Ba × Cs)/(Bi × Sn × Te) display a downward-decreasing then upward-increasing trend, further indicating hidden mineralization at depth. This inference is supported by the predominance of propylitic alteration and the deep polarization anomaly revealed by audio-magnetotelluric imaging. pXRF analysis provides a fast, efficient, and environmentally friendly approach, showing strong potential for rapid geochemical evaluation in porphyry Cu exploration. Full article

Branched horizontal wells are widely applied in oil and gas development. However, their complex structures make cuttings transport and deposition problems more pronounced. In this study, a three-dimensional branched wellbore model was established based on an intelligent drilling and completion simulation system. A computational fluid dynamics (CFD) approach, incorporating the Eulerian–Eulerian two-fluid model and the kinetic theory of granular flow, was employed to investigate the effects of wellbore diameter, eccentricity, curvature, flow rate, and rheological parameters on cuttings transport behavior. Results from the steady-state simulations indicate that increasing the wellbore diameter and eccentricity intensifies cuttings deposition at the connection section, with the lower-region concentration rising significantly as the eccentricity increases from 0% to 60%. A larger curvature enhances local flow disturbance but reduces the overall cuttings transport efficiency. Increasing the flow rate improves hole cleaning but may promote cuttings accumulation near the bottom of the main wellbore. As the flow behavior index increases from 0.4 to 0.8, the average cuttings concentration rises from 0.0996 to 0.1008, and the pressure drop increases from 1,010,894 Pa to 1,042,880 Pa, indicating improved transport capacity but higher energy consumption. Experimental results are consistent with the numerical simulation trends, confirming the model’s reliability. This study provides both theoretical and experimental support for optimizing complex wellbore structures and drilling fluid parameters. Full article