Abstract:The workability of grouting materials critically governs their effectiveness in filling rock fractures and reinforcing rock masses.This study aimed to develop a high-performance grouting mate-rial utilizing ultra-fine slag powder.A systematic investigation was conducted through orthogonal ex-perimental design and range analysis,employing cement,ultra-fine slag powder,sodium silicate,and sodium hydroxide as raw materials.The variations in key performance indicators,including viscosity,fluidity,bleeding rate,and compressive strength of cement mortar,were quantitatively evaluated un-der different mix proportions.Complementary microstructural characterization via X-ray diffraction(XRD)and scanning electron microscopy(SEM)provided comparative insights into pure cement,optimized grout,and cement mortar.The experimental findings revealed that the synergistic incorporation of ultra-fine slag powder,sodium silicate,and sodium hydroxide substantially enhanced the grout's workability,achieving remarkable improvements:57.3%reduction in viscosity,25.6%increase in fluidity,and 96.7%suppression of bleeding rate.Microstructural analysis demonstrated that the hydration process modification-characterized by decreased portlandite(Ca(OH)2,CH)content and concurrent formation of limited ettringite(AFt)alongside abundant calcium silicate hy-drate(C—S—H)gel-contributed to a denser cement mortar matrix with enhanced durability.Both compressive and flexural strengths exhibited approximately linear growth with curing age,confirming the long-term stability of the optimized material.

Abstract:With the gradual depletion of shallow high-quality coal resources in central and eastern Chi-na,the shift toward deep coal mining has become a strategic imperative for ensuring national energy security.Ultra-deep vertical shafts(exceeding 1 000 m in depth),serving as critical access routes to deep coal reserves,face severe challenges including high in-situ stress,elevated water pressure,rising ground temperatures,and complex geological conditions(e.g.,swell-shrink soils,unstable rock stra-ta,grout-resistant formations,and difficult-to-freeze layers).Traditional shaft lining design theories,such as those based on the Lamé formula and codified in the code for design of coal mine shafts and chambers(GB50384-2016),exhibit significant limitations under ultra-deep conditions.These include disconnection between the shaft lining and surrounding rock,difficulties in load determination,overly broad ranges for water pressure reduction coefficients,and lack of reference for deep freezing pressure,and often resulting in excessively thick shaft linings(frequently over 2.0 m)or even uncon-structible designs.To address these critical technical bottlenecks,this paper systematically investigates and proposes a new theory of"shaft wall-surrounding rock synergistic bearing"establis-hing corresponding mechanical models and expressions for calculating shaft lining thickness.Applying this theory to the auxiliary shaft of the Cixi Mine No.1 shaft(Asia's deepest shaft at 1 341.6 m),the lining thickness beyond 1 000 m depth was optimized from 2.2 m(based on conventional calculations)to 0.8～0.9 m.At the Hulusu Mine in Western China(main shaft ϕ9.6m,auxiliary shaft ϕ10.0 m),the shaft lining thickness was reduced to 0.9 m,saving a total of 110 million CNY in investment for main shaft and auxiliary shaft.Engineering practices have validated the correctness and advancement of the new theory,providing a innovative technical pathway for deep shaft construction in coal mines and driving industry-wide technological progress.

Abstract:In order to solve the problem of poor accuracy and high difficulty in determining rock mass parameters under complex geological structure,taking the roadway of 2-1051 working face as the re-search object,the inverse analysis technology of mechanical parameters of surrounding rock based on BP neural network optimization was proposed.The measured displacement data of roadway monitoring points were used as the comparison value,and the elastic modulus,internal friction angle and cohesion were determined as the inversion parameters through parameter sensitivity analysis,and the BP neural network structure was constructed,and the parameter samples were trained and opti-mized by matlab toolbox.The elastic modulus is determined to be 0.824 6 GPa,the internal friction angle is 16.231 7°,and the cohesion is 0.735 9 MPa.The test results are basically consistent with the in-situ measurement data of the rock mass on site.When the inversion results are introduced into the numerical model and the displacement change data obtained through forward analysis are compared with the measured data,they are also basically consistent.The inversion accuracy is relatively high and can meet the engineering prediction requirements,thus having certain application and promotion value.

Abstract:When mining the working face with a thick and hard roof,large areas of unsupported roof often occur,which leads to severe stress concentration,deformation and even instability in the small coal pillars of the drifts excavated along the coal seam.To address the problem of instability of the small coal pillars in the drifts excavated along the thick and hard roof,this paper intends to adopt the advanced roof cutting and pressure relief technology.It cuts off the lateral thick and hard roof to re-duce the load of the roof structure above the roadway,and studies the reasonable height and angle of roof cutting.At the same time,the reasonable width of the small coal pillar is determined under the effect of roof cutting and pressure relief to ensure the stable bearing capacity of the small coal pillar and control the stability of the surrounding rock of the drift excavation.After on-site application,it was found that when the advanced roof cutting height is 9 m,the cutting angle is 15°,and the width of the coal pillar is set at 5 m,the coal pillar can be stably supported,and the overall formation effect of the roadway is good,and the deformation of the surrounding rock can meet the requirements of the working face.The research results of this paper can provide a reference for the design of the setting of small coal pillars in drift excavation along the thick and hard roof.

Abstract:Retarding cement slurry is a key material in mining engineering,and its performance is easily affected by the water-cement ratio,additives,temperature and other factors,directly determi-ning the efficiency and safety of the project.As the national mining strategy gradually develops to-wards deep and ultra-deep wells,it faces extreme environments such as high temperatures and high pressures at the bottom of the well,which raises higher requirements for the performance of retarding cement slurry.Currently,research on retarding cement slurry focuses on single factors,lacking com-prehensive evaluation.This paper systematically elaborates on the core performance indicators of re-tarding cement slurry,including rheological properties,setting time,stone rate,and strength,based on the current research status in the country.The results show that the performance of retarding ce-ment slurry is regulated by multiple factors;the rheological properties depend on the type and dosage of dispersants and retarders;the setting time is jointly determined by the type and dosage of the re-tarder and temperature;the stone rate and strength are regulated by the water-cement ratio and addi-tives;and durability is affected by expansion agents and freeze-thaw effects.Through multi-dimen-sional analysis,this provides a systematic reference for the performance optimization and engineering practice of retarding cement slurry,to expand its application potential in deep mining.

Abstract:Weakly cemented Cretaceous sandstone,widely distributed in China's Ordos Basin,poses geomechanical challenges during shaft sinking and significantly influences lining load characteristics.Accurate characterization of its mechanical behavior is critical for optimizing lining design considering rock-lining interactions.However,the friable nature of this type of sandstone often prevents the re-covery of intact core samples for laboratory testing.To address this limitation,we developed a press-ing-heating(P-H)reconstitution methodology.This technique involves:mechanical compaction of crushed sandstone to enhance intergranular contact,followed by controlled thermal treatment at min-eral-specific temperatures approaching solidus points,inducing localized grain-boundary softening and even partial melting to regenerate weak cementation.Comparative analysis demonstrated that the re-constituted specimens replicate primary mechanical parameters of clay-rich sandstone cores within a deviation less than 10%.Unlike conventional methods requiring cementitious additives,P-H approach preserves intrinsic mineralogical properties,enabling systematic investigation of cementation-controlled physical-mechanical behaviors of weakly cemented sandstones.

Abstract:In view of the technical problems faced by the construction of the super-large section Matou-men(the excavation width is 13.30 m and the height is 21.16 m)at the junction of the auxiliary shaft and the 2-2 coal mine bottom in Caojiatan Coal Mine which is located in the soft rock stratum in West-ern China,this study comprehensively considers the complex geological conditions,adopts the collab-orative construction technology of"step-by-step excavation+collaborative support+reinforced concrete permanent lining",and puts forward"self-closed arch steel frame+integral steel formwork".This technology system effectively solves the problems of construction accuracy and efficiency of complex joints in mass concrete structures.The engineering application results show that the technology suc-cessfully overcomes the key technical challenges such as instability control of large-section surrounding rock,water disaster prevention and complex structure pouring,and provides reliable technical reference for similar super-large-section Matoumen projects in soft rock mining areas in Western China.

Abstract:In response to the engineering challenges of complex geological conditions,multiple overlap-ping processes,and insufficient visualization in the construction of shaft sinking systems,as well as the limitations of traditional physical model production such as low accuracy,high cost,and cumber-some processes,a combination of BIM technology and 3 D printing technology are used to establish a standardized process for physical model production based on BIM+3 D printing technology,which im-proves the level of vertical shaft visualization and construction efficiency.Taking the Anhui Nihe I-ron Mine as an example,the key technology for making physical models of shaft sinking systems was studied,and high-precision,low-cost,and short cycle physical simulation models were achieved.This provides a new and reliable means for making physical models in the process of mine construction,and also provides a three-dimensional visualization product delivery form for mine construction,which has important engineering application value.

Abstract:To address the issue of rapid and accurate fault diagnosis in mining hydraulic pillar systems,this paper proposes a fault diagnosis method combining Fourier Transform with an attention-based Convolutional Neural Network(FFT-CBAM-CNN).This method first uses Fourier Transform to convert the multi-channel one-dimensional time-domain signals of the hydraulic system into frequency-domain signals,capturing the frequency characteristics of the signals more effectively.Then,Convo-lutional Neural Networks(CNN)combined with Convolutional Block Attention Modules(CBAM)are employed for feature extraction and classification.Experimental results show that the FFT-CBAM-CNN based diagnosis method achieves an average accuracy of 97.75%with a standard deviation of 0.012 2,demonstrating higher accuracy and stability compared to methods using only CNN and FFT-CNN.

Abstract:Taking the ground grouting treatment of the broken and leaking shaft in the auxiliary shaft of Chenmanzhuang Coal Mine as an example,the changes in the shaft wall strain during the grouting process were analyzed through the shaft wall strain monitoring system.The results show that the ground grouting effectively"released"and"suppressed"the additional stress of the shaft wall,but could not fundamentally eliminate the additional stress;the vertical strain was mainly"released",while the horizontal strain was mainly"accumulated",but the degree of strain"release"or"accumu-lation"at different layers and in different directions was different;under the condition of ensuring safety,there was no obvious regularity between the grouting volume and grouting pressure and the triggering of shaft wall strain;the height difference between the grouting point and the monitoring point had an important influence on the change of shaft wall strain,while the angle difference between the two had no obvious influence bias.This conclusion can provide guidance for similar mine shaft wall fracture prevention and treatment projects.

Abstract:To investigate the relationship between the longitudinal wave velocity and stress in loaded coal-rock bodies,experiments were conducted under uniaxial loading and cyclic loading/unloading conditions to measure the transverse longitudinal wave velocity of the loaded coal-rock bodies.The re-sults show that the longitudinal wave velocity increases with the increase of the compressive strength of the sample,and the two variables approximately follow a linear relationship.The transverse longi-tudinal wave velocity decreases with the increase of the axial stress,and it shows a phased change a-long with the development and variation of internal fractures in the coal-rock body.As the stress in-creases,axial micro-fractures gradually form,develop,and connect within the sample,and the longi-tudinal wave velocity begins to decrease and the decreasing speed accelerates.When the sample fails and macroscopic fractures appear,the longitudinal wave velocity drops sharply.The propagation of the longitudinal wave is significantly affected by the strength and stress state of the coal-rock body,and it is sensitive to the changes of both.The research conclusions provide certain references for the data analysis of rock stress distribution characteristics through methods such as microseismic in un-derground coal mines.

Abstract:To investigate the influence of cracks on the damage deformation of circular tunnel surround-ing rock,similar materials were prepared using the surrounding rock of a coal mine roadway in a min-ing district of the Zhujixi Mine in the Huainan Mining Area as the prototype material.Miniature speci-mens containing holes and cracks with varying dip angles,lengths,and positions were fabricated.Through biaxial loading tests on holed and cracked specimens,the effects of prefabricated cracks and holes on specimen deformation and failure were studied.The results indicate that all specimens under-went three stages during loading:crack initiation,crack propagation,and failure.Based on formation mechanisms and morphological characteristics,secondary cracks can be classified into five categories:tensile cracks,shear cracks,tensile-shear composite cracks,wing cracks,and anti-wing cracks.The failure modes of specimens exhibited significant differences under varying crack parameters.

Abstract:To address the technical challenges in raise boring construction of high-pressure penstocks in pumped storage power stations,including difficult deviation control in extremely hard rock(Protodya-konov scale f≥16),severe drill tool wear,and high risk of drill tool drop in deep shafts(≥400 m)with large diameters(≥2.5m)traversing multiple fault zones,this paper proposes a combined con-struction method of"directional drilling for precision pilot hole+raise boring for efficient reaming".Taking the 460 m deep high-pressure penstock shaft at a Pumped Storage Power Station as a case study,the key techniques are detailed:① BMC-D90 directional drill rig's precision pilot hole drilling(ϕ350 mm)in granite formations;② BMC600 raise boring machine's safe and efficient rea-ming measures.Engineering practice demonstrates that this technology effectively resolves critical challenges in raise boring through hard rock fault zones,providing successful experience for similar large-diameter shaft constructions under complex geological conditions.

Abstract:Coal is the dominant and fundamental energy source in China's energy system.With the con-tinuous advancement of the Western Development Strategy in China,the development of large-scale coal bases in this region is in the ascendant.The strata in the Western China are mostly shallow soil and thick bedrock,with characteristics such as low strength,weak cementation,and good drillability.Currently,the freeze sinking method or the ordinary method is mainly used for vertical shaft con-struction.Until 2021,the shaft drilling method was successfully applied for the intake and return shaft projects of the Kekagai Coal Mine in the Western China,filling the gap in drilling construction in water-rich rock stratums in Western China.This paper elaborates on the core principles and process of shaft drilling method construction,analyzes the technical advantages and limitations compared to the traditional freezing method,summarizes the engineering application results of the shaft drilling method in water-rich soft rock strata in the Western China and outlines the current technical research directions and expansion application directions.

Abstract:In the field of mining and other underground engineering,the full/partial section tunnel bor-ing machine(TBM)has become one of the important equipment for the construction of shafts,roadways and other projects.The main engine of the full/partial section TBM usually relies on the in-teraction between the gripper and the surrounding rock to provide technical support such as thrust and torque for the roadheader's rock breaking tunneling.This paper conducts a comparative analysis of the functional characteristics and differences between the support shoe structures of open-cut tunneling machines used in tunnel excavation and shaft sinking machines employed for vertical shaft excavation,in the context of the characteristics of support shoe type tunneling machines utilized in well and shaft engineering construction;This study analyzes the adaptability of the main support shoe structure of the tunnel boring machine to geological conditions and proposes methods for the optimization design of the main support shoe structure.The aim is to provide support for the equipment design of boring ma-chines and the rapid advancement of tunnel engineering.

Abstract:The monitoring of goaf surface is an inevitable requirement to ensure mine safety production and ecological environment protection.Aiming at the safety and stability of goaf surface in No.11219 working face of Xiaojihan Coal Mine,Shaanxi Province,the ground deformation monitoring system was established by using GPS-RTK technology,and the surface settlement of the goaf was compre-hensively observed.The spatio-temporal evolution law of surface settlement deformation in the goaf was obtained,which has important theoretical significance and practical value for the structural de-sign,applicability and long-term stability of the proposed house.The observation results show that the ultimate surface settlement at measurement points of the goaf could be above 600 mm,and the maxi-mum deformation rate reaches 8.100 mm/d.According to the deformation rate,the deformation-time curve can be divided into three stages,of which the subsidence accounts for about 90%of the total subsidence during the active stage.Compared with the ground subsidence,ground movement and de-formation in the goaf have a more complex process,which should also be taken seriously.

Abstract:In response to the severe wear of cutting tools in drilling method shaft sinking through weak-ly cemented Jurassic strata in Western China,this study focuses on the mill-tooth roller bits commonly used in drilling method shaft sinking.The wear of mill-tooth roller bits was classified based on field measurement data.Tests were conducted on abrasive factors such as drilling rotation speed,rock com-pressive strength,tensile strength,hardness and mud viscosity,and the influence of these factors as well as installation radius on roller bit wear were analyzed.Through correlation analysis,the key fac-tors affecting the wear of mill-tooth roller bits were identified,and a predictive model for wear volume was established based on these key factors.The results show that the wear of mill-tooth roller bits can be classified into five levels:slight wear,moderate wear,intermediate wear,severe wear and complete failure.The wear volume of mill-tooth roller bits is positively correlated with rotation speed,installa-tion radius,rock compressive strength,rock hardness and rock tensile strength,but negatively correla-ted with mud viscosity.Based on the field data from the 10th and 11th trips out of the hole during the advanced drilling of the north ventilation shaft at the Taohutu Coal Mine in Ordos City in the western mining area,the accuracy of the prediction model for the average wear of milling cutters per bit was validated.The research findings can provide an effective theoretical reference for predicting the wear of milling cutters used in shaft sinking by the drilling method in the Jurassic weak-cemented rock forma-tions of the western mining area,as well as for similar cutters.

Abstract:In response to the sudden water outburst incident in the eastern main tunnel of the Central Yellow River Diversion Project in Shanxi Province,a comprehensive study was conducted using theo-retical analysis and numerical simulation techniques to investigate the mechanisms underlying sudden water outbursts during the tunnel's passage through a water-rich fault zone.The study revealed that sudden water outbursts are influenced by the coupled effects of geological conditions and construction-induced disturbances.Using FLAC3 D software to establish a three-dimensional fluid-solid coupling model,the study systematically analyzed the influence of excavation disturbances,groundwater pres-sure,and fault zones on sudden water outbursts.The results showed that excavation disturbances caused groundwater to accelerate toward the exposed surface,while high water pressure exacerbated concentrated seepage in rock layers with varying permeability,significantly increasing the risk of shear failure in the surrounding rock.The rock mass within the fault zone has high permeability and weak mechanical properties,resulting in a sharp increase in water outburst risk as the tunnel face ap-proaches the fault.The research findings can provide reference for the prevention and control of similar water outburst disasters.

Abstract:To address the limitations of traditional evaluation methods in tunnel engineering risk predic-tion:such as over-reliance on empirical judgment,limited prediction accuracy,and poor adaptability to intelligent evaluation requirements in complex engineering scenarios——this study explores the appli-cation of machine learning algorithms.Initially,the study systematically reviews the core basic princi-ples of typical machine learning algorithms.Subsequently,it focuses on the full process of developing accurate risk prediction models,conducting in-depth analysis of key technical steps including data pre-processing,feature clustering and recombination,model training optimization,and quantitative evalu-ation of prediction results.The research findings not only provide practical technical support for intel-ligent risk assessment in fields like water conservancy and underground engineering but also offer new research insights for the iterative optimization of risk prediction models and the exploration of their engineering application practices in this domain.

Abstract:During the coal mining process in the working face with hard roof,large-scale roof caving is prone to occur in the goaf.When the roof collapses over a wide area,the mine pressure is manifested intensely,which seriously affects the safe production of the working face.To study the mine pressure law of the overlying strata after the hard roof is cut in the working face,the gently inclined coal seam with hard roof in the 9303 working face of Xipang Well was taken as the research object.The mechani-cal test,numerical simulation and theoretical analysis methods were adopted to analyze the variation law of the stress and subsidence of the overlying strata after the roof cutting.The results show that after the pressure relief of the working face,the pressure relief zone can be divided into the goaf pres-sure relief zone,the roof cutting pressure relief zone and the protective coal pillar pressure relief zone,and the stress in these zones is less than the original rock stress value.The lateral support pressure on the left side of the goaf overlying strata is greater than that on the right side,and it is about twice the original rock stress.The subsidence of the overlying strata in the pressure relief zone of the track road-way is the largest,followed by that in the goaf overlying strata,and the subsidence of the overlying strata in the pressure relief zone of the belt roadway is the smallest.The maximum value of the over-lying strata subsidence occurs in the middle position of the pressure relief zone of the track roadway.The research results provide an important theoretical basis for the safe mining of the mine.