Abstract:To address the issues of high cost,complex equipment,and difficulty in ensuring and pre-cisely controlling the flow ratio accuracy of traditional dual-fluid grouting pumps,a dual-fluid grouting pump ratio adjustment system based on PID control(proportional-integral-differential con-trol)is proposed.The system achieves precise control of the grouting ratio of the dual-fluid grouting pump by setting the proportional coefficients of the flow rates of grouting pump A and grouting pump B,using two flow feedback signals and two PID closed-loop controls.It simplifies the equipment and reduces the cost.A simulation model was established using Matlab to conduct dynamic performance simulation and experimental verification of the system scheme.The dynamic variation laws of the sys-tem under different parameter changes were analyzed.The results show that this algorithm has stabil-ity and reliability when the grouting system is disturbed.

Abstract:In light of the weak bearing capacity of the coal body and the complexity of controlling the surrounding rock in the waist lane of the thick coal seam in Hongqingliang coal mine,a support scheme was proposed.This scheme involved the implementation of an Anchor mesh cable in conjunc-tion with an Anchor cable and a steel belt.The selection of this scheme was informed by a thorough a-nalysis of the coal body's characteristics.seam and the stability of the surrounding rock,and simula-ted the effect of the support before and after the roadway using the FLAC3D software.The findings re-vealed that this scheme can effectively control the surrounding rock of the roadway in the thick coal seam and improve the deformation of the surrounding rock of the roadway.The programme was found to be capable of effectively controlling the deformation of the surrounding rock of thick coal seams and improving the bearing capacity of the coal body.The on-site monitoring results indicate that the"An-chor net cable+Anchor cable steel belt"support programme has achieved the expected outcomes,with the deformation of the surrounding rock exhibiting stability after 120 days and the roadway meet-ing the design requirements for utilisation.

Abstract:During the excavation of coal mine tunnels,when encountering fault fracture zones,the sup-port problem of the roof becomes particularly prominent,which has an impact on the safety and pro-duction efficiency of the mine.Based on real cases from Shanxi Zezhou Tian Tai He Rui Coal Industry,Yangquan Coal Industry Group Yicheng Shan'ao Coal Industry Company Limited,and Guizhou Panjiang Jingmei Company Limited,this paper deeply explores the support technology for tunnels passing through fault fracture zones.Through the optimization of various support methods such as anchor rods,anchor cables,grouting,and spraying,a composite support method was pro-posed,and the effects of various processes were analyzed in depth.Through experimental verification,when these measures are comprehensively applied,the stability of the roof has been significantly en-hanced,the deformation of the tunnel has been appropriately controlled,thus ensuring the safety and efficiency of coal mine excavation.

Abstract:Starting from the aspects of the refrigeration capacity of the refrigeration system,the heat dissipation capacity of the freezing unit,and the ammonia charging volume per unit refrigeration ca-pacity in the freezing refrigeration design of the western vertical shaft,this paper conducts a theoreti-cal analysis of the main problems in the freezing refrigeration design of the western vertical shaft.It is concluded that it is necessary to pay attention to the operating conditions of the refrigeration machine during the freezing construction,reasonably design the equipment configuration,and reduce the am-monia charging volume per unit refrigeration capacity to improve the safety coefficient of the construc-tion.The intersection time of the freezing shaft in the western region is short,which can provide ref-erence for relevant professional technicians.

Abstract:Addressing the issue that coal mining machine bearings are susceptible to noise interference under complex working conditions,leading to the failure of traditional fault diagnosis methods,this paper proposes a cooperative diagnosis method based on Local Characteristic-scale Decomposition(LCD)and Singu-lar Value Decomposition(SVD).The method first employs LCD to perform multi-scale decomposition on vibration signals,extracting Intrinsic Scale Components(ISC)containing fault information,and then filters effective ISC based on an improved envelope entropy criterion to remove redundant infor-mation.Subsequently,SVD is utilized to perform secondary noise reduction on the filtered ISC,en-hancing fault features.Finally,characteristic frequencies are extracted through envelope spectrum a-nalysis to realize the identification of different fault types.In a field test using the MG-1200 coal min-ing machine,the method successfully identified three operating conditions:normal operation,early-stage fault,and severe fault,and the extracted fault characteristic frequencies were consistent with theoretical calculations and actual conditions.The research results indicate that this method can effec-tively suppress noise interference and accurately extract weak fault features,providing a new technical means and approach for fault diagnosis of coal mining machine bearings.

Abstract:This study proposes a novel drilling device to address issues such as poor stability,significant disturbance,and high risk of stuck pipe encountered by conventional drilling tools in frac-tured formation environments.The performance of the new drilling device was systematically evaluated using a combination of numerical simulation and field testing.Results show that compared to conventional drilling tools,the new drilling device demonstrates superior drilling speed in fractured formations,significantly improving operational efficiency.Its innovative debris removal mechanism substantially enhances the rate of rock chip removal,effectively preventing borehole clogging.Moreo-ver,it causes minimal disturbance to the surrounding formation,greatly reducing the risk of geolog-ical hazards.

Abstract:In response to the difficulty in supporting the surrounding rock of the along-the-goaf road-way,taking the return airway of the 2205 working face in Yitian Coal Mine as the engineering back-ground,the reasonable setting of the protective coal pillar on the side of the along-the-goaf return air-way was carried out through theoretical calculation,and the excavation position of the return airway was determined.The combined support technology of anchor,net and cable was adopted,and the sup-port parameters were reasonably designed.Practical experience shows that the width of the protective coal pillar is set reasonably,achieving the maximum recovery of coal resources.The design of support parameters is reasonable,and the deformation of the surrounding rock of the roadway can meet the production requirements,ensuring the safety of coal face mining.This provides a reference for the set-ting of protective coal pillars in other mining roadways of this mine.