Abstract: To ensure the safety of supercritical carbon dioxide storage in sandstone lens bodies，the initiation，propagation and evolution of cracks were studiedA lenticular geological model and a numerical calculation model were established to analyze the transport mechanism of supercritical carbon dioxide fluid in fracturesABAQUS numerical simulation software was used to establish a fluidsolid coupling model for fracture propagation simulationThe results show that when there are initial cracks，the cracks appear to be long，fast，and curved，and when there are no initial cracks，the cracks appear to be short，slow，and flatIn the case of 0° and 30° initial fracture angle，the change of fracture width and area with pore water pressure is similar，showing a linear increasing trend as a whole；in the case of 60° initial fracture angle，the change of fracture expansion is complex，which mainly depends on the selection of initial injection point and migration channel in injection fractureThe results of the study should be paid attention to in the selection of carbon dioxide storage sites
Abstract: The monitoring of soil water content in the dumping area of mining area is of great significance to the development of mineral resources，ecological restoration and early warning of drought in ChinaIn this paper，four different depths（1cm，3 cm，5 cm，10 cm） of soil samples were continuously monitored from 10：00 to 14：00 using Spequoia multispectral camera and ECH2O soil moisture sensorSoil spectral reflectance of four bands（550 nm，660 nm，735 nm，790 nm） and soil water content data were collectedThe soil water content inversion model with singleband or multiband spectral reflectance combination as the inversion factor was established by using the methods of partial least squares regression，ridge regression and back propagation（BP） neural networkThe results show that the inversion accuracy of the two regression methods is low，and the highest R2 is only 0606The GRNBP model with the combination of green（550 nm），red edge（735 nm） and nearinfrared（790 nm） as the inversion factor has the best inversion effect，corresponding to the soil water content inversion model of 1 cm，3 cm，5 cm and 10 cm depthThe coefficient of determination（R2） is 0866，08，0975，0911，and the root mean square error（RMSE） is 0333，0361，0103，0315In our research，a variety of methods are used to invert the soil water content at different depthsThe optimal inversion model is GRNBP modelThe best inversion depth is 5 cmThe method has high precision and can further develop the surface moisture monitoring of the mining area
Abstract: To solve the problems of low crack rate and large overhanging roof after directional presplitting cumulative blasting technology is implemented under the condition of hard roof，through theoretical analysis，numerical simulation and field monitoring，the deep and shallow hole combined cumulative energy blasting technology is proposed This paper analyzes the problems of single deep hole combined cumulative energy in hard roof，and points out that optimizing the layout of boreholes and blasting parameters is the main way to improve the blasting effect The technical principle of deep and shallow hole combined cumulative energy blasting is studied，and the theory of combined energy field and mechanical mechanism of combined pilot hole are put forward During the deep and shallow hole blasting，the stress field of the inner section and the outer part can be formed At the same time，the outer part of the deep hole can play the role of the pilot hole in the shallow hole blasting，and finally form the presplitting surface within the scope of the roof cutting Through the monitoring of blasting effect，the crack rate in the hole is increased by 30%，and the variation law of roof pressure is obtained The roof falling and filling in time can eliminate the fracture impact of hard roof and reduce the difficulty of surrounding rock control The research results can provide a reference for directional presplitting high-efficiency cumulative energy blasting under the condition of hard roof
Abstract: Quantitative evaluation of blasting damage has always been a matter of great concern to the engineering blasting fieldIn this paper，an active confining pressure and boundary constraint device is designed and developed to solve the problem of boundary constraint in traditional indoor small specimen blasting and punching problem caused by poor sealing effectBased on CT scan and 3D reconstruction，the method of testing and calculating the rock damage after blasting is proposedThe method can be used to quantitatively evaluate and analyze the degree of damage and fracture after the rock specimen is blasted with small chargeUsing the device and the method，the laboratory blasting test of red sand stone of small charge under different relative confining pressure was carried out，the CT scan and CT image binarization processing of the postexplosion specimen was carried out，and the rock specimen was reconstructed based on Mimics 1001It is found that the reconstructed model has strong similarity with the real postexplosion specimenFinally，fractal dimension and damage degree are calculatedThe research results provide a new idea for blasting damage evaluation.
Abstract: Groundwater reservoir is one of the effective measures for mine groundwater treatment，but mine water has a weakening effect on the mechanical performance of reservoir dam，which threatens the safety and stability of groundwater reservoirTherefore，it is necessary to carry out the study on the deterioration of rock mechanical properties under the action of mine waterBased on the groundwater reservoir of Lingxin Coal Mine，the deterioration of mechanical properties of gritstone under the effect of mine water immersion was study through laboratoryThe test results show that the mass change of the immersed test piece is related to the specific surface area，the interstitial and the rock mineral compositionUnder small water pressure，the permeability of gritstone is exponentially attenuatedAs the water pressure increases further，the permeability begins to increase as the particles blocking the pores are washed，and the greater the water pressure，the higher the rate of increase of permeabilityWith the increase of immersion time，the tensile strength of rock has a rapid decrease，then slows down and linearly deteriorates；the uniaxial compressive strength first decreases rapidly，then increases slightly，then decreasesThe deterioration of the mechanical properties of gritstone is caused by the infiltration of mine water into the pores of the rock，the ensuing hydration expansion and the dissolution of some minerals in the rockThe increase in uniaxial compressive strength is related to the pore water pressure caused by pore blockage.
Abstract: Taking Huipodi coal mine as the engineering background，the asymmetric deformation mechanism of the mining roadway under the island coal pillar was studied by theoretical analysis，numerical simulation and field measurement，and the corresponding floor heave prevention and control measures were proposedThe results show that the rock mass below the island coal pillar has the characteristics of zoning failure and is mainly shear failure，while the rock mass below the mined area is mainly tensile failure，and the rock mass failure morphology is inverted trapezoidRoadway 11-1021 is located at the junction of shear failure and tensile failure rock mass，which results in different degrees of damage and damage of the surrounding rock on both sides of the roadway，so the roadway exhibits asymmetric deformation characteristics，that is，the rock of roadway near the coal pillar side has a large internal stress and a small amount of deformation，while the stress near the goaf side rock is small and the floor heave is largeBased on the stress and deformation distribution characteristics of the surrounding rock on both sides of the roadway，a floor heave prevention and control technology based on the idea of anti-binding is put forward and verified on siteThe results show that when the roadway is not affected by the mining，the floor heave volume of the area treated by the floor heave prevention measures is greatly reduced，and the drum speed tends to be stable with time; when the roadway is affected by the mining，the amount of floor heave in the treatment area of the control measures was reduced by nearly 1/2，meeting the production requirements.
Abstract: Establishing mass transfer models of mineral porous materials in wet state is of great significance for understanding the internal moisture distribution and optimizing parameters during drying processesBased on LewisScherwood drying model，a onedimensional heat and mass transfer diffusive model by convective drying of porous materials was established by using the dynamic vaporization latent heat and exponential capillary diffusion coefficientThe average relative error of the improved model was determined to be 46% by comparing the experimental and the calculated value of water content decrease under the condition of convective drying on three porous material samplesBy comparing the improved model，the traditional model using constant latent heat and constant diffusion coefficient，and the results from drying experiment of porous material samples，it is verified that the improved model has higher accuracy than the traditional modelThe improved model is suitable for predicting the water distribution in porous mineral materials，which provides a reference for study of the prediction method of the water content in porous mineral materials in different drying conditions.
Abstract: Aiming at the problem of positioning error compensation of coal machine equipment airborne operating arm，a method of positioning error compensation based on piecewise linear regression was proposedThe forward and reverse kinematics equations were established based on the kinematics analysis of a typical airborne multijoint operating arm of coal machine equipmentThe fixed Шtype running path of the operating arm was designed based on the three working positionsThe position information of multiple positions in the same path was collected many timesThe measurement value and target value were analyzedThe target value was corrected to realize error compensationThe experimental results show that the method of piecewise linear regression can reduce the root mean square error in x，y and z directions to less than 100 mm，and the absolute value error to less than 100 mm，which can meet the requirement of error within 100 mm.
Abstract: The setting load of hydraulic support plays an important role in the roofcontrolThere are two methods to control the setting load of hydraulic support，one is openloop control by manual control valve of three position four port，the other is pilot control by solenoid directional control valve of two position three portHowever，these two methods can hardly make the setting load reach the expected value and remain stableEven when the expected value is reached，pressure drop and fluctuation generally existBased on this，a mathematical model of electrohydraulic force control system is established，then the stability of the system is analyzed by using MATLABIt is obtained that there are no openloop zeros and poles in the right half S plane of the PoleZero diagram of the system，so the system is a minimum phase system；the number of cycles of counterclockwise winding（-1，j0） from the Nyquist diagram is 0，and the system phase margin is 941° and the amplitude margin is 107 dB，so the system is stable；the step response is stable for 115 s，the impulse response is stable for 90 sAn adaptive PID control method based on BP Neural Network is proposed，and a threelayer neural network control model is establishedQuadratic performance index is used to control errorThe weight coefficients of the output and hidden layers are updated by using supervised Hebb learning rules and gradient descent algorithmThen three control parameters of the PID controller are obtained by trainingThe simulation results show that：it takes about 885 s for the setting load to reach the expected value and maintain stability when the expected input is step signal，and 91 s when the expected input is the square wave signalCompared with no BP neural network PID control，the response time is increased by about 13 times.
Abstract: The offset wrist robot with prismatic link for mining equipment can withstand large loads and has a large operating rangeIn this paper，this type of robot is studied，and two characteristics of its architecture are foundOne is that the solution for the fifth degree of freedom is equivalent to the solution for the angle between a special line and a special planeThe other one is that the distance from the origin to the intersection of vector axis 3 and vector axis 4 is a fixed valueThe two characteristcs make it possible to obtain the solution of the fifth and sixth degrees of freedom by iterative searching methodA new method of robot kinematics solution is proposedIt is not necessary to establish the coordinate frames attached to all the linksThe whole calculation process is completed in the global coordinate systemThe forward kinematics is completed step by step in sequence and，the inverse kinematics is completed step by step by returning methodThe new method has the advantages of short calculation time and high accuracy，which solves the problem that the traditional numerical method is not conducive to industrial application and promotes the application of the Pieper robot which has offset wrist with prismatic link in the welding of cutting head and underground drilling.
Abstract: Significant results have been achieved in the application of distributed underground water reservoirs inShendong areaNingdong area has begun to demonstrate its feasibilityHowever，the mine water in Ningdong area is mostly of high turbidity and high salinity，so the pretreatment of the reservoir water is requiredThe experiment compares the flocculation effect of fly ashbased composite flocculant and unfilled coal ash flocculant，and explores the influence factors of fly ashbased flocculant，and determines the optimal dosage and test conditionsIn view of the characteristics of high turbidity and high salinity mine water，this experiment，using fly ash as raw material，to obtain high turbidity and high ore by mixing it with polyacrylamide（PAM），polyaluminum chloride（PAC） and chitosan，gets flocculants for treating high turbidity and high salinity mine waterThe experiment compares the flocculation effect of fly ashbased composite flocculant and unfilled coal ash flocculant，and explores the influencing factors of fly ashbased flocculant，and determines the optimal dosage and test conditionsThe experimental results show that：1The treatment effect of mine water in the five treatment groups is：PAM+PAC+chitosan+fly ash >PAM+PAC+chitosan > PAM+PAC>PAM>PAC；2The optimum condition of fly ash composite flocculant in temperature is 25° C，pH 7，stirring strength 220 r / min，stirring time 20 min；3Under the optimal conditions，the removal rates of salinity，suspended solids，calcium ions，total hardness and sulfate by composite flocculants are 1216%，9804%，8057%，7786% and 9544%；4It is feasible to use fly ashbased composite flocculant as pretreatment flocculant for the treatment of high salinity high suspended solid water in the groundwater reservoirThis article provides experimental theoretical basis and technical support for the pretreatment of flocculation in the groundwater reservoir.
Abstract: Large amount of water glass and oleic acid added to the tungsten ore mineral processing resulted in high concentration of water glass residual in the flotation wastewaterThus，the flotation wastewater was gelatinous and it was difficult for the suspended substance to settleResearches at home and abroad about flotation wastewater treatment are focused on the removal of organic mineral process reagent and heavy metalIn the practical mineral flotation wastewater treatment project，polyaluminium chloride（PAC） was generally used as coagulant to remove the suspended substance which was difficult to settleThis paper screened and combined the different coagulant and coagulant aid，meanwhile optimized the experimental parameters to improve the effluent quality and meet the reusable water quality standard requirementsThe experimental results showed the prepared simulated flotation wastewater based on the investigation of actual flotation wasterwater quality had the characteristics as follows：pH was 1226，turbidity was 1 390 NTU，suspended substance was 2 780 mg/L，Zeta potential was -59.9 mV. Calcium chloride（CaCl2） and 15 million molecular weight cationic polyacrylamide（PAM） were selected as the optimum coagulant and coagulant aid，the dosage was 500 mg/L and 30 mg/ L respectivelyUnder the experimental conditions of 450 r/min rapid stirring for 5 min，160 r/min slow stirring for 2 min，followed by settlement for 20 min，the turbidity of the supernatant was 7.11 NTU and the removal rate could reach 99.48%
Abstract: The stability and fluidity of dense medium suspension are two contradictory factors that affect the separation performance of dense medium cycloneBy dense medium suspension density and apparent viscosity measurement，the effect of dense medium properties on the separation performance was investigated，and the best coal slime content was determined by labscale dense medium separationThe result showed that coal slime content was the major factor to affect the dense medium stability and fluidityUnder the same dense medium suspension density，higher coal slime content resulted in slower suspension density decline and better dense medium stabilityCoal slime content required for stability of dense medium suspension variedDense medium suspension of higher density could become stable with less coal slime contentThe effect of coal slime content on the fluidity was opposite to that on stabilityHigher suspension density and coal slime content could lead to higher viscosity and fluidity deteriorationIn the labscale dense medium separation，20% of coal slime content was optimal with the lowest mismatch rate acquired in suspension density of 1.50 g/cm3
Sponsored by: China University of Mining and Technology (Beijing)
Competent unit: Ministry of Education, People's Republic of China
