| Ingate is the connecting part between the vertical shaft and horizontal roadway of the shaft yard.It is located at the throat of the mine.It has long service life,complex structure form,large size and dense nearby chambers.With the increasing depth of the new mine,compared with the shallow stratum,the original rock stress of the deep shaft ingate is being large,the stability of the surrounding rock is poor,and it is frequently disturbed by the blasting operation of the adjacent roadway and chamber.The deep shaft ingate and the adjacent shaft lining were often damaged,which seriously threatened the safety and production of the mine.Therefore,taking the ingate of the East return air shaft of Zhangji coal mine as the engineering background,the comprehensive combination of indoor test,theoretical analysis,model test,numerical calculation and field test is adopted to systematically studied the damage mechanism and control of the deep shaft ingate lining structure under the action of blasting disturbance.The main contents are as follows:（1）The static and dynamic mechanical tests were used to study the mechanical properties and constitutive model of concrete in ingate lining structure.Firstly,common C60 high-strength concrete（HSC）,new lining materials steel fiber reinforced high-strength concrete（SFRC）and reactive powder concrete（RPC）were prepared according to the field conditions,and their main physical and mechanical parameters were obtained through experiments.Secondly,the high strain rate cyclic impact test of various concrete materials was carried out by Split Hopkinson pressure bar（SHPB）,and the ultrasonic wave velocity of concrete after cyclic impact was measured by ultrasonic detector.The graded and cumulative damage degree of different concrete were given.The test results showed that HSC had obvious impact brittleness under10-20s-1 high strain rate cyclic impact,SFRC and RPC appeared remarkable anti cyclic impact disturbance characteristics.The cumulative damage degree of cyclic impact of SFRC-1.0 and RPC-1.5 was the smallest,which were 0.323 and 0.216 respectively.They were high-quality materials for the deep shaft ingate lining structure in the coal mine.The damage evolution law of concrete materials under cyclic impact load was revealed.Then,based on the Weibull distribution density function,the D-P criterion was introduced as the failure criterion of micro element,and three kinds of dynamic damage constitutive equations of concrete were established.These equations were basically consistent with the results of SHPB test and could be better embedded through LS-DYNA user-defined material interface which provided a basis for the numerical analysis of the lining structure of deep shaft ingate under the action of blasting disturbance.（2）Based on the similarity theory,the similarity criterion of deep shaft ingate lining structure model test under blasting disturbance was deduced.According to the similar indexes,the HSC and SFRC ingate lining structure models of deep shaft were designed and the specimens were poured.After the static load was applied to the lining structure through the large-scale model test system,the black powder was used as the blasting material to exert the cyclic blasting disturbance on the model.The sound velocity and strain were measured by ultrasonic detector and dynamic resistance strain gauge,and damage degree values of the model structure were obtained.The test results showed that under the confining pressure of 250KPa,the damage caused by two blasting disturbances of the deep shaft ingate lining structure was mainly located at the junction section of the structure,in which the damage degree of arch crown,arch shoulder and side wall was high.The maximum damage degree of HSC and SFRC-1.0lining model were 0.032 and 0.0043 respectively,and no obvious damage was found in other parts.At the same time,the test results also showed that,under the action of cyclic blasting,the joint section of shaft ingate lining on the same side of the first blasting operation was disturbed by"first strong then weak"cyclic blasting,and its cumulative damage degree was greater than the other joint section disturbed by"first weak then strong"cyclic blasting action,thus revealing the damage distribution characteristics and evolution law of the deep shaft ingate lining structure under the disturbance of cyclic blasting.（3）Using Hyper Mesh,the numerical analysis model of the deep shaft lining structure ingate in coal mine was established.The LS-DYNA user-defined material interface function was used,and the dynamic damage constitutive equation of concrete was embedded to simulate and analyze the deep shaft ingate lining structure of with different concrete materials and the cyclic blasting disturbance of different blasting charge under different surrounding rock pressure.The numerical simulation results showed that,under the action of surrounding rock pressure,the stress concentration area of the deep shaft ingate lining structure was located at the intersection of the shaft and the drift,which was mainly distributed at the intersection of the vault,the side wall and along the bottom corner.Among them,the tensile stress at the intersection of the drift bottom corner and the shaft was the largest.Under the confining pressure of250KPa,the maximum tensile stress reaches 1.66 MPa.The damage of ingate lining structure disturbed by blasting under the surrounding rock pressure was obviously affected by the amount of blasting charge.When the surrounding rock pressure of HSC structure was 50KPa,150KPa and 250KPa,the amount threshold of water gel explosive was 12.6kg,11.7kg and 9.9kg respectively.Under the same conditions,the dose thresholds of SFRC-1.0 structure were 15.1kg,14.1kg and 13.7kg respectively.It could be seen that the threshold of SFRC-1.0 was significantly higher than that of HSC,which showed excellent anti blasting disturbance characteristics in the lining structure of deep shaft ingate.After the blasting disturbance was applied,the damage degree of the interface section of the lining structure of the deep shaft ingate was the most significant,among which the damage degree of the arch crown,arch shoulder and side wall was the highest,the maximum damage degree of HSC and SFRC-1.0 model were0.0863 and 0.025 respectively,and the damage of other parts was not obvious.The two blasting disturbance damage at first were compared with the model test,and it was found that the damage location and damage degree results were in good agreement.With the increase of blasting cycles,the cumulative damage effect of the two materials was obvious.At the same time,with the increase of the distance between the blasting working face and the joint part,the disturbance influence gradually weakened.When the distance from the ingate reached 26.0m and 18.2m,the damage of the two lining materials caused by blasting disturbance could be almost negligible.（4）According to the engineering geological conditions and construction technology of ingate in the East return air shaft of Zhangji coal mine,according to the research results,the combined control technology of high-strength shotcrete anchor support,SFRC material lining structure,vibration reduction isolation hole and blasting charge control was proposed,which could adapt to the deep shaft ingate lining structure under the action of surrounding rock pressure and blasting disturbance load.The engineering application and field monitoring showed that the control technology could well prevent the damage and damage of the ingate lining structure caused by the disturbance of blasting load,and ensure the safe use of the ingate lining structure.In conclusion,the dynamic damage evolution laws of high-strength concrete and new concrete lining materials were obtained by SHPB cyclic impact test,and three dynamic damage constitutive equations of concrete were proposed.Through the combination of indoor test,model test,numerical simulation and engineering application,the damage distribution characteristics and evolution law of deep shaft ingate lining structure disturbed by cyclic blasting with different concrete materials were revealed.It was proposed that steel fiber high strength concrete and reactive powder concrete were ideal materials for deep shaft ingate lining structure.Thus,it could effectively control the damage and failure of the deep shaft ingate lining due to the disturbance of blasting load,and ensured the safe operation of ingate.Figure[115]Table[16]Reference[165]... |
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