Stability Of Concrete Support Structure In Deepmine Roadway Under Impact Ground Pressure

Along with the rapid development of China’s economy,the increasing demand for coal consumption has prompted a further increase in the depth of coal mining in Chi na.At thesame time,the hidden dangers caused by the frequent occurrence of impact pressure accidents are increasing.Almost all mine roadways will be devastated after b eing damaged by the impact pressure and cannot be used any more.In view of the f act that the main transportationroadway support method in China is concrete injection+ bolt support,it is necessary to study the stability of the concrete support structure of deep mine roadway under the impact of ground pressure.This paper takes a deep mine roadway in Heilongjiang Province as the prototype,and adopts the research method of downhole actual measurement plus numerical simu lation.Firstly,the underground eddy current explosion-proof range finder is used to ob serve the settlement of the roof and floor of the roadway and the horizontal converge nce of the two gangs.The section top plate settlement diagram,the section horizontal convergence rate diagram,the section roof subsidence fitting curve,the section cleara nce displacement regression analysis result summary,etc.,total 50 maps and tables.B ased on the field test,we used the regression function curve to predict the roadway.The final roof settlement value and horizontal convergence value for each section.The roof sinking rate of the roadway reached a maximum value of 11.97 mm/d on the th ird day after the blasting impact pressure,and then quickly fell back.When the fifth day,the rate was close to 0 mm/d.The horizontal convergence rate reaches a maximu m value of 3.88 mm/d one day after construction,and finally the rate is close to 0 mm/d after the 13th day.It can be seen that the impact of the blasting ground pressu re on the roadway support structure is mainly manifested in:The impact time of the t op and bottom support structures is short,generally about 5 days.However,for the t wo-way support of the roadway,the action time is relatively long,and it usually takes about 15 days to stabilize.The impact force with short action time is inevitably larg e,and vice versa;therefore,in the design of the roadway support structure,it is nece ssary to meet the strength of the support structure of the roadway top floor and the s upport structure of the roadway is more secure than the support structure of the road way.Economic and effective.Take the representative section K4 as an example:when the surrounding rock ma ss of the roadway is type II and the concrete support+anchor is used for the roadw ay support form(the length of the bolt is 2.4m,the spacing between the rows is 0.5*0.5m,and the thickness of the concrete spray is 0.2m)The final settlement of the roo f is 35.33mm,the horizontal convergence value is 19.23mm;the numerical simulation value of the K4 section is 50.40mm,and the horizontal convergence value is 24.18m m;at this time,the roadway is in a stable state;as the roadway continues to be cons tructed,the surrounding rock mass type of the roadway When the type Ⅱ is over-type to the V-type rock mass,the roadway support form is not changed.The re-numerica 1 simulation shows that the displacement change of the two-way TX direction of the r oadway reaches 44.84%;the displacement increment of the roadway roof reaches 37.62%;The displacement increment of the structure TZ direction reaches 57.54%;at this time,the roadway has suffered a certain degree of damage.After redesigning and stre ngthening the support(the length of the anchor rod is 3.0m,the spacing of the bolts and the column is encrypted from the original 0.5m to 0.3m;the thickness of the con crete spray is 0.25m)and then simulated,the displacement of the two lanes of the ro adway is obtained from the original 6.6985mm becomes 1.3654mm;the maximum dis placement of the roadway roof is changed from the original 54.3276mm to 11.6188m m;the relative convergence value of the roadway and the relative value of the roof si nking meet the requirements of the V-type rock mass,that is,it is stable.status.It ca n be seen that when the surrounding rock type of the deep mine roadway is close to the V type,it is very effective to use the anchor bolt length,reduce the inter-bolt,t he row spacing and appropriately thicken the thickness of the concrete spray layer.