Study On Mechanical Characteristics Of Quartz Schist Of Different Depth Under One-dimensional Coupled Static And Dynamic Loads

The mining process of the deep rock mass is actually the failure process of the rock under the static load of the in-situ stress and subjected to the action of dynamic load of blasting stress.On the background of deep mining engineering under high stress in Xitieshan Lead-zinc Mine,this paper based on Chinese Postdoctoral Fund Projects(2014M562529XB),by uniaxial compression test using RMT-150C rock mechanics test system,conventional impact test and one dimensional static and dynamic loading test using SHPB test device,studies and researches on the static and dynamic mechanical properties of different depth of quartz schist in Xitieshan Lead-zinc Mine,and the test results were verified and supplemented by ANSYS/LS-DYNA finite element analysis software as well,which offer a reference for blasting scheme design of deep mining pillar and prevention work of geological disaster and help mines solve some problems such as the large consumption of explosives,boundaries are difficult to control,partial tunnels appear rip spalling with the increase of mining depth and blasting frequent and etc.The main research contents and results are as follows(1)According to the different depth of quartz schist under uniaxial compression test and conventional impact testing,we can find that the static compressive strength and dynamic compressive strength of the rock increase with the increase of the buried depth,also,in the case of the same depth,the dynamic compressive strength of the rock is greater than that of the static load.(2)Under the impact of frequent small incident energy in one dimensional static and dynamic loading test,the absorption energy and the reflection energy of the specimen can be stabilized in a small numerical range,most of the energy is released in a transmission way and the specimen can be kept in good integrity,which indicate that under the condition of high stress mining in the deep part of Xitieshan Lead-zinc Mine,control each blasting charge to minimize dynamic disturbance as far as possible,which can ensure the stability of pillar and surrounding rock very well to reduce the occurrence of geological disasters.(3)Through numerical simulation,we can find that after applying axial static pressure rocks can be deformed,certain elastic strain energy can be stored in the interior of the rock,and the dynamic compressive strength of rock will be increased.When the axial static pressure less than 40MPa,the dynamic compressive strength increases with the increase of the axial static pressure.When the axial static pressure more than 40MPa,cracks appear in the rock,microscopic damage occurs,and then the dynamic compressive strength decreases.(4)In the actual production of Xitieshan Lead-zinc Mine,when the mining depth is less than 1428m,with the increase of buried depth,internal porosity of rock will be compressed more closely under the action of stress,and then the dynamic compressive strength will increase and when the mining depth is more than 1428m the stress will be too large,the crack of the rock is expanded through,and then the dynamic compressive strength is reduced.Therefore,Xitieshan Lead-zinc Mine in the mining more than 1428m deep pillar can consider reduce explosive charge,saving production cost,reducing the dynamic disturbance.(5)The absorption of energy of rock first increase and then decrease with the axial static pressure increasing,and reach the maximum energy in the axial static pressure 35MPa.Rock ceases to absorb energy,and even begins to release its stored elastic energy,when the axial static pressure is greater than the 59.9Mpa,which provides necessary condition for rock burst,therefore,after the vertical stress reached 59.9MPa under pillar,The occurrence of the phenomenon of rock burst should be carefully monitored in Xitieshan Lead-zinc Mine.