School of Resource and Environment Engineering,Jiangxi University of Science and Technology; Jiangxi Provincial Key Laboratory of Mining Engineering

Weathered rare earth ore contains a large amount of mediumheavy rare earth,the permeability of ore body seriously affects the mining efficiency.This paper proposes that the use of the explosive impact load can cause multiple disturbances to the rare earth ore body,change the internal microstructure,improve the permeability and keep the ore body stable.In order to explore the mechanical properties and permeability coefficient of weakly weathered granite under multiple perturbations from blast impact load,the Hopkinson impact testing machine,RMT-150C hydraulic servo testing machine and Nuclear Magnetic Resonance were used to respectively carry out a step by step cyclic impact test and static compress test (after the disturbance).The porosity and permeability coefficient of the specimen were measured.The results of research show that a fracture compaction stage exists in weakly weathered granite under cyclic impact,but it is not obvious.The stress relaxation platform exists in the crack propagation stage of weakly weathered rock under a step by step cyclic impact test,and it becomes more obvious with the increase of impact speed.The peak stress increases with the increase of impact velocity.At the aspect of static characteristics (after impact),the duration of crack compaction stage increases and the elastic stage decreases,the crack initiation stress σci,crack damaging stress σcd and uniaxial compressive peak strength σf decrease,and the critical strain increases gradually with the increase of impact times.There are three types of pores in the test specimen,the number of medium pores increase under the step by step loading,the number of small and large pores keep unchanged.After three impacts,the effective porosity and permeability coefficient of the specimen were greater than the initial value,and the peak stress is reduced by about 13%.The aim of increasing permeability based on the stability of ore body is realized.

国家自然科学基金资助项目(51404111);江西省自然科学基金资助项目(20192BAB206017)

刘伟，曾鹏，闫雷，等.循环冲击下弱风化岩石力学特性与渗透率演化[J].煤炭学报,2021,46(6):1855-1863.
LIU Wei,ZENG Peng,YAN Lei,et al.Mechanical properties and permeability evolution of weakly weathered rocks under cyclic impact[J].Journal of China Coal Society,2021,46(6):1855-1863.