Rock Creep Properties Test In Deep Mine And Deformation Mechanism Of Anchored Surrounding Rock

With the gradual development of deep coal mining, the rheological behaviors of deep well's rock are more significant in a complex stress environment and the mine strata support is more difficult. In this paper, integrated approaches of laboratory tests, theoretical analysis and numerical simulation were adopted to study anchored rock creep properties and anchor support deformation mechanism.Laboratory creep tests of anchored and non-anchored deep pink sandstone, red sandstone were done by using RLJW-2000 rheological testing machine for a long time. The results showed that, bolted rock creep stress threshold was increased by 30% ofσc around, and creep value at each stress level stage was controlled markedly; anchored specimen's long-term strength was increased by 5%～10% ofσc, it still had a certain load-bearing capacity after destroyed.Anchored body's creep constitutive model was established, model answers of anchored Generalized Kelvin (B-K) and anchored Burgers (B-B) were derived, the control mechanism of bolted rock creep deformation was illustrated from the view of mechanical rationale. At the same time, FLAC software redevelopment was carried out, in which two new anchored constitutive models were compiled into Dynamic Link Libraries, numerical calculations showed that, the results of anchored constitutive model and bolt unit in FLAC were quite similar, but the calculation workload with the new model was simplified, and the software's run efficiency was greatly improved.A rheological pull test device was independently designed, a large number of anchored system pulling rheological tests had been done in the laboratory. At the same time, the shear stress distribution on the interface between anchor and bonding material, matrix and bonding material was also investigated. The results showed that, anchorage shear stress distribution on the interface was uneven:first increased and then decreased along the axial direction; then shear stress transmission on the interfaces had different degrees of decay, but the characteristics of shear stress distribution were similar; the anchorage stress on the interface changes were related with time under actions of long-term loads, the significantly affected areas were mainly concentrated in the drawing section and the central section of anchor segments; interface failure was the main type of anchored system damage.Shear stress transmission aging pattern of anchorage interface was proposed, rheological damage of anchored system was divided into three characteristic stages of visco-elastic, visco-plastic and visco-off. Through the testing surveillance, we found that the bolt ends' displacements were experienced two stages of weak creep and strong creep, bolt displacements'strong creep was corresponded to visco-off phase of anchorage interface.The long-term stability prediction of roadway was carried out, GA-FLAC anti-analysis system was developed by using Genetic Algorithm, the rheological parameters'smart inversion of surrounding rocks was realized; GP model analysis system was developed by using Genetic Programming method, model identification about the non-linear process of anchored system's instability failure was done. The application of Evolutionary Algorithms improved the accuracy of inversion recognition, made results of deep rock's rheological instability predictions more scientific and objective.