The Research On Damages And Deformation Properties Of Deep Rock

With decreasing and exhausting of shallow resources, the mining depth of underground mineral resource is deeper and deeper.The deep rock is at complex environment at high temperature and pressure. This make the geological problems of geotechnical engineering become more and more outstanding. In this thesis, the deformation,damage and acoustic emission(AE) of deep rock due to uniaxial compression load,triaxial compression load and confining pressure unloading have been investigated with the method of a combination of experimental investigation, theoretical analysis and numerical simulation.The rock model of uniaxial compression test was carried out Meaningwhile, the AE signal at the process of compression was monitored by AE instrument as well. In the initial stages of the loading it has a few AE signs while at about 20% peak load lots of sonic emission activity appeared. Keep loading propagating of cracks become much slower and has a low emission rate simultaneously, at 75% of the peak load AE become much active.The deep rock specimens are subjected to uniaxial compression tests at the different stress and strain, the relation of damage and strain, the relation of damage and stress, the relation of loading time and AE ringing counts ,and the relation of loading time and AE energy. BY regarding AE counts and AE energy as damage variable establishing damage models and giving damage evolution tendency, we will find theory and experimentare anastomosingBecause AE is the elastic wave that the crack development releases, the AE message can take the measure of the damage development. The reasoning of regarding the "normalization" of the count as damage variable has been verifed further. With the basis of AE events and using subsection curve damage model gives out evolution equation of damage, the result consistent to the curve of count-time. With unloading different surrounding compression value and rate, we find the change of axial strain become more sufficing when the speed of unloading confining pressure becomes smaller. This prove the development transmission and transfer of rock fracture will have enough time when the speed of unloading confining pressure become smaller, and more fracture surface produced and the rock brocken even more complete. Conversely, if the speed of unloading confining pressure become bigger, fracture transmission and stress transfer become inadequacy, rupture will become abruptly.Simultaneously, we can see in the curve the distribution of rock specimen strength show discreteness, this should be come from rock structure characteristic The structure characteristic make localized rock produce large deformation, and the non-uniform of local deformation make other position of rock is at complex stress condition, that led to the result of test is different.