Experimental Research On Mechanical Properties Of Specific Combined Angle Jointed Rock Mass Under Loading And Unloading Condition

In the process of long geologic effect,the rock mass was cut by structural planeswith different shapes and directions into discontinuous rock mass with certainstructures, which led to its complicated mechanical characteristic. In this paper, thespecific non-interpenetrated jointed rock mass was studied by uniaxial compressiontest, the conventional triaxial compression test and unloading test into revealtheloading and unloading mechanics characteristics of jointed rock mass. and theconcrete contents are as follows:1) The intact rock specimen and jointed rock mass with different connectivity(k=0.30, k=0.45, k=0.60), different angle and quantities(β=30°、β=45°、β=60°、β=30°+45°、β=30°+60°) was researched through different confiningpressure (2MPa、4MPa、6MPa、8MPa、10MPa) jointed rock mass test, uniaxialcompression the conventional triaxial compression test under different confiningpressure, unloading (pre peak unloading) test; study of different joint connectivity,different joint inclination and quantities of non-persistent jointed rock massdeformation, a loading and unloading conditions, parameters, strength failurecharacteristics, and with complete specimens were compared. The results show thatnon-interpenetrated jointed rock mass under loading and unloading conditions exhibitanisotropic mechanical properties, and with increase of jointed connectivity rate, theperformance of this anisotropy is more obvious.2) Non-interpenetrated jointed rock specimen in the loading and unloading testout of the mechanical properties, failure mode, mechanical parameters have obviousdifferences, the failure mechanism of rock mass with different loading and unloadingstate.The major damage of double joint specimen occured mainly along the largerangle joint surface.A linear type of Mohr-Coulomb strength criterion andHoek-Brown criterion can be the main surface interaction.3)A two-dimensional finite element calculation has been conducted on a slope inDagangshan hydropower station, using results of triaxial unloading test on jointsamples, it shows that calculated displacement of its changing trend is consistent withthe monitoring value, its magnitude is consistent with the monitoring value.It meansthat the method of selection of the calculation model and calculation is reasonable.