Study On Mechanical And Creep Properties Of Jointed Rocks With Different Inclination Angles And Penetration

In underground engineering,rock joints pose a great threat to the construction and operation of underground engineering,so it is of practical engineering significance to study the influence of rock joints on rock.In this paper,sandstone as the prototype,choose cement:sand:clay:water 1:1.7:0.1:The rock specimens with non-penetrating plane type joints,which consist of joint inclination angles of 30°,45°,60° and joint connectivity degrees of 5mm,10mm,and 15mm,were made,and their mechanical properties and creep properties were studied.The main research contents and results are as follows:(1)Uniaxial and axial tests were carried out on jointed rock specimens(5MPa,10MPa,15MPa)triaxial compression test.Under the same confining pressure,the peak stress of jointed rock specimen increases with the increase of joint inclination angle,but decreases with the increase of joint connectivity.At the same time,under uniaxial compression,the elastic modulus develops linearly with the increase of joint connectivity and joint inclination angle The elastic modulus shows a nonlinear development trend with the increase of joint connectivity and joint inclination angle.When the joint inclination angle is small,the cohesion and internal friction angle gradually decrease with the increase of joint connectivity.When the joint inclination angle is 60°,the cohesion and internal friction angle show a nonlinear development trend.With the increase of joint connectivity,the cohesion and internal friction angle increase with the increase of joint connectivity It can be seen that different joints have different effects on the mechanical properties of rock like specimens under uniaxial and triaxial compression.(2)Uniaxial creep pressure tests of jointed rock specimens at four stress levels are carried out.With the increase of loading stress,the instantaneous strain gradually decreases,and the instantaneous strain gradually decreases with the increase of joint connectivity,while the development trend of instantaneous strain with the increase of joint inclination Angle changes from first decreasing and then increasing to gradually increasing.The stable creep rate increases gradually with the increase of creep loading stress.When the joint inclination Angle is 30° and 45°,the stable creep rate decreases gradually with the increase of joint connectivity.When the joint inclination Angle is 60°,the stable creep rate increases first and then decreases with the increase of joint connectivity.When the connectivity of joints is 10mm and 15mm,the stable creep rate increases gradually with the increase of the joint tilt Angle.In conclusion,the existence of the above mentioned joints has a great influence on the instantaneous strain and creep rate of rock-like specimens.(3)The uniaxial compression test on the specimens of jointed rock after creep shows that the peak strength of uniaxial compression after creep is obviously lower than that of direct uniaxial compression,and the gap between the peak strength and the peak strength increases with the increase of joint connectivity.It can be seen that creep has a significant influence on the mechanical properties of jointed rock.Figure 46 Table 13 Reference 80...