Wave Test Methods For Mechanical Parameters Of Jointed Rock Mass

The complex rock masses can be used in infrastructural engineering construction such as instance highway, railway, industrial and civil construction, water conservancy and hydropower engineering with the rapid development of economic construction in our country. Determining accurately the mechanical parameters of rock masses plays an important role in engineering design, construction and construction stability, etc. So, propagation rule of stress wave in rock masses is studied. Wave testing methods for mechanical properties of jointed rock mass is proposed. The study results will provide a new method to measure the deformation parameters of engineering rock mass.Mechanical parameters of different scales jointed rock masses use different test method. In this paper, mechanical parameters of jointed rock masses is carried out in Dexing copper mine in Jiangxi province.The large scale jointed rock mass is assumed to be Kelvin medium. The propagation process of stress wave in rock masses is analyzed using drilling and blasting in rock mass generating stress wave on the surface. The test method for mechanical parameters of jointed rock mass is put forward based on the time and space attenuation law of seismic waves. The test result of viscosity coefficient is 2.18 MPa?s, dynamic elastic modulus is 2.52 GPa. The test result of static elastic modulus of jointed rock mass is 1.58 GPa using boring elastic modulus instrument in situ. The dynamic elastic modulus is 1.6 times of the static elastic modulus.The smaller thickness rock mass visco-elastic joint is equivalent to the standard linear solid model. The propagation law of stress wave in the jointed rock mass is studied. The measurement method for normal stiffness and normal viscosity coefficient of joints is deduced based on the waveform change rule. The study results indicated that: the joint had the properties of low-pass filter. The waveform variation coefficient decreased with the increase of the viscosity coefficient and stiffness. The effective frequency range of wavelet is 800~1200Hz measuring parameters of joint in situ. The difference of the calculated waveform and measured waveform in incident side was analyzed using waveform variation coefficient. The calculation results of joint normal stiffness was 1.03 GPa/m, normal viscous coefficient was 5.7 MPa?s.The damage degree of soft interlayer is assumed to change with quadratic curve change rule for weak interlayer of mechanical parameters changing gradually. The propagation model for stress wave in soft interlayer is established. And the measuring method for elastic modulus of weak interlayer is put forward. The results indicated that the difference of calculated waveform and measured waveform in incident side is studied using coefficient of waveform change of stress wave. The waveform change coefficient decreased firstly and then increased with the increase of the peak damage degree of interlayer. The peak dynamic elastic modulus was 2.14 GPa when waveform change coefficient was lowest. The peak dynamic elastic modulus increased approximately linear with increasing dominant frequency of wavelet. The static peak elastic modulus was 0.74 GPa using linear fitting. The equivalent dynamic elastic modulus of soft rock strata was 4.24 GPa based on the equal deformation principle.