Search

To further improve accuracy and reliability of describing the roughness feature of the structural plane, and more comprehensively reflect influences of the morphological differences, the fluctuation of the profile was decomposed into three principal characteristics: amplitude, inclination, and curvature, which represent the change characteristics of height, angle, and bending of the profile. The data of the three characteristics were obtained by 10 standard profiles established by Barton. And the distribution curves of the three characteristics were analyzed. Then, the power spectral density (PSD), which can well describe the microscopic morphology, was used to analyze the spectral characteristics of amplitude, inclination and curvature. The fractal parameters (corresponding to the slope of the PSD curve) and roughness parameters (corresponding to the intercept of the PSD curve) were got from the logarithmic PSD curves. The relationship among , and the joint roughness coefficient (JRC) was studied, and the expressive forms of JRC with the new index were established. Meanwhile, the new index was extended to reveal the characterization of three-dimensional morphology, which was also used to calculate surface roughness of a marble surface obtained by the shear test. The results show that the new index has an extremely slight evaluation error, and can reflect the anisotropic property and effectively character morphology features of the structural plane, which provides a reference for characterizing the roughness of the structural plane and it is of great significance to study shear mechanical properties of the structural plane.

Dynamic disturbance is an important influence factor that causes the sliding instability of rock discontinuity and then triggers strong dynamic geological disasters, such as earthquakes and rock bursts. In order to study the mechanical response and disaster-causing mechanism of rock discontinuity under dynamic disturbance loading, a multifunctional shear test apparatus for rock discontinuity under dynamic disturbance loading (DDST-1800) is independently developed. The test apparatus is composed of normal and shear loading units with quasi-static loading, various normal boundary conditions, dynamic disturbance loading with complex and wide-frequency waveform (0.5−50 Hz), and wide-range shear velocity loading (0.000 1−10 mm /s) functions, pendulum impact system, cyclic shear box unit, data acquisition and control units. This apparatus can conduct the following typical tests by programmed operations: a monotonic or cyclic direct shear test of rock discontinuity under Constant Normal Load (CNL), Constant Normal Stiffness (CNS), Unloading Normal Load (UNL), Variable Normal Stiffness (VNS), and Dynamic Normal Load (DNL) boundary conditions with different shear velocity, superimposed dynamic disturbance shear test of rock discontinuity in both normal and tangential directions of rock discontinuity under pre-set normal and shear stress conditions, velocity and stress step tests, and pendulum hammer-driven impact test of rock discontinuity under pre-set normal and shear stress conditions. Preliminary experimental studies were carried out and the results verified the stability and accuracy of the new apparatus. The research and development of the new apparatus have important scientific significance and engineering value for clarifying the dynamic response characteristics of rock discontinuity under dynamic disturbance loading and deeply understanding the triggering effect and activation instability mechanism of strong dynamic geological disasters such as earthquakes and rock bursts related to rock discontinuity.