Long-Wavelength Elastic Wave Propagation Across Naturally Fractured Rock Masses

Evolution of Joint Roughness Degradation from Cyclic Loading and Its Effect on the Elastic Wave Velocity

“…The degradation of the replicated specimen from a low level of cyclic loading may differ from that of a rock specimen, but the rational geophysical behavior of a jointed rock mass can be investigated using an artificially replicated specimen. Mechanical properties of dental gypsum specimens were standardized by controlling for the ratio of gypsum to water (2:1) and curing them at room temperature (27 ± 2°C) for 48 h. Table 1 shows the average material properties of the gypsum specimen, and these are identical to those material properties considered in previous studies (Mohd-Nordin et al 2014). Three types of naturally fractured rock surfaces were replicated from weathered granite, as shown in Fig.…”

“…Quasi-static resonant column (QSRC) components consisting of an oscilloscope, a signal conditioner, and accelerometers were placed on the loading bench to evaluate P-and S-wave velocities during normal stress. The acquisition of a signal and its processing were based on previous research (Fratta and Santamarina 2002;Mohd-Nordin et al 2014). It should be noted that the QSRC test was conducted at the maximum stress level of cyclic loading.…”

“…According to the description of JRC profile characteristics developed by Barton and Choubey (1977) and enhanced using P max by Mohd-Nordin et al (2014), five features of the joint surface (smooth, planar, undulating, rough, and irregular) should be evaluated to quantify the JRC. Tables 2 and 5, joint profiles obtained from the replicated surface of weathering grade II were initially evaluated as JRC 6-8 because they appeared rough and planar, with an average P max value of 3.65 mm before cyclic loading.…”

“…Previous studies have examined the propagation of elastic waves across multiple jointed rock masses by considering joint surface conditions (Mohd-Nordin et al 2014;Huang et al 2014a;Cha et al 2009). One of the main findings is that the roughness and unevenness of a replicated natural rock joint surface have significant effects on the propagation of elastic waves.…”

“…The undulation and unevenness of a rock joint surface are recognized by its peak-to-valley height (Hotar and Novotny 2005) to classify the rock joint surface profile. In particular, Mohd-Nordin et al (2014) applied the JRC to naturally fractured rock surfaces using the scan line technique through the implementation of the peak-to-valley height. In this regard, the maximum peak-to-valley height (P max ) can be used as a meaningful quantitative indicator of the degree of roughness of a rock joint surface.…”