Dynamic Characteristics of Jointed Rock Masses with a Natural Rubber Latex Dampening Layer under Seismic Loading Conditions

In rock dynamics problems, evaluating the dynamic characteristics of a jointed rock mass during the propagation of shear waves generated by seismic and other explosive loading is of utmost importance. The effectiveness of natural rubber latex (NRL) as a dampening layer in rock joints has been investigated. The effectiveness of joint spacing on the dynamic response of rocks has been studied using gypsum plaster samples with one to four horizontal joints layered with a 3-mm-thick NRL filling. The dynamic characteristics were evaluated using resonant column (RC) and cyclic torsional shear (CTS) tests across varying strain amplitudes, confining pressures, and loading frequencies. The results revealed that NRL-filled joints consistently exhibited reduced shear modulus and enhanced damping ratios compared to plain jointed specimens. The influence of joint spacing, confining pressure, strain amplitude, and frequency was quantified using regression analysis, showing that NRL-filled specimens were more responsive to joint spacing, while plain joints were more affected by strain amplitude and confining pressure. The viscoelastic nature of NRL contributed to improved energy dissipation, particularly under cyclic loading, in which CTS tests showed greater damping sensitivity than RC. The Ramberg–Osgood and modified hyperbolic models were used to fit the experimental results acquired from RC and CTS tests. These findings confirm that incorporating NRL in jointed systems can substantially improve attenuation characteristics under seismic-type loads. This study offers a practical material-level solution for mitigating dynamic amplification in jointed rock masses, providing a foundation for further exploration in field-scale geotechnical applications.