ROCK MASS STRENGTH IN RELATION TO LANDSLIDE PROGRESSION

This study focused on quantifying the rock mass strength of the landslides triggered on Glenstrae Farm by the 2016 Kaikoura earthquake. We conducted point load testing on samples taken from three landslides of varying sizes located on Glenstrae Farm to analyze the rock mass strength at each slide location. After testing metasandstone samples obtained from each of the tree sites as lumps and cores for strength, we determined the overall average uniaxial compressive strength was 3.38 MPa. Overall, the rock mass strength only varied by a few decimals among the three slide sites despite the differences in landslide size and volume. The intact rock sampled at the three sites (designated sites A, B, and C) was found at varying depths below residual soil on Glenstrae Farm. At site A, the depth from surface to intact rock is only a few millimeters, while the depth from surface to intact rock at site B is roughly 0.5 m and site C is about 2 m. The rock mass in the landslides is highly fractured and weathered in addition to being very weak. We determined that the condition of the rock mass in conjunction with the varying depths from the surface to the layer of intact rock is most likely what caused the high number of landslides with widely varying sizes to result from the 2016 Kaikoura earthquake on Glenstrae Farm. However, in order to confirm these conclusions, more research needs to be done on the continuous progression and behavior of the landslides triggered by the Kaikoura earthquake.