Natural rock-slope stability issues at Masada national monument: A case study

The stability of three key-blocks at the snake path cliff of Masada monument is studied using 2-D and 3-D static and pseudo-static limit equilibrium analyses under dry and saturated conditions. The block size varies between 500 to 1400 tons. The response of the blocks to seismically induced ground motions is monitored using in-situ displacement transducers. All three blocks exhibited a simultaneous displacement in the order of 1mm during a single seismic event at the Gulf of Eilat. The sensitivity of the blocks to remote seismic tremors is explained by a pronounced topographic effect at Masada, amounting to amplification by a factor of 3.5. The results of the stability analyses indicate that the 3-D solution requires higher support force in comparison to the 2-D solution when water pressures in the joints is considered. It is therefore concluded that in the solution of rock slope stability problems where joint water pressures can be developed, application of two-dimensional solutions could be ominously un-conservative. Application of 2-D true dynamic DDA code in the north face of the mountain is performed where the slope consists of several hundred blocks. It is demonstrated that the duration of earthquake vibration is key factor in the numerical prediction of anticipated damage.