Rock masses stresses investigation based on overcoring with CSIRO cell test and 3D finite element modeling in Aqabat Al-Sulbat Road at Aseer Province, Saudi Arabia: Numerical approach

At present time, rock mechanics is considered an important science during the phase of design and implementation of any project in Civil and Mining Engineering (highway, bridges, tunnels, dams, and so on.) especially when we speak about interaction between the project and the rock masses by choosing the appropriate foundation. In addition, rock masses slopes stability is a real problem and represents an important concern in Assyr Province in order to avoid rock fall process on the main roads and buildings. Therefore, due to the characteristics of this province, where various mountainous terrain in which various metamorphic and igneous rocks can be investigated. For this reason, it is necessary to explore, inspect, investigate and understand the natural stresses within these rock masses taking into a consideration the third dimension. Moreover, we assumed that the rock masses considered as isotropic medium in the first time. In the second phase, it considered as anisotropic medium introducing the thickness of each layer in the model. In another hand, based on literature review, several methods of measuring natural stresses in rock masses have been used, including the over-coring method with CSIRO cell involved in this research to estimate the natural stresses using 3D Finite Element modeling. In this sense, the state of stresses within the rock masses depends on the characteristics of CSIRO cell and the dimension of the over-coring hole. Furthermore, in order to achieve the 3D modeling the characteristics of the rock masses mentioned before introduced in the model using "Surfrac" program written in Pascal and FORTRAN, coupled with "Abaqus" software to simulate the stresses matrix in the model. As a result, the main findings of this research is summarized in three points: the first, dealing with the CSIRO cell itself where the direction of the gauge is important during the measurement of stresses, in fact, the perpendicular gauges work better than the parallel to the hole axis. The second one, it is evident from the model that the direction of hole must be perpendicular to the dip direction of the rock layers allows to give better results compared to others. The third one, the selection of the measurement site requires involving the regional stresses of the study area according to geological investigation. Finally, it is interesting to carry out geophysical exploration in the study area to understand the local tectonic movement of rock masses. Moreover, detailed map can be highlighted the main fractures and faults network and overlap it with the most important projects deployed in Assyr province for maintenance and monitoring.