Abstract
This paper focuses on the study of the mechanical behavior of sandy limestone rocks. These rocks are provided from the historical caves of El Haouaria, which are located on of the North Eastern seacoast of Tunisia, and were created during the Punic era. Nowadays, these caves suffer from cracks, randomly distributed with a variable opening size. While, it appears that damage risk monitoring of the El Haouaria caves is a priority, linked questions concerning the mechanical behavior of the cave's rocks still remain, mainly because of its variable porosity and evolution with time. Understating its behavior will be a main tool to build a monitoring program, leading to an optimum reinforcement solution. Aside from uniaxial tests performed on several undistributed samples of a porosity ranged between 30 % and 50 %, triaxial tests were also conducted on undistributed specimens with a porosity of 30% and 50 %. All the results showed a significant effect of the porosity on the mechanical properties. The nonlinear Hoek-Brown criterion was used to model the shear failure, introducing few changes in order to consider the porosity influence. It was found that this criterion provides a satisfactory estimation of shear strength and its dependency on the porosity. Intact rock parameters and their porosity dependency were determined from compression and bending tests of undistributed samples. However, in situ rocks were considered as micro-fissured, principally for U3 layer, and the Geological Strength Index (GSI) was determined for the fissured rock.