The Role of Porosity on the Mechanical Resistance of the Rock of a Monument: The Case of the Punic Caves in El Haouaria

Abstract

This paper aims to investigate experimentally the role of the variable internal porosity on mechanical resistance and water retention curve as a main hydraulic property. The rock, object of our study, belongs to the caves of El Haouaria are located on the seacoast of the North East of Tunisia. Actually, the caves contain series of cracks with different types, which need a technical solution to improve the caves and avoid the collapse risk. This research might have the base issue of a technical solution So, experimental study include triaxial shear experiences and unconfined compression tests. These experimental tests were carried out in the laboratory by using several samples of rock. These samples are characterized by various types of porosity ranging nearly from 30% to 50% . Completely dried and different moisture water contents were first imposed on the rock samples, and then, separately, a series of tests were performed. The test results showed a significant effect of porosity on both retention water property and mechanical properties such as stiffness, compression and shear resistance. Moisture water content in the rock has an influence on its resistance and the successively imposed drying-wetting cycles was at the origin of porosity increase and consequently the environmental hydraulic were the main origin of the reduction of rock resistance. From this experimental investigation, the stability of the caves can only be studied through experiments. As shown above our work relied mainly on lab experiments. The stady of the cave stability passes necessarily by the study of the rock and the convenient improvement technique might be a solution to limit the disorders.