Mechanical properties of carbonate fault rocks

The purpose of the present study is to investigate the mechanical properties, mainly wave velocity, strength, deformability and degradation characteristics of carbonate fault rocks in the laboratory. The investigated materials present a complex behavior, mainly controlled by their tectonic disturbance, which has not been thoroughly studied due to practical limitations in sampling preparation and execution of laboratory tests. A novel procedure to prepare samples from the studied rocks was successfully performed. Two (2) intact, parent rock types (i.e., intact limestone, intact limestone-dolomite breccia) and five (5) fault rock types (i.e., two types of limestone fault breccias, two types of fractured marly limestones and one type of tectono-diagenetic dolomite breccia) were retrieved from five locations in Lefkada Island, Greece. The mechanical properties of the intact, parent rocks were determined to define the degree of strength reduction due to the tectonic disturbance of the fault rocks. The mechanical properties of the fault rocks significantly vary, a fact that is attributed to their structural and textural properties. These properties were quantified using a novel image processing technique and two (2) discrete algorithms. The durability characteristics of the studied rocks were also assessed through freeze-thaw and slake durability tests. The specimens with a higher tectonic disturbance yielded increased degradation characteristics, in repeated freeze-thaw and slaking cycles proving that the behavior of the material can drastically change over time due to weathering and erosion processes. . The findings of this paper suggest that the behavior of fault rocks cannot be approximated by the existing rock mechanics principles and therefore, a more focused methodology to derive their mechanical properties is needed.