ISRM Suggested Method for the Needle Penetration Test

Excerpt

Estimation of mechanical properties of intact rock is usually required for assessment of the stability of rock structures. They are also important elements of the rock classifications used in empirical assessment of rock masses. Measurement of these properties requires laboratory testing, which must be performed on samples of certain dimensions to fulfill testing standards and/or suggested methods. Laboratory tests are also time-consuming due to sample preparation, as well as experimental procedures often require high-capacity loading devices. High-quality core samples recommended by standards and/or suggested methods for the laboratory tests cannot always be obtained, particularly from weak and clay-bearing rocks. For these reasons, some simple and inexpensive index test methods have been developed to indirectly estimate the mechanical properties of intact rock (ISRM 2007). However, even preparation of smaller samples from weak and clay-bearing rocks for some index tests is still troublesome. In addition, geo-engineering and/or restoration studies on natural and man-made historical rock structures and monuments or buildings built with masonry construction techniques may require the determination of mechanical properties of intact rock. Sampling from such ancient sites is not allowed due to preservation, and environmental and other concerns resulting in the lack of mechanical data for those studies. …