Identifying the geological interface of the stratum of tunnel granite and classifying rock mass according to drilling energy theory

In the operation of a drill machine, its energy is primarily applied to break the rocks at the front. According to energy conservation theory, the real energy consumed by breaking rocks can reflect the lithology of the rock. Therefore, an experiment involving advanced geological drilling is conducted on fault 0+417 of the fifth hole in the first of the storage caverns of unlined crude oil in Qingdao City, China. The change curves of drilling and penetrating specific energies are generated based on drilling parameters, which are in turn obtained by the system that monitors the drilling process. A rock mass can be segregated into different zones as per the index of penetrating specific energy, and each zone corresponds to rocks with different lithologies. This method is used to classify rock masses and to identify the geological interface in a granite stratum. Simultaneously, tunnel seismic prediction is conducted on the storage caverns. Results as obtained using the drilling energy and geophysical prospecting methods are consistent. The drilling parameters of a digital drill machine are well correlated with rock lithology in granite stratum, and the values of these parameters decrease significantly. This paper suggests that the change curve of penetrating specific energy is well correlated with rock lithology, and the energy method can be used to classify rock mass. Based on the relationship between the energy curves and the classification of rock mass, faults or fractures occur in the granite stratum when drilling energy is less than 5.6 kJ.