关键词: 能量理论, 钻进能量, 凝灰岩地层, 界面识别, 围岩分级

Abstract: When a drill machine is working, energy of broking rock is produced from the action of torque and propulsion. The torque is resulted from the rotation of the bit, on which the propulsion is acting. When drilling conditions are certain, physical mechanical properties of rocks can be reflected from the energy consumed to break the rocks per unit volume. Based on this theory, advance geological drilling experiment has been performed on fault FK4+375.5 around the subsea tunnel across Qingdao Jiaozhou bay and the drilling parameters of tuff stratum and the variation of drilling energy with the displacement of bit are obtained. Parameters of a drill have been monitored in drilling process and analyzed using energy theory. The results show that, there is a good correlation between the drilling parameters of a digital drill machine and rock lithology. When surrounding rocks are integrated, hard and in the absence of fracture water, the drilling parameters are high. Conversely, when surrounding rocks are fractured, or in the presence of faults, fracture water and intercalated gouge, there are abrupt changes in the drilling rate, propulsion, rotational speed, torque and hit energy. The values of these parameters decrease markedly. The obtained results are consistent with core-drilling and advance geological prediction using tunnel seismic prediction (TSP). The above method is used in the classification of surrounding rock. According to the relation between energy curves and classification of surrounding rock, faults or fractured zones will appear in tuff stratum when the value of drilling energy is less than 0.95 kJ.

Key words: energy theory, drilling energy, tuff stratum, identification of geological interface, classification of surrounding rock