Experimental study on nonlinear flow properties of pipe-fissure water in carbonate rocks during failures

This study focus on nonlinear flow properties of pipe-fissure water in carbonate rocks during failures. A visible flow experiment was carried out to observe pipe-fissure water during rock failures. Flow transition patterns of pipes and fissures water were quantitatively described according to the experiment data of flows in rocks under multi-level loading. The results show that the pipe fluid pattern is closely related to the roughness of the pipe-wall. The laminar flow at primarily cracks changes gradually into the transition flow at broken rocks. Pipe spalling can induce fluid pattern alternation with time duration. The precursory characteristics of transition fluid patterns of the pipe and fissure express as the critical point of flows. Pipe flow transforms into fissure flow with a feature of fractional evolution during carbonate rocks failure. The fractional index can be quantitatively used to define the critical transition process of the pipe into fissure flow.