Nonlinear hysteretic evolution characteristics of rock deformation and permeability
Tang Jie1, Wang Hao1, Li Jian1, Su Wenhan1, Guan Jian2
1. School of Geosciences, China University of Petroleum (East China), Qingdao, Shandong 266580, China;
2. Geophysical Research Institute of Shengli Oilfield Branch Co., Dongying, Shandong 257022, China
Abstract：Rocks and other non-uniform materials have strong nonlinear elastic behavior and significant hysteresis behavior (strain-stress state with discrete memory effect). In this paper,we use multi-level and multi-stage cyclic loading test combined with theoretical analysis to study nonlinear hysteresis characteristics of the rock. We introduce the concept of Preisach-Mayergoyz (PM) density to analyze static uniaxial compression tests at values well below the critical strength,and to characterize the elasticity of materials with hysteresis in their stress-strain relationship. The PM density can be deduced from a particular force protocol following basic data treatment. Hysteresis and discrete memory effect are inherent characteristics of rocks. The PM inversion procedure is tested for simulated stress-strain data. The final theoretical analysis can give better results to explain the experimental observations.
