Rock Physics Modeling of Unconsolidated Sands: Accounting for Partial Friction Grain Contacts and Heterogeneous Stress Field

摘要

A partial friction heterogeneity model of a random-compacted granular pack can be formulated using two parameters (f(p),f(mu)) to account for (1) macroscopic stress heterogeneity distribution of grain packs and (2) microscopic partial friction on the area of grain contact. This proposed partial friction heterogeneity model indicates that surface friction between grain contact is non ignorable, which results in tangential loading path being irreversible. Meanwhile, the tangential stress causes partial sliding on grain contact surface. Macroscopically, the effective shear modulus increases when either fraction of partial slip grain contacts or micro-friction on the area of grain contacts increases.