An experimental investigation into the stress-dependent mechanical behavior of cohesive soil with application to wellbore instability

[摘要] (cont.) Increases in outer diameter and strain rate lead to a reduction in the minimum borehole pressure. The initial cavity stiffness ratio decreases as consolidation stress level increases. Drained tests have larger cavity strain at a given cavity pressure and lower minimum pressure than the undrained tests. The borehole closure curves were analyzed using a framework originally developed for interpreting undrained shear properties in model pressuremeter tests (Silvestri, 1998). Backfigured undrained strength ratios from these analyses range from su/[sigma];;vc=0.19-0.21 corresponding to an average between the measured triaxial compression and extension strength ratios. The relationship between su/[sigma];;vc and overconsolidation ratio is consistent with element tests.

[发布机构] Massachusetts Institute of Technology