Investigation on the experimental determination of the apparent preconsolidation stress and effective-sealing condition for clay cap rock

The relationship between generalized preconsolidation pressure and brittle-ductile transition pressure in sedimentary soft rock

“…Therefore, several other terms have been used instead of P C , such as yield stress (Mu et al 2020), consolidation yield stress (Hong & Tsuchida 1999), gross yielding stress (Jiang et al 2007), quasi-preconsolidation pressure (Ma et al 2014), and so on. For sedimentary rocks, a characteristic stress called apparent preconsolidation pressure has also been obtained by the method used to determine the P C of soil (Nygard et al 2004;Gutierrez et al 2008;Smith et al 2017;Yuan et al 2017;Liu et al 2018). However, the physical meaning of apparent preconsolidation pressure, which is typically determined empirically, remains poorly understood.…”

“…Based on the strain softening and strain hardening behavior of OC and NC soils, Nygard et al (2004; and Gutierrez et al (2008) first determined in laboratory studies that the value of BDT pressure is close to that of apparent P C . These findings were later applied to evaluate the sealing characteristics of cap rocks (Liu et al 2018), and the exploration and production of shale gas (Yuan et al 2017), with satisfactory results. However, to date, the relationship between apparent P C and BDT pressure in sedimentary soft rock has not been studied theoretically.…”