Volume loss consolidation

Compaction of Holocene sediments includes dewatering of sediments (primary consolidation), rearrangement of mineral structure of the sediment and subsequent loss of volume (secondary consolidation), and the decomposition of organic matter in the sediment. This is the most important process affecting subsidence in Louisiana coastal areas however, it is a very difficult process to evaluate. 

The unconfined compressive strength of chalk ranges from moderately weak (much of the Upper Chalk) to moderately strong (much of the Lower Chalk of Yorkshire and the Middle Chalk of Norfolk). However, the unconfined compressive strength of chalk undergoes a marked reduction when it is saturated (Bell et al., 1999). For instance, the Upper Chalk from Kent may suffer a loss on saturation amounting to approximately 70%. Chalk compresses elastically up to a critical pressure, the apparent preconsolidation pressure. Marked breakdown and substantial consolidation occurs at higher pressures. The coefficients of consolidation, Cy, and volume compressibility, triy, are around 1135 m a- and 0.019 m MN- respectively. 

Fig. 1 Process feasibility window for the thermal processing of a self-reinfOTced composite from the fibre and matrix precursor into a composite structure. The process-feasible window is dictated by four boundaries of temperature and pressure (based rui [22, 23]). (a) When excessive temperature is applied, molecular relaxatimi of the fibrous reinfOTcement can occur, resulting in a loss in mechanical properties and, at the miset of fibre melting, a loss of reinforcemcmt volume fraction. (b) In a similar way to excessive temperature, an excess in applied pressure can encourage flow, disrupting molecular alignment and resulting in a loss in mechanical properties. Conversely, the lower temperature and pressure houndaries of the process-feasible windows (c) and (d), respectively, are dictated by the need to apply a minimum temperature and pressure to achieve adequate composite consolidation...

It can be seen that the strain increases while the stress in the consolidation direction keeps constant. The strain increase lessens with progressing time. At the end of the creep phase at approx. 90 min a further strain increase can still be observed. This shows that also dry bulk solids show creep even though the increase of strain is very small. During the creep phase the relaxation, which would occur after a consolidation followed by a constant volume phase, is compensated. The loss of stress due to conversion from elastic to plastic deformation of the sample is added by a very slow consolidation during the creep phase. 

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