Fig. 3.
The image has two parts. Part a shows three cylindrical specimens placed upright. From left to right, they are labelled recompacted, O P A, and cemented sand. A vertical ruler beside the specimens provides a height reference. The O P A specimen appears dark and uniform, while the cemented sand specimen has a lighter and granular texture. Part b shows a graph with void ratio on the vertical axis and effective axial stress in kilopascals on the horizontal axis using a logarithmic scale from 10 to 100000 kilopascals. Curves represent crushed O P A sandy, intact O P A sandy, sand cement dry, and cemented sand from Arroyo et al. 2005. The crushed O P A sandy curve starts near a void ratio of about 1.05 and decreases steadily with increasing stress. The intact O P A sandy curve remains near a void ratio of about 0.20 with slight reduction. The sand cement dry and cemented sand curves show intermediate void ratios that decrease gradually as stress increases.(a) Synthetic caprock and reservoir samples after compaction and saturation; (b) void ratio evolution with applied effective axial stress