We are grateful for the comments made by Colin Warren concerningthe stratigraphy of the sediments beneath Dubai Dry Dock. Likehim we have seen these sediments at various stages in the developmentof the Dry Dock and elsewhere. The great diversity of strength,particle size, and range of composition of these sediments hadto be considered all too briefly in the paper which was alreadyof considerable length. Paragraph 4 of page 118, however, coversmost of the points relevant to this diversity. We consideredin some detail the relative weighting to be attached to theloss of material as fine particles and loss due to solutionof gypsum, concluding that gypsum solution was the main causeof the settlement. The evidence from early cores shows thatweak, silty layers of gypsum occurred at depths of about -17.5and -21mHD. These could not be found in subsequent boreholes.We consider that the main settlement related to the removalof one of these layers (the upper one). More general removalof sulphate also took place but did not appear to lead to settlementof the magnitude recorded because the gypsum was dispersed withinstronger rocks. There can be no doubt that gypsum solution hasoccurred and that the amount of gypsum originally present wasof the correct order to account for the settlement observedand the recorded progress of the settlement. We found severalthin layers of uncemented carbonate clay and silt in cores takenat various stages in the
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Related articles in Quarterly Journal of Engineering Geology and Hydrogeology:
The influence of ground and groundwater geochemistry on construction in the Middle East
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Quarterly Journal of Engineering Geology and Hydrogeology 1985 18: 101-127.
[Abstract]
