Evaluation of cementation of Jeju coastal sediments using in situ tests

초록

A series of SPT, CPT and SPS tests were performed for Jeju coastal sediments in order to investigate the possibility of detecting the cementation of granular sediments by in situ tests. Plotting the in situ test results into the G(max)/q(c)-q(c1) and (G(max)/p(a))/N-60-(N-1)(60) relations suggested by Schnaid et al. (Proceedings of 1st international conference on site characterization, Balkema Pub, Rotterdam 2004) indicates that the Jeju calcareous sediments are cemented. It is also observed that the q(c)/N ratio of Jeju sediments is much higher than the (q(c)/p(a))/N-60-D-50 relation suggested by Kulhawy and Mayne (Manual on estimating soil properties for foundation design, EPRI, Ithaca 1990). It is suggested a relative density > 100 % obtained using the q(c)-D-R-sigma(v)' relation suggested for uncemented sands indicates cementation of the in situ sediments. The G(max)/q(c) value of Jeju sediments was found to be 2-6 times larger than that of uncemented sands at the same normalized cone resistance. It is concluded that in situ penetration resistances are relatively insensitive to the cementation of granular soil while the deformation moduli are significantly affected by the cementation, and that the relative density and G(max) of cemented sediments can be seriously misjudged unless the effect of cementation on in situ penetration test results is considered.

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