Evaluation of cementation of Jeju coastal sediments using in situ tests

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)/N₆₀–(N₁)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)/N₆₀–D₅₀ 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–σ_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.