Pile monitoring, using strain and acceleration gages mounted near the pile top during driving, was carried out during the installation of two offshore platforms in the Xijiang Field, in about 325 ft water depth off the southern coast of China. The soils in the area are generally normally consolidated clays intersected by dense sand strata. The measurements assisted the contractor to identify hammer problems and improve hammer performance, and assisted the owner in checking pile adequacy and wave equation analyses. Post installation analysis of the data using signal matching techniques resulted in insights about damping and quake factors appropriate to the software, as well as soil resistances to driving (SRD) during continuous driving and after delays in the mixed sand and clay profiles encountered in this area. The findings should aid future installation planning in this area. This monitoring effort reflects a growing recognition of the value of dynamic monitoring to engineers and installation contractors involved with construction control or assessment of foundation adequacy, and for supplemental information in the event of unexpected conditions.
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