Evaluation of Crane Pad Performance on Partially Improved Ground Adjacent to a Seawall-Paper

Paper

Pdf Summary

The paper evaluates the performance of a crawler-crane pad built on partially improved ground beside a 10-ft-high seawall. During crane erection, one corner of the mats settled about 3.5 inches. A ground-improvement program had installed 94 dry soil-mix (DSM) piers, but near-surface obstructions prevented 20 piers from reaching their intended depth of approximately 25 ft.<br /><br />To assess crane safety and potential effects on the seawall, the authors conducted geotechnical investigations and laboratory testing, then developed two-dimensional finite-element models using PLAXIS. The models represented the soil layers, DSM piers, crane mats, and seawall, and considered both a heavy lift and sustained crane loading. Because soft clay remained beyond the western edge of the pier area, the analyses also evaluated excavating and replacing some of that material with compacted crushed stone.<br /><br />Results indicated that the crane surcharge would add little load to the seawall: the pad was sufficiently set back, and the DSM piers helped limit load transfer. Settlement analyses showed that consolidation of the remaining clay would contribute substantially to total settlement, with much of it occurring within three months. The predicted maximum cross-track differential settlement was about 1.2 inches over roughly 24 ft, considered acceptable.<br /><br />The authors concluded that crane operation was feasible if weak dredged soils just west of the DSM piers were excavated and replaced with crushed stone. The work was completed in a four-week period, and the crane subsequently operated without excessive settlement or seawall distress.

Keywords

crawler-crane pad

dry soil-mix piers

ground improvement

seawall

finite element modeling

PLAXIS

differential settlement

consolidation settlement

crane surcharge

compacted crushed stone