Jet Grout Underpinning to Support the Waterman Hospital-Paper

Paper

Pdf Summary

The Waterman Hospital in Tavares, Florida, expanded its Emergency Department with a roughly 20-foot-deep excavation beside an existing hospital wing. Ambulance access and the helipad had to remain operational, and the adjacent building had shallow foundations bearing on loose, easily disturbed sand.<br /><br />A combination of earth-retention systems was used. Tied-back soldier beams and lagging supported areas away from the building, while structural jet-grout columns underpinned the existing footings and retained soil beside the excavation. The columns transferred building loads below excavation level and were designed for combined axial and bending stresses, with a required unconfined compressive strength of at least 1,000 psi. Single-fluid jet grouting was selected to provide control over column diameter and spoil return.<br /><br />Installation beneath the footings was sequenced in stages to limit temporary loss of support and create a continuous wall. Quality control included a pre-production test program, visual examination of exhumed test columns, strength testing of wet-grab samples from surface spoils, and automated recording of drilling and grouting parameters. Twenty-eight-day sample strengths ranged from 1,000 to 2,800 psi; wet-grab results were generally conservative compared with in-situ material.<br /><br />The jet-grout system successfully supported the building and retained the excavation without disruptive noise or vibration. Monitoring recorded maximum settlement of only 1/16 inch, with no cracking or structural distress.

Keywords

Waterman Hospital

Tavares Florida

Emergency Department expansion

excavation support

jet grouting

structural jet-grout columns

earth retention system

soldier beams and lagging

building underpinning

settlement monitoring