Monitoring the Installation and Curing of a Large Diameter ACIP Pile in Very Dense Sand: Fid-Bau Portal

Monitoring the Installation and Curing of a Large Diameter ACIP Pile in Very Dense Sand

Vipulanandan, C. / Guvener, O. / McClelland, M.

In this study, installation and curing of a 760 mm (30-inch) diameter and 10 m (32 ft) long ACIP pile with a design capacity of 800 kN (92 tons) in very dense sand was investigated. The dense sand layer was about 11 m (35 ft.) thick and was located 7 m (23 ft.) below ground. During the installation, torque on the gear box advancing the auger was recorded and it varied from 2.5 to 50 kN.m (2000 ft-lbs to 36,000 ft-lbs). The auger advancement rate varied from 12 to 83 mm/sec. The grout was characterized using the flow cylinder method and the flow diameter was 20 cm (8 inch). The grout volume ratio and pumping pressures were monitored at every 1 m (3 ft) lift during grouting. The curing of the pile was monitored using axial vibrating wire strain gages at four levels (10 gages) and lateral vibrating wire strain gages at two levels (two gages). The residual strains and temperature profiles in the curing pile was monitored over period of a week to determine the appropriate time for load testing the pile. The peak temperature from the edge of the pile to the center of the pile varied by over 8°C and the peak temperature in the pile was 63 °C in the center of the pile. The maximum temperature measured was over 40 °C higher than the surrounding ground temperature. The average time to reach the peak temperature in the pile was 0.35 days. The average maturity for the grout used in the pile was 1180 °C-hrs. The average residual axial and lateral strains in the pile after 7 days of curing were compressive and increased with depth.