Credit Valley Hospital Pre-loaded Micropiles for Vertical Expansion of Parking Garage SMART Contractometer Results Nadir Ansari, Isherwood Associates Jim Bruce, Geo-Foundations Contractors Inc.
92 micropiles – 60 caisson augmentation; 32 grade beam t / c Socket begins below existing 1070 diameter drilled shafts 967 lineal metres of drilling 300 kPa design adhesion in till 197mm diameter boring Solid bar, #14, #18, #20 gr 75 Lightest service load = 688kN (c); 450kN (t) Heaviest service load = 1200kN (c) Credit Valley Hospital
Depth (m) Soil DescriptionN – ValuesWater Content 1 CLAYEY SILT TILL: Hard reddish brown to brown moist clayey silt; trace to some sand and fine gravel 13% % % 46512% % 6SILT: Very dense brown silt; trace sand and fine gravel, seams of fine sandy silt and fine sand 15% 76915% Soil Description
Maximum Added LoadMinimum Added Load ItemOwnerValue Scheme Pile Caps – lg6m x 6m x x 2.8 x 1.5 Pile Caps – sm4.2 x 4.2 x x 2.6 x 1.2 Pile Caps – all> 600 m m 3 Caisson Piles12860 Gr Beam Piles6432
Test Pile Specifications and Results Maximum Applied Load 1791 kN Shaft Diameter 197 mm Area of #20 bar 3168 mm 2 Yield load of bar 1637 kN Free Length of Micropile 2.5 m Anchor Length of Micropile 4.0 m Strength of Grout 52 MPa Elastic Compression (max) 3.3 mm Ultimate Soil Adhesion ± 720 kPa
Creep Plot
Contractometer Anchor Locations Anchor Position (m) Fixed Top of Pile Movement
Movement Plot
Movement Along Test Pile at 1200kN
Tensile Stress Distribution Pattern Under Preloading
Compressive Stress Distribution Pattern Under Failure loads
Distribution Pattern of the First Principal Stress around Pile Top