Cracking in Large Drilled Shaft

[riggly95]

I inspected some large drilled shaft, up to 10ft diameter. I noticed a number of radial cracks on the concrete outside the bolt circle, and initiating at the bolts/anchors. The anchors were closely spaced, about 6" c/c. My haunch is that the reinforcement cage in that heavily reinforced (including ties) drilled shaft is expands enough, under high temperature, to exert tensile force on the outer ring of concrete outside the bolt circle resulting in cracks. However, contraction of the reinforcement cage, puts the inner core of concrete (within bolt circle) in compression, therefore, little crack was observed in the central region of the concrete. Does this explanation sound reasonable?

 

[paddingtongreen]

My guess would be that some of the liquid percolated into the soil, drying the outer concrete.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin

 

[Ron]

No. Radial expansion is minor even under abnormal conditions. Likely a result of inadequate consolidation of the concrete with plastic shrinkage cracking over the top of the cage.