Assessing Depth of Well Foundation

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The case study evaluates the depth of well foundations for a bridge under construction in Faridabad, India. The drawings specified a depth of 12.2 m below the well cap, but the owner questioned whether the wells had reached this depth. Non-destructive testing was used to establish the as-built depth and help resolve the dispute.<br /><br />Two methods were applied. A low-strain sonic pulse-echo test, conducted by striking the well cap and measuring its response, indicated a strong reflection at approximately 11 m. Profile analysis also suggested a possible reduction in the well’s diameter below 9 m. A borehole parallel seismic test was then performed beside an abutment well. Changes in wave-arrival time and velocity indicated a foundation depth of about 11.2 m.<br /><br />Together, the tests showed that the well extended approximately 11–11.2 m below the cap—short of the specified 12.2 m. The findings provided an objective basis for the owner and contractor to settle the disagreement. The study demonstrates that combining parallel seismic and pulse-echo testing can reliably assess the depth of existing well foundations, extending techniques commonly used for piles to a more complex foundation type.

Keywords

well foundation

bridge construction

Faridabad

India

non-destructive testing

pulse-echo test

parallel seismic test

as-built depth

foundation dispute

foundation depth assessment