Determining Depth of Foundation of an Existing Bridge Using Geophysical Non-destructive Tests—A Case Study

To determine the depth of an existing bridge foundation for construction of an underground rail corridor, parallel seismic tests (PST) and low strain pulse-echo method (PIT) were used. Since the tunnel alignment crosses an old bridge, the depth of the bridge foundations was evaluated by non-destructive geophysical tests to assess the impact of tunneling on the existing structure. The side of the piles were exposed to perform the pile integrity test. A borehole was drilled adjacent to two piles and cased with a PVC pipe. The paper presents results of the parallel seismic tests and PIT conducted on two piles below the bridge abutments. The test results confirmed that the pile lengths ranged from 8 to 9 m.