This Small Business Innovation Research Phase I project will develop and refine non-destructive methods by which the lengths and numbers of piles and drilled shafts and the existence of severe structural defects in bridge foundations can be determined through non-destructive and non-invasive seismic survey means. The survey techniques proposed are the shear wave reflection profiling survey (SWRS) method and the ambient vibration survey (AVS) method. A secondary objective will be to determine through field experimentation any limitations that the methods may have. A known limitation is that none of the currently available conventional methods can determine pile widths. After the migration data processing step, it is possible to determine the pile width or shaft diameter and the number of piles in a pile group from the SWRS data Measuring pile numbers/group, shaft separation and width/diameter is a function of the horizontal resolution obtainable from the data, which is controlled by the field data acquisition parameters of detector spacing and source peak frequency. Specifically, shear-wave seismic reflection profiling surveys and ambient vibration surveys will be conducted, using traffic on the bridge as the exciting force, of bridge foundations along I-45 near the University of Houston in the Houston District of the Texas Department of Transportation (TxDOT) as a means of verifying the validity and utility of both methods. The Houston District of TxDOT has indicated that they will assist the project in gaining access to the test sites and to the as-built construction records. The Federal Highway Administration estimates that over the next 20 years $164.9 billion must be invested to address the tremendous rehabilitation backlog and improve accruing bridge deficiencies. The benefits of the proposed research would be very significant cost savings in the rehabilitation of bridge foundations by identifying which bridge foundations are safe and which need rehabilitation. The potential for such significant cost savings will make the commercial availability of a survey system a profitable undertaking for both the system supplier and the end user.
