MSE walls support laterally loaded drilled shafts


Shafts in MSE walls are used to support sound barrier walls near highways and major roads when a residential area is nearby. The traditional design, which isolates the shafts from the MSE mass to simplify the design, requires rock sockets and large-diameter shafts, and thus, is very costly. An alternative design was proposed and verified through a full-scale MSE test wall in this research. In this design, the shafts are seated on the bedrock and supported by the MSE mass. The field single and group shaft lateral load testing demonstrated that the shaft could carry significant loads when the shaft was located at two times the shaft diameter (36 in.). There was a group effect when the shafts were spaced at 15ft apart and located at a distance of two times diameter of the shafts. Even though the geogrid layers were cut around the shaft, they were involved in resisting the lateral load from the shaft. The segmental blocks were tolerable to the differential movement induced by the shaft and effective in hiding the local deformation even at the wall facing deflection more than 5in. As a result, the alternative design approach investigated appears to be technically viable for the specific wall system used in the testing. This research has demonstrated an economic alternative to the standard KDOT method, allowing future noise wall construction to occur more economically.

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