Expansive soils damage to residential and light commercial occur in many parts of the United States and it has been estimated to cause annual losses on the order of $6-7 million. The project will test laboratory models and full- scale prototypes of a device called foundation isolation tube which is intended to greatly reduce damage to structure foundations caused by expansive soils. In both sets of tests, the performance of instrumented drilled shafts constructed both, with and without foundation isolation tubes will be monitored during periods of soil moisture variation. Comparison of the performance of these shafts will verify the effectiveness of this mitigation technique in reducing axial loads due to the vertical movement of expansive soils. The results of this research will provide an improved understanding of the nature of subsurface moisture migration in the vicinity of drilled shaft foundations. Guidelines for the use of this technique will be developed allowing geotechnical engineers to design more reliable and economical foundations in expansive soils sites.
