An instrumented on-grade slab model was constructed on a site underlain by expansive clay soil located in a dry climate at amarillo, texas. the site was instrumented with moisture cells to measure changes in soil moisture content and thermocouple psychrometers to measure changes in soil suction as the seasons changed. the instrumentation was arranged so that changes in soil moisture and soil suction both vertically and horizontally could be measured, outside as well as beneath the covered surface. surface elevation points were established at 3-ft centers over the entire site to measure changes in surface elevations and to relate the movements measured beneath the covered surface to those of the adjacent soil in response to the same climatological event. a series of deep bench marks at elevations of 2, 6.5, 9, and 14 ft was established to monitor the depths to which measurable soil shrink-swell occurred. all instrumentation and elevation measurements were recorded on a monthly basis. one complete year of measurements is reported. surface and subsurface elevation changes and soil suction trends are presented, showing that the slab modelat this dry climate site has developed into a well-defined edge lift distortion mode, heaving a maximum of more than 2 in. around the perimeter of the covered surface. this paper appeared in transportation research record no. 1137, soil mechanics considerations in arid and semiarid areas. for covering abstract see irrd no 817740.
Abstract