Abstract
Clayey sand is widely distributed and commonly encountered in geotechnical engineering practice. To understand its bearing capacity behavior under unsaturated conditions, plate load tests are performed on sand–kaolin mixture samples with varying water tables. The distributions of suction and volumetric water content with depth are measured by vibrating wire piezometers and soil moisture sensors, respectively. It is shown by the test results that the bearing capacity increases when the water table in the soil sample drops. The influence of suction on the bearing capacity is found to be dependent on the height of the water table and the hydraulic loading history of the soil sample. The plate load test results are interpreted using bearing capacity equations. Good agreement is obtained between measured and calculated bearing capacities. This study provides a simple method to estimate the bearing capacity of in situ unsaturated soil foundations.
Highlights
The plate load test (PLT) is conventionally used in engineering practice to measure the bearing capacity of foundations or back-calculate the soil parameters
Test on the surface of each soil sample: one test under fully saturated conditions, the other study the effect of water tables bearing capacity, PLTsofwere twoTo tests under unsaturated conditions thaton thethe water table was at the three same level the performed on the surface of each soil sample: one test under fully saturated conditions, the geotextile and 240 mm higher than the geotextile, respectively
If the water table is lower than 1.5 B below the footing, the bearing capacity may be estimated using the measurements of one vibrating wire piezometer and one soil moisture sensor installed at the depth of 0.75 B
Summary
The plate load test (PLT) is conventionally used in engineering practice to measure the bearing capacity of foundations or back-calculate the soil parameters. PLTs have been performed on unsaturated clay and sand samples [2,6–8] It is shown by the test data that suction has a significant influence on the bearing capacity. The seasonal fluctuation of the groundwater table due to infiltration and evaporation results in the changes in suction profile in the soil [14,15] This natural phenomenon may have significant influences on the bearing capacity. Research shows that the bearing capacity of unsaturated soil depends on the wetting or drying processes the soil has undergone even when the water table remains the same [3] This is because the distribution of suction (s) and degree of saturation (Sr ) in the soil foundation are dependent on the hydraulic loading history due to hysteresis. Soil samples with a certain prepared to systematically investigate the influences of hydraulic loading ing density history were and water table on the PLT results.
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