| Abstract: | Forty full scale field tests were conducted on belled pier foundations at seven gravel Gobi sites in Gansu province and Xinjiang Uygur Autonomous Region in China. The uplift load displacement response of belled pier foundations in gravel Gobi almost followed the same pattern and presented three phase behaviors. Under tensile load, the onset of the curve usually started from the elastic linear part resulting from the compression and compaction of gravel Gobi above the enlarged base. And consequently, with the occurrence and further development of a plastic zone around the foundation, the uplift load displacement curve turned into an elasto plastic stage. Finally, the formation of whole rupture surface brought to the entire shearing damage of Gobi soil. The ultimate uplift bearing capacities were obtained by using the slope tangent method for all test foundations. Based on the theory of limiting equilibrium, the Mohr Coulomb yielding criterion and slip line field method, the circle arc rupture surface boundary condition was introduced. And the theoretical calculation equation to determine the ultimate uplift bearing capacity of the belled pier foundation in gravel Gobi was obtained. The theoretical results were compared with those of the tests and they turned out in good agreement. |
