THE EFFECTS OF THE GEOMETRIC PARAMETERS OF A CIRCULAR SHALLOW FOUNDATION ON ITS UPLIFT BEARING CAPACITY IN LOESS SOIL

摘要

In order to revel the effect of the geometric size parameter of a circular shallow foundation on its uplift capacity in loess soil, the shaft diameter d, the enlarge angle of the slab and the embedment ratio h(t)/D of the shallow foundation were chosen to determine the field test schemes using the orthogonal test method. The field uplift tests were carried out on the tested foundations at a site located in Gangu County, Tianshui City, Gansu Province, China. The uplift load vs. the outward displacement curves of all the test foundations were recorded using automatic electronic measuring instrument. The test results revel that all the uplift load vs. outward displacement curves of the tested foundations are non-linear and take on an obvious three stages. Through the analysis on all the uplift load vs. outward displacement curves, the uplift capacities are achieved using the L-1-L-2 graphic method. By analyzing the relationship between the uplift capacities and the geometric parameters (enlarge angle of slab theta, the embedment ratio h(t)/D and the shaft diameter d) of the tested foundations, it is concluded that the uplift capacities of all the tested foundations increase with the increase of theta, h(t)/D and d, and the influencing degree of the three geometric factors on the uplift capacity of the circular shallow foundation is theta d h(t)/D.