Study On Bearing Capacity Of Shallow Foundation On Sandy Soils

The bearing capacity is important and basic problems in geotechnical engineering. The additional stresses in ground are constantly changing when the soil suffers external load. Then the ground will deform, and the foundation will settle. When the stress increase to the ultimate value, the ground will damage which lead to instability of foundation. From the initial formation to the development process of soil mechanics, the bearing capacity arouses many researchers attention. However, the classical limit equilibrium theory, small size model tests and in-situ soil test, etc many kinds of theories and test methods were applied to analysis and confirmation of bearing capacity, these methods have not yet solve the problem because of many factors. In recent years, with the rapid developments of finite element numerical analysis method and centrifugal technology, these new research methods are also applied to the classical problem. Due to the constraint of research conditions, these methods have not yet be used widely. Therefore, based on the existing experiment technology and analysis methods of Dalian University of Technology, in this paper, the author does a series of comparative studies as follows to solve bearing capacity through centrifugal model test and numerical simulation.(1) Because the quality of sample preparation plays a very important role in the geotechnical model tests. In this paper, some sand pouring tests are carried out on test sand by developing an apparatus of sand pourer. Though a series of comparative studies, the influences of sand flow rate, drop height and different containers on the relative density of the sample are obtained. It is shown that the relative density of the sample increases gradually with the increasing of drop height, while decreases with the increasing of the sand flow rate. Those two factors will affect each other with the different components of sand flow rate and drop height. Also, the shape of container has effect on Dr of the sample.(2) A series of centrifugal model tests with different sample relative densities, centrifugal acceleration、shapes and sizes of shallow foundations and so on are carried out by the advanced world and domestic first drum centrifuge. Discuss the influence of the above factors on centrifugal model tests of bearing capacity on sandy soil. And show the difference of bearing capacity and particle size effect between circular foundation and square foundation.(3) Based on finite element software ABAQUS, some numerical simulations which are in the same working conditions of centrifugal model tests are carried out. To contrast the results of numerical simulation, theoretical formula and centrifugal model tests, it is shown that there are some differences among the three methods of bearing capacity.