Study Of Failure Mechanism And Ultimate Bearing Capacity Of The Foundations On Inhomogeneous Medium

It is often the case in Foundation Engineering that foundation subsoils are consisted of more than one layer. Up to now, Hansen's method and Meyerof's method for two-layered subsoils are the only two options for estimating the bearing capacity. But the methods can only treat some simple cases, can not deal with muti-layered subsoils. Therefore the mechanism of failure and the methods of estimating the ultimate bearing capacity should be further studied for inhomogeneous medium. In this paper, in-site test, model test with different scales and elastoplastic FEM was performed to study the problem. The research stratagem and conclusions can be summarized as follow:1. Information concerning with the bearing capacity of footings on inhomogeneous medium was collected and evaluated;2. Since there are less test-experience on the bearing capacity of footings on inhomogeneous medium in home or abroad, model test were designed and performed to determine the bearing capacity and the mechanism with vertical and inclined loads;3. Meyerhof-Hanna method to estimate the ultimate bearing capacity of foundations on two-layered subsoils was improved. Measured results from in-site loading tests in Tannin Harbor andfrom in-door model tests were compared with predictions from the limit equilibrium methods. A method of estimating the bearing capacity for inhomogeneous medium was suggested to meet every case;4. According to the results from model tests, the elastoplastic FEM were performed to study the procession of the change of the stress and strain in inhomogeneous medium and to simulate the procession of the forming of the failure surface during loading, and the failure mechanism was studied;5. In Harbor Engineering, reliability has been introduced to the design of foundations based on the limit equilibrium methods. In this paper perturbation stochastic finite element program was compiled to calculate and analysis the reliability of the foundation on muti-layered subsoils.