Study On The Material Experiment And The Bearing Mechanism Of Cast-in-situ Steel-slag Concrete Thin-wall Pipe Pile

Based on the work of former researchers, the mechanical properties of the material of the pipe pile are studied in this thesis by indoor experiment; also the bearing mechanism is analysed combined with the famous geotechnical FEM software PLAXIS and the influences of length of pile, diameter and the ratio of the stiffness of pile to the stiffness of soil on the bearing mechanism are discussed. For details ,the main contents are as follow:1.The research is conducted on the confecting method of steel-slag concrete by indoor experiment. Through comparison of the physical and mechanical properties between steel-slag concrete and plain concrete, it can analyze the advantages of using steel-slag concrete. Based on the test results, empirical formulae is developed, which provides some bases for practical projects. The mechanical properties of steel-slag concrete prevails more advantages than the plain concrete, also the quantities of cement and gravel are reduced, consequently reducing the capital cost of the project materials, so this method is economically and safely to be used and it can solve the environmental problems of unused steel-slag.2.The FEM software PLAXIS is introduced and its theories and numerical methods are given. The standard drained triaxial test and the oedometer test are subjected to simulations of various laboratory tests in order to validate the reliability with measured test data. Also the load-settlement curves by field test and FEM on a practical engineering are compared. The reliability is validated further on.3.The static loading test is modeled by PLAXIS , based on this, the basic bearing mechanism is analysed which comprise the rule of the load-settlement curves, inner and outer friction resistance, end bearing , stress distribution along pile depth and the dissipation of excess pore pressures. Also the influences of the length, diameter, and the ratio of the stiffness of pipe to the stiffness of soil on the bearing mechanisms are discussed. Based on these, some useful conclusions are reached.