Transient-dynamic-FEM Analysis Of The Course Of Vibration-driving The Thin-wall Large-diameter Cylinder Structure

The LDCS (Large-diameter Cylinder Structure) is characterized by simple form, stressed reasonably, constructed conveniently and low cost, which can meet the requirements that ports develops towards open deep sea and big river estuaries. Tianjin University together with other scientific research units has conducted massive thorough research on load-bearing and instabilities destruction mechanism of the LDCS influenced by the wave, the tidal current and the silt flushes load for many years, has obtained rich achievements in scientific research, has formed scientific analysis and computation methods and has successfully applied the research results in projects. However, such questions require continuously thorough and credible research, as are the LDCS stresses and strains functioned by the longitudinal vibration load , interaction mechanism with the soil body and the drive-into possibility in the construction process, these problems have restricted the further promoted application of the LDCS.Based on vibration experiments data about driving-thin-wall LDCS during the secondary phase renovations of deep water channel at the entrance to Yangtze River ,and according to the theory of elastic stress waves, soil dynamics, nonlinear numerical computation method, this thesis is about the mechanism of vibration driving the LDCS into soil, the property of the force on the LDCS done by soil, the distribution of stress and strain, the driving possibility of the LDCS and the method of modeling soil. And the model of nonlinear viscous elastic-plastic FEM model has been built. Furthermore, the possibility of modeling soil by using solid element is analyzed in the thesis. The major research work can be summarized as follows.1. Profoundly analyzed the interaction mechanism between soil and the structure in the driving process. Pointed out the factors which influenced the LDCS driving process.2. Based on the current experiment data together with the stress wave theory and soil dynamics. Nonlinear numerical model of LDCS has been established, which works under vibration load, transient-dynamic-FEM analysis method of using numerical simulation of distribute element has been applied.3. Analyzed the driving possibility and the stress-strain of the LDCS in some projects, which can supply data for designers.4. The vibration parameters have been optimized ,made the driving stress and strain less when the LDCS reaches the designed elevation.5. Based on the ALE method, the penalty contact method, and the slave search method in LS-DYNA, put forward a preliminary plan to solve the vibration driving LDCS modeling soil with solid element.