Study Of Sinking-resistance And Compaction Effect Of Static-press Pile

Pile foundation is one of the basic foundation forms widely used in the civil engineering. Static-press piling has been used in the groundsill building for many of its advantages. Taking into account the choice of pile and equipment type, the pile-sinking resistance must be estimated and the probability of pile-sinking should be evaluated before the construction. In addition, with analyzing the affect of pile-sinking compaction effect, the defending suggestions also need to be put forward before the construction. The previous studies indicated that the pile-sinking resistance and the pile-sinking compaction effect related to various theories and are complicated. Although many insights, especially the calculating methods and formula from the aspect of the pile-sinking compaction, were brought forward by the previous scholars, up to the present, no universal calculating method or formula for guiding the design and construction of the static-press piling has been obtained.Based on abundance engineering datum and partly archetype experiments, further study of the pile-sinking resistance and the pile-sinking compaction effect was carried out in this study with the techniques such as theoretically analysis, numerical analysis and computer simulation. The main conclusions are as follows:1. Taking full advantage of the previous study results, detailed investigation on the affecting factors and variation rules of the pile-sinking resistance was carried out. An experimental formula for calculating the pile-sinking resistance was achieved by taking the specific penetration resistance of static cone penetration test as the main parameters. Considering the disturbing of the soil during the pile-sinking, the concept of the soil sensitive was introduced and also the recommendatory value of the soil sensitive for the clay layers in Shanghai area was presented. The formula in this study was validated by using large numbers of actual engineering datum and experimental datum, and also the method of evaluating the pile-sinking resistance and the formula of evaluating the pile-sinking resistance with other parameters was offered.2. An artificial neural network model for evaluating the pile-sinking resistance was established and trained with large numbers of actual engineering datum. The modeling result was also validated. It indicates that the artificial neural network modeling the pile-sinking resistance is an easy, feasible and effective way to evaluate the pile-sinking resistance. It can be reinforced and tested each other with the result evaluating by the experimental formula.3. Based on abundance engineering datum, the correlation between the pile-sinking resistance of static-press piling and the ultimate bearing capacity of single pile in the different strata combination in Shanghai area was obtained. From the aspect of bearing capacity of single pile' time-dependent, the correlation of the bearing capacity of single pile, the pile-sinking resistance and resting time was also presented by large amount of experimental datum.4. The formula for calculating the surface displacement caused by the pile-sinking compaction effect in the saturated soft clay was acquired by using the Segaseta's source-source (or confluence) theory, and the results was also corrected according to different affective factors. At the same time, the calculating methods and value ranges for different correctional coefficients were listed. Finally, some useful defending suggestions for the pile-sinking compaction effect were provided.5. The software using to calculate the pile-sinking resistance and the pile-sinking compaction effect was compiled. It is easily operated and the results are outputted by calculation report format, which avoids complicated calculation.