Vertical Bearing Characters And Design Theory Study About Great Pile Group

Size of pile foundation of SuTong bridge is great and supporting course is deep that engineers are short of designing experience. There is no theory of pile foundation designing that fits it good. This is the engineering background of the paper.Each method of pile test done in SuTong bridge is introduced simply. And how these methods are employed is presented, too. Test show that pile grouting and employing good mud can improve bearing characters of super-pile greatly. Configuring experience of good mud is summarized.Now, side resistance and tip resistance of super-long single pile both are from statistical result of short, minor diameter pile. On the base of lots of pile test results of static test and centrifugal model test, a load transfer function of side resistance of super-long pile considering depth effect is put forward. Ultimate frictional and depth relation is embodied by a hyperbolic curve. Method of inversion is used to obtain parameters of the function. Based on mindlin solution, stress condition of pile tip is calculated using numerical integration. Mohr-column failure criteria is introduced to calculate failure surface shape of pile tip and ultimate tip resistance which is theoretic ultimate tip resistance. Moreover, simple formula was fitted. The range of construction coefficient is achieved after theoretic results and test results of some drilled piles of great bridges inland are analyzed.Uniting load transfer function of single and mechanics of elasticity, analyzing and calculating method considering slip of pile and soil and whole stiffness dynamic adjusting of pile group is put forward. Obviously, the method is more in consistent to reality. The result of the method and that of centrifugal model test is accordant that prove the method is accurate. It is impossible making archetypal test for great pile foundation. Using load transfer function from static load test of single pile, analyzing bearing characters of pile group in the method is a good idea undoubtedly. And effect of calculating parameters to result is analyzed. Moreover, efficiency of pile group based on function demanding is defined. Based on the concept, how the parameter effect the relation of efficiency of pile group and displacement of pile head is discussed.Limitation of equivalent solid foundation is pointed out. Based on the precise method mentioned above, a simple method of settlement calculating for pile group making up of super long pile is put forward. Compression of pile body and stab deformation of pile tip is considered in the simple method, which is necessary for great pile group proved by an example. The method can achieve load-displacement curve of pile head. Moreover, nonlinear of the curve is outstanding.Based on the summarization that reliability design theory is based on bearing capacity wholly, a new concept reliability design of based on settlement aim at great super-long pile group is presented. The simple method is adopted to calculate reliability level. It is a great progress in theory of pile design. Besides, distribution regular of calculating parameters and method calculating reliability level is introduced.A hybrid method which is ally load-transfer method and finite element method is put forward. The...