On Optimization Calculation Method of Effective Length for Large Diameter Pile Based on Mindlin′s Solution

Key words: 
• effective pile length、distribution form of pile shaft resistance、parabolic distribution、Mindlin′s displacement solution、optimization calculation method

Abstract: The calculation of a large diameter bored pile′s effective length is connected with its distribution of pile shaft resistance .According to different forms of pile side resistance distribution ,effective pile length calculation results often change to a large extent .Based on Mindlin′s displacement solution and in consideration of the effect of pile diameter ,the calculation equation is optimized with the assumption that the pile shaft resistance has a parabolic distribution .The influencing factors ,in accordance with the calcu-lation result of effective pile length ,have been analyzed .Finally ,the equation has been deduced in this pa-per ,combined with an engineering example ,has been analyzed and verified .The result shows that the Poisson Ratio of soil and pile diameter both impact the effective pile length .Compared with the Poisson Ratio of soil ,the effect of pile diameter is more significant .If the pile diameter remains the same ,the effect of the Poisson Ratio of soil to the effective pile length decreases as E/G power of the ratio of pile e-lastic modulus and soil share modulus increases .If the Poisson Ratio of soil remains the same ,the effect of the pile diameter to the effective pile length increases as E/G power of the ratio of pile elastic modulus and soil share modulus increases .Thus the optimized calculation result of pile effective length under the con-sideration of the effect of pile diameter is more close to the actual situation of engineering and reasonably practicable .