Abstract
Theoretical solutions on horizontal resistance of pile are introduced by using coefficient of subgrade reaction method based on Winkler's hypothesis. In the process of getting the solutions, the concept of degree of restraint for rotation at pile head α_r and effect of pile length are introduced, i.e., both of boundary conditions at pile head and pile tip are considered. Conclusions from analytical results by these solutions are summarized as follows. 1) Practically, piles, length L of which satisfies the condition βL≧3 are classified into long pile and theoretical solutions on horizontal resistance of infinite length pile can be applied. β is the coefficient shown by Eq. (3). 2) Degree of restraint for rotation at pile head α_r is influensive factor even in long pile case, and is related to bending moment or displacement at pile head in the form of linear function. 3) Not only α_r but also difference of pile length, i.e., boundary condition at pile tip affect considerably stress and displacement of pile in short pile case (β<3). For instance, as regards bending moment at pile head, about 10 % larger value than infinite pile length case appears in the range around βL=1.5 for free or fix condition at pile tip, and 30 to 40 % larger value appears in the range around βL=1.0 for pin condition at pile tip. If both boundary conditions at pile head and pile tip are fix in case of extremely short pile, bending moment distribution of pile becomes similar to case of short column. So that, it's necessary to use the solutions for case of finite length pile by considering boundary conditions at pile head and pile tip. 4) It becomes possible to analyze horizontal resistance of pile foundation mixed with different length piles under the same building, because the solutions shown in this paper cover all the pile length from the finite to the infinite.
