钉形搅拌桩单桩承载力及荷载传递特性的数值模拟研究

Numerical simulation of bearing capacity and load transfer behavior of single T-shaped deep mixing column

在现场试验的基础上,对钉形桩单桩承载力及荷载传递特性进行了三维数值模拟。模拟结果表明:在其他条件相同的情况下,钉形桩的单桩极限承载力在一定范围内随扩大头高度增加而增大,随扩大头直径增加而增大,但单位水泥用量的单桩极限承载力随H/L和D/d均先增大后减小,存在最优值。从单桩承载力角度看,钉形桩存在有效桩长。钉形桩的桩身荷载主要集中在扩大头部分,是主要承载部位。由于扩大头的作用,钉形桩的桩身轴力在变截面附近有较大的衰减,其他条件相等,在各自的极限荷载下,钉形桩下部桩体的轴力大于常规桩,桩身侧摩阻力比常规桩发挥更加充分。

The bearing capacity and load transfer behavior of a single T-shaped deep mixing column are analyzed by 3-D numerical simulation based on field test. The results indicate that when other parameters stay the same, the ultimate bearing capacity of a single T-shaped deep mixing column increases with the height H and diameter D of enlarged column cap; but the ultimate bearing capacity of unit cement volume increases with H/L and D/d at first to the maximum, and then decreases; where L is pile length, d is pile diameter. There is critical column length ofT-shaped deep mixing column on bearing capacity. Most of the column load concentrates on the enlarged column cap which is the main beating part of T-shaped deep mixing column. As the effect of enlarged column cap, the column load at the variable section attenuates greatly. When other parameters stay the same, the axial force and side friction of lower T-shaped deep mixing column are larger than those of conventional deep mixing column under their respective ultimate loads.