小口径钻孔灌注桩桩身内力随锚固长度变化的规律

Variation Law of Internal Force of Small Bored Pile with Anchoring Length

为探究倾斜式小口径钻孔灌注桩桩身锚固长度对桩身位移及内力的影响,以贵州正习公路边坡滑坡抢险治理工程为背景,结合经验法计算获得了灌注桩理论锚固长度,并通过FLAC3D数值模拟了不同锚固长度条件下,倾斜式小口径钻孔灌注桩桩身位移及内力分布变化,研究结果表明:(1)小口径钻孔灌注桩锚固长度<2 m时,不同位置的桩受力不均衡,除靠近滑坡推力的后排桩承受剪力外,其余桩几乎不承受剪力;(2)小口径钻孔灌注群桩锚固深度在6~8 m时,各排桩间桩身应力分布较均衡,超过8 m后,应力峰值反而增大,且应力分布更为集中;(3)小口径钻孔灌注桩桩身锚固深度宜控制在8 m左右,桩身内力分布最为均衡,在保证支护性能的条件下,此时经济效应最高。

In order to explore the influence of anchoing length on pile displacement and internal force,The background of this paper is the landslide rescue and treatment project of Zhengxi Highway in Guizhou province,this paper calculated the theoretical anchoing length of the cast-in pile with empirical method,and used FLAC3D to numerically simulate the conditions of different anchorage lengths.The results show that(1)When the anchoring length of small bored piles is less than 2 m,the loads of piles at different positions are unbalanced,except for the back piles close to the landslide thrust,the remaining piles hardly bear the shear force;(2)When the anchoring depth of small-diameter borehole grouting pile group is 6~8 m,the pile stress distribution among each row of piles is more balanced,and when the anchoring depth exceeds 8 m,the stress peak value increases and the stress distribution becomes more concentrated.(3)The anchoring depth of small bored pile body should be controlled at about 8 m,and the internal force distribution of pile body is the most balanced.Under the condition of ensuring support performance,the economic effect is the highest at this time.