不同因素对基坑桩锚支护结构变形的影响

The influence of different factors on the deformation of pile-anchor supporting structure of foundation pit

以南昌某高层建筑深基坑工程为背景,利用FLAC3D软件建模,模拟分析桩径、锚索及土体强度等参数在不同条件下桩锚支护结构变形规律。结果表明桩径超过800 mm以后再通过增大桩径的办法来减小桩身水平位移效果并不明显,说明在一定条件下不宜过度采用大直径桩。第1层锚索离支护桩桩顶的距离越小,桩身的挠曲曲率变大,反而容易导致桩身的开裂。当锚索倾角在10°~25°时,水平位移在可控范围之内,小于10°的情况下水平位移迅速增大。如果土的抗剪强度指标降低30%以上,则桩身水平位移会迅速增大,容易产生不利后果。如果将抗剪强度指标降低控制在20%以内,变形比小于0.6%,属于可控范围。

Based on the deep foundation pit project of a high-rise building in Nanchang,FLAC3D software was used to simulate and analyze the deformation law of pile-anchor support structure under different conditions with parameters such as pile diameter,anchor cable and soil strength.The results showed that it was not obvious to reduce horizontal displacement of pile by increasing the pile diameter after the pile diameter exceeded 800 mm,indicating that large diameter pile should not be used excessively under some conditions.The smaller the distance from the first layer of anchorage cable to the top of supporting pile,the larger the bending curvature of the pile body,which may easily lead to the cracking of the pile body.When the inclination angle of the anchor cable was between 10°and 25°,the horizontal displacement was within the controllable range.When less than 10°,the horizontal displacement increased rapidly.If the shear strength of the soil was reduced by more than 30%,the horizontal displacement of the pile would increase rapidly,which was likely to have adverse consequences.If the reduction of shear strength index was controlled within 20%,the deformation ratio was less than 0.6%,which was controllable.