冲吸式钻孔灌注桩的抗拔承载力

本文根据轻亚粘土及粉砂中14根（D-45,60cm,L=4.2～6.0m）抗拔和2根（D=60cm,L=9.0～12m）抗压原型桩的试验结果讨论了桩长对极限抗拔侧摩阻力的影响以及单桩抗拔与抗压侧摩阻力与桩顶位移的发展规律。提出了单桩拔、压侧摩阻力比值随桩入土深度变化的数值。观测了不同入土深度的试桩在加载过程中柱周地面的变形。还提供了桩距S=2D的双桩抗拔的桩群效率系数值（η=0.9）。

Uplift Capacity of Bored Piles Installed by “Jetting and Suction” Drill

This paper is based upon the results of static load tests on 14 uplift （D=45, 60cm; L = 4.2¹2m） and 2 compression （D=60cm, L = 9, 12m） prototype piles in silty clay and silts. Influences of the variation of pile length on ultimate uplift skin friction and development of shaft resistance in uplift and compression versus pile top displacement are discussed.The ratios of skin friction in uplift to that in compression are presented and found to be varying with depths of penetration.Displacement patterns of ground surface around piles of different penetration during uplift are observed.A group efficiency of 0.9 for 2-piles groups with 2D spacing is also suggested.