厚层黄土状土中扩底墩竖向承载性状

Vertical bearing behavior of belled pier in thick loess-like soil

根据同一试验场地厚层非湿陷性黄土状土中8根大直径扩底墩、2根等直径桩的竖向承载力静载试验,对扩底墩的竖向承载性状进行了研究。结果表明,在其他条件相同时,随扩底墩直径D的增大,虽单位面积极限端阻力有不同程度的降低,但墩的极限承载力Qu增大;当D和墩身直径d不变时,总极限侧阻力所占墩顶极限荷载的百分比随长径比L/d的增大而增大;d不变时,随长径比L/D的增加,各墩的墩顶荷载呈起伏变化,总端阻所占百分比(比等直径桩大)相应降低,平均极限侧阻力(比等直径桩小)相应增大,而L/D=3时,其承载性状较好;在扩底墩墩身直径d与等直径桩相同、入土长度相当的情况下,前者承载力比后者大,且沉降小。

Based on the load tests of 8 large diameter belled piers and 2 friction piles, the vertical bearing behavior of the belled pier in non-collapsing loess-like soil is studied. The result shows that if other conditions are the same, the bearing capacity of belled pier （kN） increases and the end resistance decreases as the increase of the belled diameter. When both belled diameter （D） and shaft diameter （d） remain constants, the total ultimate side resistance enhances with Lld increasing. When the shaft diameter （d） is changeless, the bearing capacity of belled pier changes irregularly with LID increasing; the percentage of total end resistance （greater than equal-diameter pile） decreases; the average ultimate side resistance （smaller than equal-diameter pile） increases; but better bearing behavior occurs as LID=3. If the shaft diameter and the length of belled pier in soil are the same with the friction pile, the bearing capacity of the former is greater than the latter; and the settlement is smaller than the latter.