Numerical Analysis on Group Pile Effect of Pressure Grouted Helical Pile Group
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摘要: 螺旋桩芯劲性复合桩（Helix Stiffened Cement Mixing Pile，简称HSCMP）是一种新型复合桩，其群桩效应及承载力变化规律尚不明确。基于有限元数值模拟方法，对HSCMP桩间距与叶片直径比（Sg/DH）和水泥土强度与桩周土强度比（Cref/Su）进行参数化分析，并将分析结果与群桩效应系数理论计算结果对比。结果表明：保持叶片直径和土的基本性能不变的情况下，群桩承载力与水泥土强度及桩间距正相关；Sg/DH≤2时，理论计算结果与数值模拟结果相似，随着Sg/DH增加，数值模拟结果与应力叠加法结果较为吻合；Sg/DH≤2时，桩间土应力叠加效应显著，易导致螺旋桩芯–水泥土柱的界面破坏，但Cref/Su≥40时，破坏模式不再发生改变，表现为水泥土柱–土的界面破坏。Abstract: Helix Stiffened Cement Mixing Pile (HSCMP) is a new type of composite pile, and its group pile effect and bearing capacity variation law is still unclear. Based on the finite element numerical simulation method, the ratio of HSCMP pile spacing to helix diameter (Sg/DH) and the ratio of cement soil strength to soil strength around the pile (Cref/Su) were parametrically analyzed and the results were compared with the theoretical calculation of the group pile effect coefficient. The results show that the group pile bearing capacity is positively correlated with soil strength and pile spacing when the helix diameter and soil properties are kept constant; when Sg/DH≤2, the existing theoretical calculation results are similar to the numerical simulation results, and the numerical simulation results are more consistent with the stress superposition method as Sg/DH increases; when Sg/DH≤2, the stress superposition effect of soil between piles is significant, which is easy to lead to the damage of the interface of helical pile core-cement soil column, but when Cref/Su≥40, the damage mode will not be changed again, and it is shown as the damage of the interface of cement soil column-soil.
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Key words:
- HSCMP group pile /
- group pile effect /
- failure mode /
- numerical simulation
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表 1 土层物理力学性质指标
土层名称 厚度/m 压缩模量${E}_{\rm{s}}$/MPa 不排水抗剪强度${S}_{\rm{u}}$/kPa 素填土 1.20 3.45 26.17 黏土 1.30 5.32 27.16 淤泥 8.00 1.79 5.68 含砂姜黏土 1.20 9.86 102 黏土 2.20 10.00 114.36 黏土夹砂 6.10 9.36 227.70 
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表 3 群桩抗压极限承载力
Sg/DH Cref/Su 极限承载力Qu/kN 位移/mm 4 1 473 39 5 1100 42 10 1455 52 20 1570 43 40 1580 43 60 1584 39 80 1587 38
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