槽口桩竖向承载特性模型试验与计算分析

doi:10.13229/j.cnki.jdxbgxb.20231082

摘要/Abstract

摘要：

针对新型槽口桩竖向荷载作用下的承载特性，分别通过室内模型试验和离散元数值模型分析普通桩和槽口桩承载性能及桩侧土体破坏形态的差异性，并探讨现场施工过程中成桩工艺对槽口桩桩侧土体抗剪强度的影响。结果表明：槽口桩极限承载力是普通桩的1.4倍，材料利用率是普通桩的1.9倍；槽口桩和普通桩桩端阻力分担比为30.3%、64.9%，分别主要表现为端承摩擦桩和摩擦端承桩的承载特征；槽口处具有明显的端承效应和挤土效应，桩侧摩阻力受土体间剪切力影响较大，沿桩身呈连续起伏的塑性破坏面；考虑桩身结构参数设计时，应避免发生槽口间应力叠加或独立承载破坏现象，最优距径比h/D=1.06~1.46；应用Terzaghi和Peck的土压力理论及应力路径方法表明，挤扩成孔工艺能够显著提高桩侧土体抗剪强度。

关键词: 地基处理, 槽口桩, 模型试验, 荷载传递, 离散元, 位移场, 破坏面

Abstract:

Aiming at the bearing characteristics of slotted pile under vertical load， the difference of load bearing performance and failure mode of soil around pile of ordinary pile and slotted pile were analyzed through laboratory model test and a discrete element simulation analysis model respectively， and the influence of pile-forming technology on shear strength of soil at the side of slotted pile was also discussed. The results show that the ultimate bearing capacity of notched pile is 1.4 times that of the ordinary pile， and the material utilization rate is 1.9 times that of the ordinary pile. The pile end resistance sharing ratio of slotted pile and ordinary pile is 30.3 % and 64.9 %， which mainly shows the bearing characteristics of the end bearing friction pile and friction end bearing pile. There are obvious end bearing effect and soil squeezing effect at the slot， the side friction of pile is greatly affected by the shear force between soils， and the plastic failure surface from the top of pile to the end of pile is continuously fluctuating. Considering the design of the structure parameters of the slotted pile， the phenomenon of stress superposition or independent load failure between the slots should be avoided， and the optimal ratio between slot distance and pile diameter h/D is 1.06-1.46. The earth pressure theory of Terzaghi and Peck and the stress path method are used to show that The shear strength of soil on the side of the pile is significantly improved by extrusion and expansion process for forming holes.

Key words: foundation treatment, slotted pile, model test, load transfer, discrete element simulation, displacement field, failure surface

中图分类号:

TU473

邓友生,姚志刚,宫亚峰,冯忠居,李龙,张克钦. 槽口桩竖向承载特性模型试验与计算分析[J]. 吉林大学学报(工学版), 2025, 55(7): 2308-2319.

You-sheng DENG,Zhi-gang YAO,Ya-feng GONG,Zhong-ju FENG,Long LI,Ke-qin ZHANG. Model test and calculating analysis on vertical bearing mechanism of slotted pile[J]. Journal of Jilin University(Engineering and Technology Edition), 2025, 55(7): 2308-2319.

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桩号	桩长L/mm	外径D/mm	内径d/mm	变径比d/D	槽距h/mm	距径比 h/D
S1	800	50	-	-	-	-
S2	800	50	40	0.8	62	1.24
S3	800	50	30	0.6	62	1.24
S4	800	50	35	0.7	89	1.78
S5	800	50	35	0.7	73	1.46
S6	800	50	35	0.7	62	1.24

参数		取值
颗粒	密度/（kg·m^－3）	2 200
	法向和切向刚度比/（N·m^－1）	1.9×10⁶
	摩擦因数	0.36
	局部阻尼	0.7
桩和墙体	法向和切向刚度比/（N·m^－1）	1.9×10⁶
	摩擦因数	0.3
	密度/（kg·m^－3）	2 650