多层土中根桩的非线性沉降简化计算方法

罗晓光; 任伟新; 殷永高

doi:10.11779/CJGE202202019

多层土中根桩的非线性沉降简化计算方法 English Version

罗晓光^{1, 2,},
任伟新^3, ,,
殷永高¹

1.
合肥工业大学土木与水利工程学院, 安徽合肥 230009
2.
湘潭大学土木工程与力学学院, 湖南湘潭 411105
3.
深圳大学土木与交通工程学院滨海城市韧性基础设施教育部重点实验室(筹), 广东深圳 518060

基金项目:

国家重点研发计划项目 2019YFB2102702

国家自然科学基金项目 51778204

详细信息

作者简介:
罗晓光(1983—)，男，博士，主要从事基础工程及桩基检测方面的研究。E-mail: 2017010051@mail.hfut.edu.cn

通讯作者:
任伟新，E-mail: renwx@szu.edu.cn

中图分类号: TU476.9
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出版历程
- 收稿日期: 2020-04-14
- 网络出版日期: 2022-09-22
- 刊出日期: 2022-01-31

Simplified nonlinear method for settlement of root piles in multi-layered soils

1.
School of Civil Engineering, Hefei University of Technology, Hefei 230009, China
2.
School of Civil Engineering and Mechanics, Xiangtan University, Xiangtan 411105, China
3.
Key Laboratory for Resilient Infrastructures of Coastal Cities, Ministry of Education, School of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China

摘要

摘要: 根桩是一种新型桩基础，它通过从桩身预留位置将一定数量的水平根键顶入桩周土体中来提高桩基承载力。为分析多层土中根桩的非线性沉降问题，基于双曲线函数提出了土–根键的荷载传递模型，并推导建立了一种多层土中根桩的非线性沉降简化计算方法，基于MATLAB编制了根桩的非线性沉降分析程序。以安徽省池州长江公路大桥工程两根现场试桩为例，对该方法与现场荷载试验结果以及其它分析方法进行了比较。结果表明，该方法与实测结果吻合较好，较其它分析方法更符合根桩的荷载沉降曲线特性。根桩参数分析表明，根桩的荷载沉降特性对根键的布置型式以及根键侧壁土的荷载传递参数取值不敏感，但对根键底部土的荷载传递参数取值较敏感。
- 根桩 /
- 多层土 /
- 非线性沉降计算 /
- 根键 /
- 双曲线荷载传递函数 /
- 荷载试验 /
- 参数分析
Abstract: The root pile is a new type of pile, which improves the bearing capacity by penetrating a certain number of horizontal roots into soils from the reserved position of the piles. The load transfer model for the roots of a root pile is proposed based on the hyperbolic function, and a simplified nonlinear method for settlement of the root piles in multilayered soils is derived. An effective computer program based on MATLAB is developed for nonlinearly analyzing the load-settlement behavior of the root piles. The comparisons among the proposed method, other analytical methods and the root pile load test results on sites are carried out in terms of two real case root piles in Chizhou Yangtze River Highway Bridge in Anhui Province, China. It is demonstrated that the proposed method can achieve a good agreement with the measured results, and the load-settlement curve calculated by this method is more consistent with the real load-settlement characteristics of the root piles compared with that of the other analysis methods. The parameter study of the root piles shows that the load-settlement behavior of the root piles is not sensitive to the layout of roots and the load transfer parameters selected at root side-soil interface, but sensitive to the load transfer parameters selected at root base-soil interface.
- root pile /
- multi-layered soil /
- nonlinear settlement analysis /
- root /
- hyperbolic load transfer function /
- pile load test /
- parameter study

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图 1 根桩结构示意图

Figure 1. Schematic diagram of root pile

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图 2 桩–根键–土相互作用系统模型

Figure 2. Pile-roots-soil interaction model

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图 3 非线性计算程序流程图

Figure 3. Flow chart of nonlinear calculation process

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图 4 双曲线荷载传递函数模型

Figure 4. Hyperbolic load transfer function model

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图 5 桩位土层示意图

Figure 5. Soil stratigraphy for the real case root pile site

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图 6 ^#1，^#2试桩桩身结构图

Figure 6. Schematic details for root piles No. 1 and No. 2

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图 7 荷载试验照片

Figure 7. Photography of site pile load tests

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图 8 ^#1试桩荷载–沉降曲线比较结果

Figure 8. Comparisons of load-settlement curves for site root pile No. 1

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图 9 ^#2试桩荷载–沉降曲线比较结果

Figure 9. Comparisons of load-settlement curves for site root pile No. 2

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图 10 不同桩体结构型式的影响

Figure 10. Influences of different structural types of root piles

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图 11 根键–土荷载传递参数影响

Figure 11. Influences of load transfer parameters selected at root-soil interface

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表 1 基础形状系数

Table 1 Geometrical coefficients of foundation

形状系数	圆形	L/B
形状系数	圆形	1	1.5	2	3	4	5
ω	0.79	0.88	1.08	1.22	1.44	1.61	1.72

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表 2 系数C₁，C₂，C₃

Table 2 Coefficients C₁, C₂ and C₃

内摩擦角/(°)	C₁（砂土）	C₁（黏土）	C₂	C₃
2	0.07	0.04	1.20	5.63
4	0.16	0.09	1.43	6.19
6	0.28	0.16	1.72	6.81
8	0.44	0.25	2.06	7.53
10	0.64	0.36	2.47	8.35
12	0.87	0.50	2.97	9.29
14	1.26	0.69	3.59	10.37
16	1.73	0.95	4.34	11.63
18	2.33	1.27	5.26	13.10
20	3.14	1.70	6.40	14.84
22	4.22	2.26	7.82	16.88
24	5.70	3.01	9.60	19.32
26	7.70	4.07	11.85	22.25
28	10.16	5.38	14.72	25.80
30	14.26	7.32	18.40	30.14
32	19.51	9.90	23.18	35.49
34	27.27	13.83	29.44	42.17
36	37.32	18.92	37.75	50.59
38	54.75	27.10	48.93	61.35
40	77.85	38.20	64.20	75.31

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表 3 工程场地土层参数

Table 3 Soil layers and parameters for real case soils

土层	厚度/m	c/kPa	$\varphi$ /(°)	μ	$\gamma$ /(kg·m^-3)	E₀/MPa
粉质黏土	4.25	13.2	5.9	0.42	1860	4.36
淤泥质粉质黏土	5.60	13.8	6.7	0.42	1980	3.66
粉细砂	30.00	7.0	30.0	0.3	2000	31.00
中粗砂	3.40	5.0	33.0	0.25	2000	36.00
卵石土	4.30	1.0	36.0	0.24	2150	60.00
圆砾土	7.50	1.0	38.0	0.23	2150	61.00
中风化泥质粉砂岩	—	50.0	25.0	0.35	2450	300.00

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表 4 虚拟桩结构型式

Table 4 Structural types of fictitious piles

桩体布置型式	根键数量	根键层数	每层根键数量	根键层间距/m	顶层根键距桩顶/m	根键几何尺寸/m
无根键圆桩	0	0	0	—	—	—
无根键圆桩（1.4D）	0	0	0	—	—	—
根桩型式A	40	10	4	1	6	0.35×0.16×0.16
根桩型式B	40	5	8	2	6	0.35×0.16×0.16
根桩型式C	40	5	8	1	2	0.35×0.16×0.16
根桩型式D	40	5	8	1	9	0.35×0.16×0.16

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表 5 虚拟桩的荷载传递参数

Table 5 Load transfer parameters of fictitious piles

1/a_s/(MN·m^-3)	1/b_s/MPa	1/a_b/(MN·m^-3)	1/b_b/MPa	1/a_r/(MN·m^-3)	1/b_r/MPa	1/a_v/(MN·m^-3)	1/b_v/MPa
86.96	0.05	57.47	7.46	86.96	0.05	111.73	4.50

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