考虑变井阻的多元复合地基固结理论研究

白垚; 卢萌盟; 杨康; 赵明

doi:10.6052/j.issn.1000-4750.2022.05.0439

考虑变井阻的多元复合地基固结理论研究

白垚^1,,
卢萌盟^1, ,,
杨康^2,,
赵明^3,

1.
中国矿业大学力学与土木工程学院，江苏，徐州 221116
2.
中国矿业大学深部岩土力学与地下工程国家重点实验室，江苏，徐州 221116
3.
浙江木石建设项目管理咨询有限公司，浙江，杭州 311199

基金项目: 国家自然科学基金项目(51878657，52178373)；江苏省高校“青蓝工程”项目

详细信息

作者简介:
白　垚(1998−)，男，陕西延安人，硕士，主要从事软黏土力学与地基处理等方面研究(E-mail: baiyao98@163.com)

杨　康(1998−)，男，湖南岳阳人，博士生，主要从事软黏土力学与地基处理等方面研究(E-mail: tb21220024b1@cumt.edu.cn)

赵　明(1986−)，男，浙江杭州人，高工，硕士，主要从事地基处理与工程项目管理等方面研究(E-mail: zhaoming1108@163.com)

通讯作者:
卢萌盟(1979−)，男，陕西咸阳人，教授，博士，博导，主要从事软黏土力学与地基处理等方面教学和研究(E-mail: lumm79@126.com)

中图分类号: TU47
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出版历程
- 收稿日期: 2022-05-13
- 修回日期: 2022-08-18
- 网络出版日期: 2022-09-01
- 刊出日期: 2024-06-24

STUDY ON THE CONSOLIDATION BEHAVIORS OF MULTI-REINFORCEMENT COMPOSITE FOUNDATION CONSIDERING TIME-DEPENDENT WELL RESISTANCE

1.
School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
2.
State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
3.
Zhejiang Wood and Stone Construction Project Management Consulting Co., Ltd., Hangzhou, Zhejiang 311199, China

摘要

摘要:
该文以塑料排水板联合水泥搅拌桩多元复合地基为研究对象，通过假定排水板的渗透系数随时间呈指数型衰减，考虑了排水板在固结过程中的淤堵效应对地基固结性状的影响。同时，该文还考虑排水板的涂抹效应、水泥搅拌桩的扰动效应以及土体的径-竖向耦合渗流，推导得出多元复合地基的固结控制方程及其解答。通过与已有解答和现场试验的对比分析，验证该文解答的正确性。最后，采用参数敏感性分析法对多元复合地基固结性状进行研究。研究结果表明：复合地基井阻因子 $\theta$ 对固结后期影响较大，当 $\theta$ 值较大时，径向渗流由于排水板的淤堵效应将提前终止，最终仅由竖向渗流使得地基达到完全固结；初始渗透系数 ${k_0}$ 越大，井阻因子 $\theta$ 越小，涂抹作用越弱，板和桩的置换率越高，复合地基固结速率就越快。
- 多元复合地基 /
- 排水板 /
- 变井阻效应 /
- 固结 /
- 淤堵效应
Abstract:
This paper studies the multi-reinforcement composite foundation improved by prefabricated vertical drains (PVDs) with cement mixing piles, and the influence of clogging effect of PVDs is considered by assuming the permeability coefficient of PVDs decays exponentially with time. In addition, the smear effect of PVDs, the disturbance effect of the cement mixing pile, and the coupled radial-vertical flow within the soil are considered. The governing equations of consolidation of the multi-reinforcement composite foundation and the corresponding solutions are derived. The solutions is verified by comparison with several existing solutions and three field tests. Finally, the consolidation behavior of the multi-reinforcement composite ground is analyzed by a series of parametrical analysis. The results show the well resistance factor $\theta$ has a great influence on the later stage of consolidation process. A large value for $\theta$ will result in the radial flow ceasing in advance. Consequently, the consolidation will be completed only via the vertical flow. The following factors will lead to a faster consolidation rate, including a larger value of the initial permeability coefficient ${k_0}$ , a smaller value for the well resistance factor $\theta$ , weaker smearing effect, and larger replacement ratios of PVDs and piles.
- multi-reinforcement composite foundation /
- PVDs /
- inconstant well resistance effect /
- consolidation /
- clogging effect

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图 1 地基单元划分与等效模型

Figure 1. The selection of the typical unit of and the equivalent model

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图 2 模型单元剖面示意图

Figure 2. Schematic diagram of the model unit section

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图 3 两种常见荷载

Figure 3. Two typical load schemes

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图 4 地基厚度对固结度的影响

Figure 4. The effect of ground thickness on the average degree of consolidation

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图 5 涂抹区大小对固结度的影响

Figure 5. The effect of the size of the smeared zone on the average degree of consolidation

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图 6 涂抹区与非涂抹区的渗透系数之比对固结度的影响

Figure 6. The effect of the ratio of the permeability coefficient of the smeared zone to the non-smeared zone on the average degree of consolidation

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图 7 排水板井径比对固结度的影响

Figure 7. Effect of the ratio of the diameter of the influence zone to the equivalent diameter of PVD on the average degree of consolidation

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图 8 模型单元与水泥搅拌桩的半径之比对固结度的影响

Figure 8. Influence of the diameter ratio of the unit cell to the cement mixing pile on the average degree of consolidation

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排水板的初始渗透系数 ${k_0}$ 对固结度的影响

Figure 9. Influence of initial permeability coefficient k₀ of PVDs on the average degree of consolidation

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排水板的井阻因子 $\theta$ 对固结度的影响

Influence of well resistance factor $\theta$ of PVDs on the average degree of consolidation

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图 11 土体、排水板及整个地基内平均孔压随时间的消散曲线

Figure 11. Dissipation curves of average excess pore pressures over time in soil, PVDs and the entire ground

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图 12 级数解的收敛性

Figure 12. Convergence of the proposed series solution

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图 13 固结度的理论解和实测值的对比

Figure 13. Comparison of predicted average degree of consolidation with measured data

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图 14 固结度的理论解和实测值的对比

Figure 14. Comparison of predicted average degree of consolidation with measured data

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图 15 固结度的理论解和实测值的对比

Figure 15. Comparison of predicted average degree of consolidation with measured data

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表 1 模型参数取值表

Table 1 The parameters in calculation

参数	取值	参数	取值
H/m	13	k_v/(×10⁻⁹ m/s)	1.63
H/R_n	10	k_h/k_v	2
R_n/r_d	39.4	k₀/(×10⁻⁵ m/s)	5.5
R_n/r_p	5.2	E_s/MPa	1.68
r_sd/r_d	2	E_p/E_s	50
r_sp/r_p	3	E_d/E_s	1
k_sd/k_h	1/3	σ₀/kPa	10
k_sp/k_h	0.3	$\theta$ /(×10⁻⁷s⁻¹)	1

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表 2 模型参数取值表

Table 2 The parameters in calculation

参数	取值	参数	取值
H/m	13.0	k_h/k_v	2
R_n/m	1.155	k_h/k_sd	3
R_n/r_d	39.4	k_d/k_h	10⁴
R_n/r_p	5.2	E_s/MPa	1.68
r_sd/r_d	3	E_p/E_s	7
k_v/(×10⁻⁹ m/s)	1.63	−	−

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表 3 模型参数取值表

Table 3 The values of the parameters in calculation

参数	取值	参数	取值
H/m	10.5	k_h/k_v	2
R_n/m	1.039	k_h/k_sd	3
R_n/r_d	39.4	k_d/(×10⁻⁶ m³/s)	35
R_n/r_p	5.2	E_s/MPa	1.25
r_sd/r_d	3	E_p/E_s	9.4
k_v/(×10⁻⁹ m/s)	1.61	−	−

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表 4 模型参数取值表

Table 4 The values of the parameters in calculation

参数	复合层取值	固结层取值	参数	复合层取值	固结层取值
H/m	10	10	k_h/k_v	4.7	2.0
R_n/m	1.44	2.50	k_h/k_sd	3	3
R_n/r_d	39.4	39.4	k_d/k_h	10⁴	1.5×10⁴
R_n/r_p	5.2	−	E_s/MPa	10.4	7.4
r_sd/r_d	3	3	E_p/E_s	2.9	4.1
k_v/(×10⁻⁹ m/s)	2.38	1.77	−	−	−

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