基于CPTU测试的深厚软土场地大面积PST管桩施工挤土效应研究

郑金伙; 沈铭龙; 江涛; 陈华晗

doi:10.20265/j.cnki.issn.1007-2993.2024-0152

基于CPTU测试的深厚软土场地大面积PST管桩施工挤土效应研究

doi: 10.20265/j.cnki.issn.1007-2993.2024-0152

福建省建筑设计研究院有限公司，福建福州　350001

详细信息

作者简介:
郑金伙，男，1973年生，硕士，教授级高级工程师，主要从事岩土工程施工与设计。E-mail：zjh@fjadi.com.cn

中图分类号: TU473
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- 文章访问数: 14
- HTML全文浏览量: 3
- PDF下载量: 2
- 被引次数: 0
出版历程
- 收稿日期: 2024-04-08
- 修回日期: 2024-05-16
- 录用日期: 2024-08-29
- 刊出日期: 2025-08-08

Large area construction squeezing effect of PST piles in deep soft soil sites based on CPTU testing

Fujian Provincial Institute of Architectural Design and Research Co., Ltd., Fuzhou 350001, Fujian, China

摘要

摘要: 为了分析 PST管桩在深厚软土场地大面积施工过程中的挤土效应，采用多功能高精度孔压静力触探（CPTU）测试技术对PST桩施工前后软土层的侧壁摩阻力、超孔隙水压力及其消散过程进行了测试。测试结果表明：同层淤泥中，水平固结系数随深度的加深不断减小，同时挤土效应本身也会加剧软土固结系数的降低，管桩越长，挤土效应缓解所需要的时间越久；群桩施工组织顺序对挤土效应影响显著，远离测点施工引起的孔隙水压力增量仅为朝向测点施工时的29%；在PST 桩施工后一段时间内，场地软土强度受扰动降低，降低幅度可达40%，约120 d后软土层的土体强度可基本恢复至施工前水平；对于近接上部透水层的浅层软土，在打桩后软土发生了动力固结，长期强度较施工前有所提升。
- PST管桩 /
- 挤土效应 /
- CPTU /
- 超孔隙水压力
Abstract: To analyze the soil squeezing effect during the large-scale construction process of PST pipe piles, the multifunctional high-precision pore pressure static penetration test (CPTU) technology was used to test the side wall friction resistance, excess pore water pressure, and dissipation process of the soft soil layer before, during, and after the construction of PST piles. The test results show that in the same layer of silt, the horizontal consolidation coefficient decreases continuously with depth, and the squeezing effect itself also intensifies the decrease in the consolidation coefficient of soft soil. When the pipe piles are longer, the time required to alleviate the squeezing effect is longer; The influence of pile group construction organization on the control of the soil compaction effect is significant, and the pore water pressure increment caused by construction away from the measuring point is only 29% of that caused by construction towards the measuring point; After the construction of PST piles, the strength of the soft soil on the site was reduced by disturbance, with a reduction of up to 40%. After about 120 days, the soil strength of the soft soil layer can recover to the level before construction. For shallow soft soil adjacent to the upper permeable layer, dynamic consolidation occurs after pile driving, and the long-term strength has improved compared to before construction.
- PST pipe pile /
- squeezing effect /
- CPTU /
- excess pore water pressure

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图 1 桩位及测试点布置图（单位：mm）

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图 2 CPTU1超孔隙水压力消散曲线

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图 3 PST桩群施工顺序及测点布置图（单位：mm）

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图 4 CPTU5测试点孔压消散曲线

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图 5 CPTU5测试点附加超孔隙水压力与测距关系曲线

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图 6 土体强度试验布置图（单位：mm）

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图 7 淤泥层侧壁摩阻力随时间变化曲线

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表 1 土层物理力学性质指标

土层名称	厚度/m	状态	重度/（kN·m⁻³）	含水量/%	天然孔隙比e	灵敏度	超固结比OCR	压缩模量/MPa	黏聚力 c/kPa	内摩擦角φ/（°）
素填土	0.60～3.80	松散	18.5					4	1	20
淤泥	2.00～18.40	流塑	15.7	67.67	1.831	4.27	0.81	1.74	5.93	6.15
粉质黏土	0.60～9.80	可塑	18.6	32.45	0.903			6.24	20.65	15.90
卵石	0.90～12.20	稍密—中密	20.5					26	3	35
角砾	0.50～13.00	稍密	20.1					22	2	30

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表 2 各工况淤泥层的t₅₀及水平固结系数

序号	测试点编号	对应桩径/mm	测试深度/m	对应土层	t₅₀/s	对应时间段	计算水平固结系数C_h /(10⁻³ cm²·s⁻¹)
1	CPTU1	400	5	淤泥	860	管桩施工前	0.250
			8	淤泥	1120	管桩施工前	0.192
			10	淤泥	1700	管桩施工前	0.126
2	CPTU2	400	5	淤泥	2640	管桩施工中	0.080
3	CPTU3	400	5	淤泥	9020	管桩施工中	0.024
4	CPTU4	400	5	淤泥	11880	管桩施工中	0.018

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