| 设置裙筒与半刚性连接桩的沉箱复合基础承载性能研究 |
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| 引用本文： | 刘高,过超,付佰勇,石海洋.设置裙筒与半刚性连接桩的沉箱复合基础承载性能研究[J].中国公路学报,2019,32(9):101-114. |
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| 作者姓名： | 刘高 过超 付佰勇 石海洋 |
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| 作者单位： | 公路长大桥建设国家工程研究中心, 北京 100011 |
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| 基金项目： | 国家重点研发计划项目（2018YFC0809604）；黔科合重大专项（2016-3013）；中交集团重大科技项目（2016-ZJKJ-PTSJ05） |
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| 摘 要： | 为提高深水、厚覆盖层、强风、巨浪等复杂环境条件下跨海特大型桥梁深水基础的承载能力,针对琼州海峡跨海大桥主通航孔2×1 500 m三塔斜拉桥的中塔基础,提出了设置裙筒与半刚性连接桩的新型沉箱复合基础的设计方案及施工工艺.该新型沉箱复合基础由底部周圈带有裙筒的沉箱、打入地基中的钢管桩与后注浆垫层组成,其能够降低沉箱复合基础对水下垫层平整度和裙筒入土深度的要求,提高施工效率和质量.为进一步研究其承载性能,通过数值模拟和模型试验分别开展了沉箱基础、设置半刚性连接桩的沉箱复合基础、设置裙筒与半刚性连接桩的沉箱复合基础等3种基础方案在竖向荷载、竖向与水平向组合荷载作用下的受力性能研究.研究结果表明:设置裙筒与半刚性连接桩的沉箱复合基础具有优越的竖向和水平向承载能力,其在竖向荷载作用下,通过后注浆形成的碎石混凝土垫层强度较高且处于裙筒侧向约束状态,可将上部竖向荷载传递至裙筒、群桩基础和桩间土,并通过裙筒和群桩基础传至到地基深部,从而有效提高了软弱厚覆盖层地基中沉箱基础的竖向承载力并可减小基础沉降;在竖向和水平向荷载的组合作用下,裙筒能够充分调动筒内外浅层土体的水平抗力,半刚性连接桩则驱动塑性区向深处延伸,从而有效提高了基础的水平向承载能力并减小水平位移.研究成果可为琼州海峡等跨海通道的特大型桥梁深水基础建设提供重要参考.
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| 关 键 词： | 桥梁工程 沉箱复合基础 数值分析 模型试验 裙筒 半刚性连接桩 承载性能 |
| 收稿时间： | 2018-07-09 |
Bearing Behaviors of Composite Caisson Foundation Set with Skirt Tubes and Semi-rigid Connected Piles |
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| LIU Gao,GUO Chao,FU Bai-yong,SHI Hai-yang.Bearing Behaviors of Composite Caisson Foundation Set with Skirt Tubes and Semi-rigid Connected Piles[J].China Journal of Highway and Transport,2019,32(9):101-114. |
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| Authors: | LIU Gao GUO Chao FU Bai-yong SHI Hai-yang |
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| Affiliation: | Highway Bridge National Engineering Research Centre, Beijing 100011, China |
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| Abstract: | The aim of this paper is to improve the bearing capacity of the deep-water foundation of super-large bridges under complex environmental conditions such as deep water, thick overburden, strong wind, and huge waves. Accordingly, the middle tower of the 2×1 500 m three-tower cable-stayed bridge of the Qiongzhou strait crossing scheme was used as a research object, and a prototype design and construction technology for a new composite caisson foundation set with skirt tubes and semi-rigid connected piles was specially proposed. The new composite caisson foundation, which is composed of a skirt-tubes caisson, driven-in steel piles, and a post-grouting cushion, can reduce the requirements of composite caisson foundation on the smoothness of underwater cushions and the penetration depth of skirt tubes, thereby improving construction efficiency and quality. To study the bearing behavior further, a performance analysis of three foundations was conducted. The three foundations included a caisson foundation, a composite caisson foundation set with semi-rigid connection piles, and a composite caisson foundation set with skirt tubes and semi-rigid connected piles under vertical load, vertical and horizontal loads were conducted through a numerical simulation and model test. The results show that the composite caisson foundation set with skirt tubes and semi-rigid connected piles has superior vertical and horizontal bearing capacity. Under a vertical load, the gravel concrete bedding formed by post-grouting has relatively higher strength and is in a restrained condition of lateral skirt tubes. This enables the vertical load of the bridge superstructure to be passed to the skirt tubes, foundation of the piles, and soil between piles, and then to the deeper foundation through the skirt tubes and foundation of the piles. Thus, it can effectively improve the vertical bearing capacity of the foundation in the thick cover of the soft foundation and reduce the foundation settlement. Under vertical and horizontal loads, the skirt tubes can fully use the horizontal resistance of shallow soil both inside and outside, and semi-rigid connection piles will drive the plastic zone to extend deeper, effectively improving the foundation horizontal bearing capacity and reducing horizontal displacement. These results can be used as important references for the deep-water foundations of long-span strait bridges such as the Qiongzhou strait crossing and other huge sea-crossing projects. |
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| Keywords: | bridge engineering composite caisson foundation numerical analysis model test skirt tubes semi-rigid connected piles bearing behaviors |
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