Application of High Power Vibroflotation Gravel Pile in the Treatment of Liquefied Foundation
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摘要: 北京某地铁车辆段占地面积约20 hm2,场地20 m深度范围内的饱和粉细砂②5层为地震液化层,该液化层厚度约为5 m,液化等级为轻微—中等(局部为严重)。在轨道交通工程中首次应用大功率(100 kW)、疏排振冲碎石桩对液化地基进行处理,检测结果及施工实践表明,该方法既满足地基液化处理设计要求,同时也为后期灌注桩原位施工创造了条件。此外,该工程应用大功率振冲碎石桩与CFG桩组合地基处理方式解决了地基液化和轨道路基工后沉降问题。Abstract: A subway depot in Beijing covers an area of about 20 hectares. The ②5 layers of saturated silty fine sand within 20 m depth of the site will produce liquefaction. The liquefaction grade is slight to medium (locally serious), and the thickness of liquefiable layer is 5 m. In the rail transit project, the high-power 100 kW vibroflotation gravel pile is used to treat the liquefied foundation for the first time. The test results show that the vibroflotation gravel pile with large pile spacing not only meets the design requirements of foundation liquefaction treatment, but also creates conditions for the in-situ construction of cast-in-place pile in the later stage. At the same time, the combination of high-power vibroflotation gravel pile and CFG pile foundation treatment is applied to the site, which solves the problems of foundation liquefaction and post construction settlement of track subgrade.
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Key words:
- high power /
- vibroflotation gravel pile /
- foundation liquefaction /
- CFG pile
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表 1 主要土层性质描述
土层编号 土层性质 ①粉土填土 黄褐色,松散,含草根、砖渣 ①1杂填土 杂色,松散,含沥青、砖渣、灰渣 ②粉土 黄褐色—灰色,中密—密实,高—中高压缩性,
含云母、有机质②3粉细砂 灰色,稍密—中密,饱和,低压缩性,
含云母、氧化铁,有机质②5粉细砂 灰色,松散—稍密,饱和,低压缩性,
含云母、氧化铁,有机质③4中粗砂 褐黄色,中密—密实,饱和,低压缩性,
含云母、氧化铁、有机质④粉质粘土 灰色,中高—中压缩性,
含云母、氧化铁、有机质⑤1中粗砂 灰色,密实,饱和,低压缩性,
含云母、氧化铁、有机质表 2 振冲碎石桩试桩主要参数
试桩区域 桩顶标高/m 桩长/m 桩间距/(m×m) 桩径/m 功率/kW Ⅰ Ⅰ1 17.0 9.5 2.8×2.8 1.0 100 Ⅰ2 17.0 9.5 2.5×2.5 1.0 100 Ⅰ3 17.0 9.5 2.0×2.0 0.8 75 Ⅱ Ⅱ1 17.3 8.0 2.8×2.8 1.0 100 Ⅱ2 17.3 8.0 2.5×2.5 1.0 100 Ⅱ3 17.3 8.0 2.0×2.0 0.8 75 Ⅲ 17.6 10.0 3.0×3.0 1.0 100 -
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