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中南大学学报(自然科学版)

Journal of Central South University

第51卷    第9期    总第313期    2020年9月

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文章编号:1672-7207(2020)09-2514-11
珠海深厚淤泥地层中大直径桩插入比对基坑变形特性的影响
陈晓庆1, 2,丁文其1, 2,曲红波3,乔亚飞1, 2,逯兴邦1, 2,赖颂英3

(1. 同济大学 土木学院,地下建筑与工程系,上海,200092;
2. 同济大学 岩土及地下工程教育部重点实验室,上海,200092;
3. 中国建筑第二工程局有限公司 华南分公司,广东 深圳,650021
)

摘 要: 依托横琴口岸大规模基坑群工程,通过现场监测、数值计算和统计分析相结合的手段,揭示珠海深厚软弱淤泥地层中大直径桩插入比对基坑变形特性的影响。横琴口岸基坑群开挖深度为9.2~13.3 m,采用直径为1 500 mm或1 600 mm、插入比为2.50~3.70的超长大直径灌注桩作为围护结构。研究结果表明:受淤泥层分布的影响,围护结构的侧移模式有悬臂式、鼓肚式以及弓型3种,侧移存在明显的滞后性和时间依赖性。围护结构最大侧移、最大侧移深度以及地表沉降均随淤泥层厚度的增大而增大,地表最大沉降点与围护结构之间的距离为0.75He~1.00He(He为基坑开挖深度);围护结构最大侧移随插入比的增大而呈非线性减小,近似呈“三段线”关系:当插入比大于1.60时,最大侧移将稳定在0.22%He~0.40%He;当插入比小于1.20时,基坑存在踢脚破坏的风险;最大侧移深度随着插入比的增大而逐渐减小,最后稳定在1.15He~1.35He;最大沉降点与围护结构之间的距离受插入比的影响较小。相比于其他软土地区的围护结构,插入比大多处于0.70~1.00,珠海横琴岛内基坑由于存在深厚淤泥层,所需的插入比明显较大。

 

关键字: 基坑变形特性;深厚淤泥;大直径围护桩;插入比;数值分析

Influence of insertion ratio of large-diameter piles in deep mud stratum on deformation characteristics of foundation pit in Zhuhai
CHEN Xiaoqing1, 2, DING Wenqi1, 2, QU Hongbo3, QIAO Yafei1, 2, LU Xingbang1, 2, LAI Songying3

1. Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai 200092, China;
2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University,Shanghai 200092, China;
3. South China Branch, China Construction Second Engineering Bureau Ltd., Shenzhen 650021, China

Abstract:The influence of the insertion ratio of large-diameter piles in the deep and soft mud stratum on the deformation characteristics of foundation pit was revealed via field monitoring, numerical simulation and statistical analysis of the Hengqin port large-scale foundation pit group. The excavation depth of the Hengqin port foundation pit was from 9.2 m to 13.3 m; the cast-in-place piles with diameter of 1 500 mm or 1 600 mm were used as the retaining structure and their insertion ratios were in the range of 2.50-3.70. The results show that, owing to the distribution of mud layer, there are three modes of the deflection of piles, including the cantilever type, bulging belly type and bow type. The deflection is also characterized by the hysteresis and rheology. The maximum deflection and its depth, the surface settlement all increase with the thickening of the mud layer, and the distance between the location of the maximum settlement and the retaining piles ranges from 0.75He to 1.00He, where He is the excavation depth. The maximum deflection decreases nonlinearly with the increase of the insertion ratio, and their relationship can be approximately descried as "three segment lines". When the insertion ratio of the retaining piles is larger than 1.60, the deflection will be stable at 0.22%He-0.40%He; when the insertion ratio is smaller than 1.20, the foundation pit will have the risk of skirting damage. As the insertion ratio increases, the depth of the maximum deflection decreases and is finally stable at 1.15He-1.35He, and the distance between the maximum settlement point and the retaining structure is almost unaffected by the insertion ratio. Compared with other soft soil areas where the insertion ratio is mostly between 0.70 and 1.00, the required insertion ratio in Hengqin Island is much larger owing to the deep mud layer.

 

Key words: deformation characteristics of foundation pit; deep mud; large-diameter retaining pile; insertion ratio; numerical simulation

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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