STUDY ON BEARING CHARACTERISTICS OF BAMBOO-PILE SOIL-NAIL COMPOSITE SUPPORT SYSTEMS
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摘要: 针对浅基坑工程中,单排桩或双排桩支护体系存在支护薄弱或过度支护的问题,通过室内模型试验,对比研究了常规单排桩和齿状竹桩分别与土钉组成的复合支护体系的受力特点,分析不同复合支护结构下桩体受力、地表沉降、桩顶水平位移和土钉轴力的分布及变化规律。研究发现:齿状排桩复合支护结构中桩体承担荷载较大,最大正弯矩为263.04 N·m,最大负弯矩为198.25 N·m,但仍远小于单排桩复合支护结构的弯矩最大值。同时齿状排桩支护结构对桩顶位移的约束能力要优于单排桩支护体系。而两种支护结构下的土钉轴向应力均呈"中间大,两边小"的分布规律,且新型支护结构中的土钉的极限抗拔力较大。初步表明齿状排桩-土钉复合支护体系可应用到浅基坑支护中,支护效果比传统单排桩复合支护体系好,满足基坑开挖的临时性支护要求。Abstract: Aiming at the problem of insufficient or excessive support for parallel single-row or double-row pile support systems in a large amount of shallow foundation excavation, a series of indoor model tests were conducted, the load-bearing characteristics of composite support systems were studied between the conventional single-row pile-soil-nail system and the dentate pile-soil-nail system. To different composite support structure, the distribution and evolution of laws on stress of piles, ground subsidence, horizontal displacement of pile tops and axial forces in soil nails were analyzed. The results showed that the piles arranged in serration bore a large part of loads acting on the composite support structure and the maximum positive and negative bending moments were 263.04 N·m and 198.25 N·m respectively, which were all less than the homologous ones in the structure of the sing-row pile support system. At the same time, the pile support system arranged in serration had a better capacity to restrain the displacement of the pile tops than the single-row pile support system. The axial stress of soil nails in the two types of support systems also showed the tend of "large in the middle parts and small in both ends", and the soil nails in the new support system had higher pullout resistance. It initially showed that the serrated bamboo-pile-soil-nail composite support system could be applied to shallow foundation excavation, and the support capacity was stronger than the traditional single-row pile composite support system, which could meet the temporary support requirements of foundation excavation.
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Key words:
- excavation engineering /
- bamboo pile /
- support structure /
- bamboo nail
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