土钉墙在疏排桩支护基坑中的加固效果试验研究  

Experimental study on reinforcement effect of soil-nailed wall in pit excavation supported with scattered row piles

作　　者：古海东 杨敏[2] 

机构地区：[1]浙江省交通规划设计研究院,浙江杭州310006 [2]同济大学,上海100092

出　　处：《土木工程学报》2015年第1期129-138,148,共11页China Civil Engineering Journal

基　　金：国家自然科学基金(40972179)

摘　　要：采用同济大学中型岩土离心机进行9组疏排桩-土钉墙组合支护基坑的离心机模型试验。基于离心机模型试验结果,探讨土钉墙在疏排桩支护基坑中的加固效果,并推导土钉墙支护刚度的简化计算公式,研究土钉墙支护刚度对疏排桩-土钉墙组合支护结构支护特性的影响规律。研究结果表明:在疏排桩间设置土钉能有效减小支护结构地表沉降,土钉越长、间距越小时支护结构地表沉降值也越小,加密土钉间距比增加土钉长度对减小支护结构地表沉降更为有效;设置土钉能显著减小支护桩的桩身内力和变形,随着土钉长度的增加和土钉间距的减小,排桩的桩身内力分布规律逐渐由悬臂排桩支护特性向带支撑的支护桩特性转变;通过设置土钉不仅能提高支护结构的稳定性,还能改变支护结构的破坏模式,随着土钉墙支护刚度的增大,会使土钉墙的支护特性得到增强,形成以土钉墙支护特性为主导的疏排桩-土钉墙组合支护结构,相反,则以疏排桩支护特性为主导。A series of centrifuge model tests of pit excavation supported with scattered piles and soil nails were carried out in Tongji University. Based on the results from nine groups of model tests,the reinforcement effect of soil-nailed wall in pit excavation supported with scattered row piles was investigated. A simplified formula for the stiffness of soil-nailed wall was derived,and then,the impact of the stiffness of soil nails on the features of scattered row piles-soil-nailed wall composite supporting structure was studied. The results show that installing soil nails between scattered row piles may effectively reduce the subsidence of pit excavation. Moreover,with the increase of the nail length or the decrease of the spacing of soil nails,the subsidence may decrease,but densifying soil nails may be more effective in reducing the subsidence of supporting structure compared to increasing the length of soil nails. In addition,installing soil nails between piles may significantly reduce the internal forces and deformations of piles. With the increase of nail length and the decrease of soil nail spacing,the distribution of internal force of scattered row piles will be gradually shifted from the support characteristics of cantilever row pile to the characteristics of soldier piles. As a result,installing soil nails can not only improve the stability of the supporting structure,but also can change the failure mode of supporting structure. With the increase of the stiffness of soil nails,the supporting features of soil-nailed wall will be enhanced,leading to the soilnailed wall dominated scattered row piles-soil-nailed wall composite supporting structure. Conversely,the supporting structure is dominated by the features of scattered row piles.

关 键 词：疏排桩 土钉墙 加固效果 离心机模型试验 

分 类 号：TU476[建筑科学—结构工程]