预应力锚索对微型桩结构抗滑性能影响的试验研究  

Experimental Research on Effect of Prestressed Anchor Cable on Anti-Sliding Performance of Micropile Structure

作　　者：胡田飞[1,2] 朱本珍 刘建坤[1] 郑静 梁龙龙 

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]中铁西北科学研究院有限公司,甘肃兰州730000

出　　处：《中国铁道科学》2017年第3期10-18,共9页China Railway Science

基　　金：科技部科研院所技术开发研究专项资金资助项目(2009EG123201);铁道部科技研究开发计划项目(2010G018-C-3)

摘　　要：在传统微型桩顶部联系梁上加设斜向预应力锚索,构成新型复合挡锚结构的锚索微型桩。采用分级加载方式进行双排传统微型桩和锚索微型桩加固土质边坡的室内模型试验,并结合相同条件的FLAC3D数值计算,对比分析锚索微型桩和传统微型桩以及采用两者加固后边坡的变形和受力特征,进而探讨锚索微型桩的抗滑机理。结果表明:相比传统微型桩,经锚索微型桩加固后边坡的变形和联系梁的位移明显减小;锚索微型桩周围产生应力集中区,形成结构—土体的复合骨架体系,阻滞了致滑应力和变形沿滑坡方向的传递;预应力锚索有效增强了微型桩结构的侧向刚度,结构侧向倾斜变形减小;微型桩的内力和外力分布趋于均匀,有利于及时和充分地发挥桩体的力学性能;随着堆载的逐级增加,微型桩结构的变形过程分为小变形、大变形和极限破坏3个阶段,对应的桩—锚荷载分担比呈先增大、后减小和再增大的变化规律,极限破坏阶段的分担比稳定在1.3~1.5之间。A new type of compound anti-sliding system with retaining and anchoring effect, called ＂anchor cable micropile structure＂, was presented through setting oblique prestressed anchor cable on the connection beam at the top of traditional micropile structure. Two groups of model experiments, in which a soil slope was reinforced by the double-row traditional micropiles and anchor cable micropiles respectively, were designed and conducted by graded loading. Besides, the numerical calculation of same experimental conditions was also conducted by FLAC^3D. Then, the deformation and stress characteristics of the slope reinforced by anchor cable micropiles, traditional mieropiles and both of them were analyzed comparatively, and the anti-sliding mechanism of anchor cable micropiles was further studied. Results indicate that： compared with traditional micropile structure, the deformation of slope and the displacement of connection beam are obviously reduced after being reinforced by anchor cable micropiles. Stress concentration region distributes around anchor cable micropiles and a compound strueture-soil skeleton is formed, the slip stress and deformation are prevented from transferring along the landslide direction. The lateral stiffness of the mieropile structure is effectively enhanced by the prestressed anchor cable, and the lateral inclined deform- ation of the structure is decreased. The distribution of internal and external forces of micropiles tends to be uniform, which is advantageous to exert the mechanical properties of pile body timely and fully. With the gradual increase of load, the deformation process of micropile structure can be divided into three stages, including small deformation, large deformation and limit-equilibrium failure. Corresponding to the three stages above, the change law of load sharing ratio of pile over cable is increasing firstly, then decreasing and increasing again lastly, among which the ratio value of the last stage is roughly from 1.3 to 1.5.

关 键 词：锚索微型桩 模型试验 抗滑性能 位移 弯矩 桩侧土压力 桩—锚荷载分担比 

分 类 号：U213.152.1[交通运输工程—道路与铁道工程]