超前微桩复合土钉支护稳定及变形简化计算方法  

SIMPLIFIED METHOD FOR STABILITY AND DEFORMATION ANALYSIS OF COMPOSITE SOIL NALING WITH PRE-INSTALLED MICRO-PILES

作　　者：宋二祥[1,2] 宋广[1,2,3] 

机构地区：[1]清华大学土木工程系,北京100084 [2]土木工程安全与耐久教育部重点实验室,北京100084 [3]电力规划设计总院,北京100120

出　　处：《工程力学》2014年第3期52-62,共11页Engineering Mechanics

基　　金：国家支撑计划项目(2008BAJ06B01-5)

摘　　要：超前微桩复合土钉支护是一种经济有效的基坑支护形式,但对其设计分析方法的研究远落后于工程实践。该文在对此种复合土钉支护的构造及工作性能进行简要分析的基础上,对其整体稳定验算方法和变形计算方法进行讨论,借鉴已有的一些相关研究提出了相应的简化计算方法。针对其整体稳定验算,提出考虑微桩-土相对刚度采用不大于2.5倍特征长度上土体被动抗力来考虑微桩作用的建议,从而给出一种较为简便的整体稳定验算方法,就一些实际工程的计算对比表明所建议的方法合理可行。针对其坑壁位移计算,在仔细分析此种支护体系受力变形机理的基础上,基于基坑支护计算的增量法及弹性地基梁求解的链杆法,提出一种思路清晰的简化计算方法,给出了具体的计算模型、参数确定方法及问题求解方法,并通过与有限元计算及工程实测的对比对所提出的方法进行了检验。Composite soil nailing with pre-installed micro-piles is a type of economical and effective support system for deep excavation. The study on its design analysis method is however far behind current engineering practice. In this paper, the constitution and working performance of this type of composite soil nailing is first discussed, then the calculation methods for its global stability and deformation are studied and simplified calculation methods have been proposed. For the global stability checking, it is suggested to use the passive resistance force on a maximum characteristic-length of 2.5 times for the pile, which reflects the pile stiffness relative to the soil, to consider the contribution of the micro-pile to the global stability. A formula for the calculation width of piles under lateral loading is also given. Thereafter, a relatively simple method has been put forward for the stability analysis, which is proved to be reasonable through comparison with finite element calculation and some analysis of practical engineering projects. For the calculation of displacements of the excavated pit wall, a relatively simple and clear method has been proposed based on the incremental calculation method and the theory of a beam on elastic foundation by the careful consideration for the deformation mechanism of this type of supporting system. The calculation model, together with the load and stiffness parameter determination method, is established, and the validity of the method is also proved by the comparisonwith finite element analysis and field measurements.

关 键 词：超前微桩 复合土钉支护 整体稳定 变形 基坑支护 简化计算方法 

分 类 号：TD350.1[矿业工程—矿井建设]