基于增量法的土钉墙支护设计方法研究

Design of soil nail wall based on incremental calculation method

对于土钉支护设计,与复杂的计算分析相比,简化设计方法更加实用。在增量法的基础上,提出了一套基于增量法的完整的土钉墙设计方法。土钉支护设计计算所用的荷载建议采用考虑放坡的库仑主动土压力;土钉的内力可采用增量法进行计算,进而求出土钉所需的钢筋直径;建议采用库仑滑动面确定土钉的最大内力作用点,根据已确定的土钉的最大内力和库仑滑动面的位置计算土钉伸入到锚固土体里的长度,从而得到各排土钉的总长度;整体稳定采用《建筑基坑支护技术规程》(JGJ120—99)建议的方法进行验算。提供了一个成功应用基于增量法的土钉墙设计方法进行设计的工程实例,工程实践表明应用该方法进行设计是简便可行的。

For design of soil nail wall,a simplified design method can be more important in practice than the complicated analysis and calculation.This paper presents a complete design procedure based on the incremental calculation method of soil nail.Coulomb active earth pressure of excavated slope is adopted as the loading for soil nail design and calculation.The soil nail forces are calculated based on incremental method,thus to ascertain the sizes of soil nail rebar.Critical Coulomb sliding surface is assumed for the determination of maximum points of soil nail forces,based on the calculated maximum soil nail forces and Coulomb sliding surface the anchored length and furthermore the total length of each row of soil nails can be determined.Global stability checking can be made using the recommended method in the 'Technical Specification for Retaining and Protection of Building Foundation Excavations'.Engineering application of the incremental design method in soil nail wall project is presented,which demonstrates the feasibility of this method.