变形协调情况下土钉墙内力和位移的计算方法

CALCULATION METHOD OF INNER FORCE AND DISPLACEMENT OF SOIL-NAILING WALL CONSIDERING DEFORMATION COORDINATION

土钉墙的内力主要包括土钉轴力、钉土剪力和面层受力,而土钉墙变形的过程是土钉、面层和土体之间相互协调共同作用的过程,传统的计算模型都是从力矩平衡的力学角度出发,不能合理解释土钉内力和变形的相互关系。通过对土钉墙受力和变形机制的分析,利用Mindlin解计算在虚拟开挖应力和钉土剪力共同作用下土体侧向位移,结合钉土剪力和钉土相对位移的线性关系以及钉土剪力在最危险滑动面位置等于0的特点,计算土钉轴力、钉土剪力和土钉墙在开挖面位置的变形。土钉被动区段钉土剪力超出其极限值的部分转移至面层,假定面层受力增量呈三角形分布,根据静力平衡得到面层受力分布。通过与工程实测资料的对比分析,初步验证土钉墙内力和变形计算方法的合理性和可行性。

Inner force of soil-nailing wall mainly includes axial force of nail, shear force between soil and nail, and distribution force of composite facing. The process of soil-nailing wall deformation is the process of distortion coordination and interaction of several factors among nails, composite facing and soil mass. Traditional calculation model based on moment equilibrium can not give a reasonable explanation of relationship between inner force and deformation of soil-nailing wall. Through analysis of the mechanism of force and deformation of soil-nailing wall, lateral displacement of soil mass under combination of virtual excavation stress and shear force between soil and nail by Mindlin solution is calculated, by combing with linear relationship between shear force and relative displacement with zero shear force at potential sliding plane, axial force of soil nail, shear force between soil and nail and deformation at excavation surface can be calculated. Parts beyond limited value for shear force of nail in passive area is transferred to composite facing, and its incremental force is assumed as triangle distribution. And then distribution force of composite facing is obtained according to static equilibrium. Finally, the measured data from three projects of soil-nailing wall are used to illustrate the validity of the calculation model.