深基坑锚拉式支护结构的有限差分算法研究
Research of finite difference method on retaining structures withanchors in deep excavation engineering

为克服现行规范建议采用单参数m法的缺点，将分析水平推力桩的综合刚度原理和双参数法延伸至作用有水平分布荷载的基坑锚拉式支护结构变形和内力计算中，建立一种基于此原理和方法的改进的弹性地基梁有限差分算法。此外，为考虑动态施工过程，引入增量法对各工况进行计算分析，并根据现场实测数据，反演出合适的综合刚度和双参数。研究结果表明：该方法得到的水平位移和弯矩，均与实测结果吻合良好，而采用单参数m法却很难使支护结构的位移和内力同时较好地与实测值相符。文中反分析所得的综合刚度和地基抗力双参数，可应用于同一基坑工程相同结构或同一地区工程地质条件和支护结构相似的设计计算，无疑可获得较现行单参数法更为准确的设计计算结果。
To overcome the defects of the single parameter m method recommended in the current specification, the composite stiffness principle with bi-parameter method applied to piles subjected to laterally concentrated loads was extended to the calculation of the deformation and internal force on retaining structure with anchors in deep excavation. Based on the principle and the method, the modified finite difference solution of beam on elastic foundation was presented. In addition, the incremental method was introduced to consider the dynamic construction process. The composite stiffness-EIwith bi-parameters-m and nwere obtained through the back analyses of the field measurement. The result shows that both the horizontal displacement and bending moment calculated by the method proposed in this paper were in good agreement with the measured data. In contrast, the result by the current single-parameter method was unsatisfactory. The parameters obtained through the back analyses can be applied to the uniform structures in the same foundation pit or similar retaining structures and engineering geological conditions in the same areas. Undoubtedly it can obtain more accurate results than the current single parameter method