深基坑支护结构分析的共同变形法

在分析基坑工程通用弹性地基梁法优缺点的基础上，建立了考虑结构变形与土体相互作用的共同变形法计算模型及分析程序。通过分析及计算比较认为，运用共同变形法计算时，可采用与通用弹性地基梁法相同的地基反力系数，文中讨论了土体水平地基反力系数的取值方法对计算结果的影响。研究表明，共同变形法在实践中是可行的并较通用弹性地基梁法更合理。

METHOD OF COMMON DEFORMATION FOR ANALYSIS OF SUPPORTING STRUCTURE IN DEEP EXCAVATION

Based on the study of the advantages and shortcomings of the general elastic foundation beam method for deep excavation, the authors proposed a computational model and analysis procedure of common deformation method considering interaction between supporting structure and soil layers. The common deformation method comprises the following analysis steps: (1) Calculating of the initial static pressure; (2) Defining the horizontal foundation reacting force coefficients representing soil around the wall, stiffness of the wall, and the struts or anchors; (3) Calculating of the incremental displacement; (4) Recalculation of the earth pressure by adding the initial static earth pressures to the changes in earth pressure, which is derived from the multiplication of incremental displacement by reacting force coefficient; (5) Comparing the earth pressure with soil strength limitation criteria i.e., the convention al active or passive limit. If any strength is infringed, a set of correction forces is calculated, which then will be used to restore the earth pressures consistent with the strength criteria and plastic deformation within the soil. (6) Replacing the forces used in the step (1) new forces. Repeat the step (3) to (5)until convergence is achieved. (7) Calculating the total displacements, earth pressures, strut forces, wall shear stresses and bending moments. A comparison of the results of two computation methods has demonstrated that the horizontal foundation reacting force coefficient, which is same as in the general elastic foundation beam method, could be used in the common deformation method. Different methods (constant or “m” method) of selecting the horizontal foundation reacting force coefficient may have important influence on the results of computation. Our study suggested that the common deformation method is useful in the practice, and more reasonable than the general elastic foundation beam method.