桩梁式托换结构设计方法及其应用

为了合理地设计地铁上盖建筑物桩基托换工程中的桩梁式托换结构，提出了桩梁式托换结构变形的控制标准和控制措施。通过25个试件的试验研究，证实新旧混凝土交接面具有明显的破坏预兆和良好的延性性能；并建立了新旧混凝土交接面承载力的计算公式，进而提出了桩梁式托换结构承载力和变形的计算方法。该设计方法应用于广州地铁一号线和二号线的建筑物桩基托换工程中，各项实测指标均达到了控制目标，证实了这一设计方法的合理性。

Design Method for the Underpinning Structure Composed of Piles and Beams and Its Application

In order to correctly design the underpinning str uc ture composed of piles and beams in the pile-foundation underpinning project fo r the super-buildings of metro, a standard and several measures to control the deformation of underpinning structure were proposed. On the basis of experimenta l results of 25 specimens, it was proved that the boundary plane between the new and the old concrete had obvious destruction foreboding and excellent protendin g performance, and a formula for calculating the bearing capacity of the boundar y plane was established. Therefore, the calculating method for the bearing capac ity and the deformation of underpinning structure were derived. The proposed des igning method has been successfully used in the underpinning work of Guangz hou Metro Lines 1 and 2. From the fact that all measured items met the contr olling indices well, which proves the rationality of the designing method.