既有建筑地基横向加筋灌浆托换加固特性研究

PROPERTY STUDY OF THE LATERAL REINFORCEMENT GROUTING SUBSTITUTIONS FOR EXISTING BUIDING'S GROUND

针对既有建筑物天然地基上的筏板基础、在筏板基础周围布桩、在筏板基础周围布桩以及在筏板下的软土灌浆、在筏板基础周围布桩以及筏板下的软土灌浆同时采用横向加筋托换等4种基础形式,采用有限元计算方法,计算分析了地基竖向变形、基础板内的剪力以及弯矩分布。在计算条件下,横向加筋灌浆托换加固,能有效地减小建筑物沉降,沉降仅为天然地基的一半。能减少基础板内的附加应力,与仅在建筑物外围基础下布桩加固相比,基础板的最大剪力和最大弯矩分别减少了54%、47%以上。横向加筋灌浆加固后地基的力学特性更接近于天然地基性质。因既有建筑物地基基础多按天然地基设计,有利于既有建筑物的基础工作,不会在既有建筑物基础内引起过大的应力调整。另外,横向加筋灌浆托换技术通过在室外施工的方法加固室内地基土,在不影响底层居民正常生活、不影响工厂正常生产的情况下,使得既有建筑物下的地基土获得整体加固。

Adopting the FEM, calculation and analysis have been undergone for ground vertical deformation, shear force within foundation slab and distribution of bending moment on the basis of four modes that are raft on the natural foundation of existing building,piling surrounding raft basis, soft soil grouting and lateral reitfforcement grouting substitution separately. Under the calculated circumstance, the way of lateral reinforcement grouting substitution is able to abate both the structure＇s settlement, accounting for only half of the natural one, and contemporarily additional stress within the foundation slab, whose most shear force and bending moment are decreased by over 54% and 47% respectively compared with reinforced piling around the structure periphery. Furthermore, the strengthened foundation＇s mechanical property is closer to that of the natural one under which most structures are designed, favoring the base work and avoiding excessive stress adjustment inside the foundation. In addition, the construction of strengthening the foundation by the technique is carried out outdoors for the purpose of overall stabilization without influencing either the normal life of citizens on the ground floor or factory＇ work.