型钢斜撑加强结构在基坑支护与换撑中的应用研究

APPLICATION RESEARCH OF STEEL INCLINED SUPPORT REINFORCED STRUCTURE IN FOUNDATION PIT SUPPORT AND SUPPORT REPLACEMENT

拆换撑施工是基坑工程中具有重要影响的工况之一,为保障在此工况条件下支护结构的承载稳定性,减小基坑侧向变形,以国内某在建深基坑工程为例,探究型钢斜撑梁加强结构在基坑支护及换撑施工时的应用效果。首先以弹性支点法对有无型钢斜撑加强结构下的基坑围护结构内力变形及坑外地表沉降进行计算分析,同时对型钢斜撑梁构件抗剪强度进行验算,在此基础上进一步结合现场监测情况对型钢斜撑加强结构的应用效果进行分析。结果显示采用型钢斜撑加强结构可有效减小围护结构侧向变形达40%,桩身弯矩及剪力分别减小31.8%及28.7%,减小地表沉降达35%,同时减小支撑梁轴力,计算结果均小于规范限值,表明型钢斜撑梁构件应用于基坑取得了预期效果。相关结论可为类似基坑工程提供参考。

The removal and replacement of bracing is one of the important working conditions in foundation pit projects.Taking a domestic deep foundation pit project under construction as the case,we explore the application effect of the steel inclined support strengthening structure in the foundation pit bracing and support replacement construction to ensure the bearing stability of the supporting structure under this working condition and reduce the lateral deformation of the foundation pit.The elastic fulcrum method is used to calculate and analyze the internal force deformation of the foundation pit retaining structure and the external surface settlement of the pit with and without the reinforced structure of shaped steel diagonal support.At the same time,the shear strength of the shaped steel diagonal support component is calculated.The application of the reinforced structure of shaped steel diagonal support is further analyzed in combination with the on-site monitoring.The results show that the lateral deformation of the retaining structure can be reduced by 40%,and the bending moment and shearing stress of the pile is reduced by 31.8%and 28.7% respectively;the ground settlement can be reduced by 35%,and the axial force of the support beam can be reduced by using the reinforced structure of section steel diagonal bracing.The calculated results are less than the limit value of the specification,which indicates that the application of section steel diagonal bracing beam members to this foundation pit has achieved the desired results.Relevant conclusions may provide the reference for similar foundation pit projects.