基坑主动变形控制-轴力伺服系统应用探讨

Active deformation control of foundation pit-discussion on application of axial force servo system

结合深圳某基坑工程,对基坑采用混凝土内支撑主动变形控制系统进行讨论。从原理、理论与实际案例三个方面,系统阐述混凝土内支撑轴力伺服系统在基坑支护生命周期内的工作机制和伺服轴力取值方法。根据实际案例建立计算机模型,对比分析考虑施工顺序时不同支撑刚度下伺服轴力的取值结果以及轴力伺服系统对基坑变形控制的效果,并得到伺服轴力与支撑刚度两者之间的影响关系。结果表明:轴力伺服系统能按需求主动有效控制基坑挡土结构的变形;引入伺服系统后,支撑刚度不再作为基坑变形的控制条件;支撑截面尺寸的确定以强度控制为原则;支撑刚度与伺服轴力呈负相关,支撑刚度对初始伺服力和最大伺服力基本没有影响。

Combined with a foundation pit project in Shenzhen, the active deformation control system of concrete inner support for foundation pit is discussed. From the three aspects of principle, theory and practical cases, this paper systematically expounds the working mechanism and servo axial force value selection method of concrete internal support axial force servo system in the life cycle of foundation pit support. According to the actual case, the computer model is established to compare and analyze the value of the servo axial force under different support stiffness when considering the construction sequence and the effect of the axial force servo system on the deformation control of the foundation pit, and the influence relationship between the servo axial force and the support stiffness is obtained. The results show that: the axial force servo system can actively and effectively control the deformation of the retaining structure of the foundation pit;after the introduction of servo system, the support stiffness is no longer used as the control condition of foundation pit deformation;the determination of support section size is based on the principle of strength control;the support stiffness has a negative correlation with the servo axial force, and has little effect on the initial servo force and the maximum servo force.