轴力自补偿支撑对支护结构受力变形影响研究

Effect of auto-compensating steel struts on stress and deformation behaviors of supporting structures

轴力自补偿钢支撑能及时补偿因墙体变形造成的部分预应力损失,实现控制基坑变形的目的。基于自补偿钢支撑作用机制与弹性地基梁法,采用'集中力+弹簧单元'并联作用的混合边界,建立考虑支撑轴力自补偿的连续墙受力平衡方程。将该方法应用于某隧道工程中的基坑工程,模拟以支撑轴力为控制目标的自补偿钢支撑和传统预应力钢支撑作用下基坑施工过程,并对比分析这两种支撑体系对连续墙受力变形发展变化的影响。结果表明,自补偿钢支撑不仅能及时弥补预应力损失,且较预应力钢支撑能更有效限制墙体变形,但过大的轴力控制阈值会引起坑外墙体弯矩显著增大。进一步结合现场试验数据,检验算法合理性。

Auto-compensating steel struts can supply the part of prestress loss of steel struts caused by wall deformations to unexcavated side and limit deformations of retaining walls effectively. Based on working mechanism of auto-compensating struts and spring-beam model, the mixed boundary condition of single force and springs is used to build the equilibrium of retaining walls supported by auto-compensating struts. Then the process of excavation in a tunnel project using auto-compensating struts and prestressed struts is simulated. The controlling target of auto-compensating steel struts is axial force. The comparison of development of the bending moments and deformation behaviors of retaining walls during excavation is carried out. The results show that the auto-compensating struts can supply prestress loss and limit wall deformations better than prestressed struts. However, bending moments on unexcavated side increases significantly supported by auto-compensating struts. Finally, rationality of the method is proved by comparing with field data.