预应力型钢组合支撑受力性能分析及试验研究

Experimental study on prestressed assembly steel strut system in foundation excavations

预应力型钢组合支撑是近年来国内出现的新型钢支撑,该项技术除了具有可回收的优点外,还具有高强连接、可施加预应力、可靠性高等优点,因而在国内的应用不断增多。虽然该项技术已渐趋成熟,但是仍有一些问题亟待研究。因而在支撑跨度较大、土质较差的杭州城西某工程进行多组支撑加压、观测试验。型钢组合支撑实际刚度略小于理论刚度,支撑预应力锁定值是影响基坑变形的关键因素,应采取措施保证支撑预应力满足要求;型钢组合支撑的承载力取决于支撑的稳定性,型钢组合支撑的承载力满足设计要求,且有较高的冗余度;型钢组合支撑的温度应力变化幅度约占实际轴力的29.1%,占设计轴力的7.4%,温度应力对支撑承载力的影响处于可控水平。

The prestressed assemble steel support system(PASS)is an innovative steel support which can be recycled and prestressed and has a lot of advantages,such as high-strength connection and high reliability,so it has been used more and more in China.To solve some problems urgently,a series of PASS pressure and observation experiments are carried out in a project with large span and poor soil in the west of Hangzhou.The experiment shows that the measured stiffness of PASS is slightly less than that in theory,and the critical factor for deformation of the foundation pit is the supporting prestress.The carrying capacity of PASS depends on the stability of support,so it should meet the design requirements and has a lertain redundancy.The maximum stress of PASS varing with temperature is about 29.1%of the actual axial force or 7.4%of the design axial force,and the influences of temperature stress are controllable.