地铁车站基坑钢支撑预加轴力幅度研究

基于郑州市轨道交通4号线如意湖北站基坑工程,选取5个断面进行现场试验,第2、4道钢支撑施加不同幅度的预加轴力,现场监测了基坑开挖全过程中支撑轴力和地下连续墙墙体的水平位移,分析总结了支撑轴力和地下连续墙墙体水平位移随基坑开挖的变化规律。运用ABAQUS建立了基坑开挖三维有限元模型,得到数值分析结果,再与实测结果进行对比,验证了模型的可靠性。基于该模型,对比研究了预加轴力为0.1~0.8倍钢支撑设计轴力条件下支撑轴力和地下连续墙墙体水平位移,结果表明,钢支撑预加轴力为0.2~0.3倍的设计轴力标准值时较为合理,这一结果与当前规范建议值有较大差异。

Study on the Pre-axial Force Amplitude of Steel Support for Foundation Pit of Subway Station

Based on the foundation pit project of Ruyihu North Station of Zhengzhou Rail Transit Line 4, five sections were selected for on-site test. Applying pre-axial force of different amplitudes to the 2nd and 4th steel supports, on-site monitoring of the supporting axial force and the horizontal displacement of the underground continuous wall in the whole process of foundation pit excavation. The variation law of supporting axial force and horizontal displacement of underground continuous wall with the foundation pit excavation is analyzed and summarized. Using ABAQUS to establish a three-dimensional finite element model for foundation pit excavation, and the numerical analysis results are obtained. The results are compared with the measured results to verify the reliability of the model. Based on the model, the axial force of the supporting axial force and the horizontal displacement of the wall of the underground continuous wall are compared and studied when the pre-axial force is 0.1~0.8 times design axial force. The results show that the pre-axial force of the steel support is reasonable, when it is 0.2~0.3 times of the design axial force standard value. This result is quite different from the current specification.