列车振动荷载下锚索预应力现场监测及数值分析

振动会引起基坑加固系统中锚索预应力的损失,影响基坑稳定性,而有关列车振动荷载对锚索预应力的实际影响还未见报道。因此,分析列车振动对深大基坑围护结构中锚索预应力的影响,具有重大理论意义和实际指导意义。以石家庄六线隧道明挖段紧邻京广铁路深大基坑预应力锚索加固体系为工程背景,采用现场监测的方法,分析实际工程环境下,列车振动荷载引起的锚索预应力损失;采用Flac-3D软件进行数值分析,进一步印证列车振动荷载对锚索预应力的影响。综合考虑既有线路运行性质和基坑使用周期,提出限速(不超过80 km/h为宜)通过明挖基坑区段,尽早施作隧道主体结构,减小基坑暴露时间的合理化建议。以减小锚索预应力损失,提高基坑加固效果,保证基坑安全与稳定。

Field Monitoring and Numerical Analysis of Anchor Cable Prestress under Train Vibration Load

The vibration may cause the prestress loss of anchor cables in the reinforcement system,which affects the stability of the foundation pit. The actual effect caused by the train vibration load on the prestress of the anchor cables has not been reported. Therefore, the analysis of the influence on prestressed anchor cable caused by train vibration has great theoretical and practical significance. With reference to the practical engineering of the deep foundation pit anchor reinforcement system near the existing Beijing ~ Guangzhou railway,the prestress loss of anchor cable caused by train vibration load is analyzed by means of field monitoring in the actual engineering environment. Numerical analysis with Flac-3D software is conducted to confirm this conclusion. It is proposed that reducing the train speed below 80 km / h and constructing the main structure of the tunnel as soon as possible can effectively reduce the prestress loss,improve the pit reinforcement effect,and ensure the safety and stability of the foundation pit.