邻近既有地铁线基坑工程的自适应支撑系统变形控制技术

Deformation Control Technology of Self-adaptive Support System on Deep Foundation Pit Engineering Adjacent to Operating Subway Lines

预应力钢支撑是深基坑变形控制的重要手段之一,但传统钢支撑施工、监测技术由于自身的缺陷,无法满足实时、有效控制基坑变形的要求。以某邻近既有地铁线的基坑工程为背景,采用有限元数值分析方法定量分析了钢支撑预应力对深基坑围护桩变形的影响。介绍了一套自适应支撑系统施工技术,对其在本基坑工程中的应用效果进行了分析。研究结论表明,支撑预应力损失对基坑变形有较大影响,与支撑无预应力时的桩体变形值相比较,支撑施加设计预应力时的桩体变形值减小约40%;自适应支撑系统对深基坑施工的变形真正实现了动态、实时及昼夜不间断的监测与控制,可解决基坑开挖过程中邻近既有地铁线路变形控制难题。

The pre-stressed steel support is one of the important means to control the deformation during the construction of deep foundation pit,but due to the inherent defects,the traditional steel support and monitoring technique can′t meet the requirements of deformation control effectively.Taking a metro foundation pit adjacent to existing subway lines as the background,the influence of the pre-stressed steel support on the deformation of retaining piles is quantitatively analyzed by the finite element numerical analysis method.Then,a set of construction technology of self-adaptive support system is introduced.The researches results indicate that the loss of pre-stress steel support has great influence on the deformation of retaining piles;compared to the deformation of foundation pit without pre-sterss steel support,the deformation value of the self-adaptive support system will be decreased to about40%.So,this system could realize dynamic display,realtime control,24-hour monitoring and control of the deformation of retaining piles,also could effectively solve problems of deformation control during the construction of deep foundation pit adjacent to operating subway lines.