复杂周边环境深基坑支护结构设计及监测分析

某深基坑紧邻含有三层防空洞室的高边坡,边坡上有基础形式不明的九层建筑物,基坑周边有不规范堆载且施工期为雨季。边坡采用微型桩加洞室内支撑加固,基坑采用桩锚结构支护。在基坑开挖过程中对基坑变形发展进行监测,重点对坑顶水平位移、桩身变形及锚索拉力进行监测,根据监测结果及数据得出:桩锚支护结构可以对此类环境下的基坑变形起到良好的约束作用;施工工况及坑外堆载对锚索使用寿命及边坡变形有较大的影响;锚索反张拉、补张拉、混凝土回填等措施可有效减缓边坡变形速率;监测数据的采集及分析对于处于此类环境的基坑更为重要,可以更好的预测基坑变形的趋势,对施工进行合理的调整。

Structural Design and Monitoring Analysis of Deep Foundation Pit Supporting under Complex Surroundings

A deep foundation pit is located adjacent to a high slope which contains three-floor air-raid shelter. There is a nine-floor building with unknown form of foundation on the slope. Around the foundation there is lots of surcharge load and the construction is carried out in rainy season. The slope is strengthened by micro pile and inner support, and the pile anchor supporting structure is used to support the pit. In order to get the deformation trend of the foundation and some useful conclusions, which may be used for other similar projects, we monitored the development of foundation pit deformation during the process of excavation, focusing on monitoring the horizontal displacement of pit using total station, deformation of pile by inclinometer and anchor cable tension monitoring by anchor rally. According to the monitoring data, we found that: the pile-anchor supporting structure in such an environment has played a good role to reduce the deformation of slope; the construction conditions and heaped load have a significant impact on the working life of anchor and the slope deformation; the anti-tensioning anchor, supplement tension, concrete backfill and other measures can effectively reduce the slope deformation rate; the monitoring data acquisition and analysis is more important for the foundation pit in such an environment, it can better forecast the trend of foundation pit deformation, and make reasonable adjustments for the construction.