公路隧道深基坑围护桩受力与变形监测

针对某市南北快速干线隧道17. 8 m深基坑工程,采用同济启明星Qimstar~?基坑支护结构软件,对基坑开挖过程中围护桩的受力情况进行模拟计算,并用测斜仪对围护桩的水平位移进行现场实时监测,研究桩体受力特点及变形规律.结果表明:模拟结果与监测结果在数值上比较接近,且变化趋势一致;桩身最大水平位移与基坑土层的开挖深度密切相关,随开挖深度的增加而发生非线性增大;受基坑时空效应的影响,桩体最大变形部位不断下移,桩身形状也由最初的前倾形曲线逐步向弓形曲线发展,最终在距基坑设计开挖总深度的2/3处达到11. 25 mm的最大值;在基坑底板浇筑完成后,围护桩变形趋于稳定.

Force and deformation monitoring of retaining piles of deep foundation pit in expressway tunnel

Aiming at the 17.8 m deep foundation pit engineering of north-south expressway in one city, the force situation of retaining piles during the excavation process of foundation pit was simulated and calculated with a retaining structure software Tongji Qimstar^®. In addition, the on-site and real-time monitoring of horizontal displacement of retaining piles was performed with the inclinometer to study the force features and deformation rule of retaining piles. The results show that the simulated results are consistent with the monitored ones, and their variation trends are similar. The maximum horizontal displacement of pile bodies is closely related to the soil excavation depth of foundation pit, which nonlinearly increases with the increasing excavation depth. Subjected to the time-space effect of foundation pit, the largest deformation parts of pile bodies continually move down, the pile shape also evolves from the initial forward curve to the arcuate curve, and the pile bodies eventually reach the maximum value of 11.25 mm at about 2/3 of designed total excavation depth of foundation pit. After the pouring on bottom plate of foundation pit, the deformation of retaining pile tends to be stable.