干坞基坑双排灌注桩支护结构受力变形监测与分析

Monitoring and analysis on stress deformation of double row cast-in-place pile support structure in dry dock foundation pit

大连湾海底隧道工程干坞基坑周边存在热电厂、高耸烟囱等建筑物,对基坑支护结构的安全性提出了更高的要求,因此需要在基坑开挖过程中对支护结构进行监测,以确保干坞基坑和周边建筑物的安全可靠。本工程该位置采用双排咬合灌注桩支护结构,在开挖施工期间对双排灌注桩桩身内力与桩身水平位移进行监测。监测数据表明:双排灌注桩支护体系能有效保护高耸烟囱周边的干坞基坑安全;桩身内力在物理特性相差较大的不同土层交界面存在转折点;双排灌注桩前后两排桩桩身变形存在显著差异,前排桩变形类似单排桩,后排桩存在3个较为明显的弯折点,后排桩整体受力变形较大。

There are thermal power plants,high chimneys around the dry dock foundation pit of Dalian Bay subsea tunnel,which puts forward higher requirements for the safety of the foundation pit support structure.Therefore,it is necessary to monitor the support structure during the foundation pit excavation to ensure the safety and reliability of the dry dock foundation pit and surrounding buildings.In this project,the support structure of double row secant cast-in-place piles was adopted to monitor the internal force and the horizontal displacement of double row cast-in-place piles during excavation.The monitoring data show that the support system of double row cast-in-place piles can effectively protect the safety of the dry dock foundation pit around the high chimney.There is a turning point in the interface of different soil layers where the physical properties of pile are quite different.The deformation of the two rows of piles before and after the double row cast-in-place piles is significantly different.The deformation of the front row piles is similar to that of the single row piles,and there are three obvious bending points in the rear row piles,and the overall stress deformation of the rear row piles is larger.