沉管隧道基础灌砂管底压力的监测试验研究

Study of Monitoring Experiment of Bottom Pressure of Gravel Filling Pipe for Foundation of Immersed Tunnel

为确保沉管隧道的工程质量,对沉管隧道基础灌砂施工进行实时监测十分必要。通过沉管隧道等比例灌砂模型试验,探索一种新的基础灌砂施工的实时监测方法——基于管底压力监测系统及其分析方法,并对不同工况下灌砂过程中管底压力的变化状况进行研究。研究表明:1)最先灌砂孔在灌砂过程中不同方位同间距的底板压力呈现完全类似的变化规律,底板压力呈波浪型起伏而逐渐增大,该变化对应砂积盘的形成与消散状况;2)结合观察窗的观测结果,可确定砂积盘扩展的压力门槛值;3)先期灌砂孔对后期灌砂孔的底板压力影响明显,致使其不同方位底板压力变化更大、更复杂,后期灌砂砂积盘形成的压力大于前期灌砂砂积盘所形成的压力。

The real-time monitoring of gravel filling for immersed tunnel foundation is very important. Experiment is made on a same-scale gravel filling model. A new kind of method for real-time monitoring of gravel filling for immersed tunnel foundation based on gravel filling pipe bottom pressure monitoring system and related analysis is developed; and the variation of gravel filling pipe bottom pressure under different construction eonditions is studied. The study results show that ： 1 ） The bottom pressure variation laws, wave shape and increases gradually, of gravel filling pipe No. 1 with different filling direetions and same spacing are the same; the variation laws are related to formation and dissipation of gravel deposit. 2 ） The pressure threshold value of gravel deposit expansion can be determined according to the observation results. 3 ） The influence of bottom pressure of early gravel filling pipe on that of later gravel filling pipe is obvious, resulting in the larger and more complex variation of bottom pressure of later gravel filling pipe with different filling directions. The pressure of gravel deposit formed by later gravel filling is larger than that formed by early gravel filling.