电力隧道先隧后井施工中简易井应用的若干问题研究

SEVERAL ISSUES ON SIMPLY-CONSTRUCTED WELL OF ELECTRIC TUNNEL WHEN TUNNELS FOLLOWED BY WELL EXCAVATION

针对电力隧道,提出一种无内支撑、节约高效的圆形简易工作井建设思路,开展简易工作井与常规方案对比分析,借助有限元法分析开口环管片变形对简易工作井参数的敏感性,探讨简易工作井结构设计中的关键技术。研究结果表明:简易工作井施工工艺、可行性及对周围环境影响等方面均优于常规工作井,其造价仅为常规方案的7%,极大节约了成本。简易工作井施工过程中,局部管片破除形成了开口的非稳定结构,导致管片变形显著增大,影响范围主要体现在开口环及其两侧2环管片上,故施工时需对开口环及影响明显的4环管片设置临时支撑,以确保结构安全稳定。管片变形受工作井壁厚与周围软弱土层影响显著,其中最大位移值随井壁厚度的增加近似呈二次方增长,而井的直径与管片开口环数则对管片变形影响较小,工作井尺寸应在满足整体刚度与净空要求的前提下不宜取大。

The simply-constructed well which is no inner supporting,efficient and circular was proposed. The comparison between simply-constructed well and conventional scheme was conducted and parameters sensitivity analysis of the well to segment deformation was conducted with finite element method as well as the key technology of structures design was explored. The results show that the construction technology,feasibility and influence on surrounding environment of simply-constructed well are superior to conventional one. The project cost of simply-well is only 7% of the conventional scheme,so it greatly saves the cost. It will form unstable structure when local segments were broken and segment deformations greatly increase. The influencing scope of the deformation is manifested on the snap rings and two segment rings on both sides,so it should add temporary supports for spilt ring and four segment rings which are obviously affected to ensure structures safety. The effect of well thickness and soft soil on segment deformation is significant,while the effect of the diameter and spilt rings is very small. It suggests that the size of working well should not be big on the premise of meeting the requirements of global stiffness and clearance.