下穿既有地铁盾构区间的矿山法隧道核心土优化分析

Optimization Analysis of Core Soil of Mined Tunnel Crossing under the Existing Shield Tunnel

在穿越工程中,通常采用预留核心土技术控制隧道开挖过程中掌子面的稳定和变形。结合北京地铁6号线下穿既有盾构区间的矿山法隧道施工实例,对预留核心土的纵向长度和横向尺寸效应进行优化分析。研究结果表明:掌子面稳定性与其核心土高度成正比,而核心土纵向长度取0.5倍洞跨、上下底宽度比为2/3时利于掌子面稳定,其结论可供类似工程参考。

Technology of core soil was used to maintain excavation face stability and deformation during crossing engineering. Based on the engineering practices of beijing subway NO. 6 line with the mine tunneling method undererossing the existing shield interval of NO. 4 subway line. Optimiazation analysis of core soil of longitudinal length and horizontal size effect has been studied. The study show that the stability of core soil was proportional to it＇ s height, the reasonable longitudinal length was 0.5 times tunnel span and the ratio of top and bottom width was 2/3. The conclusion provides a good reference to similar works.