盾构下穿地铁运营隧道沉降规律分析

为确保盾构安全顺利地下穿地铁运营隧道,避免下穿过程中引起运营隧道过量沉降,影响既有线运营安全,以北京地铁14号线阜通西站~望京站盾构区间隧道下穿地铁15号线运营隧道为工程背景,对左右线盾构2次下穿15号线运营隧道施工过程和沉降情况进行对比分析。在分析右线盾构首次下穿地铁运营隧道结构沉降规律的基础上,制定了左线盾构二次下穿运营隧道的施工参数和相关控制措施,确保了二次下穿运营隧道结构沉降控制在-3 mm以内,取得了良好的效果。研究结果表明:通过设定较高的土压力,采用盾体上的径向注浆孔向盾体和土体之间的空隙注入填充物,提高同步注浆浆液质量和及时进行二次补浆等措施能够有效减小运营隧道结构沉降;盾构施工引起15号线运营隧道的横向沉降范围与施工参数基本无关,左右线穿越有明显的叠加效应,叠加区域内,横向沉降显著影响区域在0~4 D;在不采取超前预加固措施的基础上,仅通过合理设定盾构施工参数和隧道内采取相关措施,能够将15号线隧道结构沉降控制在-3 mm以内。研究结果具有较强的工程实用价值,特别是对盾构下穿运营隧道施工方案的制定具有较强参考价值,也可为国内外类似盾构下穿既有线工程提供借鉴。

Analysis on settlement regularity when shields underneath pass subway tunnels

To make sure shields can safely and smoothly underneath pass operation tunnels,to avoid excessive settlements and impact on the safety when existing lines work,the paper based on the project that Beijing subway line 14 of the interval between Futong west station to Wangjing station underneath pass subway line 15,compared with the left and right line shields underneath pass subway line 15 twice and settlement status.And basing on the analysis of settlements regularity of right line firstly underneath passing operation tunnels,laying down construction parameters and related controlling measures when left line secondly underneath pass operation tunnels,such methods ensure the settlements can be controlled within-3 mm with good results.Research results showed：by setting higher earth pressure,injecting fillers into the space between shields and earth by using radial injected holes in shields,improving the quality of synchronous grouting slurry and timely making secondary grouting,such measures can effectively decrease the subway structural settlements;for the case that shield constructions result in horizontal settlement range of Line 15,which was nothing to do with the construction parameters,there were obvious stacking effects of left and right Lines passing,within the stacking areas,horizontal settlement obvious areas was 0 ～ 4 D.Without taking any pre-reinforcement measures,but just by setting reasonable shield construction parameters and adopting related measures inside tunnels,which can make the settlements controlled within-3 mm for Line15.The research results have strong practical values,and can provide lessons when similar shields underneath pass existing lines both at home and abroad.