地铁盾构隧道始发端近距离侧穿老旧建筑沉降控制措施

地铁车站端头附近建筑物易受基坑降水、基坑开挖、盾构始发、盾构掘进等多重影响。为研究新建地铁盾构隧道施工对既有老旧建筑的影响,以太原地铁2号线某盾构区间为例,根据工程地质情况及周边环境情况,设计提出如下措施:(1)盾构始发采用“钢套筒+洞外3 m冻结壁”的加固措施;(2)建筑物外侧打设复合锚杆桩主动加固建筑物;(3)盾构管片采用多孔管片,盾构通过后再注浆加固地层。数值模拟和现场实测表明,“钢套筒+洞外3 m冻结壁”的加固措施可有效保证富水砂层盾构始发的施工安全;盾构隧道侧穿建筑时,采用复合锚杆桩可有效控制建筑沉降。

The Settlement Control Measurements of Metro Tunnel Closely Passing by Old Buildings at the Shield Originating End

The buildings near the end of the subway stations are susceptible to multiple impacts such as foundation pit dewatering,foundation pit excavation,shield launching,and shield tunneling.In order to study the influences of the construction of metro shield tunneling on existing old buildings,by taking a shield tunnel of Taiyuan subway line 2 as an example,the following measurements were proposed during design according to the geological condition of the project and the surrounding environment:(1)The reinforcement measures of“steel sleeve+3 m frozen wall outside the cave”were adopted for shield tunneling;(2)Composite anchor piles on the outside of the building were set to actively reinforce the building;(3)Porous segments were adopted,and the stratum was reinforced by grouting after the shield passed.Numerical simulation and field measurement showed that the reinforcement measures of“steel sleeve+3 m frozen wall outside the cave”effectively ensured the safety of the initial construction of the shield in the water-rich sand layer.The composite anchor pile was suggested for the control of the settlement of old buildings.